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-rw-r--r--compiler/ccgexprs.nim3482
1 files changed, 2234 insertions, 1248 deletions
diff --git a/compiler/ccgexprs.nim b/compiler/ccgexprs.nim
index 82cc3a1fb..545d43ae8 100644
--- a/compiler/ccgexprs.nim
+++ b/compiler/ccgexprs.nim
@@ -9,125 +9,148 @@
 
 # included from cgen.nim
 
+when defined(nimCompilerStacktraceHints):
+  import std/stackframes
+
+proc getNullValueAuxT(p: BProc; orig, t: PType; obj, constOrNil: PNode,
+                      result: var Rope; count: var int;
+                      isConst: bool, info: TLineInfo)
+
 # -------------------------- constant expressions ------------------------
 
-proc int64Literal(i: BiggestInt): Rope =
+proc rdSetElemLoc(conf: ConfigRef; a: TLoc, typ: PType; result: var Rope)
+
+proc int64Literal(i: BiggestInt; result: var Rope) =
   if i > low(int64):
-    result = "IL64($1)" % [rope(i)]
+    result.add "IL64($1)" % [rope(i)]
   else:
-    result = ~"(IL64(-9223372036854775807) - IL64(1))"
+    result.add "(IL64(-9223372036854775807) - IL64(1))"
 
-proc uint64Literal(i: uint64): Rope = rope($i & "ULL")
+proc uint64Literal(i: uint64; result: var Rope) = result.add rope($i & "ULL")
 
-proc intLiteral(i: BiggestInt): Rope =
+proc intLiteral(i: BiggestInt; result: var Rope) =
   if i > low(int32) and i <= high(int32):
-    result = rope(i)
+    result.add rope(i)
   elif i == low(int32):
     # Nim has the same bug for the same reasons :-)
-    result = ~"(-2147483647 -1)"
+    result.add "(-2147483647 -1)"
   elif i > low(int64):
-    result = "IL64($1)" % [rope(i)]
+    result.add "IL64($1)" % [rope(i)]
   else:
-    result = ~"(IL64(-9223372036854775807) - IL64(1))"
+    result.add "(IL64(-9223372036854775807) - IL64(1))"
 
-proc genLiteral(p: BProc, n: PNode, ty: PType): Rope =
-  if ty == nil: internalError(p.config, n.info, "genLiteral: ty is nil")
+proc intLiteral(i: Int128; result: var Rope) =
+  intLiteral(toInt64(i), result)
+
+proc genLiteral(p: BProc, n: PNode, ty: PType; result: var Rope) =
   case n.kind
   of nkCharLit..nkUInt64Lit:
-    case skipTypes(ty, abstractVarRange).kind
+    var k: TTypeKind
+    if ty != nil:
+      k = skipTypes(ty, abstractVarRange).kind
+    else:
+      case n.kind
+      of nkCharLit: k = tyChar
+      of nkUInt64Lit: k = tyUInt64
+      of nkInt64Lit: k = tyInt64
+      else: k = tyNil # don't go into the case variant that uses 'ty'
+    case k
     of tyChar, tyNil:
-      result = intLiteral(n.intVal)
+      intLiteral(n.intVal, result)
     of tyBool:
-      if n.intVal != 0: result = ~"NIM_TRUE"
-      else: result = ~"NIM_FALSE"
-    of tyInt64: result = int64Literal(n.intVal)
-    of tyUInt64: result = uint64Literal(uint64(n.intVal))
+      if n.intVal != 0: result.add "NIM_TRUE"
+      else: result.add "NIM_FALSE"
+    of tyInt64: int64Literal(n.intVal, result)
+    of tyUInt64: uint64Literal(uint64(n.intVal), result)
     else:
-      result = "(($1) $2)" % [getTypeDesc(p.module,
-          ty), intLiteral(n.intVal)]
+      result.add "(("
+      result.add getTypeDesc(p.module, ty)
+      result.add ")"
+      intLiteral(n.intVal, result)
+      result.add ")"
   of nkNilLit:
-    let t = skipTypes(ty, abstractVarRange)
-    if t.kind == tyProc and t.callConv == ccClosure:
+    let k = if ty == nil: tyPointer else: skipTypes(ty, abstractVarRange).kind
+    if k == tyProc and skipTypes(ty, abstractVarRange).callConv == ccClosure:
       let id = nodeTableTestOrSet(p.module.dataCache, n, p.module.labels)
-      result = p.module.tmpBase & rope(id)
+      let tmpName = p.module.tmpBase & rope(id)
       if id == p.module.labels:
         # not found in cache:
         inc(p.module.labels)
-        addf(p.module.s[cfsData],
+        p.module.s[cfsStrData].addf(
              "static NIM_CONST $1 $2 = {NIM_NIL,NIM_NIL};$n",
-             [getTypeDesc(p.module, ty), result])
+             [getTypeDesc(p.module, ty), tmpName])
+      result.add tmpName
+    elif k in {tyPointer, tyNil, tyProc}:
+      result.add rope("NIM_NIL")
     else:
-      result = rope("NIM_NIL")
+      result.add "(($1) NIM_NIL)" % [getTypeDesc(p.module, ty)]
   of nkStrLit..nkTripleStrLit:
-    case skipTypes(ty, abstractVarRange).kind
+    let k = if ty == nil: tyString
+            else: skipTypes(ty, abstractVarRange + {tyStatic, tyUserTypeClass, tyUserTypeClassInst}).kind
+    case k
     of tyNil:
-      result = genNilStringLiteral(p.module, n.info)
+      genNilStringLiteral(p.module, n.info, result)
     of tyString:
-      # with the new semantics for 'nil' strings, we can map "" to nil and
+      # with the new semantics for not 'nil' strings, we can map "" to nil and
       # save tons of allocations:
-      #if n.strVal.len == 0: result = genNilStringLiteral(p.module, n.info)
-      #else:
-      result = genStringLiteral(p.module, n)
+      if n.strVal.len == 0 and optSeqDestructors notin p.config.globalOptions:
+        genNilStringLiteral(p.module, n.info, result)
+      else:
+        genStringLiteral(p.module, n, result)
     else:
-      if n.strVal.isNil: result = rope("NIM_NIL")
-      else: result = makeCString(n.strVal)
+      result.add makeCString(n.strVal)
   of nkFloatLit, nkFloat64Lit:
-    result = rope(n.floatVal.toStrMaxPrecision)
+    if ty.kind == tyFloat32:
+      result.add rope(n.floatVal.float32.toStrMaxPrecision)
+    else:
+      result.add rope(n.floatVal.toStrMaxPrecision)
   of nkFloat32Lit:
-    result = rope(n.floatVal.toStrMaxPrecision("f"))
+    result.add rope(n.floatVal.float32.toStrMaxPrecision)
   else:
     internalError(p.config, n.info, "genLiteral(" & $n.kind & ')')
-    result = nil
-
-proc genLiteral(p: BProc, n: PNode): Rope =
-  result = genLiteral(p, n, n.typ)
 
-proc bitSetToWord(s: TBitSet, size: int): BiggestInt =
-  result = 0
-  when true:
-    for j in countup(0, size - 1):
-      if j < len(s): result = result or `shl`(ze64(s[j]), j * 8)
-  else:
-    # not needed, too complex thinking:
-    if CPU[platform.hostCPU].endian == CPU[targetCPU].endian:
-      for j in countup(0, size - 1):
-        if j < len(s): result = result or `shl`(Ze64(s[j]), j * 8)
-    else:
-      for j in countup(0, size - 1):
-        if j < len(s): result = result or `shl`(Ze64(s[j]), (Size - 1 - j) * 8)
+proc genLiteral(p: BProc, n: PNode; result: var Rope) =
+  genLiteral(p, n, n.typ, result)
 
-proc genRawSetData(cs: TBitSet, size: int): Rope =
-  var frmt: FormatStr
+proc genRawSetData(cs: TBitSet, size: int; result: var Rope) =
   if size > 8:
-    result = "{$n" % []
-    for i in countup(0, size - 1):
+    var res = "{\n"
+    for i in 0..<size:
+      res.add "0x"
+      res.add "0123456789abcdef"[cs[i] div 16]
+      res.add "0123456789abcdef"[cs[i] mod 16]
       if i < size - 1:
-        # not last iteration?
-        if (i + 1) mod 8 == 0: frmt = "0x$1,$n"
-        else: frmt = "0x$1, "
+        # not last iteration
+        if i mod 8 == 7:
+          res.add ",\n"
+        else:
+          res.add ", "
       else:
-        frmt = "0x$1}$n"
-      addf(result, frmt, [rope(toHex(ze64(cs[i]), 2))])
+        res.add "}\n"
+
+    result.add rope(res)
   else:
-    result = intLiteral(bitSetToWord(cs, size))
-    #  result := rope('0x' + ToHex(bitSetToWord(cs, size), size * 2))
+    intLiteral(cast[BiggestInt](bitSetToWord(cs, size)), result)
 
-proc genSetNode(p: BProc, n: PNode): Rope =
-  var cs: TBitSet
+proc genSetNode(p: BProc, n: PNode; result: var Rope) =
   var size = int(getSize(p.config, n.typ))
-  toBitSet(p.config, n, cs)
+  let cs = toBitSet(p.config, n)
   if size > 8:
     let id = nodeTableTestOrSet(p.module.dataCache, n, p.module.labels)
-    result = p.module.tmpBase & rope(id)
+    let tmpName = p.module.tmpBase & rope(id)
     if id == p.module.labels:
       # not found in cache:
       inc(p.module.labels)
-      addf(p.module.s[cfsData], "static NIM_CONST $1 $2 = $3;$n",
-           [getTypeDesc(p.module, n.typ), result, genRawSetData(cs, size)])
+      p.module.s[cfsStrData].addf("static NIM_CONST $1 $2 = ",
+           [getTypeDesc(p.module, n.typ), tmpName])
+      genRawSetData(cs, size, p.module.s[cfsStrData])
+      p.module.s[cfsStrData].addf(";$n", [])
+    result.add tmpName
   else:
-    result = genRawSetData(cs, size)
+    genRawSetData(cs, size, result)
 
 proc getStorageLoc(n: PNode): TStorageLoc =
+  ## deadcode
   case n.kind
   of nkSym:
     case n.sym.kind
@@ -141,16 +164,18 @@ proc getStorageLoc(n: PNode): TStorageLoc =
       else: result = OnUnknown
     else: result = OnUnknown
   of nkDerefExpr, nkHiddenDeref:
-    case n.sons[0].typ.kind
+    case n[0].typ.kind
     of tyVar, tyLent: result = OnUnknown
     of tyPtr: result = OnStack
     of tyRef: result = OnHeap
-    else: doAssert(false, "getStorageLoc")
+    else:
+      result = OnUnknown
+      doAssert(false, "getStorageLoc")
   of nkBracketExpr, nkDotExpr, nkObjDownConv, nkObjUpConv:
-    result = getStorageLoc(n.sons[0])
+    result = getStorageLoc(n[0])
   else: result = OnUnknown
 
-proc canMove(n: PNode): bool =
+proc canMove(p: BProc, n: PNode; dest: TLoc): bool =
   # for now we're conservative here:
   if n.kind == nkBracket:
     # This needs to be kept consistent with 'const' seq code
@@ -158,40 +183,26 @@ proc canMove(n: PNode): bool =
     if not isDeepConstExpr(n) or n.len == 0:
       if skipTypes(n.typ, abstractVarRange).kind == tySequence:
         return true
+  elif n.kind in nkStrKinds and n.strVal.len == 0:
+    # Empty strings are codegen'd as NIM_NIL so it's just a pointer copy
+    return true
   result = n.kind in nkCallKinds
+  #if not result and dest.k == locTemp:
+  #  return true
+
   #if result:
   #  echo n.info, " optimized ", n
   #  result = false
 
-proc genRefAssign(p: BProc, dest, src: TLoc, flags: TAssignmentFlags) =
-  if dest.storage == OnStack or not usesNativeGC(p.config):
-    linefmt(p, cpsStmts, "$1 = $2;$n", rdLoc(dest), rdLoc(src))
+proc genRefAssign(p: BProc, dest, src: TLoc) =
+  if (dest.storage == OnStack and p.config.selectedGC != gcGo) or not usesWriteBarrier(p.config):
+    linefmt(p, cpsStmts, "$1 = $2;$n", [rdLoc(dest), rdLoc(src)])
   elif dest.storage == OnHeap:
-    # location is on heap
-    # now the writer barrier is inlined for performance:
-    #
-    #    if afSrcIsNotNil in flags:
-    #      UseMagic(p.module, 'nimGCref')
-    #      lineF(p, cpsStmts, 'nimGCref($1);$n', [rdLoc(src)])
-    #    elif afSrcIsNil notin flags:
-    #      UseMagic(p.module, 'nimGCref')
-    #      lineF(p, cpsStmts, 'if ($1) nimGCref($1);$n', [rdLoc(src)])
-    #    if afDestIsNotNil in flags:
-    #      UseMagic(p.module, 'nimGCunref')
-    #      lineF(p, cpsStmts, 'nimGCunref($1);$n', [rdLoc(dest)])
-    #    elif afDestIsNil notin flags:
-    #      UseMagic(p.module, 'nimGCunref')
-    #      lineF(p, cpsStmts, 'if ($1) nimGCunref($1);$n', [rdLoc(dest)])
-    #    lineF(p, cpsStmts, '$1 = $2;$n', [rdLoc(dest), rdLoc(src)])
-    if canFormAcycle(dest.t):
-      linefmt(p, cpsStmts, "#asgnRef((void**) $1, $2);$n",
-              addrLoc(p.config, dest), rdLoc(src))
-    else:
-      linefmt(p, cpsStmts, "#asgnRefNoCycle((void**) $1, $2);$n",
-              addrLoc(p.config, dest), rdLoc(src))
+    linefmt(p, cpsStmts, "#asgnRef((void**) $1, $2);$n",
+            [addrLoc(p.config, dest), rdLoc(src)])
   else:
     linefmt(p, cpsStmts, "#unsureAsgnRef((void**) $1, $2);$n",
-            addrLoc(p.config, dest), rdLoc(src))
+            [addrLoc(p.config, dest), rdLoc(src)])
 
 proc asgnComplexity(n: PNode): int =
   if n != nil:
@@ -201,16 +212,20 @@ proc asgnComplexity(n: PNode): int =
       # 'case objects' are too difficult to inline their assignment operation:
       result = 100
     of nkRecList:
+      result = 0
       for t in items(n):
         result += asgnComplexity(t)
-    else: discard
+    else: result = 0
+  else:
+    result = 0
 
 proc optAsgnLoc(a: TLoc, t: PType, field: Rope): TLoc =
-  assert field != nil
-  result.k = locField
-  result.storage = a.storage
-  result.lode = lodeTyp t
-  result.r = rdLoc(a) & "." & field
+  assert field != ""
+  result = TLoc(k: locField,
+    storage: a.storage,
+    lode: lodeTyp t,
+    snippet: rdLoc(a) & "." & field
+  )
 
 proc genOptAsgnTuple(p: BProc, dest, src: TLoc, flags: TAssignmentFlags) =
   let newflags =
@@ -221,8 +236,7 @@ proc genOptAsgnTuple(p: BProc, dest, src: TLoc, flags: TAssignmentFlags) =
     else:
       flags
   let t = skipTypes(dest.t, abstractInst).getUniqueType()
-  for i in 0 ..< t.len:
-    let t = t.sons[i]
+  for i, t in t.ikids:
     let field = "Field$1" % [i.rope]
     genAssignment(p, optAsgnLoc(dest, t, field),
                      optAsgnLoc(src, t, field), newflags)
@@ -240,9 +254,9 @@ proc genOptAsgnObject(p: BProc, dest, src: TLoc, flags: TAssignmentFlags,
   case t.kind
   of nkSym:
     let field = t.sym
-    if field.loc.r == nil: fillObjectFields(p.module, typ)
-    genAssignment(p, optAsgnLoc(dest, field.typ, field.loc.r),
-                     optAsgnLoc(src, field.typ, field.loc.r), newflags)
+    if field.loc.snippet == "": fillObjectFields(p.module, typ)
+    genAssignment(p, optAsgnLoc(dest, field.typ, field.loc.snippet),
+                     optAsgnLoc(src, field.typ, field.loc.snippet), newflags)
   of nkRecList:
     for child in items(t): genOptAsgnObject(p, dest, src, newflags, child, typ)
   else: discard
@@ -254,163 +268,208 @@ proc genGenericAsgn(p: BProc, dest, src: TLoc, flags: TAssignmentFlags) =
   # tfShallow flag for the built-in string type too! So we check only
   # here for this flag, where it is reasonably safe to do so
   # (for objects, etc.):
-  if needToCopy notin flags or
+  if optSeqDestructors in p.config.globalOptions:
+    linefmt(p, cpsStmts,
+        "$1 = $2;$n",
+        [rdLoc(dest), rdLoc(src)])
+  elif needToCopy notin flags or
       tfShallow in skipTypes(dest.t, abstractVarRange).flags:
-    if dest.storage == OnStack or not usesNativeGC(p.config):
-      useStringh(p.module)
+    if (dest.storage == OnStack and p.config.selectedGC != gcGo) or not usesWriteBarrier(p.config):
       linefmt(p, cpsStmts,
-           "memcpy((void*)$1, (NIM_CONST void*)$2, sizeof($3));$n",
-           addrLoc(p.config, dest), addrLoc(p.config, src), rdLoc(dest))
+           "#nimCopyMem((void*)$1, (NIM_CONST void*)$2, sizeof($3));$n",
+           [addrLoc(p.config, dest), addrLoc(p.config, src), rdLoc(dest)])
     else:
       linefmt(p, cpsStmts, "#genericShallowAssign((void*)$1, (void*)$2, $3);$n",
-              addrLoc(p.config, dest), addrLoc(p.config, src), genTypeInfo(p.module, dest.t, dest.lode.info))
+              [addrLoc(p.config, dest), addrLoc(p.config, src), genTypeInfoV1(p.module, dest.t, dest.lode.info)])
   else:
     linefmt(p, cpsStmts, "#genericAssign((void*)$1, (void*)$2, $3);$n",
-            addrLoc(p.config, dest), addrLoc(p.config, src), genTypeInfo(p.module, dest.t, dest.lode.info))
+            [addrLoc(p.config, dest), addrLoc(p.config, src), genTypeInfoV1(p.module, dest.t, dest.lode.info)])
+
+proc genOpenArrayConv(p: BProc; d: TLoc; a: TLoc; flags: TAssignmentFlags) =
+  assert d.k != locNone
+  #  getTemp(p, d.t, d)
+
+  case a.t.skipTypes(abstractVar).kind
+  of tyOpenArray, tyVarargs:
+    if reifiedOpenArray(a.lode):
+      if needTempForOpenArray in flags:
+        var tmp: TLoc = getTemp(p, a.t)
+        linefmt(p, cpsStmts, "$2 = $1; $n",
+                [a.rdLoc, tmp.rdLoc])
+        linefmt(p, cpsStmts, "$1.Field0 = $2.Field0; $1.Field1 = $2.Field1;$n",
+          [rdLoc(d), tmp.rdLoc])
+      else:
+        linefmt(p, cpsStmts, "$1.Field0 = $2.Field0; $1.Field1 = $2.Field1;$n",
+          [rdLoc(d), a.rdLoc])
+    else:
+      linefmt(p, cpsStmts, "$1.Field0 = $2; $1.Field1 = $2Len_0;$n",
+        [rdLoc(d), a.rdLoc])
+  of tySequence:
+    linefmt(p, cpsStmts, "$1.Field0 = ($5) ? ($2$3) : NIM_NIL; $1.Field1 = $4;$n",
+      [rdLoc(d), a.rdLoc, dataField(p), lenExpr(p, a), dataFieldAccessor(p, a.rdLoc)])
+  of tyArray:
+    linefmt(p, cpsStmts, "$1.Field0 = $2; $1.Field1 = $3;$n",
+      [rdLoc(d), rdLoc(a), rope(lengthOrd(p.config, a.t))])
+  of tyString:
+    let etyp = skipTypes(a.t, abstractInst)
+    if etyp.kind in {tyVar} and optSeqDestructors in p.config.globalOptions:
+      linefmt(p, cpsStmts, "#nimPrepareStrMutationV2($1);$n", [byRefLoc(p, a)])
+
+    linefmt(p, cpsStmts, "$1.Field0 = ($5) ? ($2$3) : NIM_NIL; $1.Field1 = $4;$n",
+      [rdLoc(d), a.rdLoc, dataField(p), lenExpr(p, a), dataFieldAccessor(p, a.rdLoc)])
+  else:
+    internalError(p.config, a.lode.info, "cannot handle " & $a.t.kind)
 
 proc genAssignment(p: BProc, dest, src: TLoc, flags: TAssignmentFlags) =
   # This function replaces all other methods for generating
   # the assignment operation in C.
   if src.t != nil and src.t.kind == tyPtr:
     # little HACK to support the new 'var T' as return type:
-    linefmt(p, cpsStmts, "$1 = $2;$n", rdLoc(dest), rdLoc(src))
+    linefmt(p, cpsStmts, "$1 = $2;$n", [rdLoc(dest), rdLoc(src)])
     return
   let ty = skipTypes(dest.t, abstractRange + tyUserTypeClasses + {tyStatic})
   case ty.kind
   of tyRef:
-    genRefAssign(p, dest, src, flags)
+    genRefAssign(p, dest, src)
   of tySequence:
-    if (needToCopy notin flags and src.storage != OnStatic) or canMove(src.lode):
-      genRefAssign(p, dest, src, flags)
+    if optSeqDestructors in p.config.globalOptions:
+      genGenericAsgn(p, dest, src, flags)
+    elif (needToCopy notin flags and src.storage != OnStatic) or canMove(p, src.lode, dest):
+      genRefAssign(p, dest, src)
     else:
       linefmt(p, cpsStmts, "#genericSeqAssign($1, $2, $3);$n",
-              addrLoc(p.config, dest), rdLoc(src),
-              genTypeInfo(p.module, dest.t, dest.lode.info))
+              [addrLoc(p.config, dest), rdLoc(src),
+              genTypeInfoV1(p.module, dest.t, dest.lode.info)])
   of tyString:
-    if (needToCopy notin flags and src.storage != OnStatic) or canMove(src.lode):
-      genRefAssign(p, dest, src, flags)
+    if optSeqDestructors in p.config.globalOptions:
+      genGenericAsgn(p, dest, src, flags)
+    elif ({needToCopy, needToCopySinkParam} * flags == {} and src.storage != OnStatic) or canMove(p, src.lode, dest):
+      genRefAssign(p, dest, src)
     else:
-      if dest.storage == OnStack or not usesNativeGC(p.config):
-        linefmt(p, cpsStmts, "$1 = #copyString($2);$n", dest.rdLoc, src.rdLoc)
+      if (dest.storage == OnStack and p.config.selectedGC != gcGo) or not usesWriteBarrier(p.config):
+        linefmt(p, cpsStmts, "$1 = #copyString($2);$n", [dest.rdLoc, src.rdLoc])
       elif dest.storage == OnHeap:
         # we use a temporary to care for the dreaded self assignment:
-        var tmp: TLoc
-        getTemp(p, ty, tmp)
+        var tmp: TLoc = getTemp(p, ty)
         linefmt(p, cpsStmts, "$3 = $1; $1 = #copyStringRC1($2);$n",
-                dest.rdLoc, src.rdLoc, tmp.rdLoc)
-        linefmt(p, cpsStmts, "if ($1) #nimGCunrefNoCycle($1);$n", tmp.rdLoc)
+                [dest.rdLoc, src.rdLoc, tmp.rdLoc])
+        linefmt(p, cpsStmts, "if ($1) #nimGCunrefNoCycle($1);$n", [tmp.rdLoc])
       else:
         linefmt(p, cpsStmts, "#unsureAsgnRef((void**) $1, #copyString($2));$n",
-               addrLoc(p.config, dest), rdLoc(src))
+               [addrLoc(p.config, dest), rdLoc(src)])
   of tyProc:
-    if needsComplexAssignment(dest.t):
+    if containsGarbageCollectedRef(dest.t):
       # optimize closure assignment:
       let a = optAsgnLoc(dest, dest.t, "ClE_0".rope)
       let b = optAsgnLoc(src, dest.t, "ClE_0".rope)
-      genRefAssign(p, a, b, flags)
-      linefmt(p, cpsStmts, "$1.ClP_0 = $2.ClP_0;$n", rdLoc(dest), rdLoc(src))
+      genRefAssign(p, a, b)
+      linefmt(p, cpsStmts, "$1.ClP_0 = $2.ClP_0;$n", [rdLoc(dest), rdLoc(src)])
     else:
-      linefmt(p, cpsStmts, "$1 = $2;$n", rdLoc(dest), rdLoc(src))
+      linefmt(p, cpsStmts, "$1 = $2;$n", [rdLoc(dest), rdLoc(src)])
   of tyTuple:
-    if needsComplexAssignment(dest.t):
-      if dest.t.len <= 4: genOptAsgnTuple(p, dest, src, flags)
+    if containsGarbageCollectedRef(dest.t):
+      if dest.t.kidsLen <= 4: genOptAsgnTuple(p, dest, src, flags)
       else: genGenericAsgn(p, dest, src, flags)
     else:
-      linefmt(p, cpsStmts, "$1 = $2;$n", rdLoc(dest), rdLoc(src))
+      linefmt(p, cpsStmts, "$1 = $2;$n", [rdLoc(dest), rdLoc(src)])
   of tyObject:
     # XXX: check for subtyping?
     if ty.isImportedCppType:
-      linefmt(p, cpsStmts, "$1 = $2;$n", rdLoc(dest), rdLoc(src))
+      linefmt(p, cpsStmts, "$1 = $2;$n", [rdLoc(dest), rdLoc(src)])
     elif not isObjLackingTypeField(ty):
       genGenericAsgn(p, dest, src, flags)
-    elif needsComplexAssignment(ty):
-      if ty.sons[0].isNil and asgnComplexity(ty.n) <= 4:
+    elif containsGarbageCollectedRef(ty):
+      if ty[0].isNil and asgnComplexity(ty.n) <= 4 and
+            needAssignCall notin flags: # calls might contain side effects
         discard getTypeDesc(p.module, ty)
         internalAssert p.config, ty.n != nil
         genOptAsgnObject(p, dest, src, flags, ty.n, ty)
       else:
         genGenericAsgn(p, dest, src, flags)
     else:
-      linefmt(p, cpsStmts, "$1 = $2;$n", rdLoc(dest), rdLoc(src))
+      linefmt(p, cpsStmts, "$1 = $2;$n", [rdLoc(dest), rdLoc(src)])
   of tyArray:
-    if needsComplexAssignment(dest.t):
+    if containsGarbageCollectedRef(dest.t) and p.config.selectedGC notin {gcArc, gcAtomicArc, gcOrc, gcHooks}:
       genGenericAsgn(p, dest, src, flags)
     else:
-      useStringh(p.module)
       linefmt(p, cpsStmts,
-           "memcpy((void*)$1, (NIM_CONST void*)$2, sizeof($3));$n",
-           rdLoc(dest), rdLoc(src), getTypeDesc(p.module, dest.t))
+           "#nimCopyMem((void*)$1, (NIM_CONST void*)$2, sizeof($3));$n",
+           [rdLoc(dest), rdLoc(src), getTypeDesc(p.module, dest.t)])
   of tyOpenArray, tyVarargs:
     # open arrays are always on the stack - really? What if a sequence is
     # passed to an open array?
-    if needsComplexAssignment(dest.t):
+    if reifiedOpenArray(dest.lode):
+      genOpenArrayConv(p, dest, src, flags)
+    elif containsGarbageCollectedRef(dest.t):
       linefmt(p, cpsStmts,     # XXX: is this correct for arrays?
            "#genericAssignOpenArray((void*)$1, (void*)$2, $1Len_0, $3);$n",
-           addrLoc(p.config, dest), addrLoc(p.config, src),
-           genTypeInfo(p.module, dest.t, dest.lode.info))
+           [addrLoc(p.config, dest), addrLoc(p.config, src),
+           genTypeInfoV1(p.module, dest.t, dest.lode.info)])
     else:
-      useStringh(p.module)
       linefmt(p, cpsStmts,
-           # bug #4799, keep the memcpy for a while
-           #"memcpy((void*)$1, (NIM_CONST void*)$2, sizeof($1[0])*$1Len_0);$n",
+           # bug #4799, keep the nimCopyMem for a while
+           #"#nimCopyMem((void*)$1, (NIM_CONST void*)$2, sizeof($1[0])*$1Len_0);\n",
            "$1 = $2;$n",
-           rdLoc(dest), rdLoc(src))
+           [rdLoc(dest), rdLoc(src)])
   of tySet:
-    if mapType(p.config, ty) == ctArray:
-      useStringh(p.module)
-      linefmt(p, cpsStmts, "memcpy((void*)$1, (NIM_CONST void*)$2, $3);$n",
-              rdLoc(dest), rdLoc(src), rope(getSize(p.config, dest.t)))
+    if mapSetType(p.config, ty) == ctArray:
+      linefmt(p, cpsStmts, "#nimCopyMem((void*)$1, (NIM_CONST void*)$2, $3);$n",
+              [rdLoc(dest), rdLoc(src), getSize(p.config, dest.t)])
     else:
-      linefmt(p, cpsStmts, "$1 = $2;$n", rdLoc(dest), rdLoc(src))
-  of tyPtr, tyPointer, tyChar, tyBool, tyEnum, tyCString,
-     tyInt..tyUInt64, tyRange, tyVar, tyLent:
-    linefmt(p, cpsStmts, "$1 = $2;$n", rdLoc(dest), rdLoc(src))
+      linefmt(p, cpsStmts, "$1 = $2;$n", [rdLoc(dest), rdLoc(src)])
+  of tyPtr, tyPointer, tyChar, tyBool, tyEnum, tyCstring,
+     tyInt..tyUInt64, tyRange, tyVar, tyLent, tyNil:
+    linefmt(p, cpsStmts, "$1 = $2;$n", [rdLoc(dest), rdLoc(src)])
   else: internalError(p.config, "genAssignment: " & $ty.kind)
 
   if optMemTracker in p.options and dest.storage in {OnHeap, OnUnknown}:
     #writeStackTrace()
     #echo p.currLineInfo, " requesting"
     linefmt(p, cpsStmts, "#memTrackerWrite((void*)$1, $2, $3, $4);$n",
-            addrLoc(p.config, dest), rope getSize(p.config, dest.t),
+            [addrLoc(p.config, dest), getSize(p.config, dest.t),
             makeCString(toFullPath(p.config, p.currLineInfo)),
-            rope p.currLineInfo.safeLineNm)
+            p.currLineInfo.safeLineNm])
 
 proc genDeepCopy(p: BProc; dest, src: TLoc) =
   template addrLocOrTemp(a: TLoc): Rope =
     if a.k == locExpr:
-      var tmp: TLoc
-      getTemp(p, a.t, tmp)
+      var tmp: TLoc = getTemp(p, a.t)
       genAssignment(p, tmp, a, {})
       addrLoc(p.config, tmp)
     else:
       addrLoc(p.config, a)
 
-  var ty = skipTypes(dest.t, abstractVarRange)
+  var ty = skipTypes(dest.t, abstractVarRange + {tyStatic})
   case ty.kind
   of tyPtr, tyRef, tyProc, tyTuple, tyObject, tyArray:
     # XXX optimize this
     linefmt(p, cpsStmts, "#genericDeepCopy((void*)$1, (void*)$2, $3);$n",
-            addrLoc(p.config, dest), addrLocOrTemp(src),
-            genTypeInfo(p.module, dest.t, dest.lode.info))
+            [addrLoc(p.config, dest), addrLocOrTemp(src),
+            genTypeInfoV1(p.module, dest.t, dest.lode.info)])
   of tySequence, tyString:
-    linefmt(p, cpsStmts, "#genericSeqDeepCopy($1, $2, $3);$n",
-            addrLoc(p.config, dest), rdLoc(src),
-            genTypeInfo(p.module, dest.t, dest.lode.info))
+    if optTinyRtti in p.config.globalOptions:
+      linefmt(p, cpsStmts, "#genericDeepCopy((void*)$1, (void*)$2, $3);$n",
+              [addrLoc(p.config, dest), addrLocOrTemp(src),
+              genTypeInfoV1(p.module, dest.t, dest.lode.info)])
+    else:
+      linefmt(p, cpsStmts, "#genericSeqDeepCopy($1, $2, $3);$n",
+              [addrLoc(p.config, dest), rdLoc(src),
+              genTypeInfoV1(p.module, dest.t, dest.lode.info)])
   of tyOpenArray, tyVarargs:
+    let source = addrLocOrTemp(src)
     linefmt(p, cpsStmts,
-         "#genericDeepCopyOpenArray((void*)$1, (void*)$2, $1Len_0, $3);$n",
-         addrLoc(p.config, dest), addrLocOrTemp(src),
-         genTypeInfo(p.module, dest.t, dest.lode.info))
+         "#genericDeepCopyOpenArray((void*)$1, (void*)$2, $2->Field1, $3);$n",
+         [addrLoc(p.config, dest), source,
+         genTypeInfoV1(p.module, dest.t, dest.lode.info)])
   of tySet:
-    if mapType(p.config, ty) == ctArray:
-      useStringh(p.module)
-      linefmt(p, cpsStmts, "memcpy((void*)$1, (NIM_CONST void*)$2, $3);$n",
-              rdLoc(dest), rdLoc(src), rope(getSize(p.config, dest.t)))
+    if mapSetType(p.config, ty) == ctArray:
+      linefmt(p, cpsStmts, "#nimCopyMem((void*)$1, (NIM_CONST void*)$2, $3);$n",
+              [rdLoc(dest), rdLoc(src), getSize(p.config, dest.t)])
     else:
-      linefmt(p, cpsStmts, "$1 = $2;$n", rdLoc(dest), rdLoc(src))
-  of tyPointer, tyChar, tyBool, tyEnum, tyCString,
+      linefmt(p, cpsStmts, "$1 = $2;$n", [rdLoc(dest), rdLoc(src)])
+  of tyPointer, tyChar, tyBool, tyEnum, tyCstring,
      tyInt..tyUInt64, tyRange, tyVar, tyLent:
-    linefmt(p, cpsStmts, "$1 = $2;$n", rdLoc(dest), rdLoc(src))
+    linefmt(p, cpsStmts, "$1 = $2;$n", [rdLoc(dest), rdLoc(src)])
   else: internalError(p.config, "genDeepCopy: " & $ty.kind)
 
 proc putLocIntoDest(p: BProc, d: var TLoc, s: TLoc) =
@@ -421,11 +480,10 @@ proc putLocIntoDest(p: BProc, d: var TLoc, s: TLoc) =
     d = s # ``d`` is free, so fill it with ``s``
 
 proc putDataIntoDest(p: BProc, d: var TLoc, n: PNode, r: Rope) =
-  var a: TLoc
   if d.k != locNone:
+    var a: TLoc = initLoc(locData, n, OnStatic)
     # need to generate an assignment here
-    initLoc(a, locData, n, OnStatic)
-    a.r = r
+    a.snippet = r
     if lfNoDeepCopy in d.flags: genAssignment(p, d, a, {})
     else: genAssignment(p, d, a, {needToCopy})
   else:
@@ -433,14 +491,13 @@ proc putDataIntoDest(p: BProc, d: var TLoc, n: PNode, r: Rope) =
     # the flags field!
     d.k = locData
     d.lode = n
-    d.r = r
+    d.snippet = r
 
 proc putIntoDest(p: BProc, d: var TLoc, n: PNode, r: Rope; s=OnUnknown) =
-  var a: TLoc
   if d.k != locNone:
     # need to generate an assignment here
-    initLoc(a, locExpr, n, s)
-    a.r = r
+    var a: TLoc = initLoc(locExpr, n, s)
+    a.snippet = r
     if lfNoDeepCopy in d.flags: genAssignment(p, d, a, {})
     else: genAssignment(p, d, a, {needToCopy})
   else:
@@ -448,245 +505,264 @@ proc putIntoDest(p: BProc, d: var TLoc, n: PNode, r: Rope; s=OnUnknown) =
     # the flags field!
     d.k = locExpr
     d.lode = n
-    d.r = r
+    d.snippet = r
 
-proc binaryStmt(p: BProc, e: PNode, d: var TLoc, frmt: string) =
-  var a, b: TLoc
+proc binaryStmt(p: BProc, e: PNode, d: var TLoc, op: string) =
   if d.k != locNone: internalError(p.config, e.info, "binaryStmt")
-  initLocExpr(p, e.sons[1], a)
-  initLocExpr(p, e.sons[2], b)
-  lineCg(p, cpsStmts, frmt, rdLoc(a), rdLoc(b))
+  var a = initLocExpr(p, e[1])
+  var b = initLocExpr(p, e[2])
+  lineCg(p, cpsStmts, "$1 $2 $3;$n", [rdLoc(a), op, rdLoc(b)])
 
-proc unaryStmt(p: BProc, e: PNode, d: var TLoc, frmt: string) =
-  var a: TLoc
+proc binaryStmtAddr(p: BProc, e: PNode, d: var TLoc, cpname: string) =
+  if d.k != locNone: internalError(p.config, e.info, "binaryStmtAddr")
+  var a = initLocExpr(p, e[1])
+  var b = initLocExpr(p, e[2])
+  lineCg(p, cpsStmts, "#$1($2, $3);$n", [cpname, byRefLoc(p, a), rdLoc(b)])
+
+template unaryStmt(p: BProc, e: PNode, d: var TLoc, frmt: string) =
   if d.k != locNone: internalError(p.config, e.info, "unaryStmt")
-  initLocExpr(p, e.sons[1], a)
+  var a: TLoc = initLocExpr(p, e[1])
   lineCg(p, cpsStmts, frmt, [rdLoc(a)])
 
-proc binaryExpr(p: BProc, e: PNode, d: var TLoc, frmt: string) =
-  var a, b: TLoc
-  assert(e.sons[1].typ != nil)
-  assert(e.sons[2].typ != nil)
-  initLocExpr(p, e.sons[1], a)
-  initLocExpr(p, e.sons[2], b)
+template binaryExpr(p: BProc, e: PNode, d: var TLoc, frmt: string) =
+  assert(e[1].typ != nil)
+  assert(e[2].typ != nil)
+  var a = initLocExpr(p, e[1])
+  var b = initLocExpr(p, e[2])
   putIntoDest(p, d, e, ropecg(p.module, frmt, [rdLoc(a), rdLoc(b)]))
 
-proc binaryExprChar(p: BProc, e: PNode, d: var TLoc, frmt: string) =
-  var a, b: TLoc
-  assert(e.sons[1].typ != nil)
-  assert(e.sons[2].typ != nil)
-  initLocExpr(p, e.sons[1], a)
-  initLocExpr(p, e.sons[2], b)
+template binaryExprChar(p: BProc, e: PNode, d: var TLoc, frmt: string) =
+  assert(e[1].typ != nil)
+  assert(e[2].typ != nil)
+  var a = initLocExpr(p, e[1])
+  var b = initLocExpr(p, e[2])
   putIntoDest(p, d, e, ropecg(p.module, frmt, [a.rdCharLoc, b.rdCharLoc]))
 
-proc unaryExpr(p: BProc, e: PNode, d: var TLoc, frmt: string) =
-  var a: TLoc
-  initLocExpr(p, e.sons[1], a)
+template unaryExpr(p: BProc, e: PNode, d: var TLoc, frmt: string) =
+  var a: TLoc = initLocExpr(p, e[1])
   putIntoDest(p, d, e, ropecg(p.module, frmt, [rdLoc(a)]))
 
-proc unaryExprChar(p: BProc, e: PNode, d: var TLoc, frmt: string) =
-  var a: TLoc
-  initLocExpr(p, e.sons[1], a)
+template unaryExprChar(p: BProc, e: PNode, d: var TLoc, frmt: string) =
+  var a: TLoc = initLocExpr(p, e[1])
   putIntoDest(p, d, e, ropecg(p.module, frmt, [rdCharLoc(a)]))
 
-proc binaryArithOverflowRaw(p: BProc, t: PType, a, b: TLoc;
-                            frmt: string): Rope =
+template binaryArithOverflowRaw(p: BProc, t: PType, a, b: TLoc;
+                            cpname: string): Rope =
   var size = getSize(p.config, t)
   let storage = if size < p.config.target.intSize: rope("NI")
                 else: getTypeDesc(p.module, t)
-  result = getTempName(p.module)
-  linefmt(p, cpsLocals, "$1 $2;$n", storage, result)
-  lineCg(p, cpsStmts, frmt, result, rdCharLoc(a), rdCharLoc(b))
+  var result = getTempName(p.module)
+  linefmt(p, cpsLocals, "$1 $2;$n", [storage, result])
+  lineCg(p, cpsStmts, "if (#$2($3, $4, &$1)) { #raiseOverflow(); ",
+      [result, cpname, rdCharLoc(a), rdCharLoc(b)])
+  raiseInstr(p, p.s(cpsStmts))
+  linefmt p, cpsStmts, "};$n", []
+
   if size < p.config.target.intSize or t.kind in {tyRange, tyEnum}:
-    linefmt(p, cpsStmts, "if ($1 < $2 || $1 > $3) #raiseOverflow();$n",
-            result, intLiteral(firstOrd(p.config, t)), intLiteral(lastOrd(p.config, t)))
+    var first = newRopeAppender()
+    intLiteral(firstOrd(p.config, t), first)
+    var last = newRopeAppender()
+    intLiteral(lastOrd(p.config, t), last)
+    linefmt(p, cpsStmts, "if ($1 < $2 || $1 > $3){ #raiseOverflow(); ",
+            [result, first, last])
+    raiseInstr(p, p.s(cpsStmts))
+    linefmt p, cpsStmts, "}$n", []
+
+  result
 
 proc binaryArithOverflow(p: BProc, e: PNode, d: var TLoc, m: TMagic) =
   const
     prc: array[mAddI..mPred, string] = [
-      "$# = #addInt($#, $#);$n", "$# = #subInt($#, $#);$n",
-      "$# = #mulInt($#, $#);$n", "$# = #divInt($#, $#);$n",
-      "$# = #modInt($#, $#);$n",
-      "$# = #addInt($#, $#);$n", "$# = #subInt($#, $#);$n"]
+      "nimAddInt", "nimSubInt",
+      "nimMulInt", "nimDivInt", "nimModInt",
+      "nimAddInt", "nimSubInt"
+    ]
     prc64: array[mAddI..mPred, string] = [
-      "$# = #addInt64($#, $#);$n", "$# = #subInt64($#, $#);$n",
-      "$# = #mulInt64($#, $#);$n", "$# = #divInt64($#, $#);$n",
-      "$# = #modInt64($#, $#);$n",
-      "$# = #addInt64($#, $#);$n", "$# = #subInt64($#, $#);$n"]
-    opr: array[mAddI..mPred, string] = [
-      "($#)($# + $#)", "($#)($# - $#)", "($#)($# * $#)",
-      "($#)($# / $#)", "($#)($# % $#)",
-      "($#)($# + $#)", "($#)($# - $#)"]
-  var a, b: TLoc
-  assert(e.sons[1].typ != nil)
-  assert(e.sons[2].typ != nil)
-  initLocExpr(p, e.sons[1], a)
-  initLocExpr(p, e.sons[2], b)
+      "nimAddInt64", "nimSubInt64",
+      "nimMulInt64", "nimDivInt64", "nimModInt64",
+      "nimAddInt64", "nimSubInt64"
+    ]
+    opr: array[mAddI..mPred, string] = ["+", "-", "*", "/", "%", "+", "-"]
+  assert(e[1].typ != nil)
+  assert(e[2].typ != nil)
+  var a = initLocExpr(p, e[1])
+  var b = initLocExpr(p, e[2])
   # skipping 'range' is correct here as we'll generate a proper range check
   # later via 'chckRange'
   let t = e.typ.skipTypes(abstractRange)
-  if optOverflowCheck notin p.options:
-    let res = opr[m] % [getTypeDesc(p.module, e.typ), rdLoc(a), rdLoc(b)]
+  if optOverflowCheck notin p.options or (m in {mSucc, mPred} and t.kind in {tyUInt..tyUInt64}):
+    let res = "($1)($2 $3 $4)" % [getTypeDesc(p.module, e.typ), rdLoc(a), rope(opr[m]), rdLoc(b)]
     putIntoDest(p, d, e, res)
   else:
-    let res = binaryArithOverflowRaw(p, t, a, b,
-                                   if t.kind == tyInt64: prc64[m] else: prc[m])
-    putIntoDest(p, d, e, "($#)($#)" % [getTypeDesc(p.module, e.typ), res])
+    # we handle div by zero here so that we know that the compilerproc's
+    # result is only for overflows.
+    var needsOverflowCheck = true
+    if m in {mDivI, mModI}:
+      var canBeZero = true
+      if e[2].kind in {nkIntLit..nkUInt64Lit}:
+        canBeZero = e[2].intVal == 0
+      if e[2].kind in {nkIntLit..nkInt64Lit}:
+        needsOverflowCheck = e[2].intVal == -1
+      if canBeZero:
+        linefmt(p, cpsStmts, "if ($1 == 0){ #raiseDivByZero(); ", [rdLoc(b)])
+        raiseInstr(p, p.s(cpsStmts))
+        linefmt(p, cpsStmts, "}$n", [])
+    if needsOverflowCheck:
+      let res = binaryArithOverflowRaw(p, t, a, b,
+        if t.kind == tyInt64: prc64[m] else: prc[m])
+      putIntoDest(p, d, e, "($#)($#)" % [getTypeDesc(p.module, e.typ), res])
+    else:
+      let res = "($1)(($2) $3 ($4))" % [getTypeDesc(p.module, e.typ), rdLoc(a), rope(opr[m]), rdLoc(b)]
+      putIntoDest(p, d, e, res)
 
 proc unaryArithOverflow(p: BProc, e: PNode, d: var TLoc, m: TMagic) =
-  const
-    opr: array[mUnaryMinusI..mAbsI, string] = [
-      mUnaryMinusI: "((NI$2)-($1))",
-      mUnaryMinusI64: "-($1)",
-      mAbsI: "($1 > 0? ($1) : -($1))"]
-  var
-    a: TLoc
-    t: PType
-  assert(e.sons[1].typ != nil)
-  initLocExpr(p, e.sons[1], a)
+  var t: PType
+  assert(e[1].typ != nil)
+  var a: TLoc = initLocExpr(p, e[1])
   t = skipTypes(e.typ, abstractRange)
   if optOverflowCheck in p.options:
-    linefmt(p, cpsStmts, "if ($1 == $2) #raiseOverflow();$n",
-            rdLoc(a), intLiteral(firstOrd(p.config, t)))
-  putIntoDest(p, d, e, opr[m] % [rdLoc(a), rope(getSize(p.config, t) * 8)])
+    var first = newRopeAppender()
+    intLiteral(firstOrd(p.config, t), first)
+    linefmt(p, cpsStmts, "if ($1 == $2){ #raiseOverflow(); ",
+            [rdLoc(a), first])
+    raiseInstr(p, p.s(cpsStmts))
+    linefmt p, cpsStmts, "}$n", []
+
+  case m
+  of mUnaryMinusI:
+    putIntoDest(p, d, e, "((NI$2)-($1))" % [rdLoc(a), rope(getSize(p.config, t) * 8)])
+  of mUnaryMinusI64:
+    putIntoDest(p, d, e, "-($1)" % [rdLoc(a)])
+  of mAbsI:
+    putIntoDest(p, d, e, "($1 > 0? ($1) : -($1))" % [rdLoc(a)])
+  else:
+    assert(false, $m)
 
 proc binaryArith(p: BProc, e: PNode, d: var TLoc, op: TMagic) =
-  const
-    binArithTab: array[mAddF64..mXor, string] = [
-      "(($4)($1) + ($4)($2))", # AddF64
-      "(($4)($1) - ($4)($2))", # SubF64
-      "(($4)($1) * ($4)($2))", # MulF64
-      "(($4)($1) / ($4)($2))", # DivF64
-
-      "($4)((NU$5)($1) >> (NU$3)($2))", # ShrI
-      "($4)((NU$3)($1) << (NU$3)($2))", # ShlI
-      "($4)($1 & $2)",      # BitandI
-      "($4)($1 | $2)",      # BitorI
-      "($4)($1 ^ $2)",      # BitxorI
-      "(($1 <= $2) ? $1 : $2)", # MinI
-      "(($1 >= $2) ? $1 : $2)", # MaxI
-      "(($1 <= $2) ? $1 : $2)", # MinF64
-      "(($1 >= $2) ? $1 : $2)", # MaxF64
-      "($4)((NU$3)($1) + (NU$3)($2))", # AddU
-      "($4)((NU$3)($1) - (NU$3)($2))", # SubU
-      "($4)((NU$3)($1) * (NU$3)($2))", # MulU
-      "($4)((NU$3)($1) / (NU$3)($2))", # DivU
-      "($4)((NU$3)($1) % (NU$3)($2))", # ModU
-      "($1 == $2)",           # EqI
-      "($1 <= $2)",           # LeI
-      "($1 < $2)",            # LtI
-      "($1 == $2)",           # EqF64
-      "($1 <= $2)",           # LeF64
-      "($1 < $2)",            # LtF64
-      "((NU$3)($1) <= (NU$3)($2))", # LeU
-      "((NU$3)($1) < (NU$3)($2))", # LtU
-      "((NU64)($1) <= (NU64)($2))", # LeU64
-      "((NU64)($1) < (NU64)($2))", # LtU64
-      "($1 == $2)",           # EqEnum
-      "($1 <= $2)",           # LeEnum
-      "($1 < $2)",            # LtEnum
-      "((NU8)($1) == (NU8)($2))", # EqCh
-      "((NU8)($1) <= (NU8)($2))", # LeCh
-      "((NU8)($1) < (NU8)($2))", # LtCh
-      "($1 == $2)",           # EqB
-      "($1 <= $2)",           # LeB
-      "($1 < $2)",            # LtB
-      "($1 == $2)",           # EqRef
-      "($1 == $2)",           # EqPtr
-      "($1 <= $2)",           # LePtr
-      "($1 < $2)",            # LtPtr
-      "($1 != $2)"]           # Xor
   var
-    a, b: TLoc
-    s, k: BiggestInt
-  assert(e.sons[1].typ != nil)
-  assert(e.sons[2].typ != nil)
-  initLocExpr(p, e.sons[1], a)
-  initLocExpr(p, e.sons[2], b)
+    s, k: BiggestInt = 0
+  assert(e[1].typ != nil)
+  assert(e[2].typ != nil)
+  var a = initLocExpr(p, e[1])
+  var b = initLocExpr(p, e[2])
   # BUGFIX: cannot use result-type here, as it may be a boolean
   s = max(getSize(p.config, a.t), getSize(p.config, b.t)) * 8
   k = getSize(p.config, a.t) * 8
-  putIntoDest(p, d, e,
-              binArithTab[op] % [rdLoc(a), rdLoc(b), rope(s),
-                                      getSimpleTypeDesc(p.module, e.typ), rope(k)])
+
+  template applyFormat(frmt: untyped) =
+    putIntoDest(p, d, e, frmt % [
+      rdLoc(a), rdLoc(b), rope(s),
+      getSimpleTypeDesc(p.module, e.typ), rope(k)]
+    )
+
+  case op
+  of mAddF64: applyFormat("(($4)($1) + ($4)($2))")
+  of mSubF64: applyFormat("(($4)($1) - ($4)($2))")
+  of mMulF64: applyFormat("(($4)($1) * ($4)($2))")
+  of mDivF64: applyFormat("(($4)($1) / ($4)($2))")
+  of mShrI: applyFormat("($4)((NU$5)($1) >> (NU$3)($2))")
+  of mShlI: applyFormat("($4)((NU$3)($1) << (NU$3)($2))")
+  of mAshrI: applyFormat("($4)((NI$3)($1) >> (NU$3)($2))")
+  of mBitandI: applyFormat("($4)($1 & $2)")
+  of mBitorI: applyFormat("($4)($1 | $2)")
+  of mBitxorI: applyFormat("($4)($1 ^ $2)")
+  of mMinI: applyFormat("(($1 <= $2) ? $1 : $2)")
+  of mMaxI: applyFormat("(($1 >= $2) ? $1 : $2)")
+  of mAddU: applyFormat("($4)((NU$3)($1) + (NU$3)($2))")
+  of mSubU: applyFormat("($4)((NU$3)($1) - (NU$3)($2))")
+  of mMulU: applyFormat("($4)((NU$3)($1) * (NU$3)($2))")
+  of mDivU: applyFormat("($4)((NU$3)($1) / (NU$3)($2))")
+  of mModU: applyFormat("($4)((NU$3)($1) % (NU$3)($2))")
+  of mEqI: applyFormat("($1 == $2)")
+  of mLeI: applyFormat("($1 <= $2)")
+  of mLtI: applyFormat("($1 < $2)")
+  of mEqF64: applyFormat("($1 == $2)")
+  of mLeF64: applyFormat("($1 <= $2)")
+  of mLtF64: applyFormat("($1 < $2)")
+  of mLeU: applyFormat("((NU$3)($1) <= (NU$3)($2))")
+  of mLtU: applyFormat("((NU$3)($1) < (NU$3)($2))")
+  of mEqEnum: applyFormat("($1 == $2)")
+  of mLeEnum: applyFormat("($1 <= $2)")
+  of mLtEnum: applyFormat("($1 < $2)")
+  of mEqCh: applyFormat("((NU8)($1) == (NU8)($2))")
+  of mLeCh: applyFormat("((NU8)($1) <= (NU8)($2))")
+  of mLtCh: applyFormat("((NU8)($1) < (NU8)($2))")
+  of mEqB: applyFormat("($1 == $2)")
+  of mLeB: applyFormat("($1 <= $2)")
+  of mLtB: applyFormat("($1 < $2)")
+  of mEqRef: applyFormat("($1 == $2)")
+  of mLePtr: applyFormat("($1 <= $2)")
+  of mLtPtr: applyFormat("($1 < $2)")
+  of mXor: applyFormat("($1 != $2)")
+  else:
+    assert(false, $op)
 
 proc genEqProc(p: BProc, e: PNode, d: var TLoc) =
-  var a, b: TLoc
-  assert(e.sons[1].typ != nil)
-  assert(e.sons[2].typ != nil)
-  initLocExpr(p, e.sons[1], a)
-  initLocExpr(p, e.sons[2], b)
-  if a.t.skipTypes(abstractInst).callConv == ccClosure:
+  assert(e[1].typ != nil)
+  assert(e[2].typ != nil)
+  var a = initLocExpr(p, e[1])
+  var b = initLocExpr(p, e[2])
+  if a.t.skipTypes(abstractInstOwned).callConv == ccClosure:
     putIntoDest(p, d, e,
       "($1.ClP_0 == $2.ClP_0 && $1.ClE_0 == $2.ClE_0)" % [rdLoc(a), rdLoc(b)])
   else:
     putIntoDest(p, d, e, "($1 == $2)" % [rdLoc(a), rdLoc(b)])
 
 proc genIsNil(p: BProc, e: PNode, d: var TLoc) =
-  let t = skipTypes(e.sons[1].typ, abstractRange)
+  let t = skipTypes(e[1].typ, abstractRange)
   if t.kind == tyProc and t.callConv == ccClosure:
     unaryExpr(p, e, d, "($1.ClP_0 == 0)")
   else:
     unaryExpr(p, e, d, "($1 == 0)")
 
 proc unaryArith(p: BProc, e: PNode, d: var TLoc, op: TMagic) =
-  const
-    unArithTab: array[mNot..mToBiggestInt, string] = ["!($1)", # Not
-      "$1",                   # UnaryPlusI
-      "($3)((NU$2) ~($1))",   # BitnotI
-      "$1",                   # UnaryPlusF64
-      "-($1)",                # UnaryMinusF64
-      "($1 < 0? -($1) : ($1))", # AbsF64; BUGFIX: fabs() makes problems
-                                # for Tiny C, so we don't use it
-      "(($3)(NU)(NU8)($1))",  # mZe8ToI
-      "(($3)(NU64)(NU8)($1))", # mZe8ToI64
-      "(($3)(NU)(NU16)($1))", # mZe16ToI
-      "(($3)(NU64)(NU16)($1))", # mZe16ToI64
-      "(($3)(NU64)(NU32)($1))", # mZe32ToI64
-      "(($3)(NU64)(NU)($1))", # mZeIToI64
-      "(($3)(NU8)(NU)($1))", # ToU8
-      "(($3)(NU16)(NU)($1))", # ToU16
-      "(($3)(NU32)(NU64)($1))", # ToU32
-      "((double) ($1))",      # ToFloat
-      "((double) ($1))",      # ToBiggestFloat
-      "float64ToInt32($1)",   # ToInt
-      "float64ToInt64($1)"]   # ToBiggestInt
   var
-    a: TLoc
     t: PType
-  assert(e.sons[1].typ != nil)
-  initLocExpr(p, e.sons[1], a)
+  assert(e[1].typ != nil)
+  var a = initLocExpr(p, e[1])
   t = skipTypes(e.typ, abstractRange)
-  putIntoDest(p, d, e,
-              unArithTab[op] % [rdLoc(a), rope(getSize(p.config, t) * 8),
+
+  template applyFormat(frmt: untyped) =
+    putIntoDest(p, d, e, frmt % [rdLoc(a), rope(getSize(p.config, t) * 8),
                 getSimpleTypeDesc(p.module, e.typ)])
+  case op
+  of mNot:
+    applyFormat("!($1)")
+  of mUnaryPlusI:
+    applyFormat("$1")
+  of mBitnotI:
+    applyFormat("($3)((NU$2) ~($1))")
+  of mUnaryPlusF64:
+    applyFormat("$1")
+  of mUnaryMinusF64:
+    applyFormat("-($1)")
+  else:
+    assert false, $op
 
 proc isCppRef(p: BProc; typ: PType): bool {.inline.} =
   result = p.module.compileToCpp and
-      skipTypes(typ, abstractInst).kind == tyVar and
-      tfVarIsPtr notin skipTypes(typ, abstractInst).flags
+      skipTypes(typ, abstractInstOwned).kind in {tyVar} and
+      tfVarIsPtr notin skipTypes(typ, abstractInstOwned).flags
 
-proc genDeref(p: BProc, e: PNode, d: var TLoc; enforceDeref=false) =
-  let mt = mapType(p.config, e.sons[0].typ)
-  if mt in {ctArray, ctPtrToArray} and not enforceDeref:
+proc genDeref(p: BProc, e: PNode, d: var TLoc) =
+  let mt = mapType(p.config, e[0].typ, mapTypeChooser(e[0]) == skParam)
+  if mt in {ctArray, ctPtrToArray} and lfEnforceDeref notin d.flags:
     # XXX the amount of hacks for C's arrays is incredible, maybe we should
     # simply wrap them in a struct? --> Losing auto vectorization then?
-    #if e[0].kind != nkBracketExpr:
-    #  message(e.info, warnUser, "CAME HERE " & renderTree(e))
-    expr(p, e.sons[0], d)
-    if e.sons[0].typ.skipTypes(abstractInst).kind == tyRef:
+    expr(p, e[0], d)
+    if e[0].typ.skipTypes(abstractInstOwned).kind == tyRef:
       d.storage = OnHeap
   else:
     var a: TLoc
-    var typ = e.sons[0].typ
+    var typ = e[0].typ
     if typ.kind in {tyUserTypeClass, tyUserTypeClassInst} and typ.isResolvedUserTypeClass:
-      typ = typ.lastSon
-    typ = typ.skipTypes(abstractInst)
-    if typ.kind == tyVar and tfVarIsPtr notin typ.flags and p.module.compileToCpp and e.sons[0].kind == nkHiddenAddr:
-      initLocExprSingleUse(p, e[0][0], d)
+      typ = typ.last
+    typ = typ.skipTypes(abstractInstOwned)
+    if typ.kind in {tyVar} and tfVarIsPtr notin typ.flags and p.module.compileToCpp and e[0].kind == nkHiddenAddr:
+      d = initLocExprSingleUse(p, e[0][0])
       return
     else:
-      initLocExprSingleUse(p, e.sons[0], a)
+      a = initLocExprSingleUse(p, e[0])
     if d.k == locNone:
       # dest = *a;  <-- We do not know that 'dest' is on the heap!
       # It is completely wrong to set 'd.storage' here, unless it's not yet
@@ -705,63 +781,73 @@ proc genDeref(p: BProc, e: PNode, d: var TLoc; enforceDeref=false) =
       else:
         internalError(p.config, e.info, "genDeref " & $typ.kind)
     elif p.module.compileToCpp:
-      if typ.kind == tyVar and tfVarIsPtr notin typ.flags and
+      if typ.kind in {tyVar} and tfVarIsPtr notin typ.flags and
            e.kind == nkHiddenDeref:
         putIntoDest(p, d, e, rdLoc(a), a.storage)
         return
-    if enforceDeref and mt == ctPtrToArray:
+    if mt == ctPtrToArray and lfEnforceDeref in d.flags:
       # we lie about the type for better C interop: 'ptr array[3,T]' is
       # translated to 'ptr T', but for deref'ing this produces wrong code.
       # See tmissingderef. So we get rid of the deref instead. The codegen
       # ends up using 'memcpy' for the array assignment,
       # so the '&' and '*' cancel out:
-      putIntoDest(p, d, lodeTyp(a.t.sons[0]), rdLoc(a), a.storage)
+      putIntoDest(p, d, e, rdLoc(a), a.storage)
     else:
       putIntoDest(p, d, e, "(*$1)" % [rdLoc(a)], a.storage)
 
+proc cowBracket(p: BProc; n: PNode) =
+  if n.kind == nkBracketExpr and optSeqDestructors in p.config.globalOptions:
+    let strCandidate = n[0]
+    if strCandidate.typ.skipTypes(abstractInst).kind == tyString:
+      var a: TLoc = initLocExpr(p, strCandidate)
+      linefmt(p, cpsStmts, "#nimPrepareStrMutationV2($1);$n", [byRefLoc(p, a)])
+
+proc cow(p: BProc; n: PNode) {.inline.} =
+  if n.kind == nkHiddenAddr: cowBracket(p, n[0])
+
 proc genAddr(p: BProc, e: PNode, d: var TLoc) =
   # careful  'addr(myptrToArray)' needs to get the ampersand:
-  if e.sons[0].typ.skipTypes(abstractInst).kind in {tyRef, tyPtr}:
-    var a: TLoc
-    initLocExpr(p, e.sons[0], a)
-    putIntoDest(p, d, e, "&" & a.r, a.storage)
+  if e[0].typ.skipTypes(abstractInstOwned).kind in {tyRef, tyPtr}:
+    var a: TLoc = initLocExpr(p, e[0])
+    putIntoDest(p, d, e, "&" & a.snippet, a.storage)
     #Message(e.info, warnUser, "HERE NEW &")
-  elif mapType(p.config, e.sons[0].typ) == ctArray or isCppRef(p, e.sons[0].typ):
-    expr(p, e.sons[0], d)
+  elif mapType(p.config, e[0].typ, mapTypeChooser(e[0]) == skParam) == ctArray or isCppRef(p, e.typ):
+    expr(p, e[0], d)
+    # bug #19497
+    d.lode = e
   else:
-    var a: TLoc
-    initLocExpr(p, e.sons[0], a)
+    var a: TLoc = initLocExpr(p, e[0])
     putIntoDest(p, d, e, addrLoc(p.config, a), a.storage)
 
 template inheritLocation(d: var TLoc, a: TLoc) =
   if d.k == locNone: d.storage = a.storage
 
-proc genRecordFieldAux(p: BProc, e: PNode, d, a: var TLoc) =
-  initLocExpr(p, e.sons[0], a)
-  if e.sons[1].kind != nkSym: internalError(p.config, e.info, "genRecordFieldAux")
+proc genRecordFieldAux(p: BProc, e: PNode, d: var TLoc, a: var TLoc) =
+  a = initLocExpr(p, e[0])
+  if e[1].kind != nkSym: internalError(p.config, e.info, "genRecordFieldAux")
   d.inheritLocation(a)
   discard getTypeDesc(p.module, a.t) # fill the record's fields.loc
 
 proc genTupleElem(p: BProc, e: PNode, d: var TLoc) =
   var
-    a: TLoc
-    i: int
-  initLocExpr(p, e.sons[0], a)
-  let tupType = a.t.skipTypes(abstractInst)
+    i: int = 0
+  var a: TLoc = initLocExpr(p, e[0])
+  let tupType = a.t.skipTypes(abstractInst+{tyVar})
   assert tupType.kind == tyTuple
   d.inheritLocation(a)
   discard getTypeDesc(p.module, a.t) # fill the record's fields.loc
   var r = rdLoc(a)
-  case e.sons[1].kind
-  of nkIntLit..nkUInt64Lit: i = int(e.sons[1].intVal)
+  case e[1].kind
+  of nkIntLit..nkUInt64Lit: i = int(e[1].intVal)
   else: internalError(p.config, e.info, "genTupleElem")
-  addf(r, ".Field$1", [rope(i)])
+  r.addf(".Field$1", [rope(i)])
   putIntoDest(p, d, e, r, a.storage)
 
 proc lookupFieldAgain(p: BProc, ty: PType; field: PSym; r: var Rope;
                       resTyp: ptr PType = nil): PSym =
+  result = nil
   var ty = ty
-  assert r != nil
+  assert r != ""
   while ty != nil:
     ty = ty.skipTypes(skipPtrs)
     assert(ty.kind in {tyTuple, tyObject})
@@ -769,177 +855,290 @@ proc lookupFieldAgain(p: BProc, ty: PType; field: PSym; r: var Rope;
     if result != nil:
       if resTyp != nil: resTyp[] = ty
       break
-    if not p.module.compileToCpp: add(r, ".Sup")
-    ty = ty.sons[0]
+    if not p.module.compileToCpp: r.add(".Sup")
+    ty = ty[0]
   if result == nil: internalError(p.config, field.info, "genCheckedRecordField")
 
 proc genRecordField(p: BProc, e: PNode, d: var TLoc) =
-  var a: TLoc
+  var a: TLoc = default(TLoc)
+  if p.module.compileToCpp and e.kind == nkDotExpr and e[1].kind == nkSym and e[1].typ.kind == tyPtr:
+    # special case for C++: we need to pull the type of the field as member and friends require the complete type.
+    let typ = e[1].typ.elementType
+    if typ.itemId in p.module.g.graph.memberProcsPerType:
+      discard getTypeDesc(p.module, typ)
+
   genRecordFieldAux(p, e, d, a)
   var r = rdLoc(a)
-  var f = e.sons[1].sym
-  let ty = skipTypes(a.t, abstractInst + tyUserTypeClasses)
+  var f = e[1].sym
+  let ty = skipTypes(a.t, abstractInstOwned + tyUserTypeClasses)
   if ty.kind == tyTuple:
     # we found a unique tuple type which lacks field information
     # so we use Field$i
-    addf(r, ".Field$1", [rope(f.position)])
+    r.add ".Field"
+    r.add rope(f.position)
     putIntoDest(p, d, e, r, a.storage)
   else:
-    var rtyp: PType
+    var rtyp: PType = nil
     let field = lookupFieldAgain(p, ty, f, r, addr rtyp)
-    if field.loc.r == nil and rtyp != nil: fillObjectFields(p.module, rtyp)
-    if field.loc.r == nil: internalError(p.config, e.info, "genRecordField 3 " & typeToString(ty))
-    addf(r, ".$1", [field.loc.r])
+    if field.loc.snippet == "" and rtyp != nil: fillObjectFields(p.module, rtyp)
+    if field.loc.snippet == "": internalError(p.config, e.info, "genRecordField 3 " & typeToString(ty))
+    r.add "."
+    r.add field.loc.snippet
     putIntoDest(p, d, e, r, a.storage)
+  r.freeze
 
 proc genInExprAux(p: BProc, e: PNode, a, b, d: var TLoc)
 
 proc genFieldCheck(p: BProc, e: PNode, obj: Rope, field: PSym) =
   var test, u, v: TLoc
-  for i in countup(1, sonsLen(e) - 1):
-    var it = e.sons[i]
+  for i in 1..<e.len:
+    var it = e[i]
     assert(it.kind in nkCallKinds)
-    assert(it.sons[0].kind == nkSym)
-    let op = it.sons[0].sym
-    if op.magic == mNot: it = it.sons[1]
-    let disc = it.sons[2].skipConv
+    assert(it[0].kind == nkSym)
+    let op = it[0].sym
+    if op.magic == mNot: it = it[1]
+    let disc = it[2].skipConv
     assert(disc.kind == nkSym)
-    initLoc(test, locNone, it, OnStack)
-    initLocExpr(p, it.sons[1], u)
-    initLoc(v, locExpr, disc, OnUnknown)
-    v.r = obj
-    v.r.add(".")
-    v.r.add(disc.sym.loc.r)
+    test = initLoc(locNone, it, OnStack)
+    u = initLocExpr(p, it[1])
+    v = initLoc(locExpr, disc, OnUnknown)
+    v.snippet = newRopeAppender()
+    v.snippet.add obj
+    v.snippet.add(".")
+    v.snippet.add(disc.sym.loc.snippet)
     genInExprAux(p, it, u, v, test)
-    let id = nodeTableTestOrSet(p.module.dataCache,
-                               newStrNode(nkStrLit, field.name.s), p.module.labels)
-    let strLit = if id == p.module.labels: genStringLiteralDataOnly(p.module, field.name.s, e.info)
-                 else: p.module.tmpBase & rope(id)
-    if op.magic == mNot:
-      linefmt(p, cpsStmts,
-              "if ($1) #raiseFieldError($2);$n",
-              rdLoc(test), genStringLiteralFromData(p.module, strLit, e.info))
+    var msg = ""
+    if optDeclaredLocs in p.config.globalOptions:
+      # xxx this should be controlled by a separate flag, and
+      # used for other similar defects so that location information is shown
+      # even without the expensive `--stacktrace`; binary size could be optimized
+      # by encoding the file names separately from `file(line:col)`, essentially
+      # passing around `TLineInfo` + the set of files in the project.
+      msg.add toFileLineCol(p.config, e.info) & " "
+    msg.add genFieldDefect(p.config, field.name.s, disc.sym)
+    var strLit = newRopeAppender()
+    genStringLiteral(p.module, newStrNode(nkStrLit, msg), strLit)
+
+    ## discriminant check
+    template fun(code) = linefmt(p, cpsStmts, code, [rdLoc(test)])
+    if op.magic == mNot: fun("if ($1) ") else: fun("if (!($1)) ")
+
+    ## call raiseFieldError2 on failure
+    var discIndex = newRopeAppender()
+    rdSetElemLoc(p.config, v, u.t, discIndex)
+    if optTinyRtti in p.config.globalOptions:
+      let base = disc.typ.skipTypes(abstractInst+{tyRange})
+      case base.kind
+      of tyEnum:
+        const code = "{ #raiseFieldErrorStr($1, $2); "
+        let toStrProc = getToStringProc(p.module.g.graph, base)
+        # XXX need to modify this logic for IC.
+        # need to analyze nkFieldCheckedExpr and marks procs "used" like range checks in dce
+        var toStr: TLoc = default(TLoc)
+        expr(p, newSymNode(toStrProc), toStr)
+        let enumStr = "$1($2)" % [rdLoc(toStr), rdLoc(v)]
+        linefmt(p, cpsStmts, code, [strLit, enumStr])
+      else:
+        const code = "{ #raiseFieldError2($1, (NI)$2); "
+        linefmt(p, cpsStmts, code, [strLit, discIndex])
+
     else:
-      linefmt(p, cpsStmts,
-              "if (!($1)) #raiseFieldError($2);$n",
-              rdLoc(test), genStringLiteralFromData(p.module, strLit, e.info))
+      # complication needed for signed types
+      let first = p.config.firstOrd(disc.sym.typ)
+      var firstLit = newRopeAppender()
+      int64Literal(cast[int](first), firstLit)
+      let discName = genTypeInfo(p.config, p.module, disc.sym.typ, e.info)
+      const code = "{ #raiseFieldError2($1, #reprDiscriminant(((NI)$2) + (NI)$3, $4)); "
+      linefmt(p, cpsStmts, code, [strLit, discIndex, firstLit, discName])
+
+    raiseInstr(p, p.s(cpsStmts))
+    linefmt p, cpsStmts, "}$n", []
 
 proc genCheckedRecordField(p: BProc, e: PNode, d: var TLoc) =
+  assert e[0].kind == nkDotExpr
   if optFieldCheck in p.options:
-    var a: TLoc
-    genRecordFieldAux(p, e.sons[0], d, a)
+    var a: TLoc = default(TLoc)
+    genRecordFieldAux(p, e[0], d, a)
     let ty = skipTypes(a.t, abstractInst + tyUserTypeClasses)
     var r = rdLoc(a)
-    let f = e.sons[0].sons[1].sym
+    let f = e[0][1].sym
     let field = lookupFieldAgain(p, ty, f, r)
-    if field.loc.r == nil: fillObjectFields(p.module, ty)
-    if field.loc.r == nil:
+    if field.loc.snippet == "": fillObjectFields(p.module, ty)
+    if field.loc.snippet == "":
       internalError(p.config, e.info, "genCheckedRecordField") # generate the checks:
     genFieldCheck(p, e, r, field)
-    add(r, ropecg(p.module, ".$1", field.loc.r))
-    putIntoDest(p, d, e.sons[0], r, a.storage)
+    r.add(".")
+    r.add field.loc.snippet
+    putIntoDest(p, d, e[0], r, a.storage)
+    r.freeze
   else:
-    genRecordField(p, e.sons[0], d)
+    genRecordField(p, e[0], d)
+
+proc genUncheckedArrayElem(p: BProc, n, x, y: PNode, d: var TLoc) =
+  var a = initLocExpr(p, x)
+  var b = initLocExpr(p, y)
+  d.inheritLocation(a)
+  putIntoDest(p, d, n, ropecg(p.module, "$1[$2]", [rdLoc(a), rdCharLoc(b)]),
+              a.storage)
 
 proc genArrayElem(p: BProc, n, x, y: PNode, d: var TLoc) =
-  var a, b: TLoc
-  initLocExpr(p, x, a)
-  initLocExpr(p, y, b)
+  var a = initLocExpr(p, x)
+  var b = initLocExpr(p, y)
   var ty = skipTypes(a.t, abstractVarRange + abstractPtrs + tyUserTypeClasses)
-  var first = intLiteral(firstOrd(p.config, ty))
+  var first = newRopeAppender()
+  intLiteral(firstOrd(p.config, ty), first)
   # emit range check:
-  if optBoundsCheck in p.options and tfUncheckedArray notin ty.flags:
+  if optBoundsCheck in p.options and ty.kind != tyUncheckedArray:
     if not isConstExpr(y):
       # semantic pass has already checked for const index expressions
-      if firstOrd(p.config, ty) == 0:
+      if firstOrd(p.config, ty) == 0 and lastOrd(p.config, ty) >= 0:
         if (firstOrd(p.config, b.t) < firstOrd(p.config, ty)) or (lastOrd(p.config, b.t) > lastOrd(p.config, ty)):
-          linefmt(p, cpsStmts, "if ((NU)($1) > (NU)($2)) #raiseIndexError();$n",
-                  rdCharLoc(b), intLiteral(lastOrd(p.config, ty)))
+          var last = newRopeAppender()
+          intLiteral(lastOrd(p.config, ty), last)
+          linefmt(p, cpsStmts, "if ((NU)($1) > (NU)($2)){ #raiseIndexError2($1, $2); ",
+                  [rdCharLoc(b), last])
+          raiseInstr(p, p.s(cpsStmts))
+          linefmt p, cpsStmts, "}$n", []
       else:
-        linefmt(p, cpsStmts, "if ($1 < $2 || $1 > $3) #raiseIndexError();$n",
-                rdCharLoc(b), first, intLiteral(lastOrd(p.config, ty)))
+        var last = newRopeAppender()
+        intLiteral(lastOrd(p.config, ty), last)
+        linefmt(p, cpsStmts, "if ($1 < $2 || $1 > $3){ #raiseIndexError3($1, $2, $3); ",
+                [rdCharLoc(b), first, last])
+        raiseInstr(p, p.s(cpsStmts))
+        linefmt p, cpsStmts, "}$n", []
+
     else:
       let idx = getOrdValue(y)
       if idx < firstOrd(p.config, ty) or idx > lastOrd(p.config, ty):
-        localError(p.config, x.info, "index out of bounds")
+        localError(p.config, x.info, formatErrorIndexBound(idx, firstOrd(p.config, ty), lastOrd(p.config, ty)))
   d.inheritLocation(a)
   putIntoDest(p, d, n,
-              ropecg(p.module, "$1[($2)- $3]", rdLoc(a), rdCharLoc(b), first), a.storage)
+              ropecg(p.module, "$1[($2)- $3]", [rdLoc(a), rdCharLoc(b), first]), a.storage)
 
 proc genCStringElem(p: BProc, n, x, y: PNode, d: var TLoc) =
-  var a, b: TLoc
-  initLocExpr(p, x, a)
-  initLocExpr(p, y, b)
-  var ty = skipTypes(a.t, abstractVarRange)
+  var a = initLocExpr(p, x)
+  var b = initLocExpr(p, y)
   inheritLocation(d, a)
   putIntoDest(p, d, n,
-              ropecg(p.module, "$1[$2]", rdLoc(a), rdCharLoc(b)), a.storage)
+              ropecg(p.module, "$1[$2]", [rdLoc(a), rdCharLoc(b)]), a.storage)
 
-proc genBoundsCheck(p: BProc; arr, a, b: TLoc) =
-  let ty = skipTypes(arr.t, abstractVarRange)
+proc genBoundsCheck(p: BProc; arr, a, b: TLoc; arrTyp: PType) =
+  let ty = arrTyp
   case ty.kind
   of tyOpenArray, tyVarargs:
-    linefmt(p, cpsStmts,
-      "if ($2-$1 != -1 && " &
-      "((NU)($1) >= (NU)($3Len_0) || (NU)($2) >= (NU)($3Len_0))) #raiseIndexError();$n",
-      rdLoc(a), rdLoc(b), rdLoc(arr))
-  of tyArray:
-    let first = intLiteral(firstOrd(p.config, ty))
-    if tfUncheckedArray notin ty.flags:
+    if reifiedOpenArray(arr.lode):
       linefmt(p, cpsStmts,
         "if ($2-$1 != -1 && " &
-        "($2-$1 < -1 || $1 < $3 || $1 > $4 || $2 < $3 || $2 > $4)) #raiseIndexError();$n",
-        rdCharLoc(a), rdCharLoc(b), first, intLiteral(lastOrd(p.config, ty)))
+        "($1 < 0 || $1 >= $3.Field1 || $2 < 0 || $2 >= $3.Field1)){ #raiseIndexError4($1, $2, $3.Field1); ",
+        [rdLoc(a), rdLoc(b), rdLoc(arr)])
+    else:
+      linefmt(p, cpsStmts,
+        "if ($2-$1 != -1 && ($1 < 0 || $1 >= $3Len_0 || $2 < 0 || $2 >= $3Len_0))" &
+        "{ #raiseIndexError4($1, $2, $3Len_0); ",
+        [rdLoc(a), rdLoc(b), rdLoc(arr)])
+    raiseInstr(p, p.s(cpsStmts))
+    linefmt p, cpsStmts, "}$n", []
+
+  of tyArray:
+    var first = newRopeAppender()
+    intLiteral(firstOrd(p.config, ty), first)
+    var last = newRopeAppender()
+    intLiteral(lastOrd(p.config, ty), last)
+    linefmt(p, cpsStmts,
+      "if ($2-$1 != -1 && " &
+      "($2-$1 < -1 || $1 < $3 || $1 > $4 || $2 < $3 || $2 > $4)){ #raiseIndexError(); ",
+      [rdCharLoc(a), rdCharLoc(b), first, last])
+
+    raiseInstr(p, p.s(cpsStmts))
+    linefmt p, cpsStmts, "}$n", []
+
   of tySequence, tyString:
     linefmt(p, cpsStmts,
       "if ($2-$1 != -1 && " &
-      "(!$3 || (NU)($1) >= (NU)($3->$4) || (NU)($2) >= (NU)($3->$4))) #raiseIndexError();$n",
-      rdLoc(a), rdLoc(b), rdLoc(arr), lenField(p))
+      "($1 < 0 || $1 >= $3 || $2 < 0 || $2 >= $3)){ #raiseIndexError4($1, $2, $3); ",
+      [rdLoc(a), rdLoc(b), lenExpr(p, arr)])
+    raiseInstr(p, p.s(cpsStmts))
+    linefmt p, cpsStmts, "}$n", []
+
   else: discard
 
 proc genOpenArrayElem(p: BProc, n, x, y: PNode, d: var TLoc) =
-  var a, b: TLoc
-  initLocExpr(p, x, a)
-  initLocExpr(p, y, b) # emit range check:
-  if optBoundsCheck in p.options:
-    linefmt(p, cpsStmts, "if ((NU)($1) >= (NU)($2Len_0)) #raiseIndexError();$n",
-            rdLoc(b), rdLoc(a)) # BUGFIX: ``>=`` and not ``>``!
-  inheritLocation(d, a)
-  putIntoDest(p, d, n,
-              ropecg(p.module, "$1[$2]", rdLoc(a), rdCharLoc(b)), a.storage)
+  var a = initLocExpr(p, x)
+  var b = initLocExpr(p, y)
+  if not reifiedOpenArray(x):
+    # emit range check:
+    if optBoundsCheck in p.options:
+      linefmt(p, cpsStmts, "if ($1 < 0 || $1 >= $2Len_0){ #raiseIndexError2($1,$2Len_0-1); ",
+              [rdCharLoc(b), rdLoc(a)]) # BUGFIX: ``>=`` and not ``>``!
+      raiseInstr(p, p.s(cpsStmts))
+      linefmt p, cpsStmts, "}$n", []
+
+    inheritLocation(d, a)
+    putIntoDest(p, d, n,
+                ropecg(p.module, "$1[$2]", [rdLoc(a), rdCharLoc(b)]), a.storage)
+  else:
+    if optBoundsCheck in p.options:
+      linefmt(p, cpsStmts, "if ($1 < 0 || $1 >= $2.Field1){ #raiseIndexError2($1,$2.Field1-1); ",
+              [rdCharLoc(b), rdLoc(a)]) # BUGFIX: ``>=`` and not ``>``!
+      raiseInstr(p, p.s(cpsStmts))
+      linefmt p, cpsStmts, "}$n", []
+
+    inheritLocation(d, a)
+    putIntoDest(p, d, n,
+                ropecg(p.module, "$1.Field0[$2]", [rdLoc(a), rdCharLoc(b)]), a.storage)
 
 proc genSeqElem(p: BProc, n, x, y: PNode, d: var TLoc) =
-  var a, b: TLoc
-  initLocExpr(p, x, a)
-  initLocExpr(p, y, b)
+  var a = initLocExpr(p, x)
+  var b = initLocExpr(p, y)
   var ty = skipTypes(a.t, abstractVarRange)
   if ty.kind in {tyRef, tyPtr}:
-    ty = skipTypes(ty.lastSon, abstractVarRange) # emit range check:
+    ty = skipTypes(ty.elementType, abstractVarRange)
+  # emit range check:
   if optBoundsCheck in p.options:
-    if ty.kind == tyString and (not defined(nimNoZeroTerminator) or optLaxStrings in p.options):
-      linefmt(p, cpsStmts,
-              "if (!$2 || (NU)($1) > (NU)($2->$3)) #raiseIndexError();$n",
-              rdLoc(b), rdLoc(a), lenField(p))
-    else:
-      linefmt(p, cpsStmts,
-              "if (!$2 || (NU)($1) >= (NU)($2->$3)) #raiseIndexError();$n",
-              rdLoc(b), rdLoc(a), lenField(p))
+    linefmt(p, cpsStmts,
+            "if ($1 < 0 || $1 >= $2){ #raiseIndexError2($1,$2-1); ",
+            [rdCharLoc(b), lenExpr(p, a)])
+    raiseInstr(p, p.s(cpsStmts))
+    linefmt p, cpsStmts, "}$n", []
+
   if d.k == locNone: d.storage = OnHeap
   if skipTypes(a.t, abstractVar).kind in {tyRef, tyPtr}:
-    a.r = ropecg(p.module, "(*$1)", a.r)
+    a.snippet = ropecg(p.module, "(*$1)", [a.snippet])
+
+  if lfPrepareForMutation in d.flags and ty.kind == tyString and
+      optSeqDestructors in p.config.globalOptions:
+    linefmt(p, cpsStmts, "#nimPrepareStrMutationV2($1);$n", [byRefLoc(p, a)])
   putIntoDest(p, d, n,
-              ropecg(p.module, "$1->data[$2]", rdLoc(a), rdCharLoc(b)), a.storage)
+              ropecg(p.module, "$1$3[$2]", [rdLoc(a), rdCharLoc(b), dataField(p)]), a.storage)
 
 proc genBracketExpr(p: BProc; n: PNode; d: var TLoc) =
-  var ty = skipTypes(n.sons[0].typ, abstractVarRange + tyUserTypeClasses)
-  if ty.kind in {tyRef, tyPtr}: ty = skipTypes(ty.lastSon, abstractVarRange)
+  var ty = skipTypes(n[0].typ, abstractVarRange + tyUserTypeClasses)
+  if ty.kind in {tyRef, tyPtr}: ty = skipTypes(ty.elementType, abstractVarRange)
   case ty.kind
-  of tyArray: genArrayElem(p, n, n.sons[0], n.sons[1], d)
-  of tyOpenArray, tyVarargs: genOpenArrayElem(p, n, n.sons[0], n.sons[1], d)
-  of tySequence, tyString: genSeqElem(p, n, n.sons[0], n.sons[1], d)
-  of tyCString: genCStringElem(p, n, n.sons[0], n.sons[1], d)
+  of tyUncheckedArray: genUncheckedArrayElem(p, n, n[0], n[1], d)
+  of tyArray: genArrayElem(p, n, n[0], n[1], d)
+  of tyOpenArray, tyVarargs: genOpenArrayElem(p, n, n[0], n[1], d)
+  of tySequence, tyString: genSeqElem(p, n, n[0], n[1], d)
+  of tyCstring: genCStringElem(p, n, n[0], n[1], d)
   of tyTuple: genTupleElem(p, n, d)
   else: internalError(p.config, n.info, "expr(nkBracketExpr, " & $ty.kind & ')')
+  discard getTypeDesc(p.module, n.typ)
+
+proc isSimpleExpr(n: PNode): bool =
+  # calls all the way down --> can stay expression based
+  case n.kind
+  of nkCallKinds, nkDotExpr, nkPar, nkTupleConstr,
+      nkObjConstr, nkBracket, nkCurly, nkHiddenDeref, nkDerefExpr, nkHiddenAddr,
+      nkHiddenStdConv, nkHiddenSubConv, nkConv, nkAddr:
+    for c in n:
+      if not isSimpleExpr(c): return false
+    result = true
+  of nkStmtListExpr:
+    for i in 0..<n.len-1:
+      if n[i].kind notin {nkCommentStmt, nkEmpty}: return false
+    result = isSimpleExpr(n.lastSon)
+  else:
+    result = n.isAtom
 
 proc genAndOr(p: BProc, e: PNode, d: var TLoc, m: TMagic) =
   # how to generate code?
@@ -962,60 +1161,87 @@ proc genAndOr(p: BProc, e: PNode, d: var TLoc, m: TMagic) =
   # tmp = a
   # end:
   # a = tmp
-  var
-    L: TLabel
-    tmp: TLoc
-  getTemp(p, e.typ, tmp)      # force it into a temp!
-  inc p.splitDecls
-  expr(p, e.sons[1], tmp)
-  L = getLabel(p)
-  if m == mOr:
-    lineF(p, cpsStmts, "if ($1) goto $2;$n", [rdLoc(tmp), L])
-  else:
-    lineF(p, cpsStmts, "if (!($1)) goto $2;$n", [rdLoc(tmp), L])
-  expr(p, e.sons[2], tmp)
-  fixLabel(p, L)
-  if d.k == locNone:
-    d = tmp
+  when false:
+    #if isSimpleExpr(e) and p.module.compileToCpp:
+    #getTemp(p, e.typ, tmpA)
+    #getTemp(p, e.typ, tmpB)
+    var tmpA = initLocExprSingleUse(p, e[1])
+    var tmpB = initLocExprSingleUse(p, e[2])
+    tmpB.k = locExpr
+    if m == mOr:
+      tmpB.snippet = "((" & rdLoc(tmpA) & ")||(" & rdLoc(tmpB) & "))"
+    else:
+      tmpB.snippet = "((" & rdLoc(tmpA) & ")&&(" & rdLoc(tmpB) & "))"
+    if d.k == locNone:
+      d = tmpB
+    else:
+      genAssignment(p, d, tmpB, {})
   else:
-    genAssignment(p, d, tmp, {}) # no need for deep copying
-  dec p.splitDecls
+    var
+      L: TLabel
+    var tmp: TLoc = getTemp(p, e.typ)      # force it into a temp!
+    inc p.splitDecls
+    expr(p, e[1], tmp)
+    L = getLabel(p)
+    if m == mOr:
+      lineF(p, cpsStmts, "if ($1) goto $2;$n", [rdLoc(tmp), L])
+    else:
+      lineF(p, cpsStmts, "if (!($1)) goto $2;$n", [rdLoc(tmp), L])
+    expr(p, e[2], tmp)
+    fixLabel(p, L)
+    if d.k == locNone:
+      d = tmp
+    else:
+      genAssignment(p, d, tmp, {}) # no need for deep copying
+    dec p.splitDecls
 
 proc genEcho(p: BProc, n: PNode) =
-  # this unusal way of implementing it ensures that e.g. ``echo("hallo", 45)``
+  # this unusual way of implementing it ensures that e.g. ``echo("hallo", 45)``
   # is threadsafe.
   internalAssert p.config, n.kind == nkBracket
   if p.config.target.targetOS == osGenode:
-    # bypass libc and print directly to the Genode LOG session
-    var args: Rope = nil
+    # echo directly to the Genode LOG session
+    var args: Rope = ""
     var a: TLoc
-    for it in n.sons:
+    for i, it in n.sons:
       if it.skipConv.kind == nkNilLit:
-        add(args, ", \"\"")
-      else:
-        initLocExpr(p, it, a)
-        addf(args, ", $1? ($1)->data:\"\"", [rdLoc(a)])
+        args.add(", \"\"")
+      elif n.len != 0:
+        a = initLocExpr(p, it)
+        if i > 0:
+          args.add(", ")
+        case detectStrVersion(p.module)
+        of 2:
+          args.add(ropecg(p.module, "Genode::Cstring($1.p->data, $1.len)", [a.rdLoc]))
+        else:
+          args.add(ropecg(p.module, "Genode::Cstring($1->data, $1->len)", [a.rdLoc]))
     p.module.includeHeader("<base/log.h>")
-    linefmt(p, cpsStmts, """Genode::log(""$1);$n""", args)
+    p.module.includeHeader("<util/string.h>")
+    linefmt(p, cpsStmts, """Genode::log($1);$n""", [args])
   else:
     if n.len == 0:
-      linefmt(p, cpsStmts, "#echoBinSafe(NIM_NIL, $1);$n", n.len.rope)
+      linefmt(p, cpsStmts, "#echoBinSafe(NIM_NIL, $1);$n", [n.len])
     else:
-      var a: TLoc
-      initLocExpr(p, n, a)
-      linefmt(p, cpsStmts, "#echoBinSafe($1, $2);$n", a.rdLoc, n.len.rope)
+      var a: TLoc = initLocExpr(p, n)
+      linefmt(p, cpsStmts, "#echoBinSafe($1, $2);$n", [a.rdLoc, n.len])
     when false:
       p.module.includeHeader("<stdio.h>")
       linefmt(p, cpsStmts, "printf($1$2);$n",
-              makeCString(repeat("%s", n.len) & "\L"), args)
-      linefmt(p, cpsStmts, "fflush(stdout);$n")
+              makeCString(repeat("%s", n.len) & "\L"), [args])
+      linefmt(p, cpsStmts, "fflush(stdout);$n", [])
 
 proc gcUsage(conf: ConfigRef; n: PNode) =
   if conf.selectedGC == gcNone: message(conf, n.info, warnGcMem, n.renderTree)
 
+proc strLoc(p: BProc; d: TLoc): Rope =
+  if optSeqDestructors in p.config.globalOptions:
+    result = byRefLoc(p, d)
+  else:
+    result = rdLoc(d)
+
 proc genStrConcat(p: BProc, e: PNode, d: var TLoc) =
   #   <Nim code>
-  #   s = 'Hello ' & name & ', how do you feel?' & 'z'
+  #   s = "Hello " & name & ", how do you feel?" & 'z'
   #
   #   <generated C code>
   #  {
@@ -1030,25 +1256,26 @@ proc genStrConcat(p: BProc, e: PNode, d: var TLoc) =
   #    appendChar(tmp0, 'z');
   #    asgn(s, tmp0);
   #  }
-  var a, tmp: TLoc
-  getTemp(p, e.typ, tmp)
+  var a: TLoc
+  var tmp: TLoc = getTemp(p, e.typ)
   var L = 0
-  var appends: Rope = nil
-  var lens: Rope = nil
-  for i in countup(0, sonsLen(e) - 2):
+  var appends: Rope = ""
+  var lens: Rope = ""
+  for i in 0..<e.len - 1:
     # compute the length expression:
-    initLocExpr(p, e.sons[i + 1], a)
-    if skipTypes(e.sons[i + 1].typ, abstractVarRange).kind == tyChar:
+    a = initLocExpr(p, e[i + 1])
+    if skipTypes(e[i + 1].typ, abstractVarRange).kind == tyChar:
       inc(L)
-      add(appends, ropecg(p.module, "#appendChar($1, $2);$n", tmp.r, rdLoc(a)))
+      appends.add(ropecg(p.module, "#appendChar($1, $2);$n", [strLoc(p, tmp), rdLoc(a)]))
     else:
-      if e.sons[i + 1].kind in {nkStrLit..nkTripleStrLit}:
-        inc(L, len(e.sons[i + 1].strVal))
+      if e[i + 1].kind in {nkStrLit..nkTripleStrLit}:
+        inc(L, e[i + 1].strVal.len)
       else:
-        addf(lens, "($1 ? $1->$2 : 0) + ", [rdLoc(a), lenField(p)])
-      add(appends, ropecg(p.module, "#appendString($1, $2);$n", tmp.r, rdLoc(a)))
-  linefmt(p, cpsStmts, "$1 = #rawNewString($2$3);$n", tmp.r, lens, rope(L))
-  add(p.s(cpsStmts), appends)
+        lens.add(lenExpr(p, a))
+        lens.add(" + ")
+      appends.add(ropecg(p.module, "#appendString($1, $2);$n", [strLoc(p, tmp), rdLoc(a)]))
+  linefmt(p, cpsStmts, "$1 = #rawNewString($2$3);$n", [tmp.snippet, lens, L])
+  p.s(cpsStmts).add appends
   if d.k == locNone:
     d = tmp
   else:
@@ -1057,7 +1284,7 @@ proc genStrConcat(p: BProc, e: PNode, d: var TLoc) =
 
 proc genStrAppend(p: BProc, e: PNode, d: var TLoc) =
   #  <Nim code>
-  #  s &= 'Hello ' & name & ', how do you feel?' & 'z'
+  #  s &= "Hello " & name & ", how do you feel?" & 'z'
   #  // BUG: what if s is on the left side too?
   #  <generated C code>
   #  {
@@ -1068,158 +1295,250 @@ proc genStrAppend(p: BProc, e: PNode, d: var TLoc) =
   #    appendChar(s, 'z');
   #  }
   var
-    a, dest: TLoc
-    appends, lens: Rope
+    a, call: TLoc
+    appends, lens: Rope = ""
   assert(d.k == locNone)
   var L = 0
-  initLocExpr(p, e.sons[1], dest)
-  for i in countup(0, sonsLen(e) - 3):
+  var dest = initLocExpr(p, e[1])
+  for i in 0..<e.len - 2:
     # compute the length expression:
-    initLocExpr(p, e.sons[i + 2], a)
-    if skipTypes(e.sons[i + 2].typ, abstractVarRange).kind == tyChar:
+    a = initLocExpr(p, e[i + 2])
+    if skipTypes(e[i + 2].typ, abstractVarRange).kind == tyChar:
       inc(L)
-      add(appends, ropecg(p.module, "#appendChar($1, $2);$n",
-                        rdLoc(dest), rdLoc(a)))
+      appends.add(ropecg(p.module, "#appendChar($1, $2);$n",
+                        [strLoc(p, dest), rdLoc(a)]))
     else:
-      if e.sons[i + 2].kind in {nkStrLit..nkTripleStrLit}:
-        inc(L, len(e.sons[i + 2].strVal))
+      if e[i + 2].kind in {nkStrLit..nkTripleStrLit}:
+        inc(L, e[i + 2].strVal.len)
       else:
-        addf(lens, "($1 ? $1->$2 : 0) + ", [rdLoc(a), lenField(p)])
-      add(appends, ropecg(p.module, "#appendString($1, $2);$n",
-                        rdLoc(dest), rdLoc(a)))
-  linefmt(p, cpsStmts, "$1 = #resizeString($1, $2$3);$n",
-          rdLoc(dest), lens, rope(L))
-  add(p.s(cpsStmts), appends)
-  gcUsage(p.config, e)
+        lens.add(lenExpr(p, a))
+        lens.add(" + ")
+      appends.add(ropecg(p.module, "#appendString($1, $2);$n",
+                        [strLoc(p, dest), rdLoc(a)]))
+  if optSeqDestructors in p.config.globalOptions:
+    linefmt(p, cpsStmts, "#prepareAdd($1, $2$3);$n",
+            [byRefLoc(p, dest), lens, L])
+  else:
+    call = initLoc(locCall, e, OnHeap)
+    call.snippet = ropecg(p.module, "#resizeString($1, $2$3)", [rdLoc(dest), lens, L])
+    genAssignment(p, dest, call, {})
+    gcUsage(p.config, e)
+  p.s(cpsStmts).add appends
 
 proc genSeqElemAppend(p: BProc, e: PNode, d: var TLoc) =
   # seq &= x  -->
   #    seq = (typeof seq) incrSeq(&seq->Sup, sizeof(x));
   #    seq->data[seq->len-1] = x;
-  let seqAppendPattern = if not p.module.compileToCpp:
-                           "$1 = ($2) #incrSeqV3(&($1)->Sup, $3);$n"
-                         else:
-                           "$1 = ($2) #incrSeqV3($1, $3);$n"
-  var a, b, dest, tmpL: TLoc
-  initLocExpr(p, e.sons[1], a)
-  initLocExpr(p, e.sons[2], b)
-  let seqType = skipTypes(e.sons[1].typ, {tyVar})
-  lineCg(p, cpsStmts, seqAppendPattern, [
-      rdLoc(a),
-      getTypeDesc(p.module, e.sons[1].typ),
-      genTypeInfo(p.module, seqType, e.info)])
+  var a = initLocExpr(p, e[1])
+  var b = initLocExpr(p, e[2])
+  let seqType = skipTypes(e[1].typ, {tyVar})
+  var call = initLoc(locCall, e, OnHeap)
+  if not p.module.compileToCpp:
+    const seqAppendPattern = "($2) #incrSeqV3((TGenericSeq*)($1), $3)"
+    call.snippet = ropecg(p.module, seqAppendPattern, [rdLoc(a),
+      getTypeDesc(p.module, e[1].typ),
+      genTypeInfoV1(p.module, seqType, e.info)])
+  else:
+    const seqAppendPattern = "($2) #incrSeqV3($1, $3)"
+    call.snippet = ropecg(p.module, seqAppendPattern, [rdLoc(a),
+      getTypeDesc(p.module, e[1].typ),
+      genTypeInfoV1(p.module, seqType, e.info)])
+  # emit the write barrier if required, but we can always move here, so
+  # use 'genRefAssign' for the seq.
+  genRefAssign(p, a, call)
   #if bt != b.t:
   #  echo "YES ", e.info, " new: ", typeToString(bt), " old: ", typeToString(b.t)
-  initLoc(dest, locExpr, e.sons[2], OnHeap)
-  getIntTemp(p, tmpL)
-  lineCg(p, cpsStmts, "$1 = $2->$3++;$n", tmpL.r, rdLoc(a), lenField(p))
-  dest.r = ropecg(p.module, "$1->data[$2]", rdLoc(a), tmpL.r)
-  genAssignment(p, dest, b, {needToCopy, afDestIsNil})
+  var dest = initLoc(locExpr, e[2], OnHeap)
+  var tmpL = getIntTemp(p)
+  lineCg(p, cpsStmts, "$1 = $2->$3++;$n", [tmpL.snippet, rdLoc(a), lenField(p)])
+  dest.snippet = ropecg(p.module, "$1$3[$2]", [rdLoc(a), tmpL.snippet, dataField(p)])
+  genAssignment(p, dest, b, {needToCopy})
   gcUsage(p.config, e)
 
-proc genReset(p: BProc, n: PNode) =
-  var a: TLoc
-  initLocExpr(p, n.sons[1], a)
-  linefmt(p, cpsStmts, "#genericReset((void*)$1, $2);$n",
-          addrLoc(p.config, a),
-          genTypeInfo(p.module, skipTypes(a.t, {tyVar}), n.info))
+proc genDefault(p: BProc; n: PNode; d: var TLoc) =
+  if d.k == locNone: d = getTemp(p, n.typ, needsInit=true)
+  else: resetLoc(p, d)
 
-proc rawGenNew(p: BProc, a: TLoc, sizeExpr: Rope) =
+proc rawGenNew(p: BProc, a: var TLoc, sizeExpr: Rope; needsInit: bool) =
   var sizeExpr = sizeExpr
   let typ = a.t
-  var b: TLoc
-  initLoc(b, locExpr, a.lode, OnHeap)
-  let refType = typ.skipTypes(abstractInst)
+  var b: TLoc = initLoc(locExpr, a.lode, OnHeap)
+  let refType = typ.skipTypes(abstractInstOwned)
   assert refType.kind == tyRef
-  let bt = refType.lastSon
-  if sizeExpr.isNil:
-    sizeExpr = "sizeof($1)" %
-        [getTypeDesc(p.module, bt)]
-  let args = [getTypeDesc(p.module, typ),
-              genTypeInfo(p.module, typ, a.lode.info),
-              sizeExpr]
-  if a.storage == OnHeap and usesNativeGC(p.config):
-    # use newObjRC1 as an optimization
-    if canFormAcycle(a.t):
-      linefmt(p, cpsStmts, "if ($1) { #nimGCunrefRC1($1); $1 = NIM_NIL; }$n", a.rdLoc)
-    else:
-      linefmt(p, cpsStmts, "if ($1) { #nimGCunrefNoCycle($1); $1 = NIM_NIL; }$n", a.rdLoc)
-    b.r = ropecg(p.module, "($1) #newObjRC1($2, $3)", args)
-    linefmt(p, cpsStmts, "$1 = $2;$n", a.rdLoc, b.rdLoc)
-  else:
-    b.r = ropecg(p.module, "($1) #newObj($2, $3)", args)
-    genAssignment(p, a, b, {})  # set the object type:
-  genObjectInit(p, cpsStmts, bt, a, false)
+  let bt = refType.elementType
+  if sizeExpr == "":
+    sizeExpr = "sizeof($1)" % [getTypeDesc(p.module, bt)]
+
+  if optTinyRtti in p.config.globalOptions:
+    if needsInit:
+      b.snippet = ropecg(p.module, "($1) #nimNewObj($2, NIM_ALIGNOF($3))",
+          [getTypeDesc(p.module, typ), sizeExpr, getTypeDesc(p.module, bt)])
+    else:
+      b.snippet = ropecg(p.module, "($1) #nimNewObjUninit($2, NIM_ALIGNOF($3))",
+          [getTypeDesc(p.module, typ), sizeExpr, getTypeDesc(p.module, bt)])
+    genAssignment(p, a, b, {})
+  else:
+    let ti = genTypeInfoV1(p.module, typ, a.lode.info)
+    let op = getAttachedOp(p.module.g.graph, bt, attachedDestructor)
+    if op != nil and not isTrivialProc(p.module.g.graph, op):
+      # the prototype of a destructor is ``=destroy(x: var T)`` and that of a
+      # finalizer is: ``proc (x: ref T) {.nimcall.}``. We need to check the calling
+      # convention at least:
+      if op.typ == nil or op.typ.callConv != ccNimCall:
+        localError(p.module.config, a.lode.info,
+          "the destructor that is turned into a finalizer needs " &
+          "to have the 'nimcall' calling convention")
+      var f: TLoc = initLocExpr(p, newSymNode(op))
+      p.module.s[cfsTypeInit3].addf("$1->finalizer = (void*)$2;$n", [ti, rdLoc(f)])
+
+    if a.storage == OnHeap and usesWriteBarrier(p.config):
+      if canFormAcycle(p.module.g.graph, a.t):
+        linefmt(p, cpsStmts, "if ($1) { #nimGCunrefRC1($1); $1 = NIM_NIL; }$n", [a.rdLoc])
+      else:
+        linefmt(p, cpsStmts, "if ($1) { #nimGCunrefNoCycle($1); $1 = NIM_NIL; }$n", [a.rdLoc])
+      if p.config.selectedGC == gcGo:
+        # newObjRC1() would clash with unsureAsgnRef() - which is used by gcGo to
+        # implement the write barrier
+        b.snippet = ropecg(p.module, "($1) #newObj($2, $3)", [getTypeDesc(p.module, typ), ti, sizeExpr])
+        linefmt(p, cpsStmts, "#unsureAsgnRef((void**) $1, $2);$n",
+                [addrLoc(p.config, a), b.rdLoc])
+      else:
+        # use newObjRC1 as an optimization
+        b.snippet = ropecg(p.module, "($1) #newObjRC1($2, $3)", [getTypeDesc(p.module, typ), ti, sizeExpr])
+        linefmt(p, cpsStmts, "$1 = $2;$n", [a.rdLoc, b.rdLoc])
+    else:
+      b.snippet = ropecg(p.module, "($1) #newObj($2, $3)", [getTypeDesc(p.module, typ), ti, sizeExpr])
+      genAssignment(p, a, b, {})
+  # set the object type:
+  genObjectInit(p, cpsStmts, bt, a, constructRefObj)
 
 proc genNew(p: BProc, e: PNode) =
-  var a: TLoc
-  initLocExpr(p, e.sons[1], a)
+  var a: TLoc = initLocExpr(p, e[1])
   # 'genNew' also handles 'unsafeNew':
   if e.len == 3:
-    var se: TLoc
-    initLocExpr(p, e.sons[2], se)
-    rawGenNew(p, a, se.rdLoc)
+    var se: TLoc = initLocExpr(p, e[2])
+    rawGenNew(p, a, se.rdLoc, needsInit = true)
   else:
-    rawGenNew(p, a, nil)
+    rawGenNew(p, a, "", needsInit = true)
   gcUsage(p.config, e)
 
-proc genNewSeqAux(p: BProc, dest: TLoc, length: Rope) =
+proc genNewSeqAux(p: BProc, dest: TLoc, length: Rope; lenIsZero: bool) =
   let seqtype = skipTypes(dest.t, abstractVarRange)
-  let args = [getTypeDesc(p.module, seqtype),
-              genTypeInfo(p.module, seqtype, dest.lode.info), length]
-  var call: TLoc
-  initLoc(call, locExpr, dest.lode, OnHeap)
-  if dest.storage == OnHeap and usesNativeGC(p.config):
-    if canFormAcycle(dest.t):
-      linefmt(p, cpsStmts, "if ($1) { #nimGCunrefRC1($1); $1 = NIM_NIL; }$n", dest.rdLoc)
-    else:
-      linefmt(p, cpsStmts, "if ($1) { #nimGCunrefNoCycle($1); $1 = NIM_NIL; }$n", dest.rdLoc)
-    call.r = ropecg(p.module, "($1) #newSeqRC1($2, $3)", args)
-    linefmt(p, cpsStmts, "$1 = $2;$n", dest.rdLoc, call.rdLoc)
-  else:
-    call.r = ropecg(p.module, "($1) #newSeq($2, $3)", args)
+  var call: TLoc = initLoc(locExpr, dest.lode, OnHeap)
+  if dest.storage == OnHeap and usesWriteBarrier(p.config):
+    if canFormAcycle(p.module.g.graph, dest.t):
+      linefmt(p, cpsStmts, "if ($1) { #nimGCunrefRC1($1); $1 = NIM_NIL; }$n", [dest.rdLoc])
+    else:
+      linefmt(p, cpsStmts, "if ($1) { #nimGCunrefNoCycle($1); $1 = NIM_NIL; }$n", [dest.rdLoc])
+    if not lenIsZero:
+      if p.config.selectedGC == gcGo:
+        # we need the write barrier
+        call.snippet = ropecg(p.module, "($1) #newSeq($2, $3)", [getTypeDesc(p.module, seqtype),
+              genTypeInfoV1(p.module, seqtype, dest.lode.info), length])
+        linefmt(p, cpsStmts, "#unsureAsgnRef((void**) $1, $2);$n", [addrLoc(p.config, dest), call.rdLoc])
+      else:
+        call.snippet = ropecg(p.module, "($1) #newSeqRC1($2, $3)", [getTypeDesc(p.module, seqtype),
+              genTypeInfoV1(p.module, seqtype, dest.lode.info), length])
+        linefmt(p, cpsStmts, "$1 = $2;$n", [dest.rdLoc, call.rdLoc])
+  else:
+    if lenIsZero:
+      call.snippet = rope"NIM_NIL"
+    else:
+      call.snippet = ropecg(p.module, "($1) #newSeq($2, $3)", [getTypeDesc(p.module, seqtype),
+              genTypeInfoV1(p.module, seqtype, dest.lode.info), length])
     genAssignment(p, dest, call, {})
 
 proc genNewSeq(p: BProc, e: PNode) =
-  var a, b: TLoc
-  initLocExpr(p, e.sons[1], a)
-  initLocExpr(p, e.sons[2], b)
-  genNewSeqAux(p, a, b.rdLoc)
-  gcUsage(p.config, e)
+  var a = initLocExpr(p, e[1])
+  var b = initLocExpr(p, e[2])
+  if optSeqDestructors in p.config.globalOptions:
+    let seqtype = skipTypes(e[1].typ, abstractVarRange)
+    linefmt(p, cpsStmts, "$1.len = $2; $1.p = ($4*) #newSeqPayload($2, sizeof($3), NIM_ALIGNOF($3));$n",
+      [a.rdLoc, b.rdLoc,
+       getTypeDesc(p.module, seqtype.elementType),
+       getSeqPayloadType(p.module, seqtype)])
+  else:
+    let lenIsZero = e[2].kind == nkIntLit and e[2].intVal == 0
+    genNewSeqAux(p, a, b.rdLoc, lenIsZero)
+    gcUsage(p.config, e)
 
 proc genNewSeqOfCap(p: BProc; e: PNode; d: var TLoc) =
   let seqtype = skipTypes(e.typ, abstractVarRange)
-  var a: TLoc
-  initLocExpr(p, e.sons[1], a)
-  putIntoDest(p, d, e, ropecg(p.module,
-              "($1)#nimNewSeqOfCap($2, $3)", [
-              getTypeDesc(p.module, seqtype),
-              genTypeInfo(p.module, seqtype, e.info), a.rdLoc]))
-  gcUsage(p.config, e)
+  var a: TLoc = initLocExpr(p, e[1])
+  if optSeqDestructors in p.config.globalOptions:
+    if d.k == locNone: d = getTemp(p, e.typ, needsInit=false)
+    linefmt(p, cpsStmts, "$1.len = 0; $1.p = ($4*) #newSeqPayloadUninit($2, sizeof($3), NIM_ALIGNOF($3));$n",
+      [d.rdLoc, a.rdLoc, getTypeDesc(p.module, seqtype.elementType),
+      getSeqPayloadType(p.module, seqtype),
+    ])
+  else:
+    if d.k == locNone: d = getTemp(p, e.typ, needsInit=false) # bug #22560
+    putIntoDest(p, d, e, ropecg(p.module,
+                "($1)#nimNewSeqOfCap($2, $3)", [
+                getTypeDesc(p.module, seqtype),
+                genTypeInfoV1(p.module, seqtype, e.info), a.rdLoc]))
+    gcUsage(p.config, e)
+
+proc rawConstExpr(p: BProc, n: PNode; d: var TLoc) =
+  let t = n.typ
+  discard getTypeDesc(p.module, t) # so that any fields are initialized
+  let id = nodeTableTestOrSet(p.module.dataCache, n, p.module.labels)
+  fillLoc(d, locData, n, p.module.tmpBase & rope(id), OnStatic)
+  if id == p.module.labels:
+    # expression not found in the cache:
+    inc(p.module.labels)
+    var data = "static NIM_CONST $1 $2 = " % [getTypeDesc(p.module, t), d.snippet]
+    # bug #23627; when generating const object fields, it's likely that
+    # we need to generate type infos for the object, which may be an object with
+    # custom hooks. We need to generate potential consts in the hooks first.
+    genBracedInit(p, n, isConst = true, t, data)
+    data.addf(";$n", [])
+    p.module.s[cfsData].add data
 
-proc genConstExpr(p: BProc, n: PNode): Rope
 proc handleConstExpr(p: BProc, n: PNode, d: var TLoc): bool =
   if d.k == locNone and n.len > ord(n.kind == nkObjConstr) and n.isDeepConstExpr:
-    let t = n.typ
-    discard getTypeDesc(p.module, t) # so that any fields are initialized
-    let id = nodeTableTestOrSet(p.module.dataCache, n, p.module.labels)
-    fillLoc(d, locData, n, p.module.tmpBase & rope(id), OnStatic)
-    if id == p.module.labels:
-      # expression not found in the cache:
-      inc(p.module.labels)
-      addf(p.module.s[cfsData], "NIM_CONST $1 $2 = $3;$n",
-           [getTypeDesc(p.module, t), d.r, genConstExpr(p, n)])
+    rawConstExpr(p, n, d)
     result = true
   else:
     result = false
 
+
+proc genFieldObjConstr(p: BProc; ty: PType; useTemp, isRef: bool; nField, val, check: PNode; d: var TLoc; r: Rope; info: TLineInfo) =
+  var tmp2 = TLoc(snippet: r)
+  let field = lookupFieldAgain(p, ty, nField.sym, tmp2.snippet)
+  if field.loc.snippet == "": fillObjectFields(p.module, ty)
+  if field.loc.snippet == "": internalError(p.config, info, "genFieldObjConstr")
+  if check != nil and optFieldCheck in p.options:
+    genFieldCheck(p, check, r, field)
+  tmp2.snippet.add(".")
+  tmp2.snippet.add(field.loc.snippet)
+  if useTemp:
+    tmp2.k = locTemp
+    tmp2.storage = if isRef: OnHeap else: OnStack
+  else:
+    tmp2.k = d.k
+    tmp2.storage = if isRef: OnHeap else: d.storage
+  tmp2.lode = val
+  if nField.typ.skipTypes(abstractVar).kind in {tyOpenArray, tyVarargs}:
+    var tmp3 = getTemp(p, val.typ)
+    expr(p, val, tmp3)
+    genOpenArrayConv(p, tmp2, tmp3, {})
+  else:
+    expr(p, val, tmp2)
+
 proc genObjConstr(p: BProc, e: PNode, d: var TLoc) =
-  #echo rendertree e, " ", e.isDeepConstExpr
   # inheritance in C++ does not allow struct initialization so
   # we skip this step here:
-  if not p.module.compileToCpp:
+  if not p.module.compileToCpp and optSeqDestructors notin p.config.globalOptions:
+    # disabled optimization: it is wrong for C++ and now also
+    # causes trouble for --gc:arc, see bug #13240
+    #[
+      var box: seq[Thing]
+      for i in 0..3:
+        box.add Thing(s1: "121") # pass by sink can mutate Thing.
+    ]#
     if handleConstExpr(p, e, d): return
-  var t = e.typ.skipTypes(abstractInst)
+  var t = e.typ.skipTypes(abstractInstOwned)
   let isRef = t.kind == tyRef
 
   # check if we need to construct the object in a temporary
@@ -1228,42 +1547,33 @@ proc genObjConstr(p: BProc, e: PNode, d: var TLoc) =
         (d.k notin {locTemp,locLocalVar,locGlobalVar,locParam,locField}) or
         (isPartOf(d.lode, e) != arNo)
 
-  var tmp: TLoc
+  var tmp: TLoc = default(TLoc)
   var r: Rope
+  let needsZeroMem = p.config.selectedGC notin {gcArc, gcAtomicArc, gcOrc} or nfAllFieldsSet notin e.flags
   if useTemp:
-    getTemp(p, t, tmp)
+    tmp = getTemp(p, t)
     r = rdLoc(tmp)
     if isRef:
-      rawGenNew(p, tmp, nil)
-      t = t.lastSon.skipTypes(abstractInst)
+      rawGenNew(p, tmp, "", needsInit = nfAllFieldsSet notin e.flags)
+      t = t.elementType.skipTypes(abstractInstOwned)
       r = "(*$1)" % [r]
       gcUsage(p.config, e)
-    else:
+    elif needsZeroMem:
       constructLoc(p, tmp)
+    else:
+      genObjectInit(p, cpsStmts, t, tmp, constructObj)
   else:
-    resetLoc(p, d)
+    if needsZeroMem: resetLoc(p, d)
+    else: genObjectInit(p, cpsStmts, d.t, d, if isRef: constructRefObj else: constructObj)
     r = rdLoc(d)
   discard getTypeDesc(p.module, t)
   let ty = getUniqueType(t)
-  for i in 1 ..< e.len:
-    let it = e.sons[i]
-    var tmp2: TLoc
-    tmp2.r = r
-    let field = lookupFieldAgain(p, ty, it.sons[0].sym, tmp2.r)
-    if field.loc.r == nil: fillObjectFields(p.module, ty)
-    if field.loc.r == nil: internalError(p.config, e.info, "genObjConstr")
-    if it.len == 3 and optFieldCheck in p.options:
-      genFieldCheck(p, it.sons[2], r, field)
-    add(tmp2.r, ".")
-    add(tmp2.r, field.loc.r)
-    if useTemp:
-      tmp2.k = locTemp
-      tmp2.storage = if isRef: OnHeap else: OnStack
-    else:
-      tmp2.k = d.k
-      tmp2.storage = if isRef: OnHeap else: d.storage
-    tmp2.lode = it.sons[1]
-    expr(p, it.sons[1], tmp2)
+  for i in 1..<e.len:
+    var check: PNode = nil
+    if e[i].len == 3 and optFieldCheck in p.options:
+      check = e[i][2]
+    genFieldObjConstr(p, ty, useTemp, isRef, e[i][0], e[i][1], check, d, r, e.info)
+
   if useTemp:
     if d.k == locNone:
       d = tmp
@@ -1271,23 +1581,36 @@ proc genObjConstr(p: BProc, e: PNode, d: var TLoc) =
       genAssignment(p, d, tmp, {})
 
 proc lhsDoesAlias(a, b: PNode): bool =
+  result = false
   for y in b:
     if isPartOf(a, y) != arNo: return true
 
 proc genSeqConstr(p: BProc, n: PNode, d: var TLoc) =
-  var arr, tmp: TLoc
+  var arr: TLoc
+  var tmp: TLoc = default(TLoc)
   # bug #668
   let doesAlias = lhsDoesAlias(d.lode, n)
   let dest = if doesAlias: addr(tmp) else: addr(d)
   if doesAlias:
-    getTemp(p, n.typ, tmp)
+    tmp = getTemp(p, n.typ)
   elif d.k == locNone:
-    getTemp(p, n.typ, d)
-  # generate call to newSeq before adding the elements per hand:
-  genNewSeqAux(p, dest[], intLiteral(sonsLen(n)))
-  for i in countup(0, sonsLen(n) - 1):
-    initLoc(arr, locExpr, n[i], OnHeap)
-    arr.r = ropecg(p.module, "$1->data[$2]", rdLoc(dest[]), intLiteral(i))
+    d = getTemp(p, n.typ)
+
+  var lit = newRopeAppender()
+  intLiteral(n.len, lit)
+  if optSeqDestructors in p.config.globalOptions:
+    let seqtype = n.typ
+    linefmt(p, cpsStmts, "$1.len = $2; $1.p = ($4*) #newSeqPayload($2, sizeof($3), NIM_ALIGNOF($3));$n",
+      [rdLoc dest[], lit, getTypeDesc(p.module, seqtype.elementType),
+      getSeqPayloadType(p.module, seqtype)])
+  else:
+    # generate call to newSeq before adding the elements per hand:
+    genNewSeqAux(p, dest[], lit, n.len == 0)
+  for i in 0..<n.len:
+    arr = initLoc(locExpr, n[i], OnHeap)
+    var lit = newRopeAppender()
+    intLiteral(i, lit)
+    arr.snippet = ropecg(p.module, "$1$3[$2]", [rdLoc(dest[]), lit, dataField(p)])
     arr.storage = OnHeap            # we know that sequences are on the heap
     expr(p, n[i], arr)
   gcUsage(p.config, n)
@@ -1298,110 +1621,129 @@ proc genSeqConstr(p: BProc, n: PNode, d: var TLoc) =
       genAssignment(p, d, tmp, {})
 
 proc genArrToSeq(p: BProc, n: PNode, d: var TLoc) =
-  var elem, a, arr: TLoc
-  if n.sons[1].kind == nkBracket:
-    n.sons[1].typ = n.typ
-    genSeqConstr(p, n.sons[1], d)
+  var elem, arr: TLoc
+  if n[1].kind == nkBracket:
+    n[1].typ = n.typ
+    genSeqConstr(p, n[1], d)
     return
   if d.k == locNone:
-    getTemp(p, n.typ, d)
+    d = getTemp(p, n.typ)
+  var a = initLocExpr(p, n[1])
   # generate call to newSeq before adding the elements per hand:
-  let L = int(lengthOrd(p.config, n.sons[1].typ))
-  genNewSeqAux(p, d, intLiteral(L))
-  initLocExpr(p, n.sons[1], a)
+  let L = toInt(lengthOrd(p.config, n[1].typ))
+  if optSeqDestructors in p.config.globalOptions:
+    let seqtype = n.typ
+    linefmt(p, cpsStmts, "$1.len = $2; $1.p = ($4*) #newSeqPayload($2, sizeof($3), NIM_ALIGNOF($3));$n",
+      [rdLoc d, L, getTypeDesc(p.module, seqtype.elementType),
+      getSeqPayloadType(p.module, seqtype)])
+  else:
+    var lit = newRopeAppender()
+    intLiteral(L, lit)
+    genNewSeqAux(p, d, lit, L == 0)
   # bug #5007; do not produce excessive C source code:
   if L < 10:
-    for i in countup(0, L - 1):
-      initLoc(elem, locExpr, lodeTyp elemType(skipTypes(n.typ, abstractInst)), OnHeap)
-      elem.r = ropecg(p.module, "$1->data[$2]", rdLoc(d), intLiteral(i))
+    for i in 0..<L:
+      elem = initLoc(locExpr, lodeTyp elemType(skipTypes(n.typ, abstractInst)), OnHeap)
+      var lit = newRopeAppender()
+      intLiteral(i, lit)
+      elem.snippet = ropecg(p.module, "$1$3[$2]", [rdLoc(d), lit, dataField(p)])
       elem.storage = OnHeap # we know that sequences are on the heap
-      initLoc(arr, locExpr, lodeTyp elemType(skipTypes(n.sons[1].typ, abstractInst)), a.storage)
-      arr.r = ropecg(p.module, "$1[$2]", rdLoc(a), intLiteral(i))
-      genAssignment(p, elem, arr, {afDestIsNil, needToCopy})
-  else:
-    var i: TLoc
-    getTemp(p, getSysType(p.module.g.graph, unknownLineInfo(), tyInt), i)
-    let oldCode = p.s(cpsStmts)
-    linefmt(p, cpsStmts, "for ($1 = 0; $1 < $2; $1++) {$n",  i.r, L.rope)
-    initLoc(elem, locExpr, lodeTyp elemType(skipTypes(n.typ, abstractInst)), OnHeap)
-    elem.r = ropecg(p.module, "$1->data[$2]", rdLoc(d), rdLoc(i))
+      arr = initLoc(locExpr, lodeTyp elemType(skipTypes(n[1].typ, abstractInst)), a.storage)
+      arr.snippet = ropecg(p.module, "$1[$2]", [rdLoc(a), lit])
+      genAssignment(p, elem, arr, {needToCopy})
+  else:
+    var i: TLoc = getTemp(p, getSysType(p.module.g.graph, unknownLineInfo, tyInt))
+    linefmt(p, cpsStmts, "for ($1 = 0; $1 < $2; $1++) {$n",  [i.snippet, L])
+    elem = initLoc(locExpr, lodeTyp elemType(skipTypes(n.typ, abstractInst)), OnHeap)
+    elem.snippet = ropecg(p.module, "$1$3[$2]", [rdLoc(d), rdLoc(i), dataField(p)])
     elem.storage = OnHeap # we know that sequences are on the heap
-    initLoc(arr, locExpr, lodeTyp elemType(skipTypes(n.sons[1].typ, abstractInst)), a.storage)
-    arr.r = ropecg(p.module, "$1[$2]", rdLoc(a), rdLoc(i))
-    genAssignment(p, elem, arr, {afDestIsNil, needToCopy})
+    arr = initLoc(locExpr, lodeTyp elemType(skipTypes(n[1].typ, abstractInst)), a.storage)
+    arr.snippet = ropecg(p.module, "$1[$2]", [rdLoc(a), rdLoc(i)])
+    genAssignment(p, elem, arr, {needToCopy})
     lineF(p, cpsStmts, "}$n", [])
 
 
 proc genNewFinalize(p: BProc, e: PNode) =
   var
-    a, b, f: TLoc
+    b: TLoc
     refType, bt: PType
     ti: Rope
-  refType = skipTypes(e.sons[1].typ, abstractVarRange)
-  initLocExpr(p, e.sons[1], a)
-  initLocExpr(p, e.sons[2], f)
-  initLoc(b, locExpr, a.lode, OnHeap)
-  ti = genTypeInfo(p.module, refType, e.info)
-  addf(p.module.s[cfsTypeInit3], "$1->finalizer = (void*)$2;$n", [ti, rdLoc(f)])
-  b.r = ropecg(p.module, "($1) #newObj($2, sizeof($3))", [
+  refType = skipTypes(e[1].typ, abstractVarRange)
+  var a = initLocExpr(p, e[1])
+  var f = initLocExpr(p, e[2])
+  b = initLoc(locExpr, a.lode, OnHeap)
+  ti = genTypeInfo(p.config, p.module, refType, e.info)
+  p.module.s[cfsTypeInit3].addf("$1->finalizer = (void*)$2;$n", [ti, rdLoc(f)])
+  b.snippet = ropecg(p.module, "($1) #newObj($2, sizeof($3))", [
       getTypeDesc(p.module, refType),
-      ti, getTypeDesc(p.module, skipTypes(refType.lastSon, abstractRange))])
+      ti, getTypeDesc(p.module, skipTypes(refType.elementType, abstractRange))])
   genAssignment(p, a, b, {})  # set the object type:
-  bt = skipTypes(refType.lastSon, abstractRange)
-  genObjectInit(p, cpsStmts, bt, a, false)
+  bt = skipTypes(refType.elementType, abstractRange)
+  genObjectInit(p, cpsStmts, bt, a, constructRefObj)
   gcUsage(p.config, e)
 
-proc genOfHelper(p: BProc; dest: PType; a: Rope; info: TLineInfo): Rope =
-  # unfortunately 'genTypeInfo' sets tfObjHasKids as a side effect, so we
-  # have to call it here first:
-  let ti = genTypeInfo(p.module, dest, info)
-  if tfFinal in dest.flags or (objHasKidsValid in p.module.flags and
-                               tfObjHasKids notin dest.flags):
-    result = "$1.m_type == $2" % [a, ti]
-  else:
-    discard cgsym(p.module, "TNimType")
-    inc p.module.labels
-    let cache = "Nim_OfCheck_CACHE" & p.module.labels.rope
-    addf(p.module.s[cfsVars], "static TNimType* $#[2];$n", [cache])
-    result = ropecg(p.module, "#isObjWithCache($#.m_type, $#, $#)", a, ti, cache)
-  when false:
-    # former version:
-    result = ropecg(p.module, "#isObj($1.m_type, $2)",
-                  a, genTypeInfo(p.module, dest, info))
+proc genOfHelper(p: BProc; dest: PType; a: Rope; info: TLineInfo; result: var Rope) =
+  if optTinyRtti in p.config.globalOptions:
+    let token = $genDisplayElem(MD5Digest(hashType(dest, p.config)))
+    appcg(p.module, result, "#isObjDisplayCheck($#.m_type, $#, $#)", [a, getObjDepth(dest), token])
+  else:
+    # unfortunately 'genTypeInfoV1' sets tfObjHasKids as a side effect, so we
+    # have to call it here first:
+    let ti = genTypeInfoV1(p.module, dest, info)
+    if tfFinal in dest.flags or (objHasKidsValid in p.module.flags and
+                                tfObjHasKids notin dest.flags):
+      result.add "$1.m_type == $2" % [a, ti]
+    else:
+      cgsym(p.module, "TNimType")
+      inc p.module.labels
+      let cache = "Nim_OfCheck_CACHE" & p.module.labels.rope
+      p.module.s[cfsVars].addf("static TNimType* $#[2];$n", [cache])
+      appcg(p.module, result, "#isObjWithCache($#.m_type, $#, $#)", [a, ti, cache])
 
 proc genOf(p: BProc, x: PNode, typ: PType, d: var TLoc) =
-  var a: TLoc
-  initLocExpr(p, x, a)
+  var a: TLoc = initLocExpr(p, x)
   var dest = skipTypes(typ, typedescPtrs)
   var r = rdLoc(a)
-  var nilCheck: Rope = nil
-  var t = skipTypes(a.t, abstractInst)
+  var nilCheck: Rope = ""
+  var t = skipTypes(a.t, abstractInstOwned)
   while t.kind in {tyVar, tyLent, tyPtr, tyRef}:
     if t.kind notin {tyVar, tyLent}: nilCheck = r
     if t.kind notin {tyVar, tyLent} or not p.module.compileToCpp:
-      r = ropecg(p.module, "(*$1)", r)
-    t = skipTypes(t.lastSon, typedescInst)
+      r = ropecg(p.module, "(*$1)", [r])
+    t = skipTypes(t.elementType, typedescInst+{tyOwned})
   discard getTypeDesc(p.module, t)
   if not p.module.compileToCpp:
-    while t.kind == tyObject and t.sons[0] != nil:
-      add(r, ~".Sup")
-      t = skipTypes(t.sons[0], skipPtrs)
+    while t.kind == tyObject and t.baseClass != nil:
+      r.add(".Sup")
+      t = skipTypes(t.baseClass, skipPtrs)
   if isObjLackingTypeField(t):
     globalError(p.config, x.info,
       "no 'of' operator available for pure objects")
-  if nilCheck != nil:
-    r = ropecg(p.module, "(($1) && ($2))", nilCheck, genOfHelper(p, dest, r, x.info))
+
+  var ro = newRopeAppender()
+  genOfHelper(p, dest, r, x.info, ro)
+  var ofExpr = newRopeAppender()
+  ofExpr.add "("
+  if nilCheck != "":
+    ofExpr.add "("
+    ofExpr.add nilCheck
+    ofExpr.add ") && ("
+    ofExpr.add ro
+    ofExpr.add "))"
   else:
-    r = ropecg(p.module, "($1)", genOfHelper(p, dest, r, x.info))
-  putIntoDest(p, d, x, r, a.storage)
+    ofExpr.add ro
+    ofExpr.add ")"
+
+  putIntoDest(p, d, x, ofExpr, a.storage)
 
 proc genOf(p: BProc, n: PNode, d: var TLoc) =
-  genOf(p, n.sons[1], n.sons[2].typ, d)
+  genOf(p, n[1], n[2].typ, d)
 
 proc genRepr(p: BProc, e: PNode, d: var TLoc) =
-  var a: TLoc
-  initLocExpr(p, e.sons[1], a)
-  var t = skipTypes(e.sons[1].typ, abstractVarRange)
+  if optTinyRtti in p.config.globalOptions:
+    localError(p.config, e.info, "'repr' is not available for --newruntime")
+  var a: TLoc = initLocExpr(p, e[1])
+  var t = skipTypes(e[1].typ, abstractVarRange)
   case t.kind
   of tyInt..tyInt64, tyUInt..tyUInt64:
     putIntoDest(p, d, e,
@@ -1415,87 +1757,144 @@ proc genRepr(p: BProc, e: PNode, d: var TLoc) =
   of tyEnum, tyOrdinal:
     putIntoDest(p, d, e,
                 ropecg(p.module, "#reprEnum((NI)$1, $2)", [
-                rdLoc(a), genTypeInfo(p.module, t, e.info)]), a.storage)
+                rdLoc(a), genTypeInfoV1(p.module, t, e.info)]), a.storage)
   of tyString:
     putIntoDest(p, d, e, ropecg(p.module, "#reprStr($1)", [rdLoc(a)]), a.storage)
   of tySet:
     putIntoDest(p, d, e, ropecg(p.module, "#reprSet($1, $2)", [
-                addrLoc(p.config, a), genTypeInfo(p.module, t, e.info)]), a.storage)
+                addrLoc(p.config, a), genTypeInfoV1(p.module, t, e.info)]), a.storage)
   of tyOpenArray, tyVarargs:
-    var b: TLoc
-    case a.t.kind
+    var b: TLoc = default(TLoc)
+    case skipTypes(a.t, abstractVarRange).kind
     of tyOpenArray, tyVarargs:
       putIntoDest(p, b, e, "$1, $1Len_0" % [rdLoc(a)], a.storage)
     of tyString, tySequence:
       putIntoDest(p, b, e,
-                  "$1->data, ($1 ? $1->$2 : 0)" % [rdLoc(a), lenField(p)], a.storage)
+                  "($4) ? ($1$3) : NIM_NIL, $2" %
+                    [rdLoc(a), lenExpr(p, a), dataField(p), dataFieldAccessor(p, a.rdLoc)],
+                  a.storage)
     of tyArray:
       putIntoDest(p, b, e,
                   "$1, $2" % [rdLoc(a), rope(lengthOrd(p.config, a.t))], a.storage)
-    else: internalError(p.config, e.sons[0].info, "genRepr()")
+    else: internalError(p.config, e[0].info, "genRepr()")
     putIntoDest(p, d, e,
         ropecg(p.module, "#reprOpenArray($1, $2)", [rdLoc(b),
-        genTypeInfo(p.module, elemType(t), e.info)]), a.storage)
-  of tyCString, tyArray, tyRef, tyPtr, tyPointer, tyNil, tySequence:
+        genTypeInfoV1(p.module, elemType(t), e.info)]), a.storage)
+  of tyCstring, tyArray, tyRef, tyPtr, tyPointer, tyNil, tySequence:
     putIntoDest(p, d, e,
                 ropecg(p.module, "#reprAny($1, $2)", [
-                rdLoc(a), genTypeInfo(p.module, t, e.info)]), a.storage)
+                rdLoc(a), genTypeInfoV1(p.module, t, e.info)]), a.storage)
   of tyEmpty, tyVoid:
     localError(p.config, e.info, "'repr' doesn't support 'void' type")
   else:
     putIntoDest(p, d, e, ropecg(p.module, "#reprAny($1, $2)",
-                              [addrLoc(p.config, a), genTypeInfo(p.module, t, e.info)]),
+                              [addrLoc(p.config, a), genTypeInfoV1(p.module, t, e.info)]),
                                a.storage)
   gcUsage(p.config, e)
 
-proc genGetTypeInfo(p: BProc, e: PNode, d: var TLoc) =
-  let t = e.sons[1].typ
-  putIntoDest(p, d, e, genTypeInfo(p.module, t, e.info))
+proc rdMType(p: BProc; a: TLoc; nilCheck: var Rope; result: var Rope; enforceV1 = false) =
+  var derefs = rdLoc(a)
+  var t = skipTypes(a.t, abstractInst)
+  while t.kind in {tyVar, tyLent, tyPtr, tyRef}:
+    if t.kind notin {tyVar, tyLent}: nilCheck = derefs
+    if t.kind notin {tyVar, tyLent} or not p.module.compileToCpp:
+      derefs = "(*$1)" % [derefs]
+    t = skipTypes(t.elementType, abstractInst)
+  result.add derefs
+  discard getTypeDesc(p.module, t)
+  if not p.module.compileToCpp:
+    while t.kind == tyObject and t.baseClass != nil:
+      result.add(".Sup")
+      t = skipTypes(t.baseClass, skipPtrs)
+  result.add ".m_type"
+  if optTinyRtti in p.config.globalOptions and enforceV1:
+    result.add "->typeInfoV1"
 
-proc genDollar(p: BProc, n: PNode, d: var TLoc, frmt: string) =
-  var a: TLoc
-  initLocExpr(p, n.sons[1], a)
-  a.r = ropecg(p.module, frmt, [rdLoc(a)])
-  if d.k == locNone: getTemp(p, n.typ, d)
+proc genGetTypeInfo(p: BProc, e: PNode, d: var TLoc) =
+  cgsym(p.module, "TNimType")
+  let t = e[1].typ
+  # ordinary static type information
+  putIntoDest(p, d, e, genTypeInfoV1(p.module, t, e.info))
+
+proc genGetTypeInfoV2(p: BProc, e: PNode, d: var TLoc) =
+  let t = e[1].typ
+  if isFinal(t) or e[0].sym.name.s != "getDynamicTypeInfo":
+    # ordinary static type information
+    putIntoDest(p, d, e, genTypeInfoV2(p.module, t, e.info))
+  else:
+    var a: TLoc = initLocExpr(p, e[1])
+    var nilCheck = ""
+    # use the dynamic type stored at offset 0:
+    var rt = newRopeAppender()
+    rdMType(p, a, nilCheck, rt)
+    putIntoDest(p, d, e, rt)
+
+proc genAccessTypeField(p: BProc; e: PNode; d: var TLoc) =
+  var a: TLoc = initLocExpr(p, e[1])
+  var nilCheck = ""
+  # use the dynamic type stored at offset 0:
+  var rt = newRopeAppender()
+  rdMType(p, a, nilCheck, rt)
+  putIntoDest(p, d, e, rt)
+
+template genDollar(p: BProc, n: PNode, d: var TLoc, frmt: string) =
+  var a: TLoc = initLocExpr(p, n[1])
+  a.snippet = ropecg(p.module, frmt, [rdLoc(a)])
+  a.flags.excl lfIndirect # this flag should not be propagated here (not just for HCR)
+  if d.k == locNone: d = getTemp(p, n.typ)
   genAssignment(p, d, a, {})
   gcUsage(p.config, n)
 
 proc genArrayLen(p: BProc, e: PNode, d: var TLoc, op: TMagic) =
-  var a = e.sons[1]
-  if a.kind == nkHiddenAddr: a = a.sons[0]
+  var a = e[1]
+  if a.kind == nkHiddenAddr: a = a[0]
   var typ = skipTypes(a.typ, abstractVar + tyUserTypeClasses)
   case typ.kind
   of tyOpenArray, tyVarargs:
-    if op == mHigh: unaryExpr(p, e, d, "($1Len_0-1)")
-    else: unaryExpr(p, e, d, "$1Len_0")
-  of tyCString:
-    useStringh(p.module)
-    if op == mHigh: unaryExpr(p, e, d, "($1 ? (strlen($1)-1) : -1)")
-    else: unaryExpr(p, e, d, "($1 ? strlen($1) : 0)")
-  of tyString:
-    if not p.module.compileToCpp:
-      if op == mHigh: unaryExpr(p, e, d, "($1 ? ($1->Sup.len-1) : -1)")
-      else: unaryExpr(p, e, d, "($1 ? $1->Sup.len : 0)")
-    else:
-      if op == mHigh: unaryExpr(p, e, d, "($1 ? ($1->len-1) : -1)")
-      else: unaryExpr(p, e, d, "($1 ? $1->len : 0)")
-  of tySequence:
-    var a, tmp: TLoc
-    initLocExpr(p, e[1], a)
-    getIntTemp(p, tmp)
-    var frmt: FormatStr
-    if not p.module.compileToCpp:
+    # Bug #9279, len(toOpenArray()) has to work:
+    if a.kind in nkCallKinds and a[0].kind == nkSym and a[0].sym.magic == mSlice:
+      # magic: pass slice to openArray:
+      var m = initLocExpr(p, a[1])
+      var b = initLocExpr(p, a[2])
+      var c = initLocExpr(p, a[3])
+      if optBoundsCheck in p.options:
+        genBoundsCheck(p, m, b, c, skipTypes(m.t, abstractVarRange))
       if op == mHigh:
-        frmt = "$1 = ($2 ? ($2->Sup.len-1) : -1);$n"
+        putIntoDest(p, d, e, ropecg(p.module, "(($2)-($1))", [rdLoc(b), rdLoc(c)]))
       else:
-        frmt = "$1 = ($2 ? $2->Sup.len : 0);$n"
+        putIntoDest(p, d, e, ropecg(p.module, "(($2)-($1)+1)", [rdLoc(b), rdLoc(c)]))
     else:
-      if op == mHigh:
-        frmt = "$1 = ($2 ? ($2->len-1) : -1);$n"
+      if not reifiedOpenArray(a):
+        if op == mHigh: unaryExpr(p, e, d, "($1Len_0-1)")
+        else: unaryExpr(p, e, d, "$1Len_0")
       else:
-        frmt = "$1 = ($2 ? $2->len : 0);$n"
-    lineCg(p, cpsStmts, frmt, tmp.r, rdLoc(a))
-    putIntoDest(p, d, e, tmp.r)
+        let isDeref = a.kind in {nkHiddenDeref, nkDerefExpr}
+        if op == mHigh:
+          if isDeref:
+            unaryExpr(p, e, d, "($1->Field1-1)")
+          else:
+            unaryExpr(p, e, d, "($1.Field1-1)")
+        else:
+          if isDeref:
+            unaryExpr(p, e, d, "$1->Field1")
+          else:
+            unaryExpr(p, e, d, "$1.Field1")
+  of tyCstring:
+    if op == mHigh: unaryExpr(p, e, d, "(#nimCStrLen($1)-1)")
+    else: unaryExpr(p, e, d, "#nimCStrLen($1)")
+  of tyString:
+    var a: TLoc = initLocExpr(p, e[1])
+    var x = lenExpr(p, a)
+    if op == mHigh: x = "($1-1)" % [x]
+    putIntoDest(p, d, e, x)
+  of tySequence:
+    # we go through a temporary here because people write bullshit code.
+    var tmp: TLoc = getIntTemp(p)
+    var a = initLocExpr(p, e[1])
+    var x = lenExpr(p, a)
+    if op == mHigh: x = "($1-1)" % [x]
+    lineCg(p, cpsStmts, "$1 = $2;$n", [tmp.snippet, x])
+    putIntoDest(p, d, e, tmp.snippet)
   of tyArray:
     # YYY: length(sideeffect) is optimized away incorrectly?
     if op == mHigh: putIntoDest(p, d, e, rope(lastOrd(p.config, typ)))
@@ -1503,47 +1902,72 @@ proc genArrayLen(p: BProc, e: PNode, d: var TLoc, op: TMagic) =
   else: internalError(p.config, e.info, "genArrayLen()")
 
 proc genSetLengthSeq(p: BProc, e: PNode, d: var TLoc) =
-  var a, b: TLoc
+  if optSeqDestructors in p.config.globalOptions:
+    e[1] = makeAddr(e[1], p.module.idgen)
+    genCall(p, e, d)
+    return
   assert(d.k == locNone)
-  var x = e.sons[1]
+  var x = e[1]
   if x.kind in {nkAddr, nkHiddenAddr}: x = x[0]
-  initLocExpr(p, x, a)
-  initLocExpr(p, e.sons[2], b)
-  let t = skipTypes(e.sons[1].typ, {tyVar})
-  let setLenPattern = if not p.module.compileToCpp:
-      "$1 = ($3) #setLengthSeqV2(&($1)->Sup, $4, $2);$n"
-    else:
-      "$1 = ($3) #setLengthSeqV2($1, $4, $2);$n"
+  var a = initLocExpr(p, x)
+  var b = initLocExpr(p, e[2])
+  let t = skipTypes(e[1].typ, {tyVar})
 
-  lineCg(p, cpsStmts, setLenPattern, [
+  var call = initLoc(locCall, e, OnHeap)
+  if not p.module.compileToCpp:
+    const setLenPattern = "($3) #setLengthSeqV2(($1)?&($1)->Sup:NIM_NIL, $4, $2)"
+    call.snippet = ropecg(p.module, setLenPattern, [
       rdLoc(a), rdLoc(b), getTypeDesc(p.module, t),
-      genTypeInfo(p.module, t.skipTypes(abstractInst), e.info)])
+      genTypeInfoV1(p.module, t.skipTypes(abstractInst), e.info)])
+
+  else:
+    const setLenPattern = "($3) #setLengthSeqV2($1, $4, $2)"
+    call.snippet = ropecg(p.module, setLenPattern, [
+      rdLoc(a), rdLoc(b), getTypeDesc(p.module, t),
+      genTypeInfoV1(p.module, t.skipTypes(abstractInst), e.info)])
+
+  genAssignment(p, a, call, {})
   gcUsage(p.config, e)
 
 proc genSetLengthStr(p: BProc, e: PNode, d: var TLoc) =
-  binaryStmt(p, e, d, "$1 = #setLengthStr($1, $2);$n")
-  gcUsage(p.config, e)
+  if optSeqDestructors in p.config.globalOptions:
+    binaryStmtAddr(p, e, d, "setLengthStrV2")
+  else:
+    if d.k != locNone: internalError(p.config, e.info, "genSetLengthStr")
+    var a = initLocExpr(p, e[1])
+    var b = initLocExpr(p, e[2])
+
+    var call = initLoc(locCall, e, OnHeap)
+    call.snippet = ropecg(p.module, "#setLengthStr($1, $2)", [
+        rdLoc(a), rdLoc(b)])
+    genAssignment(p, a, call, {})
+    gcUsage(p.config, e)
 
 proc genSwap(p: BProc, e: PNode, d: var TLoc) =
   # swap(a, b) -->
   # temp = a
   # a = b
   # b = temp
-  var a, b, tmp: TLoc
-  getTemp(p, skipTypes(e.sons[1].typ, abstractVar), tmp)
-  initLocExpr(p, e.sons[1], a) # eval a
-  initLocExpr(p, e.sons[2], b) # eval b
+  cowBracket(p, e[1])
+  cowBracket(p, e[2])
+  var tmp: TLoc = getTemp(p, skipTypes(e[1].typ, abstractVar))
+  var a = initLocExpr(p, e[1]) # eval a
+  var b = initLocExpr(p, e[2]) # eval b
   genAssignment(p, tmp, a, {})
   genAssignment(p, a, b, {})
   genAssignment(p, b, tmp, {})
 
-proc rdSetElemLoc(conf: ConfigRef; a: TLoc, setType: PType): Rope =
+proc rdSetElemLoc(conf: ConfigRef; a: TLoc, typ: PType; result: var Rope) =
   # read a location of an set element; it may need a subtraction operation
   # before the set operation
-  result = rdCharLoc(a)
+  result.add "("
+  result.add rdCharLoc(a)
+  let setType = typ.skipTypes(abstractPtrs)
   assert(setType.kind == tySet)
   if firstOrd(conf, setType) != 0:
-    result = "($1- $2)" % [result, rope(firstOrd(conf, setType))]
+    result.add " - "
+    result.add rope(firstOrd(conf, setType))
+  result.add ")"
 
 proc fewCmps(conf: ConfigRef; s: PNode): bool =
   # this function estimates whether it is better to emit code
@@ -1554,94 +1978,110 @@ proc fewCmps(conf: ConfigRef; s: PNode): bool =
   elif elemType(s.typ).kind in {tyInt, tyInt16..tyInt64}:
     result = true             # better not emit the set if int is basetype!
   else:
-    result = sonsLen(s) <= 8  # 8 seems to be a good value
+    result = s.len <= 8  # 8 seems to be a good value
 
-proc binaryExprIn(p: BProc, e: PNode, a, b, d: var TLoc, frmt: string) =
-  putIntoDest(p, d, e, frmt % [rdLoc(a), rdSetElemLoc(p.config, b, a.t)])
+template binaryExprIn(p: BProc, e: PNode, a, b, d: var TLoc, frmt: string) =
+  var elem = newRopeAppender()
+  rdSetElemLoc(p.config, b, a.t, elem)
+  putIntoDest(p, d, e, frmt % [rdLoc(a), elem])
 
 proc genInExprAux(p: BProc, e: PNode, a, b, d: var TLoc) =
-  case int(getSize(p.config, skipTypes(e.sons[1].typ, abstractVar)))
-  of 1: binaryExprIn(p, e, a, b, d, "(($1 &(1U<<((NU)($2)&7U)))!=0)")
-  of 2: binaryExprIn(p, e, a, b, d, "(($1 &(1U<<((NU)($2)&15U)))!=0)")
-  of 4: binaryExprIn(p, e, a, b, d, "(($1 &(1U<<((NU)($2)&31U)))!=0)")
+  case int(getSize(p.config, skipTypes(e[1].typ, abstractVar)))
+  of 1: binaryExprIn(p, e, a, b, d, "(($1 &((NU8)1<<((NU)($2)&7U)))!=0)")
+  of 2: binaryExprIn(p, e, a, b, d, "(($1 &((NU16)1<<((NU)($2)&15U)))!=0)")
+  of 4: binaryExprIn(p, e, a, b, d, "(($1 &((NU32)1<<((NU)($2)&31U)))!=0)")
   of 8: binaryExprIn(p, e, a, b, d, "(($1 &((NU64)1<<((NU)($2)&63U)))!=0)")
   else: binaryExprIn(p, e, a, b, d, "(($1[(NU)($2)>>3] &(1U<<((NU)($2)&7U)))!=0)")
 
-proc binaryStmtInExcl(p: BProc, e: PNode, d: var TLoc, frmt: string) =
-  var a, b: TLoc
+template binaryStmtInExcl(p: BProc, e: PNode, d: var TLoc, frmt: string) =
   assert(d.k == locNone)
-  initLocExpr(p, e.sons[1], a)
-  initLocExpr(p, e.sons[2], b)
-  lineF(p, cpsStmts, frmt, [rdLoc(a), rdSetElemLoc(p.config, b, a.t)])
+  var a = initLocExpr(p, e[1])
+  var b = initLocExpr(p, e[2])
+  var elem = newRopeAppender()
+  rdSetElemLoc(p.config, b, a.t, elem)
+  lineF(p, cpsStmts, frmt, [rdLoc(a), elem])
 
 proc genInOp(p: BProc, e: PNode, d: var TLoc) =
   var a, b, x, y: TLoc
-  if (e.sons[1].kind == nkCurly) and fewCmps(p.config, e.sons[1]):
+  if (e[1].kind == nkCurly) and fewCmps(p.config, e[1]):
     # a set constructor but not a constant set:
     # do not emit the set, but generate a bunch of comparisons; and if we do
     # so, we skip the unnecessary range check: This is a semantical extension
     # that code now relies on. :-/ XXX
-    let ea = if e.sons[2].kind in {nkChckRange, nkChckRange64}:
-               e.sons[2].sons[0]
+    let ea = if e[2].kind in {nkChckRange, nkChckRange64}:
+               e[2][0]
              else:
-               e.sons[2]
-    initLocExpr(p, ea, a)
-    initLoc(b, locExpr, e, OnUnknown)
-    b.r = rope("(")
-    var length = sonsLen(e.sons[1])
-    for i in countup(0, length - 1):
-      let it = e.sons[1].sons[i]
-      if it.kind == nkRange:
-        initLocExpr(p, it.sons[0], x)
-        initLocExpr(p, it.sons[1], y)
-        addf(b.r, "$1 >= $2 && $1 <= $3",
-             [rdCharLoc(a), rdCharLoc(x), rdCharLoc(y)])
-      else:
-        initLocExpr(p, it, x)
-        addf(b.r, "$1 == $2", [rdCharLoc(a), rdCharLoc(x)])
-      if i < length - 1: add(b.r, " || ")
-    add(b.r, ")")
-    putIntoDest(p, d, e, b.r)
-  else:
-    assert(e.sons[1].typ != nil)
-    assert(e.sons[2].typ != nil)
-    initLocExpr(p, e.sons[1], a)
-    initLocExpr(p, e.sons[2], b)
+               e[2]
+    a = initLocExpr(p, ea)
+    b = initLoc(locExpr, e, OnUnknown)
+    if e[1].len > 0:
+      b.snippet = rope("(")
+      for i in 0..<e[1].len:
+        let it = e[1][i]
+        if it.kind == nkRange:
+          x = initLocExpr(p, it[0])
+          y = initLocExpr(p, it[1])
+          b.snippet.addf("$1 >= $2 && $1 <= $3",
+               [rdCharLoc(a), rdCharLoc(x), rdCharLoc(y)])
+        else:
+          x = initLocExpr(p, it)
+          b.snippet.addf("$1 == $2", [rdCharLoc(a), rdCharLoc(x)])
+        if i < e[1].len - 1: b.snippet.add(" || ")
+      b.snippet.add(")")
+    else:
+      # handle the case of an empty set
+      b.snippet = rope("0")
+    putIntoDest(p, d, e, b.snippet)
+  else:
+    assert(e[1].typ != nil)
+    assert(e[2].typ != nil)
+    a = initLocExpr(p, e[1])
+    b = initLocExpr(p, e[2])
     genInExprAux(p, e, a, b, d)
 
 proc genSetOp(p: BProc, e: PNode, d: var TLoc, op: TMagic) =
   const
-    lookupOpr: array[mLeSet..mSymDiffSet, string] = [
+    lookupOpr: array[mLeSet..mMinusSet, string] = [
+      "for ($1 = 0; $1 < $2; $1++) { $n" &
+      "  $3 = (($4[$1] & ~ $5[$1]) == 0);$n" &
+      "  if (!$3) break;}$n",
       "for ($1 = 0; $1 < $2; $1++) { $n" &
-        "  $3 = (($4[$1] & ~ $5[$1]) == 0);$n" &
-        "  if (!$3) break;}$n", "for ($1 = 0; $1 < $2; $1++) { $n" &
-        "  $3 = (($4[$1] & ~ $5[$1]) == 0);$n" & "  if (!$3) break;}$n" &
-        "if ($3) $3 = (memcmp($4, $5, $2) != 0);$n",
-      "&", "|", "& ~", "^"]
-  var a, b, i: TLoc
-  var setType = skipTypes(e.sons[1].typ, abstractVar)
+      "  $3 = (($4[$1] & ~ $5[$1]) == 0);$n" &
+      "  if (!$3) break;}$n" &
+      "if ($3) $3 = (#nimCmpMem($4, $5, $2) != 0);$n",
+      "&",
+      "|",
+      "& ~"]
+  var a, b: TLoc
+  var i: TLoc
+  var setType = skipTypes(e[1].typ, abstractVar)
   var size = int(getSize(p.config, setType))
   case size
   of 1, 2, 4, 8:
     case op
     of mIncl:
-      var ts = "NU" & $(size * 8)
-      binaryStmtInExcl(p, e, d,
-          "$1 |= ((" & ts & ")1)<<(($2)%(sizeof(" & ts & ")*8));$n")
+      case size
+      of 1: binaryStmtInExcl(p, e, d, "$1 |= ((NU8)1)<<(($2) & 7);$n")
+      of 2: binaryStmtInExcl(p, e, d, "$1 |= ((NU16)1)<<(($2) & 15);$n")
+      of 4: binaryStmtInExcl(p, e, d, "$1 |= ((NU32)1)<<(($2) & 31);$n")
+      of 8: binaryStmtInExcl(p, e, d, "$1 |= ((NU64)1)<<(($2) & 63);$n")
+      else: assert(false, $size)
     of mExcl:
-      var ts = "NU" & $(size * 8)
-      binaryStmtInExcl(p, e, d, "$1 &= ~(((" & ts & ")1) << (($2) % (sizeof(" &
-          ts & ")*8)));$n")
+      case size
+      of 1: binaryStmtInExcl(p, e, d, "$1 &= ~(((NU8)1) << (($2) & 7));$n")
+      of 2: binaryStmtInExcl(p, e, d, "$1 &= ~(((NU16)1) << (($2) & 15));$n")
+      of 4: binaryStmtInExcl(p, e, d, "$1 &= ~(((NU32)1) << (($2) & 31));$n")
+      of 8: binaryStmtInExcl(p, e, d, "$1 &= ~(((NU64)1) << (($2) & 63));$n")
+      else: assert(false, $size)
     of mCard:
       if size <= 4: unaryExprChar(p, e, d, "#countBits32($1)")
       else: unaryExprChar(p, e, d, "#countBits64($1)")
-    of mLtSet: binaryExprChar(p, e, d, "(($1 & ~ $2 ==0)&&($1 != $2))")
+    of mLtSet: binaryExprChar(p, e, d, "((($1 & ~ $2)==0)&&($1 != $2))")
     of mLeSet: binaryExprChar(p, e, d, "(($1 & ~ $2)==0)")
     of mEqSet: binaryExpr(p, e, d, "($1 == $2)")
     of mMulSet: binaryExpr(p, e, d, "($1 & $2)")
     of mPlusSet: binaryExpr(p, e, d, "($1 | $2)")
     of mMinusSet: binaryExpr(p, e, d, "($1 & ~ $2)")
-    of mSymDiffSet: binaryExpr(p, e, d, "($1 ^ $2)")
     of mInSet:
       genInOp(p, e, d)
     else: internalError(p.config, e.info, "genSetOp()")
@@ -1649,23 +2089,32 @@ proc genSetOp(p: BProc, e: PNode, d: var TLoc, op: TMagic) =
     case op
     of mIncl: binaryStmtInExcl(p, e, d, "$1[(NU)($2)>>3] |=(1U<<($2&7U));$n")
     of mExcl: binaryStmtInExcl(p, e, d, "$1[(NU)($2)>>3] &= ~(1U<<($2&7U));$n")
-    of mCard: unaryExprChar(p, e, d, "#cardSet($1, " & $size & ')')
+    of mCard:
+      var a: TLoc = initLocExpr(p, e[1])
+      putIntoDest(p, d, e, ropecg(p.module, "#cardSet($1, $2)", [rdCharLoc(a), size]))
     of mLtSet, mLeSet:
-      getTemp(p, getSysType(p.module.g.graph, unknownLineInfo(), tyInt), i) # our counter
-      initLocExpr(p, e.sons[1], a)
-      initLocExpr(p, e.sons[2], b)
-      if d.k == locNone: getTemp(p, getSysType(p.module.g.graph, unknownLineInfo(), tyBool), d)
-      lineF(p, cpsStmts, lookupOpr[op],
-           [rdLoc(i), rope(size), rdLoc(d), rdLoc(a), rdLoc(b)])
+      i = getTemp(p, getSysType(p.module.g.graph, unknownLineInfo, tyInt)) # our counter
+      a = initLocExpr(p, e[1])
+      b = initLocExpr(p, e[2])
+      if d.k == locNone: d = getTemp(p, getSysType(p.module.g.graph, unknownLineInfo, tyBool))
+      if op == mLtSet:
+        linefmt(p, cpsStmts, lookupOpr[mLtSet],
+           [rdLoc(i), size, rdLoc(d), rdLoc(a), rdLoc(b)])
+      else:
+        linefmt(p, cpsStmts, lookupOpr[mLeSet],
+           [rdLoc(i), size, rdLoc(d), rdLoc(a), rdLoc(b)])
     of mEqSet:
-      useStringh(p.module)
-      binaryExprChar(p, e, d, "(memcmp($1, $2, " & $(size) & ")==0)")
-    of mMulSet, mPlusSet, mMinusSet, mSymDiffSet:
+      assert(e[1].typ != nil)
+      assert(e[2].typ != nil)
+      var a = initLocExpr(p, e[1])
+      var b = initLocExpr(p, e[2])
+      putIntoDest(p, d, e, ropecg(p.module, "(#nimCmpMem($1, $2, $3)==0)", [a.rdCharLoc, b.rdCharLoc, size]))
+    of mMulSet, mPlusSet, mMinusSet:
       # we inline the simple for loop for better code generation:
-      getTemp(p, getSysType(p.module.g.graph, unknownLineInfo(), tyInt), i) # our counter
-      initLocExpr(p, e.sons[1], a)
-      initLocExpr(p, e.sons[2], b)
-      if d.k == locNone: getTemp(p, a.t, d)
+      i = getTemp(p, getSysType(p.module.g.graph, unknownLineInfo, tyInt)) # our counter
+      a = initLocExpr(p, e[1])
+      b = initLocExpr(p, e[2])
+      if d.k == locNone: d = getTemp(p, setType)
       lineF(p, cpsStmts,
            "for ($1 = 0; $1 < $2; $1++) $n" &
            "  $3[$1] = $4[$1] $6 $5[$1];$n", [
@@ -1679,25 +2128,34 @@ proc genOrd(p: BProc, e: PNode, d: var TLoc) =
 
 proc genSomeCast(p: BProc, e: PNode, d: var TLoc) =
   const
-    ValueTypes = {tyTuple, tyObject, tyArray, tyOpenArray, tyVarargs}
+    ValueTypes = {tyTuple, tyObject, tyArray, tyOpenArray, tyVarargs, tyUncheckedArray}
   # we use whatever C gives us. Except if we have a value-type, we need to go
   # through its address:
-  var a: TLoc
-  initLocExpr(p, e.sons[1], a)
-  let etyp = skipTypes(e.typ, abstractRange)
+  var a: TLoc = initLocExpr(p, e[1])
+  let etyp = skipTypes(e.typ, abstractRange+{tyOwned})
+  let srcTyp = skipTypes(e[1].typ, abstractRange)
   if etyp.kind in ValueTypes and lfIndirect notin a.flags:
     putIntoDest(p, d, e, "(*($1*) ($2))" %
         [getTypeDesc(p.module, e.typ), addrLoc(p.config, a)], a.storage)
-  elif etyp.kind == tyProc and etyp.callConv == ccClosure:
+  elif etyp.kind == tyProc and etyp.callConv == ccClosure and srcTyp.callConv != ccClosure:
     putIntoDest(p, d, e, "(($1) ($2))" %
         [getClosureType(p.module, etyp, clHalfWithEnv), rdCharLoc(a)], a.storage)
   else:
-    let srcTyp = skipTypes(e.sons[1].typ, abstractRange)
     # C++ does not like direct casts from pointer to shorter integral types
     if srcTyp.kind in {tyPtr, tyPointer} and etyp.kind in IntegralTypes:
       putIntoDest(p, d, e, "(($1) (ptrdiff_t) ($2))" %
           [getTypeDesc(p.module, e.typ), rdCharLoc(a)], a.storage)
+    elif optSeqDestructors in p.config.globalOptions and etyp.kind in {tySequence, tyString}:
+      putIntoDest(p, d, e, "(*($1*) (&$2))" %
+          [getTypeDesc(p.module, e.typ), rdCharLoc(a)], a.storage)
+    elif etyp.kind == tyBool and srcTyp.kind in IntegralTypes:
+      putIntoDest(p, d, e, "(($1) != 0)" % [rdCharLoc(a)], a.storage)
     else:
+      if etyp.kind == tyPtr:
+        # generates the definition of structs for casts like cast[ptr object](addr x)[]
+        let internalType = etyp.skipTypes({tyPtr})
+        if internalType.kind == tyObject:
+          discard getTypeDesc(p.module, internalType)
       putIntoDest(p, d, e, "(($1) ($2))" %
           [getTypeDesc(p.module, e.typ), rdCharLoc(a)], a.storage)
 
@@ -1705,100 +2163,272 @@ proc genCast(p: BProc, e: PNode, d: var TLoc) =
   const ValueTypes = {tyFloat..tyFloat128, tyTuple, tyObject, tyArray}
   let
     destt = skipTypes(e.typ, abstractRange)
-    srct = skipTypes(e.sons[1].typ, abstractRange)
+    srct = skipTypes(e[1].typ, abstractRange)
   if destt.kind in ValueTypes or srct.kind in ValueTypes:
     # 'cast' and some float type involved? --> use a union.
     inc(p.labels)
     var lbl = p.labels.rope
-    var tmp: TLoc
-    tmp.r = "LOC$1.source" % [lbl]
-    linefmt(p, cpsLocals, "union { $1 source; $2 dest; } LOC$3;$n",
-      getTypeDesc(p.module, e.sons[1].typ), getTypeDesc(p.module, e.typ), lbl)
+    var tmp: TLoc = default(TLoc)
+    tmp.snippet = "LOC$1.source" % [lbl]
+    let destsize = getSize(p.config, destt)
+    let srcsize = getSize(p.config, srct)
+
+    if destsize > srcsize:
+      linefmt(p, cpsLocals, "union { $1 dest; $2 source; } LOC$3;$n #nimZeroMem(&LOC$3, sizeof(LOC$3));$n",
+        [getTypeDesc(p.module, e.typ), getTypeDesc(p.module, e[1].typ), lbl])
+    else:
+      linefmt(p, cpsLocals, "union { $1 source; $2 dest; } LOC$3;$n",
+        [getTypeDesc(p.module, e[1].typ), getTypeDesc(p.module, e.typ), lbl])
     tmp.k = locExpr
     tmp.lode = lodeTyp srct
     tmp.storage = OnStack
     tmp.flags = {}
-    expr(p, e.sons[1], tmp)
+    expr(p, e[1], tmp)
     putIntoDest(p, d, e, "LOC$#.dest" % [lbl], tmp.storage)
   else:
     # I prefer the shorter cast version for pointer types -> generate less
     # C code; plus it's the right thing to do for closures:
     genSomeCast(p, e, d)
 
-proc genRangeChck(p: BProc, n: PNode, d: var TLoc, magic: string) =
-  var a: TLoc
+proc genRangeChck(p: BProc, n: PNode, d: var TLoc) =
+  var a: TLoc = initLocExpr(p, n[0])
   var dest = skipTypes(n.typ, abstractVar)
-  # range checks for unsigned turned out to be buggy and annoying:
-  if optRangeCheck notin p.options or dest.skipTypes({tyRange}).kind in
-                                             {tyUInt..tyUInt64}:
-    initLocExpr(p, n.sons[0], a)
-    putIntoDest(p, d, n, "(($1) ($2))" %
-        [getTypeDesc(p.module, dest), rdCharLoc(a)], a.storage)
+  if optRangeCheck notin p.options or (dest.kind in {tyUInt..tyUInt64} and
+      checkUnsignedConversions notin p.config.legacyFeatures):
+    discard "no need to generate a check because it was disabled"
   else:
-    initLocExpr(p, n.sons[0], a)
-    putIntoDest(p, d, lodeTyp dest, ropecg(p.module, "(($1)#$5($2, $3, $4))", [
-        getTypeDesc(p.module, dest), rdCharLoc(a),
-        genLiteral(p, n.sons[1], dest), genLiteral(p, n.sons[2], dest),
-        rope(magic)]), a.storage)
+    let n0t = n[0].typ
+
+    # emit range check:
+    if n0t.kind in {tyUInt, tyUInt64}:
+      var first = newRopeAppender()
+      genLiteral(p, n[1], dest, first)
+      var last = newRopeAppender()
+      genLiteral(p, n[2], dest, last)
+      linefmt(p, cpsStmts, "if ($1 > ($5)($3)){ #raiseRangeErrorNoArgs(); ",
+        [rdCharLoc(a), first, last,
+        raiser, getTypeDesc(p.module, n0t)])
+      raiseInstr(p, p.s(cpsStmts))
+      linefmt p, cpsStmts, "}$n", []
+
+    else:
+      let raiser =
+        case skipTypes(n.typ, abstractVarRange).kind
+        of tyUInt..tyUInt64, tyChar: "raiseRangeErrorU"
+        of tyFloat..tyFloat128: "raiseRangeErrorF"
+        else: "raiseRangeErrorI"
+      cgsym(p.module, raiser)
+
+      let boundaryCast =
+        if n0t.skipTypes(abstractVarRange).kind in {tyUInt, tyUInt32, tyUInt64}:
+          "(NI64)"
+        else:
+          ""
+      var first = newRopeAppender()
+      genLiteral(p, n[1], dest, first)
+      var last = newRopeAppender()
+      genLiteral(p, n[2], dest, last)
+      linefmt(p, cpsStmts, "if ($5($1) < $2 || $5($1) > $3){ $4($1, $2, $3); ",
+        [rdCharLoc(a), first, last,
+        raiser, boundaryCast])
+      raiseInstr(p, p.s(cpsStmts))
+      linefmt p, cpsStmts, "}$n", []
+
+  if sameBackendTypeIgnoreRange(dest, n[0].typ):
+    # don't cast so an address can be taken for `var` conversions
+    putIntoDest(p, d, n, "($1)" % [rdCharLoc(a)], a.storage)
+  else:
+    putIntoDest(p, d, n, "(($1) ($2))" %
+      [getTypeDesc(p.module, dest), rdCharLoc(a)], a.storage)
 
 proc genConv(p: BProc, e: PNode, d: var TLoc) =
   let destType = e.typ.skipTypes({tyVar, tyLent, tyGenericInst, tyAlias, tySink})
-  if sameBackendType(destType, e.sons[1].typ):
-    expr(p, e.sons[1], d)
+  if sameBackendTypeIgnoreRange(destType, e[1].typ):
+    expr(p, e[1], d)
   else:
     genSomeCast(p, e, d)
 
 proc convStrToCStr(p: BProc, n: PNode, d: var TLoc) =
-  var a: TLoc
-  initLocExpr(p, n.sons[0], a)
-  putIntoDest(p, d, n, "($1 ? $1->data : (NCSTRING)\"\")" % [rdLoc(a)],
+  var a: TLoc = initLocExpr(p, n[0])
+  putIntoDest(p, d, n,
+              ropecg(p.module, "#nimToCStringConv($1)", [rdLoc(a)]),
+#                "($1 ? $1->data : (NCSTRING)\"\")" % [a.rdLoc],
               a.storage)
 
 proc convCStrToStr(p: BProc, n: PNode, d: var TLoc) =
-  var a: TLoc
-  initLocExpr(p, n.sons[0], a)
-  putIntoDest(p, d, n,
-              ropecg(p.module, "#cstrToNimstr($1)", [rdLoc(a)]),
-              a.storage)
+  var a: TLoc = initLocExpr(p, n[0])
+  if p.module.compileToCpp:
+    # fixes for const qualifier; bug #12703; bug #19588
+    putIntoDest(p, d, n,
+            ropecg(p.module, "#cstrToNimstr((NCSTRING) $1)", [rdLoc(a)]),
+            a.storage)
+  else:
+    putIntoDest(p, d, n,
+                ropecg(p.module, "#cstrToNimstr($1)", [rdLoc(a)]),
+                a.storage)
   gcUsage(p.config, n)
 
 proc genStrEquals(p: BProc, e: PNode, d: var TLoc) =
   var x: TLoc
-  var a = e.sons[1]
-  var b = e.sons[2]
+  var a = e[1]
+  var b = e[2]
   if a.kind in {nkStrLit..nkTripleStrLit} and a.strVal == "":
-    initLocExpr(p, e.sons[2], x)
+    x = initLocExpr(p, e[2])
     putIntoDest(p, d, e,
-      ropecg(p.module, "(!($1) || ($1)->$2 == 0)", rdLoc(x), lenField(p)))
+      ropecg(p.module, "($1 == 0)", [lenExpr(p, x)]))
   elif b.kind in {nkStrLit..nkTripleStrLit} and b.strVal == "":
-    initLocExpr(p, e.sons[1], x)
+    x = initLocExpr(p, e[1])
     putIntoDest(p, d, e,
-      ropecg(p.module, "(!($1) || ($1)->$2 == 0)", rdLoc(x), lenField(p)))
+      ropecg(p.module, "($1 == 0)", [lenExpr(p, x)]))
   else:
     binaryExpr(p, e, d, "#eqStrings($1, $2)")
 
 proc binaryFloatArith(p: BProc, e: PNode, d: var TLoc, m: TMagic) =
   if {optNaNCheck, optInfCheck} * p.options != {}:
     const opr: array[mAddF64..mDivF64, string] = ["+", "-", "*", "/"]
-    var a, b: TLoc
-    assert(e.sons[1].typ != nil)
-    assert(e.sons[2].typ != nil)
-    initLocExpr(p, e.sons[1], a)
-    initLocExpr(p, e.sons[2], b)
+    assert(e[1].typ != nil)
+    assert(e[2].typ != nil)
+    var a = initLocExpr(p, e[1])
+    var b = initLocExpr(p, e[2])
     putIntoDest(p, d, e, ropecg(p.module, "(($4)($2) $1 ($4)($3))",
-                              rope(opr[m]), rdLoc(a), rdLoc(b),
-                              getSimpleTypeDesc(p.module, e[1].typ)))
+                              [opr[m], rdLoc(a), rdLoc(b),
+                              getSimpleTypeDesc(p.module, e[1].typ)]))
     if optNaNCheck in p.options:
-      linefmt(p, cpsStmts, "#nanCheck($1);$n", rdLoc(d))
+      linefmt(p, cpsStmts, "if ($1 != $1){ #raiseFloatInvalidOp(); ", [rdLoc(d)])
+      raiseInstr(p, p.s(cpsStmts))
+      linefmt p, cpsStmts, "}$n", []
+
     if optInfCheck in p.options:
-      linefmt(p, cpsStmts, "#infCheck($1);$n", rdLoc(d))
+      linefmt(p, cpsStmts, "if ($1 != 0.0 && $1*0.5 == $1) { #raiseFloatOverflow($1); ", [rdLoc(d)])
+      raiseInstr(p, p.s(cpsStmts))
+      linefmt p, cpsStmts, "}$n", []
+
   else:
     binaryArith(p, e, d, m)
 
+proc genWasMoved(p: BProc; n: PNode) =
+  var a: TLoc
+  let n1 = n[1].skipAddr
+  if p.withinBlockLeaveActions > 0 and notYetAlive(n1):
+    discard
+  else:
+    a = initLocExpr(p, n1, {lfEnforceDeref})
+    resetLoc(p, a)
+    #linefmt(p, cpsStmts, "#nimZeroMem((void*)$1, sizeof($2));$n",
+    #  [addrLoc(p.config, a), getTypeDesc(p.module, a.t)])
+
+proc genMove(p: BProc; n: PNode; d: var TLoc) =
+  var a: TLoc = initLocExpr(p, n[1].skipAddr)
+  if n.len == 4:
+    # generated by liftdestructors:
+    var src: TLoc = initLocExpr(p, n[2])
+    linefmt(p, cpsStmts, "if ($1.p != $2.p) {", [rdLoc(a), rdLoc(src)])
+    genStmts(p, n[3])
+    linefmt(p, cpsStmts, "}$n$1.len = $2.len; $1.p = $2.p;$n", [rdLoc(a), rdLoc(src)])
+  else:
+    if d.k == locNone: d = getTemp(p, n.typ)
+    if p.config.selectedGC in {gcArc, gcAtomicArc, gcOrc}:
+      genAssignment(p, d, a, {})
+      var op = getAttachedOp(p.module.g.graph, n.typ, attachedWasMoved)
+      if op == nil:
+        resetLoc(p, a)
+      else:
+        var b = initLocExpr(p, newSymNode(op))
+        case skipTypes(a.t, abstractVar+{tyStatic}).kind
+        of tyOpenArray, tyVarargs: # todo fixme generated `wasMoved` hooks for
+                                   # openarrays, but it probably shouldn't?
+          var s: string
+          if reifiedOpenArray(a.lode):
+            if a.t.kind in {tyVar, tyLent}:
+              s = "$1->Field0, $1->Field1" % [rdLoc(a)]
+            else:
+              s = "$1.Field0, $1.Field1" % [rdLoc(a)]
+          else:
+            s = "$1, $1Len_0" % [rdLoc(a)]
+          linefmt(p, cpsStmts, "$1($2);$n", [rdLoc(b), s])
+        else:
+          if p.module.compileToCpp:
+            linefmt(p, cpsStmts, "$1($2);$n", [rdLoc(b), rdLoc(a)])
+          else:
+            linefmt(p, cpsStmts, "$1($2);$n", [rdLoc(b), byRefLoc(p, a)])
+    else:
+      if n[1].kind == nkSym and isSinkParam(n[1].sym):
+        var tmp = getTemp(p, n[1].typ.skipTypes({tySink}))
+        genAssignment(p, tmp, a, {needToCopySinkParam})
+        genAssignment(p, d, tmp, {})
+        resetLoc(p, tmp)
+      else:
+        genAssignment(p, d, a, {})
+      resetLoc(p, a)
+
+proc genDestroy(p: BProc; n: PNode) =
+  if optSeqDestructors in p.config.globalOptions:
+    let arg = n[1].skipAddr
+    let t = arg.typ.skipTypes(abstractInst)
+    case t.kind
+    of tyString:
+      var a: TLoc = initLocExpr(p, arg)
+      if optThreads in p.config.globalOptions:
+        linefmt(p, cpsStmts, "if ($1.p && !($1.p->cap & NIM_STRLIT_FLAG)) {$n" &
+          " #deallocShared($1.p);$n" &
+          "}$n", [rdLoc(a)])
+      else:
+        linefmt(p, cpsStmts, "if ($1.p && !($1.p->cap & NIM_STRLIT_FLAG)) {$n" &
+          " #dealloc($1.p);$n" &
+          "}$n", [rdLoc(a)])
+    of tySequence:
+      var a: TLoc = initLocExpr(p, arg)
+      linefmt(p, cpsStmts, "if ($1.p && !($1.p->cap & NIM_STRLIT_FLAG)) {$n" &
+        " #alignedDealloc($1.p, NIM_ALIGNOF($2));$n" &
+        "}$n",
+        [rdLoc(a), getTypeDesc(p.module, t.elementType)])
+    else: discard "nothing to do"
+  else:
+    let t = n[1].typ.skipTypes(abstractVar)
+    let op = getAttachedOp(p.module.g.graph, t, attachedDestructor)
+    if op != nil and getBody(p.module.g.graph, op).len != 0:
+      internalError(p.config, n.info, "destructor turned out to be not trivial")
+    discard "ignore calls to the default destructor"
+
+proc genDispose(p: BProc; n: PNode) =
+  when false:
+    let elemType = n[1].typ.skipTypes(abstractVar).elementType
+
+    var a: TLoc = initLocExpr(p, n[1].skipAddr)
+
+    if isFinal(elemType):
+      if elemType.destructor != nil:
+        var destroyCall = newNodeI(nkCall, n.info)
+        genStmts(p, destroyCall)
+      lineFmt(p, cpsStmts, "#nimRawDispose($1, NIM_ALIGNOF($2))", [rdLoc(a), getTypeDesc(p.module, elemType)])
+    else:
+      # ``nimRawDisposeVirtual`` calls the ``finalizer`` which is the same as the
+      # destructor, but it uses the runtime type. Afterwards the memory is freed:
+      lineCg(p, cpsStmts, ["#nimDestroyAndDispose($#)", rdLoc(a)])
+
+proc genSlice(p: BProc; e: PNode; d: var TLoc) =
+  let (x, y) = genOpenArraySlice(p, e, e.typ, e.typ.elementType,
+    prepareForMutation = e[1].kind == nkHiddenDeref and
+                         e[1].typ.skipTypes(abstractInst).kind == tyString and
+                         p.config.selectedGC in {gcArc, gcAtomicArc, gcOrc})
+  if d.k == locNone: d = getTemp(p, e.typ)
+  linefmt(p, cpsStmts, "$1.Field0 = $2; $1.Field1 = $3;$n", [rdLoc(d), x, y])
+  when false:
+    localError(p.config, e.info, "invalid context for 'toOpenArray'; " &
+      "'toOpenArray' is only valid within a call expression")
+
+proc genEnumToStr(p: BProc, e: PNode, d: var TLoc) =
+  let t = e[1].typ.skipTypes(abstractInst+{tyRange})
+  let toStrProc = getToStringProc(p.module.g.graph, t)
+  # XXX need to modify this logic for IC.
+  var n = copyTree(e)
+  n[0] = newSymNode(toStrProc)
+  expr(p, n, d)
+
 proc genMagicExpr(p: BProc, e: PNode, d: var TLoc, op: TMagic) =
   case op
   of mOr, mAnd: genAndOr(p, e, d, op)
-  of mNot..mToBiggestInt: unaryArith(p, e, d, op)
+  of mNot..mUnaryMinusF64: unaryArith(p, e, d, op)
   of mUnaryMinusI..mAbsI: unaryArithOverflow(p, e, d, op)
   of mAddF64..mDivF64: binaryFloatArith(p, e, d, op)
   of mShrI..mXor: binaryArith(p, e, d, op)
@@ -1806,108 +2436,181 @@ proc genMagicExpr(p: BProc, e: PNode, d: var TLoc, op: TMagic) =
   of mAddI..mPred: binaryArithOverflow(p, e, d, op)
   of mRepr: genRepr(p, e, d)
   of mGetTypeInfo: genGetTypeInfo(p, e, d)
+  of mGetTypeInfoV2: genGetTypeInfoV2(p, e, d)
   of mSwap: genSwap(p, e, d)
-  of mUnaryLt:
-    if optOverflowCheck notin p.options: unaryExpr(p, e, d, "($1 - 1)")
-    else: unaryExpr(p, e, d, "#subInt($1, 1)")
   of mInc, mDec:
-    const opr: array[mInc..mDec, string] = ["$1 += $2;$n", "$1 -= $2;$n"]
-    const fun64: array[mInc..mDec, string] = ["$# = #addInt64($#, $#);$n",
-                                               "$# = #subInt64($#, $#);$n"]
-    const fun: array[mInc..mDec, string] = ["$# = #addInt($#, $#);$n",
-                                             "$# = #subInt($#, $#);$n"]
-    let underlying = skipTypes(e.sons[1].typ, {tyGenericInst, tyAlias, tySink, tyVar, tyLent, tyRange})
+    const opr: array[mInc..mDec, string] = ["+=", "-="]
+    const fun64: array[mInc..mDec, string] = ["nimAddInt64", "nimSubInt64"]
+    const fun: array[mInc..mDec, string] = ["nimAddInt","nimSubInt"]
+    let underlying = skipTypes(e[1].typ, {tyGenericInst, tyAlias, tySink, tyVar, tyLent, tyRange, tyDistinct})
     if optOverflowCheck notin p.options or underlying.kind in {tyUInt..tyUInt64}:
       binaryStmt(p, e, d, opr[op])
     else:
-      var a, b: TLoc
-      assert(e.sons[1].typ != nil)
-      assert(e.sons[2].typ != nil)
-      initLocExpr(p, e.sons[1], a)
-      initLocExpr(p, e.sons[2], b)
+      assert(e[1].typ != nil)
+      assert(e[2].typ != nil)
+      var a = initLocExpr(p, e[1])
+      var b = initLocExpr(p, e[2])
 
-      let ranged = skipTypes(e.sons[1].typ, {tyGenericInst, tyAlias, tySink, tyVar, tyLent})
+      let ranged = skipTypes(e[1].typ, {tyGenericInst, tyAlias, tySink, tyVar, tyLent, tyDistinct})
       let res = binaryArithOverflowRaw(p, ranged, a, b,
         if underlying.kind == tyInt64: fun64[op] else: fun[op])
-      putIntoDest(p, a, e.sons[1], "($#)($#)" % [
+
+      putIntoDest(p, a, e[1], "($#)($#)" % [
         getTypeDesc(p.module, ranged), res])
 
   of mConStrStr: genStrConcat(p, e, d)
-  of mAppendStrCh: binaryStmt(p, e, d, "$1 = #addChar($1, $2);$n")
+  of mAppendStrCh:
+    if optSeqDestructors in p.config.globalOptions:
+      binaryStmtAddr(p, e, d, "nimAddCharV1")
+    else:
+      var call = initLoc(locCall, e, OnHeap)
+      var dest = initLocExpr(p, e[1])
+      var b = initLocExpr(p, e[2])
+      call.snippet = ropecg(p.module, "#addChar($1, $2)", [rdLoc(dest), rdLoc(b)])
+      genAssignment(p, dest, call, {})
   of mAppendStrStr: genStrAppend(p, e, d)
-  of mAppendSeqElem: genSeqElemAppend(p, e, d)
+  of mAppendSeqElem:
+    if optSeqDestructors in p.config.globalOptions:
+      e[1] = makeAddr(e[1], p.module.idgen)
+      genCall(p, e, d)
+    else:
+      genSeqElemAppend(p, e, d)
   of mEqStr: genStrEquals(p, e, d)
   of mLeStr: binaryExpr(p, e, d, "(#cmpStrings($1, $2) <= 0)")
   of mLtStr: binaryExpr(p, e, d, "(#cmpStrings($1, $2) < 0)")
   of mIsNil: genIsNil(p, e, d)
-  of mIntToStr: genDollar(p, e, d, "#nimIntToStr($1)")
-  of mInt64ToStr: genDollar(p, e, d, "#nimInt64ToStr($1)")
   of mBoolToStr: genDollar(p, e, d, "#nimBoolToStr($1)")
   of mCharToStr: genDollar(p, e, d, "#nimCharToStr($1)")
-  of mFloatToStr: genDollar(p, e, d, "#nimFloatToStr($1)")
-  of mCStrToStr: genDollar(p, e, d, "#cstrToNimstr($1)")
-  of mStrToStr: expr(p, e.sons[1], d)
-  of mEnumToStr: genRepr(p, e, d)
+  of mCStrToStr:
+    if p.module.compileToCpp:
+      # fixes for const qualifier; bug #12703; bug #19588
+      genDollar(p, e, d, "#cstrToNimstr((NCSTRING) $1)")
+    else:
+      genDollar(p, e, d, "#cstrToNimstr($1)")
+  of mStrToStr, mUnown: expr(p, e[1], d)
+  of generatedMagics: genCall(p, e, d)
+  of mEnumToStr:
+    if optTinyRtti in p.config.globalOptions:
+      genEnumToStr(p, e, d)
+    else:
+      genRepr(p, e, d)
   of mOf: genOf(p, e, d)
   of mNew: genNew(p, e)
-  of mNewFinalize: genNewFinalize(p, e)
-  of mNewSeq: genNewSeq(p, e)
+  of mNewFinalize:
+    if optTinyRtti in p.config.globalOptions:
+      var a: TLoc = initLocExpr(p, e[1])
+      rawGenNew(p, a, "", needsInit = true)
+      gcUsage(p.config, e)
+    else:
+      genNewFinalize(p, e)
+  of mNewSeq:
+    if optSeqDestructors in p.config.globalOptions:
+      e[1] = makeAddr(e[1], p.module.idgen)
+      genCall(p, e, d)
+    else:
+      genNewSeq(p, e)
   of mNewSeqOfCap: genNewSeqOfCap(p, e, d)
   of mSizeOf:
-    let t = e.sons[1].typ.skipTypes({tyTypeDesc})
-    putIntoDest(p, d, e, "((NI)sizeof($1))" % [getTypeDesc(p.module, t)])
+    let t = e[1].typ.skipTypes({tyTypeDesc})
+    putIntoDest(p, d, e, "((NI)sizeof($1))" % [getTypeDesc(p.module, t, dkVar)])
+  of mAlignOf:
+    let t = e[1].typ.skipTypes({tyTypeDesc})
+    putIntoDest(p, d, e, "((NI)NIM_ALIGNOF($1))" % [getTypeDesc(p.module, t, dkVar)])
+  of mOffsetOf:
+    var dotExpr: PNode
+    if e[1].kind == nkDotExpr:
+      dotExpr = e[1]
+    elif e[1].kind == nkCheckedFieldExpr:
+      dotExpr = e[1][0]
+    else:
+      dotExpr = nil
+      internalError(p.config, e.info, "unknown ast")
+    let t = dotExpr[0].typ.skipTypes({tyTypeDesc})
+    let tname = getTypeDesc(p.module, t, dkVar)
+    let member =
+      if t.kind == tyTuple:
+        "Field" & rope(dotExpr[1].sym.position)
+      else: dotExpr[1].sym.loc.snippet
+    putIntoDest(p,d,e, "((NI)offsetof($1, $2))" % [tname, member])
   of mChr: genSomeCast(p, e, d)
   of mOrd: genOrd(p, e, d)
   of mLengthArray, mHigh, mLengthStr, mLengthSeq, mLengthOpenArray:
     genArrayLen(p, e, d, op)
-  of mXLenStr:
-    if not p.module.compileToCpp:
-      unaryExpr(p, e, d, "($1->Sup.len)")
-    else:
-      unaryExpr(p, e, d, "$1->len")
-  of mXLenSeq:
-    # see 'taddhigh.nim' for why we need to use a temporary here:
-    var a, tmp: TLoc
-    initLocExpr(p, e[1], a)
-    getIntTemp(p, tmp)
-    var frmt: FormatStr
-    if not p.module.compileToCpp:
-      frmt = "$1 = $2->Sup.len;$n"
-    else:
-      frmt = "$1 = $2->len;$n"
-    lineCg(p, cpsStmts, frmt, tmp.r, rdLoc(a))
-    putIntoDest(p, d, e, tmp.r)
-  of mGCref: unaryStmt(p, e, d, "#nimGCref($1);$n")
-  of mGCunref: unaryStmt(p, e, d, "#nimGCunref($1);$n")
+  of mGCref:
+    # only a magic for the old GCs
+    unaryStmt(p, e, d, "if ($1) { #nimGCref($1); }$n")
+  of mGCunref:
+    # only a magic for the old GCs
+    unaryStmt(p, e, d, "if ($1) { #nimGCunref($1); }$n")
   of mSetLengthStr: genSetLengthStr(p, e, d)
   of mSetLengthSeq: genSetLengthSeq(p, e, d)
   of mIncl, mExcl, mCard, mLtSet, mLeSet, mEqSet, mMulSet, mPlusSet, mMinusSet,
      mInSet:
     genSetOp(p, e, d, op)
-  of mNewString, mNewStringOfCap, mCopyStr, mCopyStrLast, mExit,
-      mParseBiggestFloat:
-    var opr = e.sons[0].sym
+  of mNewString, mNewStringOfCap, mExit, mParseBiggestFloat:
+    var opr = e[0].sym
+    # Why would anyone want to set nodecl to one of these hardcoded magics?
+    # - not sure, and it wouldn't work if the symbol behind the magic isn't
+    #   somehow forward-declared from some other usage, but it is *possible*
     if lfNoDecl notin opr.loc.flags:
-      discard cgsym(p.module, $opr.loc.r)
+      let prc = magicsys.getCompilerProc(p.module.g.graph, $opr.loc.snippet)
+      assert prc != nil, $opr.loc.snippet
+      # HACK:
+      # Explicitly add this proc as declared here so the cgsym call doesn't
+      # add a forward declaration - without this we could end up with the same
+      # 2 forward declarations. That happens because the magic symbol and the original
+      # one that shall be used have different ids (even though a call to one is
+      # actually a call to the other) so checking into m.declaredProtos with the 2 different ids doesn't work.
+      # Why would 2 identical forward declarations be a problem?
+      # - in the case of hot code-reloading we generate function pointers instead
+      #   of forward declarations and in C++ it is an error to redefine a global
+      let wasDeclared = containsOrIncl(p.module.declaredProtos, prc.id)
+      # Make the function behind the magic get actually generated - this will
+      # not lead to a forward declaration! The genCall will lead to one.
+      cgsym(p.module, $opr.loc.snippet)
+      # make sure we have pointer-initialising code for hot code reloading
+      if not wasDeclared and p.hcrOn:
+        p.module.s[cfsDynLibInit].addf("\t$1 = ($2) hcrGetProc($3, \"$1\");$n",
+             [mangleDynLibProc(prc), getTypeDesc(p.module, prc.loc.t), getModuleDllPath(p.module, prc)])
     genCall(p, e, d)
-  of mReset: genReset(p, e)
+  of mDefault, mZeroDefault: genDefault(p, e, d)
   of mEcho: genEcho(p, e[1].skipConv)
   of mArrToSeq: genArrToSeq(p, e, d)
   of mNLen..mNError, mSlurp..mQuoteAst:
-    localError(p.config, e.info, strutils.`%`(errXMustBeCompileTime, e.sons[0].sym.name.s))
+    localError(p.config, e.info, strutils.`%`(errXMustBeCompileTime, e[0].sym.name.s))
   of mSpawn:
-    let n = lowerings.wrapProcForSpawn(p.module.g.graph, p.module.module, e, e.typ, nil, nil)
-    expr(p, n, d)
+    when defined(leanCompiler):
+      p.config.quitOrRaise "compiler built without support for the 'spawn' statement"
+    else:
+      let n = spawn.wrapProcForSpawn(p.module.g.graph, p.module.idgen, p.module.module, e, e.typ, nil, nil)
+      expr(p, n, d)
   of mParallel:
-    let n = semparallel.liftParallel(p.module.g.graph, p.module.module, e)
-    expr(p, n, d)
+    when defined(leanCompiler):
+      p.config.quitOrRaise "compiler built without support for the 'parallel' statement"
+    else:
+      let n = semparallel.liftParallel(p.module.g.graph, p.module.idgen, p.module.module, e)
+      expr(p, n, d)
   of mDeepCopy:
-    var a, b: TLoc
+    if p.config.selectedGC in {gcArc, gcAtomicArc, gcOrc} and optEnableDeepCopy notin p.config.globalOptions:
+      localError(p.config, e.info,
+        "for --mm:arc|atomicArc|orc 'deepcopy' support has to be enabled with --deepcopy:on")
+
     let x = if e[1].kind in {nkAddr, nkHiddenAddr}: e[1][0] else: e[1]
-    initLocExpr(p, x, a)
-    initLocExpr(p, e.sons[2], b)
+    var a = initLocExpr(p, x)
+    var b = initLocExpr(p, e[2])
     genDeepCopy(p, a, b)
   of mDotDot, mEqCString: genCall(p, e, d)
+  of mWasMoved: genWasMoved(p, e)
+  of mMove: genMove(p, e, d)
+  of mDestroy: genDestroy(p, e)
+  of mAccessEnv: unaryExpr(p, e, d, "$1.ClE_0")
+  of mAccessTypeField: genAccessTypeField(p, e, d)
+  of mSlice: genSlice(p, e, d)
+  of mTrace: discard "no code to generate"
+  of mEnsureMove:
+    expr(p, e[1], d)
+  of mDup:
+    expr(p, e[1], d)
   else:
     when defined(debugMagics):
       echo p.prc.name.s, " ", p.prc.id, " ", p.prc.flags, " ", p.prc.ast[genericParamsPos].kind
@@ -1916,105 +2619,139 @@ proc genMagicExpr(p: BProc, e: PNode, d: var TLoc, op: TMagic) =
 proc genSetConstr(p: BProc, e: PNode, d: var TLoc) =
   # example: { a..b, c, d, e, f..g }
   # we have to emit an expression of the form:
-  # memset(tmp, 0, sizeof(tmp)); inclRange(tmp, a, b); incl(tmp, c);
+  # nimZeroMem(tmp, sizeof(tmp)); inclRange(tmp, a, b); incl(tmp, c);
   # incl(tmp, d); incl(tmp, e); inclRange(tmp, f, g);
   var
-    a, b, idx: TLoc
+    a, b: TLoc
+  var idx: TLoc
   if nfAllConst in e.flags:
-    putIntoDest(p, d, e, genSetNode(p, e))
+    var elem = newRopeAppender()
+    genSetNode(p, e, elem)
+    putIntoDest(p, d, e, elem)
   else:
-    if d.k == locNone: getTemp(p, e.typ, d)
+    if d.k == locNone: d = getTemp(p, e.typ)
     if getSize(p.config, e.typ) > 8:
       # big set:
-      useStringh(p.module)
-      lineF(p, cpsStmts, "memset($1, 0, sizeof($2));$n",
+      linefmt(p, cpsStmts, "#nimZeroMem($1, sizeof($2));$n",
           [rdLoc(d), getTypeDesc(p.module, e.typ)])
       for it in e.sons:
         if it.kind == nkRange:
-          getTemp(p, getSysType(p.module.g.graph, unknownLineInfo(), tyInt), idx) # our counter
-          initLocExpr(p, it.sons[0], a)
-          initLocExpr(p, it.sons[1], b)
+          idx = getTemp(p, getSysType(p.module.g.graph, unknownLineInfo, tyInt)) # our counter
+          a = initLocExpr(p, it[0])
+          b = initLocExpr(p, it[1])
+          var aa = newRopeAppender()
+          rdSetElemLoc(p.config, a, e.typ, aa)
+          var bb = newRopeAppender()
+          rdSetElemLoc(p.config, b, e.typ, bb)
           lineF(p, cpsStmts, "for ($1 = $3; $1 <= $4; $1++) $n" &
               "$2[(NU)($1)>>3] |=(1U<<((NU)($1)&7U));$n", [rdLoc(idx), rdLoc(d),
-              rdSetElemLoc(p.config, a, e.typ), rdSetElemLoc(p.config, b, e.typ)])
+              aa, bb])
         else:
-          initLocExpr(p, it, a)
+          a = initLocExpr(p, it)
+          var aa = newRopeAppender()
+          rdSetElemLoc(p.config, a, e.typ, aa)
           lineF(p, cpsStmts, "$1[(NU)($2)>>3] |=(1U<<((NU)($2)&7U));$n",
-               [rdLoc(d), rdSetElemLoc(p.config, a, e.typ)])
+               [rdLoc(d), aa])
     else:
       # small set
       var ts = "NU" & $(getSize(p.config, e.typ) * 8)
       lineF(p, cpsStmts, "$1 = 0;$n", [rdLoc(d)])
       for it in e.sons:
         if it.kind == nkRange:
-          getTemp(p, getSysType(p.module.g.graph, unknownLineInfo(), tyInt), idx) # our counter
-          initLocExpr(p, it.sons[0], a)
-          initLocExpr(p, it.sons[1], b)
+          idx = getTemp(p, getSysType(p.module.g.graph, unknownLineInfo, tyInt)) # our counter
+          a = initLocExpr(p, it[0])
+          b = initLocExpr(p, it[1])
+          var aa = newRopeAppender()
+          rdSetElemLoc(p.config, a, e.typ, aa)
+          var bb = newRopeAppender()
+          rdSetElemLoc(p.config, b, e.typ, bb)
+
           lineF(p, cpsStmts, "for ($1 = $3; $1 <= $4; $1++) $n" &
-              "$2 |=((" & ts & ")(1)<<(($1)%(sizeof(" & ts & ")*8)));$n", [
-              rdLoc(idx), rdLoc(d), rdSetElemLoc(p.config, a, e.typ),
-              rdSetElemLoc(p.config, b, e.typ)])
+              "$2 |=(($5)(1)<<(($1)%(sizeof($5)*8)));$n", [
+              rdLoc(idx), rdLoc(d), aa, bb, rope(ts)])
         else:
-          initLocExpr(p, it, a)
+          a = initLocExpr(p, it)
+          var aa = newRopeAppender()
+          rdSetElemLoc(p.config, a, e.typ, aa)
           lineF(p, cpsStmts,
-               "$1 |=((" & ts & ")(1)<<(($2)%(sizeof(" & ts & ")*8)));$n",
-               [rdLoc(d), rdSetElemLoc(p.config, a, e.typ)])
+               "$1 |=(($3)(1)<<(($2)%(sizeof($3)*8)));$n",
+               [rdLoc(d), aa, rope(ts)])
 
 proc genTupleConstr(p: BProc, n: PNode, d: var TLoc) =
   var rec: TLoc
   if not handleConstExpr(p, n, d):
     let t = n.typ
     discard getTypeDesc(p.module, t) # so that any fields are initialized
-    if d.k == locNone: getTemp(p, t, d)
-    for i in countup(0, sonsLen(n) - 1):
-      var it = n.sons[i]
-      if it.kind == nkExprColonExpr: it = it.sons[1]
-      initLoc(rec, locExpr, it, d.storage)
-      rec.r = "$1.Field$2" % [rdLoc(d), rope(i)]
+
+    var tmp: TLoc = default(TLoc)
+    # bug #16331
+    let doesAlias = lhsDoesAlias(d.lode, n)
+    let dest = if doesAlias: addr(tmp) else: addr(d)
+    if doesAlias:
+      tmp = getTemp(p, n.typ)
+    elif d.k == locNone:
+      d = getTemp(p, n.typ)
+
+    for i in 0..<n.len:
+      var it = n[i]
+      if it.kind == nkExprColonExpr: it = it[1]
+      rec = initLoc(locExpr, it, dest[].storage)
+      rec.snippet = "$1.Field$2" % [rdLoc(dest[]), rope(i)]
+      rec.flags.incl(lfEnforceDeref)
       expr(p, it, rec)
 
+    if doesAlias:
+      if d.k == locNone:
+        d = tmp
+      else:
+        genAssignment(p, d, tmp, {})
+
 proc isConstClosure(n: PNode): bool {.inline.} =
-  result = n.sons[0].kind == nkSym and isRoutine(n.sons[0].sym) and
-      n.sons[1].kind == nkNilLit
+  result = n[0].kind == nkSym and isRoutine(n[0].sym) and
+      n[1].kind == nkNilLit
 
 proc genClosure(p: BProc, n: PNode, d: var TLoc) =
-  assert n.kind == nkClosure
+  assert n.kind in {nkPar, nkTupleConstr, nkClosure}
 
   if isConstClosure(n):
     inc(p.module.labels)
     var tmp = "CNSTCLOSURE" & rope(p.module.labels)
-    addf(p.module.s[cfsData], "static NIM_CONST $1 $2 = $3;$n",
-        [getTypeDesc(p.module, n.typ), tmp, genConstExpr(p, n)])
+    var data = "static NIM_CONST $1 $2 = " % [getTypeDesc(p.module, n.typ), tmp]
+    genBracedInit(p, n, isConst = true, n.typ, data)
+    data.addf(";$n", [])
+    p.module.s[cfsData].add data
     putIntoDest(p, d, n, tmp, OnStatic)
   else:
-    var tmp, a, b: TLoc
-    initLocExpr(p, n.sons[0], a)
-    initLocExpr(p, n.sons[1], b)
-    if n.sons[0].skipConv.kind == nkClosure:
+    var tmp: TLoc
+    var a = initLocExpr(p, n[0])
+    var b = initLocExpr(p, n[1])
+    if n[0].skipConv.kind == nkClosure:
       internalError(p.config, n.info, "closure to closure created")
     # tasyncawait.nim breaks with this optimization:
     when false:
       if d.k != locNone:
         linefmt(p, cpsStmts, "$1.ClP_0 = $2; $1.ClE_0 = $3;$n",
-                d.rdLoc, a.rdLoc, b.rdLoc)
+                [d.rdLoc, a.rdLoc, b.rdLoc])
     else:
-      getTemp(p, n.typ, tmp)
+      tmp = getTemp(p, n.typ)
       linefmt(p, cpsStmts, "$1.ClP_0 = $2; $1.ClE_0 = $3;$n",
-              tmp.rdLoc, a.rdLoc, b.rdLoc)
+              [tmp.rdLoc, a.rdLoc, b.rdLoc])
       putLocIntoDest(p, d, tmp)
 
 proc genArrayConstr(p: BProc, n: PNode, d: var TLoc) =
   var arr: TLoc
   if not handleConstExpr(p, n, d):
-    if d.k == locNone: getTemp(p, n.typ, d)
-    for i in countup(0, sonsLen(n) - 1):
-      initLoc(arr, locExpr, lodeTyp elemType(skipTypes(n.typ, abstractInst)), d.storage)
-      arr.r = "$1[$2]" % [rdLoc(d), intLiteral(i)]
-      expr(p, n.sons[i], arr)
+    if d.k == locNone: d = getTemp(p, n.typ)
+    for i in 0..<n.len:
+      arr = initLoc(locExpr, lodeTyp elemType(skipTypes(n.typ, abstractInst)), d.storage)
+      var lit = newRopeAppender()
+      intLiteral(i, lit)
+      arr.snippet = "$1[$2]" % [rdLoc(d), lit]
+      expr(p, n[i], arr)
 
 proc genComplexConst(p: BProc, sym: PSym, d: var TLoc) =
   requestConstImpl(p, sym)
-  assert((sym.loc.r != nil) and (sym.loc.t != nil))
+  assert((sym.loc.snippet != "") and (sym.loc.t != nil))
   putLocIntoDest(p, d, sym.loc)
 
 template genStmtListExprImpl(exprOrStmt) {.dirty.} =
@@ -2022,11 +2759,11 @@ template genStmtListExprImpl(exprOrStmt) {.dirty.} =
   let hasNimFrame = p.prc != nil and
       sfSystemModule notin p.module.module.flags and
       optStackTrace in p.prc.options
-  var frameName: Rope = nil
-  for i in 0 .. n.len - 2:
+  var frameName: Rope = ""
+  for i in 0..<n.len - 1:
     let it = n[i]
     if it.kind == nkComesFrom:
-      if hasNimFrame and frameName == nil:
+      if hasNimFrame and frameName == "":
         inc p.labels
         frameName = "FR" & rope(p.labels) & "_"
         let theMacro = it[0].sym
@@ -2036,83 +2773,82 @@ template genStmtListExprImpl(exprOrStmt) {.dirty.} =
     else:
       genStmts(p, it)
   if n.len > 0: exprOrStmt
-  if frameName != nil:
-    add p.s(cpsStmts), deinitFrameNoDebug(p, frameName)
+  if frameName != "":
+    p.s(cpsStmts).add deinitFrameNoDebug(p, frameName)
 
 proc genStmtListExpr(p: BProc, n: PNode, d: var TLoc) =
   genStmtListExprImpl:
-    expr(p, n[n.len - 1], d)
+    expr(p, n[^1], d)
 
 proc genStmtList(p: BProc, n: PNode) =
   genStmtListExprImpl:
-    genStmts(p, n[n.len - 1])
+    genStmts(p, n[^1])
+
+from parampatterns import isLValue
 
 proc upConv(p: BProc, n: PNode, d: var TLoc) =
-  var a: TLoc
-  initLocExpr(p, n.sons[0], a)
+  var a: TLoc = initLocExpr(p, n[0])
   let dest = skipTypes(n.typ, abstractPtrs)
   if optObjCheck in p.options and not isObjLackingTypeField(dest):
-    var r = rdLoc(a)
-    var nilCheck: Rope = nil
-    var t = skipTypes(a.t, abstractInst)
-    while t.kind in {tyVar, tyLent, tyPtr, tyRef}:
-      if t.kind notin {tyVar, tyLent}: nilCheck = r
-      if t.kind notin {tyVar, tyLent} or not p.module.compileToCpp:
-        r = "(*$1)" % [r]
-      t = skipTypes(t.lastSon, abstractInst)
-    discard getTypeDesc(p.module, t)
-    if not p.module.compileToCpp:
-      while t.kind == tyObject and t.sons[0] != nil:
-        add(r, ".Sup")
-        t = skipTypes(t.sons[0], skipPtrs)
-    if nilCheck != nil:
-      linefmt(p, cpsStmts, "if ($1) #chckObj($2.m_type, $3);$n",
-              nilCheck, r, genTypeInfo(p.module, dest, n.info))
-    else:
-      linefmt(p, cpsStmts, "#chckObj($1.m_type, $2);$n",
-              r, genTypeInfo(p.module, dest, n.info))
-  if n.sons[0].typ.kind != tyObject:
-    putIntoDest(p, d, n,
+    var nilCheck = ""
+    var r = newRopeAppender()
+    rdMType(p, a, nilCheck, r)
+    if optTinyRtti in p.config.globalOptions:
+      let checkFor = $getObjDepth(dest)
+      let token = $genDisplayElem(MD5Digest(hashType(dest, p.config)))
+      if nilCheck != "":
+        linefmt(p, cpsStmts, "if ($1 && !#isObjDisplayCheck($2, $3, $4)){ #raiseObjectConversionError(); ",
+                [nilCheck, r, checkFor, token])
+      else:
+        linefmt(p, cpsStmts, "if (!#isObjDisplayCheck($1, $2, $3)){ #raiseObjectConversionError(); ",
+                [r, checkFor, token])
+    else:
+      let checkFor = genTypeInfoV1(p.module, dest, n.info)
+      if nilCheck != "":
+        linefmt(p, cpsStmts, "if ($1 && !#isObj($2, $3)){ #raiseObjectConversionError(); ",
+                [nilCheck, r, checkFor])
+      else:
+        linefmt(p, cpsStmts, "if (!#isObj($1, $2)){ #raiseObjectConversionError(); ",
+                [r, checkFor])
+    raiseInstr(p, p.s(cpsStmts))
+    linefmt p, cpsStmts, "}$n", []
+
+  if n[0].typ.kind != tyObject:
+    if n.isLValue:
+      putIntoDest(p, d, n,
+                "(*(($1*) (&($2))))" % [getTypeDesc(p.module, n.typ), rdLoc(a)], a.storage)
+    else:
+      putIntoDest(p, d, n,
                 "(($1) ($2))" % [getTypeDesc(p.module, n.typ), rdLoc(a)], a.storage)
   else:
     putIntoDest(p, d, n, "(*($1*) ($2))" %
                         [getTypeDesc(p.module, dest), addrLoc(p.config, a)], a.storage)
 
 proc downConv(p: BProc, n: PNode, d: var TLoc) =
-  if p.module.compileToCpp:
-    discard getTypeDesc(p.module, skipTypes(n[0].typ, abstractPtrs))
-    expr(p, n.sons[0], d)     # downcast does C++ for us
-  else:
-    var dest = skipTypes(n.typ, abstractPtrs)
+  var arg = n[0]
+  while arg.kind == nkObjDownConv: arg = arg[0]
 
-    var arg = n.sons[0]
-    while arg.kind == nkObjDownConv: arg = arg.sons[0]
-
-    var src = skipTypes(arg.typ, abstractPtrs)
-    discard getTypeDesc(p.module, src)
-    var a: TLoc
-    initLocExpr(p, arg, a)
-    var r = rdLoc(a)
-    let isRef = skipTypes(arg.typ, abstractInst).kind in {tyRef, tyPtr, tyVar, tyLent}
-    if isRef:
-      add(r, "->Sup")
-    else:
-      add(r, ".Sup")
-    for i in countup(2, abs(inheritanceDiff(dest, src))): add(r, ".Sup")
-    if isRef:
-      # it can happen that we end up generating '&&x->Sup' here, so we pack
-      # the '&x->Sup' into a temporary and then those address is taken
-      # (see bug #837). However sometimes using a temporary is not correct:
-      # init(TFigure(my)) # where it is passed to a 'var TFigure'. We test
-      # this by ensuring the destination is also a pointer:
-      if d.k == locNone and skipTypes(n.typ, abstractInst).kind in {tyRef, tyPtr, tyVar, tyLent}:
-        getTemp(p, n.typ, d)
-        linefmt(p, cpsStmts, "$1 = &$2;$n", rdLoc(d), r)
-      else:
-        r = "&" & r
-        putIntoDest(p, d, n, r, a.storage)
-    else:
-      putIntoDest(p, d, n, r, a.storage)
+  let dest = skipTypes(n.typ, abstractPtrs)
+  let src = skipTypes(arg.typ, abstractPtrs)
+  discard getTypeDesc(p.module, src)
+  let isRef = skipTypes(arg.typ, abstractInstOwned).kind in {tyRef, tyPtr, tyVar, tyLent}
+  if isRef and d.k == locNone and n.typ.skipTypes(abstractInstOwned).kind in {tyRef, tyPtr} and n.isLValue:
+    # it can happen that we end up generating '&&x->Sup' here, so we pack
+    # the '&x->Sup' into a temporary and then those address is taken
+    # (see bug #837). However sometimes using a temporary is not correct:
+    # init(TFigure(my)) # where it is passed to a 'var TFigure'. We test
+    # this by ensuring the destination is also a pointer:
+    var a: TLoc = initLocExpr(p, arg)
+    putIntoDest(p, d, n,
+              "(*(($1*) (&($2))))" % [getTypeDesc(p.module, n.typ), rdLoc(a)], a.storage)
+  elif p.module.compileToCpp:
+    # C++ implicitly downcasts for us
+    expr(p, arg, d)
+  else:
+    var a: TLoc = initLocExpr(p, arg)
+    var r = rdLoc(a) & (if isRef: "->Sup" else: ".Sup")
+    for i in 2..abs(inheritanceDiff(dest, src)): r.add(".Sup")
+    putIntoDest(p, d, n, if isRef: "&" & r else: r, a.storage)
 
 proc exprComplexConst(p: BProc, n: PNode, d: var TLoc) =
   let t = n.typ
@@ -2123,8 +2859,10 @@ proc exprComplexConst(p: BProc, n: PNode, d: var TLoc) =
   if id == p.module.labels:
     # expression not found in the cache:
     inc(p.module.labels)
-    addf(p.module.s[cfsData], "NIM_CONST $1 $2 = $3;$n",
-         [getTypeDesc(p.module, t), tmp, genConstExpr(p, n)])
+    p.module.s[cfsData].addf("static NIM_CONST $1 $2 = ",
+         [getTypeDesc(p.module, t, dkConst), tmp])
+    genBracedInit(p, n, isConst = true, t, p.module.s[cfsData])
+    p.module.s[cfsData].addf(";$n", [])
 
   if d.k == locNone:
     fillLoc(d, locData, n, tmp, OnStatic)
@@ -2135,14 +2873,74 @@ proc exprComplexConst(p: BProc, n: PNode, d: var TLoc) =
     if t.kind notin {tySequence, tyString}:
       d.storage = OnStatic
 
+proc genConstSetup(p: BProc; sym: PSym): bool =
+  let m = p.module
+  useHeader(m, sym)
+  if sym.loc.k == locNone:
+    fillBackendName(p.module, sym)
+    fillLoc(sym.loc, locData, sym.astdef, OnStatic)
+  if m.hcrOn: incl(sym.loc.flags, lfIndirect)
+  result = lfNoDecl notin sym.loc.flags
+
+proc genConstHeader(m, q: BModule; p: BProc, sym: PSym) =
+  if sym.loc.snippet == "":
+    if not genConstSetup(p, sym): return
+  assert(sym.loc.snippet != "", $sym.name.s & $sym.itemId)
+  if m.hcrOn:
+    m.s[cfsVars].addf("static $1* $2;$n", [getTypeDesc(m, sym.loc.t, dkVar), sym.loc.snippet]);
+    m.initProc.procSec(cpsLocals).addf(
+      "\t$1 = ($2*)hcrGetGlobal($3, \"$1\");$n", [sym.loc.snippet,
+      getTypeDesc(m, sym.loc.t, dkVar), getModuleDllPath(q, sym)])
+  else:
+    let headerDecl = "extern NIM_CONST $1 $2;$n" %
+        [getTypeDesc(m, sym.loc.t, dkVar), sym.loc.snippet]
+    m.s[cfsData].add(headerDecl)
+    if sfExportc in sym.flags and p.module.g.generatedHeader != nil:
+      p.module.g.generatedHeader.s[cfsData].add(headerDecl)
+
+proc genConstDefinition(q: BModule; p: BProc; sym: PSym) =
+  # add a suffix for hcr - will later init the global pointer with this data
+  let actualConstName = if q.hcrOn: sym.loc.snippet & "_const" else: sym.loc.snippet
+  var data = newRopeAppender()
+  data.addf("N_LIB_PRIVATE NIM_CONST $1 $2 = ",
+           [getTypeDesc(q, sym.typ), actualConstName])
+  genBracedInit(q.initProc, sym.astdef, isConst = true, sym.typ, data)
+  data.addf(";$n", [])
+  q.s[cfsData].add data
+  if q.hcrOn:
+    # generate the global pointer with the real name
+    q.s[cfsVars].addf("static $1* $2;$n", [getTypeDesc(q, sym.loc.t, dkVar), sym.loc.snippet])
+    # register it (but ignore the boolean result of hcrRegisterGlobal)
+    q.initProc.procSec(cpsLocals).addf(
+      "\thcrRegisterGlobal($1, \"$2\", sizeof($3), NULL, (void**)&$2);$n",
+      [getModuleDllPath(q, sym), sym.loc.snippet, rdLoc(sym.loc)])
+    # always copy over the contents of the actual constant with the _const
+    # suffix ==> this means that the constant is reloadable & updatable!
+    q.initProc.procSec(cpsLocals).add(ropecg(q,
+      "\t#nimCopyMem((void*)$1, (NIM_CONST void*)&$2, sizeof($3));$n",
+      [sym.loc.snippet, actualConstName, rdLoc(sym.loc)]))
+
+proc genConstStmt(p: BProc, n: PNode) =
+  # This code is only used in the new DCE implementation.
+  assert useAliveDataFromDce in p.module.flags
+  let m = p.module
+  for it in n:
+    if it[0].kind == nkSym:
+      let sym = it[0].sym
+      if not isSimpleConst(sym.typ) and sym.itemId.item in m.alive and genConstSetup(p, sym):
+        genConstDefinition(m, p, sym)
+
 proc expr(p: BProc, n: PNode, d: var TLoc) =
+  when defined(nimCompilerStacktraceHints):
+    setFrameMsg p.config$n.info & " " & $n.kind
   p.currLineInfo = n.info
+
   case n.kind
   of nkSym:
     var sym = n.sym
     case sym.kind
     of skMethod:
-      if {sfDispatcher, sfForward} * sym.flags != {}:
+      if useAliveDataFromDce in p.module.flags or {sfDispatcher, sfForward} * sym.flags != {}:
         # we cannot produce code for the dispatcher yet:
         fillProcLoc(p.module, n)
         genProcPrototype(p.module, sym)
@@ -2155,13 +2953,23 @@ proc expr(p: BProc, n: PNode, d: var TLoc) =
       if sfCompileTime in sym.flags:
         localError(p.config, n.info, "request to generate code for .compileTime proc: " &
            sym.name.s)
-      genProc(p.module, sym)
-      if sym.loc.r == nil or sym.loc.lode == nil:
+      if useAliveDataFromDce in p.module.flags and sym.typ.callConv != ccInline:
+        fillProcLoc(p.module, n)
+        genProcPrototype(p.module, sym)
+      else:
+        genProc(p.module, sym)
+      if sym.loc.snippet == "" or sym.loc.lode == nil:
         internalError(p.config, n.info, "expr: proc not init " & sym.name.s)
       putLocIntoDest(p, d, sym.loc)
     of skConst:
       if isSimpleConst(sym.typ):
-        putIntoDest(p, d, n, genLiteral(p, sym.ast, sym.typ), OnStatic)
+        var lit = newRopeAppender()
+        genLiteral(p, sym.astdef, sym.typ, lit)
+        putIntoDest(p, d, n, lit, OnStatic)
+      elif useAliveDataFromDce in p.module.flags:
+        genConstHeader(p.module, p.module, p, sym)
+        assert((sym.loc.snippet != "") and (sym.loc.t != nil))
+        putLocIntoDest(p, d, sym.loc)
       else:
         genComplexConst(p, sym, d)
     of skEnumField:
@@ -2172,26 +2980,35 @@ proc expr(p: BProc, n: PNode, d: var TLoc) =
     of skVar, skForVar, skResult, skLet:
       if {sfGlobal, sfThread} * sym.flags != {}:
         genVarPrototype(p.module, n)
-      if sym.loc.r == nil or sym.loc.t == nil:
+        if sfCompileTime in sym.flags:
+          genSingleVar(p, sym, n, astdef(sym))
+
+      if sym.loc.snippet == "" or sym.loc.t == nil:
         #echo "FAILED FOR PRCO ", p.prc.name.s
         #echo renderTree(p.prc.ast, {renderIds})
         internalError p.config, n.info, "expr: var not init " & sym.name.s & "_" & $sym.id
       if sfThread in sym.flags:
         accessThreadLocalVar(p, sym)
         if emulatedThreadVars(p.config):
-          putIntoDest(p, d, sym.loc.lode, "NimTV_->" & sym.loc.r)
+          putIntoDest(p, d, sym.loc.lode, "NimTV_->" & sym.loc.snippet)
         else:
           putLocIntoDest(p, d, sym.loc)
       else:
         putLocIntoDest(p, d, sym.loc)
     of skTemp:
-      if sym.loc.r == nil or sym.loc.t == nil:
+      when false:
+        # this is more harmful than helpful.
+        if sym.loc.snippet == "":
+          # we now support undeclared 'skTemp' variables for easier
+          # transformations in other parts of the compiler:
+          assignLocalVar(p, n)
+      if sym.loc.snippet == "" or sym.loc.t == nil:
         #echo "FAILED FOR PRCO ", p.prc.name.s
         #echo renderTree(p.prc.ast, {renderIds})
         internalError(p.config, n.info, "expr: temp not init " & sym.name.s & "_" & $sym.id)
       putLocIntoDest(p, d, sym.loc)
     of skParam:
-      if sym.loc.r == nil or sym.loc.t == nil:
+      if sym.loc.snippet == "" or sym.loc.t == nil:
         # echo "FAILED FOR PRCO ", p.prc.name.s
         # debug p.prc.typ.n
         # echo renderTree(p.prc.ast, {renderIds})
@@ -2200,19 +3017,24 @@ proc expr(p: BProc, n: PNode, d: var TLoc) =
     else: internalError(p.config, n.info, "expr(" & $sym.kind & "); unknown symbol")
   of nkNilLit:
     if not isEmptyType(n.typ):
-      putIntoDest(p, d, n, genLiteral(p, n))
+      var lit = newRopeAppender()
+      genLiteral(p, n, lit)
+      putIntoDest(p, d, n, lit)
   of nkStrLit..nkTripleStrLit:
-    putDataIntoDest(p, d, n, genLiteral(p, n))
-  of nkIntLit..nkUInt64Lit,
-     nkFloatLit..nkFloat128Lit, nkCharLit:
-    putIntoDest(p, d, n, genLiteral(p, n))
+    var lit = newRopeAppender()
+    genLiteral(p, n, lit)
+    putDataIntoDest(p, d, n, lit)
+  of nkIntLit..nkUInt64Lit, nkFloatLit..nkFloat128Lit, nkCharLit:
+    var lit = newRopeAppender()
+    genLiteral(p, n, lit)
+    putIntoDest(p, d, n, lit)
   of nkCall, nkHiddenCallConv, nkInfix, nkPrefix, nkPostfix, nkCommand,
      nkCallStrLit:
-    genLineDir(p, n)
-    let op = n.sons[0]
+    genLineDir(p, n) # may be redundant, it is generated in fixupCall as well
+    let op = n[0]
     if n.typ.isNil:
       # discard the value:
-      var a: TLoc
+      var a: TLoc = default(TLoc)
       if op.kind == nkSym and op.sym.magic != mNone:
         genMagicExpr(p, n, a, op.sym.magic)
       else:
@@ -2225,7 +3047,9 @@ proc expr(p: BProc, n: PNode, d: var TLoc) =
         genCall(p, n, d)
   of nkCurly:
     if isDeepConstExpr(n) and n.len != 0:
-      putIntoDest(p, d, n, genSetNode(p, n))
+      var lit = newRopeAppender()
+      genSetNode(p, n, lit)
+      putIntoDest(p, d, n, lit)
     else:
       genSetConstr(p, n, d)
   of nkBracket:
@@ -2236,14 +3060,25 @@ proc expr(p: BProc, n: PNode, d: var TLoc) =
     else:
       genArrayConstr(p, n, d)
   of nkPar, nkTupleConstr:
-    if isDeepConstExpr(n) and n.len != 0:
+    if n.typ != nil and n.typ.kind == tyProc and n.len == 2:
+      genClosure(p, n, d)
+    elif isDeepConstExpr(n) and n.len != 0:
       exprComplexConst(p, n, d)
     else:
       genTupleConstr(p, n, d)
   of nkObjConstr: genObjConstr(p, n, d)
   of nkCast: genCast(p, n, d)
   of nkHiddenStdConv, nkHiddenSubConv, nkConv: genConv(p, n, d)
-  of nkHiddenAddr, nkAddr: genAddr(p, n, d)
+  of nkHiddenAddr:
+    if n[0].kind == nkDerefExpr:
+      # addr ( deref ( x )) --> x
+      var x = n[0][0]
+      if n.typ.skipTypes(abstractVar).kind != tyOpenArray:
+        x.typ = n.typ
+      expr(p, x, d)
+      return
+    genAddr(p, n, d)
+  of nkAddr: genAddr(p, n, d)
   of nkBracketExpr: genBracketExpr(p, n, d)
   of nkDerefExpr, nkHiddenDeref: genDeref(p, n, d)
   of nkDotExpr: genRecordField(p, n, d)
@@ -2254,18 +3089,16 @@ proc expr(p: BProc, n: PNode, d: var TLoc) =
   of nkIfExpr, nkIfStmt: genIf(p, n, d)
   of nkWhen:
     # This should be a "when nimvm" node.
-    expr(p, n.sons[1].sons[0], d)
+    expr(p, n[1][0], d)
   of nkObjDownConv: downConv(p, n, d)
   of nkObjUpConv: upConv(p, n, d)
-  of nkChckRangeF: genRangeChck(p, n, d, "chckRangeF")
-  of nkChckRange64: genRangeChck(p, n, d, "chckRange64")
-  of nkChckRange: genRangeChck(p, n, d, "chckRange")
+  of nkChckRangeF, nkChckRange64, nkChckRange: genRangeChck(p, n, d)
   of nkStringToCString: convStrToCStr(p, n, d)
   of nkCStringToString: convCStrToStr(p, n, d)
   of nkLambdaKinds:
-    var sym = n.sons[namePos].sym
+    var sym = n[namePos].sym
     genProc(p.module, sym)
-    if sym.loc.r == nil or sym.loc.lode == nil:
+    if sym.loc.snippet == "" or sym.loc.lode == nil:
       internalError(p.config, n.info, "expr: proc not init " & sym.name.s)
     putLocIntoDest(p, d, sym.loc)
   of nkClosure: genClosure(p, n, d)
@@ -2273,15 +3106,20 @@ proc expr(p: BProc, n: PNode, d: var TLoc) =
   of nkEmpty: discard
   of nkWhileStmt: genWhileStmt(p, n)
   of nkVarSection, nkLetSection: genVarStmt(p, n)
-  of nkConstSection: discard  # consts generated lazily on use
+  of nkConstSection:
+    if useAliveDataFromDce in p.module.flags:
+      genConstStmt(p, n)
+    # else: consts generated lazily on use
   of nkForStmt: internalError(p.config, n.info, "for statement not eliminated")
   of nkCaseStmt: genCase(p, n, d)
   of nkReturnStmt: genReturnStmt(p, n)
   of nkBreakStmt: genBreakStmt(p, n)
   of nkAsgn:
+    cow(p, n[1])
     if nfPreventCg notin n.flags:
       genAsgn(p, n, fastAsgn=false)
-  of nkFastAsgn:
+  of nkFastAsgn, nkSinkAsgn:
+    cow(p, n[1])
     if nfPreventCg notin n.flags:
       # transf is overly aggressive with 'nkFastAsgn', so we work around here.
       # See tests/run/tcnstseq3 for an example that would fail otherwise.
@@ -2290,22 +3128,17 @@ proc expr(p: BProc, n: PNode, d: var TLoc) =
     let ex = n[0]
     if ex.kind != nkEmpty:
       genLineDir(p, n)
-      var a: TLoc
-      if ex.kind in nkCallKinds and (ex[0].kind != nkSym or
-                                     ex[0].sym.magic == mNone):
-        # bug #6037: do not assign to a temp in C++ mode:
-        incl a.flags, lfSingleUse
-        genCall(p, ex, a)
-        if lfSingleUse notin a.flags:
-          line(p, cpsStmts, a.r & ";\L")
-      else:
-        initLocExpr(p, ex, a)
+      var a: TLoc = initLocExprSingleUse(p, ex)
+      line(p, cpsStmts, "(void)(" & a.snippet & ");\L")
   of nkAsmStmt: genAsmStmt(p, n)
-  of nkTryStmt:
-    if p.module.compileToCpp and optNoCppExceptions notin p.config.globalOptions:
+  of nkTryStmt, nkHiddenTryStmt:
+    case p.config.exc
+    of excGoto:
+      genTryGoto(p, n, d)
+    of excCpp:
       genTryCpp(p, n, d)
     else:
-      genTry(p, n, d)
+      genTrySetjmp(p, n, d)
   of nkRaiseStmt: genRaiseStmt(p, n)
   of nkTypeSection:
     # we have to emit the type information for object types here to support
@@ -2316,174 +3149,327 @@ proc expr(p: BProc, n: PNode, d: var TLoc) =
      nkFromStmt, nkTemplateDef, nkMacroDef, nkStaticStmt:
     discard
   of nkPragma: genPragma(p, n)
-  of nkPragmaBlock: expr(p, n.lastSon, d)
+  of nkPragmaBlock:
+    var inUncheckedAssignSection = 0
+    let pragmaList = n[0]
+    for pi in pragmaList:
+      if whichPragma(pi) == wCast:
+        case whichPragma(pi[1])
+        of wUncheckedAssign:
+          inUncheckedAssignSection = 1
+        else:
+          discard
+
+    inc p.inUncheckedAssignSection, inUncheckedAssignSection
+    expr(p, n.lastSon, d)
+    dec p.inUncheckedAssignSection, inUncheckedAssignSection
+
   of nkProcDef, nkFuncDef, nkMethodDef, nkConverterDef:
-    if n.sons[genericParamsPos].kind == nkEmpty:
-      var prc = n.sons[namePos].sym
-      # due to a bug/limitation in the lambda lifting, unused inner procs
-      # are not transformed correctly. We work around this issue (#411) here
-      # by ensuring it's no inner proc (owner is a module):
-      if prc.skipGenericOwner.kind == skModule and sfCompileTime notin prc.flags:
+    if n[genericParamsPos].kind == nkEmpty:
+      var prc = n[namePos].sym
+      if useAliveDataFromDce in p.module.flags:
+        if p.module.alive.contains(prc.itemId.item) and
+            prc.magic in generatedMagics:
+          genProc(p.module, prc)
+      elif prc.skipGenericOwner.kind == skModule and sfCompileTime notin prc.flags:
         if ({sfExportc, sfCompilerProc} * prc.flags == {sfExportc}) or
             (sfExportc in prc.flags and lfExportLib in prc.loc.flags) or
             (prc.kind == skMethod):
-          # we have not only the header:
-          if prc.getBody.kind != nkEmpty or lfDynamicLib in prc.loc.flags:
-            genProc(p.module, prc)
+          # due to a bug/limitation in the lambda lifting, unused inner procs
+          # are not transformed correctly. We work around this issue (#411) here
+          # by ensuring it's no inner proc (owner is a module).
+          # Generate proc even if empty body, bugfix #11651.
+          genProc(p.module, prc)
   of nkParForStmt: genParForStmt(p, n)
   of nkState: genState(p, n)
-  of nkGotoState: genGotoState(p, n)
+  of nkGotoState:
+    # simply never set it back to 0 here from here on...
+    inc p.splitDecls
+    genGotoState(p, n)
   of nkBreakState: genBreakState(p, n, d)
+  of nkMixinStmt, nkBindStmt: discard
   else: internalError(p.config, n.info, "expr(" & $n.kind & "); unknown node kind")
 
-proc genNamedConstExpr(p: BProc, n: PNode): Rope =
-  if n.kind == nkExprColonExpr: result = genConstExpr(p, n.sons[1])
-  else: result = genConstExpr(p, n)
-
-proc getDefaultValue(p: BProc; typ: PType; info: TLineInfo): Rope =
-  var t = skipTypes(typ, abstractRange-{tyTypeDesc})
+proc getDefaultValue(p: BProc; typ: PType; info: TLineInfo; result: var Rope) =
+  var t = skipTypes(typ, abstractRange+{tyOwned}-{tyTypeDesc})
   case t.kind
-  of tyBool: result = rope"NIM_FALSE"
-  of tyEnum, tyChar, tyInt..tyInt64, tyUInt..tyUInt64: result = rope"0"
-  of tyFloat..tyFloat128: result = rope"0.0"
-  of tyCString, tyString, tyVar, tyLent, tyPointer, tyPtr, tySequence, tyExpr,
-     tyStmt, tyTypeDesc, tyStatic, tyRef, tyNil:
-    result = rope"NIM_NIL"
+  of tyBool: result.add rope"NIM_FALSE"
+  of tyEnum, tyChar, tyInt..tyInt64, tyUInt..tyUInt64: result.add rope"0"
+  of tyFloat..tyFloat128: result.add rope"0.0"
+  of tyCstring, tyVar, tyLent, tyPointer, tyPtr, tyUntyped,
+     tyTyped, tyTypeDesc, tyStatic, tyRef, tyNil:
+    result.add rope"NIM_NIL"
+  of tyString, tySequence:
+    if optSeqDestructors in p.config.globalOptions:
+      result.add "{0, NIM_NIL}"
+    else:
+      result.add "NIM_NIL"
   of tyProc:
     if t.callConv != ccClosure:
-      result = rope"NIM_NIL"
+      result.add "NIM_NIL"
     else:
-      result = rope"{NIM_NIL, NIM_NIL}"
+      result.add "{NIM_NIL, NIM_NIL}"
   of tyObject:
-    if not isObjLackingTypeField(t) and not p.module.compileToCpp:
-      result = "{{$1}}" % [genTypeInfo(p.module, t, info)]
-    else:
-      result = rope"{}"
+    var count = 0
+    result.add "{"
+    getNullValueAuxT(p, t, t, t.n, nil, result, count, true, info)
+    result.add "}"
   of tyTuple:
-    result = rope"{"
-    for i in 0 ..< typ.len:
+    result.add "{"
+    if p.vccAndC and t.isEmptyTupleType:
+      result.add "0"
+    for i, a in t.ikids:
       if i > 0: result.add ", "
-      result.add getDefaultValue(p, typ.sons[i], info)
+      getDefaultValue(p, a, info, result)
     result.add "}"
-  of tyArray: result = rope"{}"
+  of tyArray:
+    result.add "{"
+    for i in 0..<toInt(lengthOrd(p.config, t.indexType)):
+      if i > 0: result.add ", "
+      getDefaultValue(p, t.elementType, info, result)
+    result.add "}"
+    #result = rope"{}"
+  of tyOpenArray, tyVarargs:
+    result.add "{NIM_NIL, 0}"
   of tySet:
-    if mapType(p.config, t) == ctArray: result = rope"{}"
-    else: result = rope"0"
+    if mapSetType(p.config, t) == ctArray: result.add "{}"
+    else: result.add "0"
   else:
     globalError(p.config, info, "cannot create null element for: " & $t.kind)
 
-proc getNullValueAux(p: BProc; t: PType; obj, cons: PNode, result: var Rope; count: var int) =
+proc isEmptyCaseObjectBranch(n: PNode): bool =
+  for it in n:
+    if it.kind == nkSym and not isEmptyType(it.sym.typ): return false
+  return true
+
+proc getNullValueAux(p: BProc; t: PType; obj, constOrNil: PNode,
+                     result: var Rope; count: var int;
+                     isConst: bool, info: TLineInfo) =
   case obj.kind
   of nkRecList:
     for it in obj.sons:
-      getNullValueAux(p, t, it, cons, result, count)
+      getNullValueAux(p, t, it, constOrNil, result, count, isConst, info)
   of nkRecCase:
-    getNullValueAux(p, t, obj.sons[0], cons, result, count)
-    for i in countup(1, sonsLen(obj) - 1):
-      getNullValueAux(p, t, lastSon(obj.sons[i]), cons, result, count)
+    getNullValueAux(p, t, obj[0], constOrNil, result, count, isConst, info)
+    var res = ""
+    if count > 0: res.add ", "
+    var branch = Zero
+    if constOrNil != nil:
+      ## find kind value, default is zero if not specified
+      for i in 1..<constOrNil.len:
+        if constOrNil[i].kind == nkExprColonExpr:
+          if constOrNil[i][0].sym.name.id == obj[0].sym.name.id:
+            branch = getOrdValue(constOrNil[i][1])
+            break
+        elif i == obj[0].sym.position:
+          branch = getOrdValue(constOrNil[i])
+          break
+
+    let selectedBranch = caseObjDefaultBranch(obj, branch)
+    res.add "{"
+    var countB = 0
+    let b = lastSon(obj[selectedBranch])
+    # designated initilization is the only way to init non first element of unions
+    # branches are allowed to have no members (b.len == 0), in this case they don't need initializer
+    if b.kind == nkRecList and not isEmptyCaseObjectBranch(b):
+      res.add "._" & mangleRecFieldName(p.module, obj[0].sym) & "_" & $selectedBranch & " = {"
+      getNullValueAux(p, t,  b, constOrNil, res, countB, isConst, info)
+      res.add "}"
+    elif b.kind == nkSym:
+      res.add "." & mangleRecFieldName(p.module, b.sym) & " = "
+      getNullValueAux(p, t,  b, constOrNil, res, countB, isConst, info)
+    else:
+      return
+    result.add res
+    result.add "}"
+
   of nkSym:
     if count > 0: result.add ", "
     inc count
     let field = obj.sym
-    for i in 1..<cons.len:
-      if cons[i].kind == nkExprColonExpr:
-        if cons[i][0].sym.name.id == field.name.id:
-          result.add genConstExpr(p, cons[i][1])
+    if constOrNil != nil:
+      for i in 1..<constOrNil.len:
+        if constOrNil[i].kind == nkExprColonExpr:
+          assert constOrNil[i][0].kind == nkSym, "illformed object constr; the field is not a sym"
+          if constOrNil[i][0].sym.name.id == field.name.id:
+            genBracedInit(p, constOrNil[i][1], isConst, field.typ, result)
+            return
+        elif i == field.position:
+          genBracedInit(p, constOrNil[i], isConst, field.typ, result)
           return
-      elif i == field.position:
-        result.add genConstExpr(p, cons[i])
-        return
     # not found, produce default value:
-    result.add getDefaultValue(p, field.typ, cons.info)
+    getDefaultValue(p, field.typ, info, result)
   else:
-    localError(p.config, cons.info, "cannot create null element for: " & $obj)
+    localError(p.config, info, "cannot create null element for: " & $obj)
 
-proc getNullValueAuxT(p: BProc; orig, t: PType; obj, cons: PNode, result: var Rope; count: var int) =
-  var base = t.sons[0]
+proc getNullValueAuxT(p: BProc; orig, t: PType; obj, constOrNil: PNode,
+                      result: var Rope; count: var int;
+                      isConst: bool, info: TLineInfo) =
+  var base = t.baseClass
   let oldRes = result
-  if not p.module.compileToCpp: result.add "{"
   let oldcount = count
   if base != nil:
+    result.add "{"
     base = skipTypes(base, skipPtrs)
-    getNullValueAuxT(p, orig, base, base.n, cons, result, count)
-  elif not isObjLackingTypeField(t) and not p.module.compileToCpp:
-    addf(result, "$1", [genTypeInfo(p.module, orig, obj.info)])
+    getNullValueAuxT(p, orig, base, base.n, constOrNil, result, count, isConst, info)
+    result.add "}"
+  elif not isObjLackingTypeField(t):
+    if optTinyRtti in p.config.globalOptions:
+      result.add genTypeInfoV2(p.module, orig, obj.info)
+    else:
+      result.add genTypeInfoV1(p.module, orig, obj.info)
     inc count
-  getNullValueAux(p, t, obj, cons, result, count)
+  getNullValueAux(p, t, obj, constOrNil, result, count, isConst, info)
   # do not emit '{}' as that is not valid C:
-  if oldcount == count: result = oldres
-  elif not p.module.compileToCpp: result.add "}"
+  if oldcount == count: result = oldRes
 
-proc genConstObjConstr(p: BProc; n: PNode): Rope =
-  result = nil
-  let t = n.typ.skipTypes(abstractInst)
+proc genConstObjConstr(p: BProc; n: PNode; isConst: bool; result: var Rope) =
+  let t = n.typ.skipTypes(abstractInstOwned)
   var count = 0
   #if not isObjLackingTypeField(t) and not p.module.compileToCpp:
-  #  addf(result, "{$1}", [genTypeInfo(p.module, t)])
+  #  result.addf("{$1}", [genTypeInfo(p.module, t)])
   #  inc count
-  getNullValueAuxT(p, t, t, t.n, n, result, count)
-  if p.module.compileToCpp:
-    result = "{$1}$n" % [result]
-
-proc genConstSimpleList(p: BProc, n: PNode): Rope =
-  var length = sonsLen(n)
-  result = rope("{")
-  let t = n.typ.skipTypes(abstractInst)
-  for i in countup(0, length - 2):
-    addf(result, "$1,$n", [genNamedConstExpr(p, n.sons[i])])
-  if length > 0:
-    add(result, genNamedConstExpr(p, n.sons[length - 1]))
-  addf(result, "}$n", [])
-
-proc genConstSeq(p: BProc, n: PNode, t: PType): Rope =
+  result.add "{"
+  if t.kind == tyObject:
+    getNullValueAuxT(p, t, t, t.n, n, result, count, isConst, n.info)
+  result.add("}\n")
+
+proc genConstSimpleList(p: BProc, n: PNode; isConst: bool; result: var Rope) =
+  result.add "{"
+  if p.vccAndC and n.len == 0 and n.typ.kind == tyArray:
+    getDefaultValue(p, n.typ.elementType, n.info, result)
+  for i in 0..<n.len:
+    let it = n[i]
+    if i > 0: result.add ",\n"
+    if it.kind == nkExprColonExpr: genBracedInit(p, it[1], isConst, it[0].typ, result)
+    else: genBracedInit(p, it, isConst, it.typ, result)
+  result.add("}\n")
+
+proc genConstTuple(p: BProc, n: PNode; isConst: bool; tup: PType; result: var Rope) =
+  result.add "{"
+  if p.vccAndC and n.len == 0:
+    result.add "0"
+  for i in 0..<n.len:
+    let it = n[i]
+    if i > 0: result.add ",\n"
+    if it.kind == nkExprColonExpr: genBracedInit(p, it[1], isConst, tup[i], result)
+    else: genBracedInit(p, it, isConst, tup[i], result)
+  result.add("}\n")
+
+proc genConstSeq(p: BProc, n: PNode, t: PType; isConst: bool; result: var Rope) =
   var data = "{{$1, $1 | NIM_STRLIT_FLAG}" % [n.len.rope]
+  let base = t.skipTypes(abstractInst)[0]
   if n.len > 0:
     # array part needs extra curlies:
     data.add(", {")
-    for i in countup(0, n.len - 1):
+    for i in 0..<n.len:
       if i > 0: data.addf(",$n", [])
-      data.add genConstExpr(p, n.sons[i])
+      genBracedInit(p, n[i], isConst, base, data)
     data.add("}")
   data.add("}")
 
-  result = getTempName(p.module)
-  let base = t.skipTypes(abstractInst).sons[0]
+  let tmpName = getTempName(p.module)
 
-  appcg(p.module, cfsData,
-        "NIM_CONST struct {$n" &
+  appcg(p.module, cfsStrData,
+        "static $5 struct {$n" &
         "  #TGenericSeq Sup;$n" &
         "  $1 data[$2];$n" &
         "} $3 = $4;$n", [
-        getTypeDesc(p.module, base), n.len.rope, result, data])
+        getTypeDesc(p.module, base), n.len, tmpName, data,
+        if isConst: "NIM_CONST" else: ""])
+
+  result.add "(($1)&$2)" % [getTypeDesc(p.module, t), tmpName]
+
+proc genConstSeqV2(p: BProc, n: PNode, t: PType; isConst: bool; result: var Rope) =
+  let base = t.skipTypes(abstractInst)[0]
+  var data = rope""
+  if n.len > 0:
+    data.add(", {")
+    for i in 0..<n.len:
+      if i > 0: data.addf(",$n", [])
+      genBracedInit(p, n[i], isConst, base, data)
+    data.add("}")
 
-  result = "(($1)&$2)" % [getTypeDesc(p.module, t), result]
+  let payload = getTempName(p.module)
+  appcg(p.module, cfsStrData,
+    "static $5 struct {$n" &
+    "  NI cap; $1 data[$2];$n" &
+    "} $3 = {$2 | NIM_STRLIT_FLAG$4};$n", [
+    getTypeDesc(p.module, base), n.len, payload, data,
+    if isConst: "const" else: ""])
+  result.add "{$1, ($2*)&$3}" % [rope(n.len), getSeqPayloadType(p.module, t), payload]
 
-proc genConstExpr(p: BProc, n: PNode): Rope =
+proc genBracedInit(p: BProc, n: PNode; isConst: bool; optionalType: PType; result: var Rope) =
   case n.kind
   of nkHiddenStdConv, nkHiddenSubConv:
-    result = genConstExpr(p, n.sons[1])
-  of nkCurly:
-    var cs: TBitSet
-    toBitSet(p.config, n, cs)
-    result = genRawSetData(cs, int(getSize(p.config, n.typ)))
-  of nkBracket, nkPar, nkTupleConstr, nkClosure:
-    var t = skipTypes(n.typ, abstractInst)
-    if t.kind == tySequence:
-      result = genConstSeq(p, n, n.typ)
-    elif t.kind == tyProc and t.callConv == ccClosure and not n.sons.isNil and
-         n.sons[0].kind == nkNilLit and n.sons[1].kind == nkNilLit:
-      # this hack fixes issue that nkNilLit is expanded to {NIM_NIL,NIM_NIL}
-      # this behaviour is needed since closure_var = nil must be
-      # expanded to {NIM_NIL,NIM_NIL}
-      # in VM closures are initialized with nkPar(nkNilLit, nkNilLit)
-      # leading to duplicate code like this:
-      # "{NIM_NIL,NIM_NIL}, {NIM_NIL,NIM_NIL}"
-      result = ~"{NIM_NIL,NIM_NIL}"
-    else:
-      result = genConstSimpleList(p, n)
-  of nkObjConstr:
-    result = genConstObjConstr(p, n)
-  else:
-    var d: TLoc
-    initLocExpr(p, n, d)
-    result = rdLoc(d)
+    genBracedInit(p, n[1], isConst, n.typ, result)
+  else:
+    var ty = tyNone
+    var typ: PType = nil
+    if optionalType == nil:
+      if n.kind in nkStrKinds:
+        ty = tyString
+      else:
+        internalError(p.config, n.info, "node has no type")
+    else:
+      typ = skipTypes(optionalType, abstractInstOwned + {tyStatic})
+      ty = typ.kind
+    case ty
+    of tySet:
+      let cs = toBitSet(p.config, n)
+      genRawSetData(cs, int(getSize(p.config, n.typ)), result)
+    of tySequence:
+      if optSeqDestructors in p.config.globalOptions:
+        genConstSeqV2(p, n, typ, isConst, result)
+      else:
+        genConstSeq(p, n, typ, isConst, result)
+    of tyProc:
+      if typ.callConv == ccClosure and n.safeLen > 1 and n[1].kind == nkNilLit:
+        # n.kind could be: nkClosure, nkTupleConstr and maybe others; `n.safeLen`
+        # guards against the case of `nkSym`, refs bug #14340.
+        # Conversion: nimcall -> closure.
+        # this hack fixes issue that nkNilLit is expanded to {NIM_NIL,NIM_NIL}
+        # this behaviour is needed since closure_var = nil must be
+        # expanded to {NIM_NIL,NIM_NIL}
+        # in VM closures are initialized with nkPar(nkNilLit, nkNilLit)
+        # leading to duplicate code like this:
+        # "{NIM_NIL,NIM_NIL}, {NIM_NIL,NIM_NIL}"
+        if n[0].kind == nkNilLit:
+          result.add "{NIM_NIL,NIM_NIL}"
+        else:
+          var d: TLoc = initLocExpr(p, n[0])
+          result.add "{(($1) $2),NIM_NIL}" % [getClosureType(p.module, typ, clHalfWithEnv), rdLoc(d)]
+      else:
+        var d: TLoc = initLocExpr(p, n)
+        result.add rdLoc(d)
+    of tyArray, tyVarargs:
+      genConstSimpleList(p, n, isConst, result)
+    of tyTuple:
+      genConstTuple(p, n, isConst, typ, result)
+    of tyOpenArray:
+      if n.kind != nkBracket:
+        internalError(p.config, n.info, "const openArray expression is not an array construction")
+
+      var data = newRopeAppender()
+      genConstSimpleList(p, n, isConst, data)
+
+      let payload = getTempName(p.module)
+      let ctype = getTypeDesc(p.module, typ.elementType)
+      let arrLen = n.len
+      appcg(p.module, cfsStrData,
+        "static $5 $1 $3[$2] = $4;$n", [
+        ctype, arrLen, payload, data,
+        if isConst: "const" else: ""])
+      result.add "{($1*)&$2, $3}" % [ctype, payload, rope arrLen]
+
+    of tyObject:
+      genConstObjConstr(p, n, isConst, result)
+    of tyString, tyCstring:
+      if optSeqDestructors in p.config.globalOptions and n.kind != nkNilLit and ty == tyString:
+        genStringLiteralV2Const(p.module, n, isConst, result)
+      else:
+        var d: TLoc = initLocExpr(p, n)
+        result.add rdLoc(d)
+    else:
+      var d: TLoc = initLocExpr(p, n)
+      result.add rdLoc(d)