summary refs log blame commit diff stats
path: root/tests/mmaptest.nim
blob: c304920af54bcf69774a5532efcd1eccabad24b8 (plain) (tree) 
7efe817ca ^
















































1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
















































                                                                            
# Small test program to test for mmap() weirdnesses

include "lib/system/ansi_c"

const
  PageSize = 4096
  PROT_READ  = 1             # page can be read 
  PROT_WRITE = 2             # page can be written 
  MAP_PRIVATE = 2            # Changes are private 

when defined(macosx) or defined(bsd):
  const MAP_ANONYMOUS = 0x1000
elif defined(solaris): 
  const MAP_ANONYMOUS = 0x100
else:
  var
    MAP_ANONYMOUS {.importc: "MAP_ANONYMOUS", header: "<sys/mman.h>".}: cint
  
proc mmap(adr: pointer, len: int, prot, flags, fildes: cint,
          off: int): pointer {.header: "<sys/mman.h>".}

proc munmap(adr: pointer, len: int) {.header: "<sys/mman.h>".}

proc osAllocPages(size: int): pointer {.inline.} = 
  result = mmap(nil, size, PROT_READ or PROT_WRITE, 
                         MAP_PRIVATE or MAP_ANONYMOUS, -1, 0)
  if result == nil or result == cast[pointer](-1):
    quit 1
  cfprintf(c_stdout, "allocated pages %p..%p\n", result, 
                     cast[int](result) + size)
    
proc osDeallocPages(p: pointer, size: int) {.inline} =
  cfprintf(c_stdout, "freed pages %p..%p\n", p, cast[int](p) + size)
  munmap(p, size-1)

proc `+!!`(p: pointer, size: int): pointer {.inline.} =
  result = cast[pointer](cast[int](p) + size)

var p = osAllocPages(3 * PageSize)

osDeallocPages(p, PageSize)
# If this fails the OS has freed the whole block starting at 'p':
echo(cast[ptr int](p +!! (pageSize*2))[])

osDeallocPages(p +!! PageSize*2, PageSize)
osDeallocPages(p +!! PageSize, PageSize)
generated by cgit-pink 1.4.1-2-gfad0 (git 2.36.2.497.gbbea4dcf42) at 2025-02-11 08:07:58 +0000
4'>524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 
#
#
#           The Nim Compiler
#        (c) Copyright 2017 Andreas Rumpf
#
#    See the file "copying.txt", included in this
#    distribution, for details about the copyright.
#

## Injects destructor calls into Nim code as well as
## an optimizer that optimizes copies to moves. This is implemented as an
## AST to AST transformation so that every backend benefits from it.

## See doc/destructors.rst for a spec of the implemented rewrite rules

import
  ast, astalgo, msgs, renderer, magicsys, types, idents,
  options, lowerings, modulegraphs,
  lineinfos, parampatterns, sighashes, liftdestructors, optimizer,
  varpartitions, aliasanalysis, dfa, wordrecg

import std/[strtabs, tables, strutils, intsets]

when defined(nimPreviewSlimSystem):
  import std/assertions

from trees import exprStructuralEquivalent, getRoot, whichPragma

type
  Con = object
    owner: PSym
    when true:
      g: ControlFlowGraph
    graph: ModuleGraph
    inLoop, inSpawn, inLoopCond: int
    uninit: IntSet # set of uninit'ed vars
    idgen: IdGenerator
    body: PNode
    otherUsage: TLineInfo
    inUncheckedAssignSection: int
    inEnsureMove: int

  Scope = object # we do scope-based memory management.
    # a scope is comparable to an nkStmtListExpr like
    # (try: statements; dest = y(); finally: destructors(); dest)
    vars: seq[PSym]
    wasMoved: seq[PNode]
    final: seq[PNode] # finally section
    locals: seq[PSym]
    body: PNode
    needsTry: bool
    parent: ptr Scope

  ProcessMode = enum
    normal
    consumed
    sinkArg

const toDebug {.strdefine.} = ""
when toDebug.len > 0:
  var shouldDebug = false

template dbg(body) =
  when toDebug.len > 0:
    if shouldDebug:
      body

proc hasDestructor(c: Con; t: PType): bool {.inline.} =
  result = ast.hasDestructor(t)
  when toDebug.len > 0:
    # for more effective debugging
    if not result and c.graph.config.selectedGC in {gcArc, gcOrc, gcAtomicArc}:
      assert(not containsGarbageCollectedRef(t))

proc getTemp(c: var Con; s: var Scope; typ: PType; info: TLineInfo): PNode =
  let sym = newSym(skTemp, getIdent(c.graph.cache, ":tmpD"), c.idgen, c.owner, info)
  sym.typ = typ
  s.vars.add(sym)
  result = newSymNode(sym)

proc nestedScope(parent: var Scope; body: PNode): Scope =
  Scope(vars: @[], locals: @[], wasMoved: @[], final: @[], body: body, needsTry: false, parent: addr(parent))

proc p(n: PNode; c: var Con; s: var Scope; mode: ProcessMode; tmpFlags = {sfSingleUsedTemp}; inReturn = false): PNode

type
  MoveOrCopyFlag = enum
    IsDecl, IsExplicitSink, IsReturn

proc moveOrCopy(dest, ri: PNode; c: var Con; s: var Scope; flags: set[MoveOrCopyFlag] = {}): PNode

when false:
  var
    perfCounters: array[InstrKind, int]

  proc showCounters*() =
    for i in low(InstrKind)..high(InstrKind):
      echo "INSTR ", i, " ", perfCounters[i]

proc isLastReadImpl(n: PNode; c: var Con; scope: var Scope): bool =
  let root = parampatterns.exprRoot(n, allowCalls=false)
  if root == nil: return false

  var s = addr(scope)
  while s != nil:
    if s.locals.contains(root): break
    s = s.parent

  c.g = constructCfg(c.owner, if s != nil: s.body else: c.body, root)
  dbg:
    echo "\n### ", c.owner.name.s, ":\nCFG:"
    echoCfg(c.g)
    #echo c.body

  var j = 0
  while j < c.g.len:
    if c.g[j].kind == use and c.g[j].n == n: break
    inc j
  c.otherUsage = unknownLineInfo
  if j < c.g.len:
    var pcs = @[j+1]
    var marked = initIntSet()
    result = true
    while pcs.len > 0:
      var pc = pcs.pop()
      if not marked.contains(pc):
        let oldPc = pc
        while pc < c.g.len:
          dbg:
            echo "EXEC ", c.g[pc].kind, " ", pc, " ", n
          when false:
            inc perfCounters[c.g[pc].kind]
          case c.g[pc].kind
          of loop:
            let back = pc + c.g[pc].dest
            if not marked.containsOrIncl(back):
              pc = back
            else:
              break
          of goto:
            pc = pc + c.g[pc].dest
          of fork:
            if not marked.contains(pc+1):
              pcs.add pc + 1
            pc = pc + c.g[pc].dest
          of use:
            if c.g[pc].n.aliases(n) != no or n.aliases(c.g[pc].n) != no:
              c.otherUsage = c.g[pc].n.info
              return false
            inc pc
          of def:
            if c.g[pc].n.aliases(n) == yes:
              # the path leads to a redefinition of 's' --> sink 's'.
              break
            elif n.aliases(c.g[pc].n) != no:
              # only partially writes to 's' --> can't sink 's', so this def reads 's'
              # or maybe writes to 's' --> can't sink 's'
              c.otherUsage = c.g[pc].n.info
              return false
            inc pc
        marked.incl oldPc
  else:
    result = false

proc isLastRead(n: PNode; c: var Con; s: var Scope): bool =
  if not hasDestructor(c, n.typ): return true

  let m = skipConvDfa(n)
  result = (m.kind == nkSym and sfSingleUsedTemp in m.sym.flags) or
      isLastReadImpl(n, c, s)

proc isFirstWrite(n: PNode; c: var Con): bool =
  let m = skipConvDfa(n)
  result = nfFirstWrite in m.flags

proc isCursor(n: PNode): bool =
  case n.kind
  of nkSym:
    sfCursor in n.sym.flags
  of nkDotExpr:
    isCursor(n[1])
  of nkCheckedFieldExpr:
    isCursor(n[0])
  else:
    false

template isUnpackedTuple(n: PNode): bool =
  ## we move out all elements of unpacked tuples,
  ## hence unpacked tuples themselves don't need to be destroyed
  ## except it's already a cursor
  (n.kind == nkSym and n.sym.kind == skTemp and
   n.sym.typ.kind == tyTuple and sfCursor notin n.sym.flags)

proc checkForErrorPragma(c: Con; t: PType; ri: PNode; opname: string; inferredFromCopy = false) =
  var m = "'" & opname & "' is not available for type <" & typeToString(t) & ">"
  if inferredFromCopy:
    m.add ", which is inferred from unavailable '=copy'"

  if (opname == "=" or opname == "=copy" or opname == "=dup") and ri != nil:
    m.add "; requires a copy because it's not the last read of '"
    m.add renderTree(ri)
    m.add '\''
    if c.otherUsage != unknownLineInfo:
       # ri.comment.startsWith('\n'):
      m.add "; another read is done here: "
      m.add c.graph.config $ c.otherUsage
      #m.add c.graph.config $ c.g[parseInt(ri.comment[1..^1])].n.info
    elif ri.kind == nkSym and ri.sym.kind == skParam and not isSinkType(ri.sym.typ):
      m.add "; try to make "
      m.add renderTree(ri)
      m.add " a 'sink' parameter"
  m.add "; routine: "
  m.add c.owner.name.s
  #m.add "\n\n"
  #m.add renderTree(c.body, {renderIds})
  localError(c.graph.config, ri.info, errGenerated, m)

proc makePtrType(c: var Con, baseType: PType): PType =
  result = newType(tyPtr, c.idgen, c.owner)
  addSonSkipIntLit(result, baseType, c.idgen)

proc genOp(c: var Con; op: PSym; dest: PNode): PNode =
  var addrExp: PNode
  if op.typ != nil and op.typ.len > 1 and op.typ[1].kind != tyVar:
    addrExp = dest
  else:
    addrExp = newNodeIT(nkHiddenAddr, dest.info, makePtrType(c, dest.typ))
    addrExp.add(dest)
  result = newTree(nkCall, newSymNode(op), addrExp)

proc genOp(c: var Con; t: PType; kind: TTypeAttachedOp; dest, ri: PNode): PNode =
  var op = getAttachedOp(c.graph, t, kind)
  if op == nil or op.ast.isGenericRoutine:
    # give up and find the canonical type instead:
    let h = sighashes.hashType(t, c.graph.config, {CoType, CoConsiderOwned, CoDistinct})
    let canon = c.graph.canonTypes.getOrDefault(h)
    if canon != nil:
      op = getAttachedOp(c.graph, canon, kind)
  if op == nil:
    #echo dest.typ.id
    globalError(c.graph.config, dest.info, "internal error: '" & AttachedOpToStr[kind] &
      "' operator not found for type " & typeToString(t))
  elif op.ast.isGenericRoutine:
    globalError(c.graph.config, dest.info, "internal error: '" & AttachedOpToStr[kind] &
      "' operator is generic")
  dbg:
    if kind == attachedDestructor:
      echo "destructor is ", op.id, " ", op.ast
  if sfError in op.flags: checkForErrorPragma(c, t, ri, AttachedOpToStr[kind])
  c.genOp(op, dest)

proc genDestroy(c: var Con; dest: PNode): PNode =
  let t = dest.typ.skipTypes({tyGenericInst, tyAlias, tySink})
  result = c.genOp(t, attachedDestructor, dest, nil)

proc canBeMoved(c: Con; t: PType): bool {.inline.} =
  let t = t.skipTypes({tyGenericInst, tyAlias, tySink})
  if optOwnedRefs in c.graph.config.globalOptions:
    result = t.kind != tyRef and getAttachedOp(c.graph, t, attachedSink) != nil
  else:
    result = getAttachedOp(c.graph, t, attachedSink) != nil

proc isNoInit(dest: PNode): bool {.inline.} =
  result = dest.kind == nkSym and sfNoInit in dest.sym.flags

proc deepAliases(dest, ri: PNode): bool =
  case ri.kind
  of nkCallKinds, nkStmtListExpr, nkBracket, nkTupleConstr, nkObjConstr,
     nkCast, nkConv, nkObjUpConv, nkObjDownConv:
    for r in ri:
      if deepAliases(dest, r): return true
    return false
  else:
    return aliases(dest, ri) != no

proc genSink(c: var Con; s: var Scope; dest, ri: PNode; flags: set[MoveOrCopyFlag] = {}): PNode =
  if (c.inLoopCond == 0 and (isUnpackedTuple(dest) or IsDecl in flags or
      (isAnalysableFieldAccess(dest, c.owner) and isFirstWrite(dest, c)))) or
      isNoInit(dest) or IsReturn in flags:
    # optimize sink call into a bitwise memcopy
    result = newTree(nkFastAsgn, dest, ri)
  else:
    let t = dest.typ.skipTypes({tyGenericInst, tyAlias, tySink})
    if getAttachedOp(c.graph, t, attachedSink) != nil:
      result = c.genOp(t, attachedSink, dest, ri)
      result.add ri
    else:
      # the default is to use combination of `=destroy(dest)` and
      # and copyMem(dest, source). This is efficient.
      if deepAliases(dest, ri):
        # consider: x = x + y, it is wrong to destroy the destination first!
        # tmp to support self assignments
        let tmp = c.getTemp(s, dest.typ, dest.info)
        result = newTree(nkStmtList, newTree(nkFastAsgn, tmp, dest), newTree(nkFastAsgn, dest, ri),
                         c.genDestroy(tmp))
      else:
        result = newTree(nkStmtList, c.genDestroy(dest), newTree(nkFastAsgn, dest, ri))

proc isCriticalLink(dest: PNode): bool {.inline.} =
  #[
  Lins's idea that only "critical" links can introduce a cycle. This is
  critical for the performance gurantees that we strive for: If you
  traverse a data structure, no tracing will be performed at all.
  ORC is about this promise: The GC only touches the memory that the
  mutator touches too.

  These constructs cannot possibly create cycles::

    local = ...

    new(x)
    dest = ObjectConstructor(field: noalias(dest))

  But since 'ObjectConstructor' is already moved into 'dest' all we really have
  to look for is assignments to local variables.
  ]#
  result = dest.kind != nkSym

proc finishCopy(c: var Con; result, dest: PNode; isFromSink: bool) =
  if c.graph.config.selectedGC == gcOrc:
    let t = dest.typ.skipTypes({tyGenericInst, tyAlias, tySink, tyDistinct})
    if cyclicType(c.graph, t):
      result.add boolLit(c.graph, result.info, isFromSink or isCriticalLink(dest))

proc genMarkCyclic(c: var Con; result, dest: PNode) =
  if c.graph.config.selectedGC == gcOrc:
    let t = dest.typ.skipTypes({tyGenericInst, tyAlias, tySink, tyDistinct})
    if cyclicType(c.graph, t):
      if t.kind == tyRef:
        result.add callCodegenProc(c.graph, "nimMarkCyclic", dest.info, dest)
      else:
        let xenv = genBuiltin(c.graph, c.idgen, mAccessEnv, "accessEnv", dest)
        xenv.typ = getSysType(c.graph, dest.info, tyPointer)
        result.add callCodegenProc(c.graph, "nimMarkCyclic", dest.info, xenv)

proc genCopyNoCheck(c: var Con; dest, ri: PNode; a: TTypeAttachedOp): PNode =
  let t = dest.typ.skipTypes({tyGenericInst, tyAlias, tySink})
  result = c.genOp(t, a, dest, ri)
  assert ri.typ != nil

proc genCopy(c: var Con; dest, ri: PNode; flags: set[MoveOrCopyFlag]): PNode =
  if c.inEnsureMove > 0:
    localError(c.graph.config, ri.info, errFailedMove, "cannot move '" & $ri &
                                                      "', which introduces an implicit copy")
  let t = dest.typ
  if tfHasOwned in t.flags and ri.kind != nkNilLit:
    # try to improve the error message here:
    if IsExplicitSink in flags:
      c.checkForErrorPragma(t, ri, "=sink")
    else:
      c.checkForErrorPragma(t, ri, "=copy")
  let a = if IsExplicitSink in flags: attachedSink else: attachedAsgn
  result = c.genCopyNoCheck(dest, ri, a)
  assert ri.typ != nil

proc genDiscriminantAsgn(c: var Con; s: var Scope; n: PNode): PNode =
  # discriminator is ordinal value that doesn't need sink destroy
  # but fields within active case branch might need destruction

  # tmp to support self assignments
  let tmp = c.getTemp(s, n[1].typ, n.info)

  result = newTree(nkStmtList)
  result.add newTree(nkFastAsgn, tmp, p(n[1], c, s, consumed))
  result.add p(n[0], c, s, normal)

  let le = p(n[0], c, s, normal)
  let leDotExpr = if le.kind == nkCheckedFieldExpr: le[0] else: le
  let objType = leDotExpr[0].typ

  if hasDestructor(c, objType):
    if getAttachedOp(c.graph, objType, attachedDestructor) != nil and
        sfOverridden in getAttachedOp(c.graph, objType, attachedDestructor).flags:
      localError(c.graph.config, n.info, errGenerated, """Assignment to discriminant for objects with user defined destructor is not supported, object must have default destructor.
It is best to factor out piece of object that needs custom destructor into separate object or not use discriminator assignment""")
      result.add newTree(nkFastAsgn, le, tmp)
      return

    # generate: if le != tmp: `=destroy`(le)
    if c.inUncheckedAssignSection != 0:
      let branchDestructor = produceDestructorForDiscriminator(c.graph, objType, leDotExpr[1].sym, n.info, c.idgen)
      let cond = newNodeIT(nkInfix, n.info, getSysType(c.graph, unknownLineInfo, tyBool))
      cond.add newSymNode(getMagicEqSymForType(c.graph, le.typ, n.info))
      cond.add le
      cond.add tmp
      let notExpr = newNodeIT(nkPrefix, n.info, getSysType(c.graph, unknownLineInfo, tyBool))
      notExpr.add newSymNode(createMagic(c.graph, c.idgen, "not", mNot))
      notExpr.add cond
      result.add newTree(nkIfStmt, newTree(nkElifBranch, notExpr, c.genOp(branchDestructor, le)))
  result.add newTree(nkFastAsgn, le, tmp)

proc genWasMoved(c: var Con, n: PNode): PNode =
  let typ = n.typ.skipTypes({tyGenericInst, tyAlias, tySink})
  let op = getAttachedOp(c.graph, n.typ, attachedWasMoved)
  if op != nil:
    if sfError in op.flags:
      c.checkForErrorPragma(n.typ, n, "=wasMoved")
    result = genOp(c, op, n)
  else:
    result = newNodeI(nkCall, n.info)
    result.add(newSymNode(createMagic(c.graph, c.idgen, "`=wasMoved`", mWasMoved)))
    result.add copyTree(n) #mWasMoved does not take the address
    #if n.kind != nkSym:
    #  message(c.graph.config, n.info, warnUser, "wasMoved(" & $n & ")")

proc genDefaultCall(t: PType; c: Con; info: TLineInfo): PNode =
  result = newNodeI(nkCall, info)
  result.add(newSymNode(createMagic(c.graph, c.idgen, "default", mDefault)))
  result.typ = t

proc destructiveMoveVar(n: PNode; c: var Con; s: var Scope): PNode =
  # generate: (let tmp = v; reset(v); tmp)
  if (not hasDestructor(c, n.typ)) and c.inEnsureMove == 0:
    assert n.kind != nkSym or not hasDestructor(c, n.sym.typ)
    result = copyTree(n)
  else:
    result = newNodeIT(nkStmtListExpr, n.info, n.typ)

    var temp = newSym(skLet, getIdent(c.graph.cache, "blitTmp"), c.idgen, c.owner, n.info)
    temp.typ = n.typ
    var v = newNodeI(nkLetSection, n.info)
    let tempAsNode = newSymNode(temp)

    var vpart = newNodeI(nkIdentDefs, tempAsNode.info, 3)
    vpart[0] = tempAsNode
    vpart[1] = newNodeI(nkEmpty, tempAsNode.info)
    vpart[2] = n
    v.add(vpart)

    result.add v
    let nn = skipConv(n)
    if hasDestructor(c, n.typ):
      c.genMarkCyclic(result, nn)
    let wasMovedCall = c.genWasMoved(nn)
    result.add wasMovedCall
    result.add tempAsNode

proc isCapturedVar(n: PNode): bool =
  let root = getRoot(n)
  if root != nil: result = root.name.s[0] == ':'
  else: result = false

proc passCopyToSink(n: PNode; c: var Con; s: var Scope): PNode =
  result = newNodeIT(nkStmtListExpr, n.info, n.typ)
  let tmp = c.getTemp(s, n.typ, n.info)
  if hasDestructor(c, n.typ):
    let typ = n.typ.skipTypes({tyGenericInst, tyAlias, tySink})
    let op = getAttachedOp(c.graph, typ, attachedDup)
    if op != nil and tfHasOwned notin typ.flags:
      if sfError in op.flags:
        c.checkForErrorPragma(n.typ, n, "=dup")
      else:
        let copyOp = getAttachedOp(c.graph, typ, attachedAsgn)
        if copyOp != nil and sfError in copyOp.flags and
           sfOverridden notin op.flags:
          c.checkForErrorPragma(n.typ, n, "=dup", inferredFromCopy = true)

      let src = p(n, c, s, normal)
      var newCall = newTreeIT(nkCall, src.info, src.typ,
            newSymNode(op),
            src)
      c.finishCopy(newCall, n, isFromSink = true)
      result.add newTreeI(nkFastAsgn,
          src.info, tmp,
          newCall
      )
    else:
      result.add c.genWasMoved(tmp)
      var m = c.genCopy(tmp, n, {})
      m.add p(n, c, s, normal)
      c.finishCopy(m, n, isFromSink = true)
      result.add m
    if isLValue(n) and not isCapturedVar(n) and n.typ.skipTypes(abstractInst).kind != tyRef and c.inSpawn == 0:
      message(c.graph.config, n.info, hintPerformance,
        ("passing '$1' to a sink parameter introduces an implicit copy; " &
        "if possible, rearrange your program's control flow to prevent it") % $n)
    if c.inEnsureMove > 0:
      localError(c.graph.config, n.info, errFailedMove,
        ("cannot move '$1', passing '$1' to a sink parameter introduces an implicit copy") % $n)
  else:
    if c.graph.config.selectedGC in {gcArc, gcOrc, gcAtomicArc}:
      assert(not containsManagedMemory(n.typ))
    if n.typ.skipTypes(abstractInst).kind in {tyOpenArray, tyVarargs}:
      localError(c.graph.config, n.info, "cannot create an implicit openArray copy to be passed to a sink parameter")
    result.add newTree(nkAsgn, tmp, p(n, c, s, normal))
  # Since we know somebody will take over the produced copy, there is
  # no need to destroy it.
  result.add tmp

proc isDangerousSeq(t: PType): bool {.inline.} =
  let t = t.skipTypes(abstractInst)
  result = t.kind == tySequence and tfHasOwned notin t[0].flags

proc containsConstSeq(n: PNode): bool =
  if n.kind == nkBracket and n.len > 0 and n.typ != nil and isDangerousSeq(n.typ):
    return true
  result = false
  case n.kind
  of nkExprEqExpr, nkExprColonExpr, nkHiddenStdConv, nkHiddenSubConv:
    result = containsConstSeq(n[1])
  of nkObjConstr, nkClosure:
    for i in 1..<n.len:
      if containsConstSeq(n[i]): return true
  of nkCurly, nkBracket, nkPar, nkTupleConstr:
    for son in n:
      if containsConstSeq(son): return true
  else: discard

proc ensureDestruction(arg, orig: PNode; c: var Con; s: var Scope): PNode =
  # it can happen that we need to destroy expression contructors
  # like [], (), closures explicitly in order to not leak them.
  if arg.typ != nil and hasDestructor(c, arg.typ):
    # produce temp creation for (fn, env). But we need to move 'env'?
    # This was already done in the sink parameter handling logic.
    result = newNodeIT(nkStmtListExpr, arg.info, arg.typ)
    let tmp = c.getTemp(s, arg.typ, arg.info)
    result.add c.genSink(s, tmp, arg, {IsDecl})
    result.add tmp
    s.final.add c.genDestroy(tmp)
  else:
    result = arg

proc cycleCheck(n: PNode; c: var Con) =
  if c.graph.config.selectedGC notin {gcArc, gcAtomicArc}: return
  var value = n[1]
  if value.kind == nkClosure:
    value = value[1]
  if value.kind == nkNilLit: return
  let destTyp = n[0].typ.skipTypes(abstractInst)
  if destTyp.kind != tyRef and not (destTyp.kind == tyProc and destTyp.callConv == ccClosure):
    return

  var x = n[0]
  var field: PNode = nil
  while true:
    if x.kind == nkDotExpr:
      field = x[1]
      if field.kind == nkSym and sfCursor in field.sym.flags: return
      x = x[0]
    elif x.kind in {nkBracketExpr, nkCheckedFieldExpr, nkDerefExpr, nkHiddenDeref}:
      x = x[0]
    else:
      break
    if exprStructuralEquivalent(x, value, strictSymEquality = true):
      let msg =
        if field != nil:
          "'$#' creates an uncollectable ref cycle; annotate '$#' with .cursor" % [$n, $field]
        else:
          "'$#' creates an uncollectable ref cycle" % [$n]
      message(c.graph.config, n.info, warnCycleCreated, msg)
      break

proc pVarTopLevel(v: PNode; c: var Con; s: var Scope; res: PNode) =
  # move the variable declaration to the top of the frame:
  s.vars.add v.sym
  if isUnpackedTuple(v):
    if c.inLoop > 0:
      # unpacked tuple needs reset at every loop iteration
      res.add newTree(nkFastAsgn, v, genDefaultCall(v.typ, c, v.info))
  elif sfThread notin v.sym.flags and sfCursor notin v.sym.flags:
    # do not destroy thread vars for now at all for consistency.
    if {sfGlobal, sfPure} <= v.sym.flags or sfGlobal in v.sym.flags and s.parent == nil:
      c.graph.globalDestructors.add c.genDestroy(v)
    else:
      s.final.add c.genDestroy(v)

proc processScope(c: var Con; s: var Scope; ret: PNode): PNode =
  result = newNodeI(nkStmtList, ret.info)
  if s.vars.len > 0:
    let varSection = newNodeI(nkVarSection, ret.info)
    for tmp in s.vars:
      varSection.add newTree(nkIdentDefs, newSymNode(tmp), newNodeI(nkEmpty, ret.info),
                                                           newNodeI(nkEmpty, ret.info))
    result.add varSection
  if s.wasMoved.len > 0 or s.final.len > 0:
    let finSection = newNodeI(nkStmtList, ret.info)
    for m in s.wasMoved: finSection.add m
    for i in countdown(s.final.high, 0): finSection.add s.final[i]
    if s.needsTry:
      result.add newTryFinally(ret, finSection)
    else:
      result.add ret
      result.add finSection
  else:
    result.add ret

  if s.parent != nil: s.parent[].needsTry = s.parent[].needsTry or s.needsTry

template processScopeExpr(c: var Con; s: var Scope; ret: PNode, processCall: untyped, tmpFlags: TSymFlags): PNode =
  assert not ret.typ.isEmptyType
  var result = newNodeIT(nkStmtListExpr, ret.info, ret.typ)
  # There is a possibility to do this check: s.wasMoved.len > 0 or s.final.len > 0
  # later and use it to eliminate the temporary when theres no need for it, but its
  # tricky because you would have to intercept moveOrCopy at a certain point
  let tmp = c.getTemp(s.parent[], ret.typ, ret.info)
  tmp.sym.flags = tmpFlags
  let cpy = if hasDestructor(c, ret.typ):
              s.parent[].final.add c.genDestroy(tmp)
              moveOrCopy(tmp, ret, c, s, {IsDecl})
            else:
              newTree(nkFastAsgn, tmp, p(ret, c, s, normal))

  if s.vars.len > 0:
    let varSection = newNodeI(nkVarSection, ret.info)
    for tmp in s.vars:
      varSection.add newTree(nkIdentDefs, newSymNode(tmp), newNodeI(nkEmpty, ret.info),
                                                           newNodeI(nkEmpty, ret.info))
    result.add varSection
  let finSection = newNodeI(nkStmtList, ret.info)
  for m in s.wasMoved: finSection.add m
  for i in countdown(s.final.high, 0): finSection.add s.final[i]
  if s.needsTry:
    result.add newTryFinally(newTree(nkStmtListExpr, cpy, processCall(tmp, s.parent[])), finSection)
  else:
    result.add cpy
    result.add finSection
    result.add processCall(tmp, s.parent[])

  if s.parent != nil: s.parent[].needsTry = s.parent[].needsTry or s.needsTry

  result

template handleNestedTempl(n, processCall: untyped, willProduceStmt = false,
                           tmpFlags = {sfSingleUsedTemp}) =
  template maybeVoid(child, s): untyped =
    if isEmptyType(child.typ): p(child, c, s, normal)
    else: processCall(child, s)

  case n.kind
  of nkStmtList, nkStmtListExpr:
    # a statement list does not open a new scope
    if n.len == 0: return n
    result = copyNode(n)
    for i in 0..<n.len-1:
      result.add p(n[i], c, s, normal)
    result.add maybeVoid(n[^1], s)

  of nkCaseStmt:
    result = copyNode(n)
    result.add p(n[0], c, s, normal)
    for i in 1..<n.len:
      let it = n[i]
      assert it.kind in {nkOfBranch, nkElse}

      var branch = shallowCopy(it)
      for j in 0 ..< it.len-1:
        branch[j] = copyTree(it[j])
      var ofScope = nestedScope(s, it.lastSon)
      branch[^1] = if it[^1].typ.isEmptyType or willProduceStmt:
                     processScope(c, ofScope, maybeVoid(it[^1], ofScope))
                   else:
                     processScopeExpr(c, ofScope, it[^1], processCall, tmpFlags)
      result.add branch

  of nkWhileStmt:
    inc c.inLoop
    inc c.inLoopCond
    result = copyNode(n)
    result.add p(n[0], c, s, normal)
    dec c.inLoopCond
    var bodyScope = nestedScope(s, n[1])
    let bodyResult = p(n[1], c, bodyScope, normal)
    result.add processScope(c, bodyScope, bodyResult)
    dec c.inLoop

  of nkParForStmt:
    inc c.inLoop
    result = shallowCopy(n)
    let last = n.len-1
    for i in 0..<last-1:
      result[i] = n[i]
    result[last-1] = p(n[last-1], c, s, normal)
    var bodyScope = nestedScope(s, n[1])
    let bodyResult = p(n[last], c, bodyScope, normal)
    result[last] = processScope(c, bodyScope, bodyResult)
    dec c.inLoop

  of nkBlockStmt, nkBlockExpr:
    result = copyNode(n)
    result.add n[0]
    var bodyScope = nestedScope(s, n[1])
    result.add if n[1].typ.isEmptyType or willProduceStmt:
                 processScope(c, bodyScope, processCall(n[1], bodyScope))
               else:
                 processScopeExpr(c, bodyScope, n[1], processCall, tmpFlags)

  of nkIfStmt, nkIfExpr:
    result = copyNode(n)
    for i in 0..<n.len:
      let it = n[i]
      var branch = shallowCopy(it)
      var branchScope = nestedScope(s, it.lastSon)
      if it.kind in {nkElifBranch, nkElifExpr}:
        #Condition needs to be destroyed outside of the condition/branch scope
        branch[0] = p(it[0], c, s, normal)

      branch[^1] = if it[^1].typ.isEmptyType or willProduceStmt:
                     processScope(c, branchScope, maybeVoid(it[^1], branchScope))
                   else:
                     processScopeExpr(c, branchScope, it[^1], processCall, tmpFlags)
      result.add branch

  of nkTryStmt:
    result = copyNode(n)
    var tryScope = nestedScope(s, n[0])
    result.add if n[0].typ.isEmptyType or willProduceStmt:
                 processScope(c, tryScope, maybeVoid(n[0], tryScope))
               else:
                 processScopeExpr(c, tryScope, n[0], maybeVoid, tmpFlags)

    for i in 1..<n.len:
      let it = n[i]
      var branch = copyTree(it)
      var branchScope = nestedScope(s, it[^1])
      branch[^1] = if it[^1].typ.isEmptyType or willProduceStmt or it.kind == nkFinally:
                     processScope(c, branchScope, if it.kind == nkFinally: p(it[^1], c, branchScope, normal)
                                                  else: maybeVoid(it[^1], branchScope))
                   else:
                     processScopeExpr(c, branchScope, it[^1], processCall, tmpFlags)
      result.add branch

  of nkWhen: # This should be a "when nimvm" node.
    result = copyTree(n)
    result[1][0] = processCall(n[1][0], s)

  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
    result = shallowCopy(n)
    inc c.inUncheckedAssignSection, inUncheckedAssignSection
    for i in 0 ..< n.len-1:
      result[i] = p(n[i], c, s, normal)
    result[^1] = maybeVoid(n[^1], s)
    dec c.inUncheckedAssignSection, inUncheckedAssignSection

  else:
    result = nil
    assert(false)

proc pRaiseStmt(n: PNode, c: var Con; s: var Scope): PNode =
  if optOwnedRefs in c.graph.config.globalOptions and n[0].kind != nkEmpty:
    if n[0].kind in nkCallKinds:
      let call = p(n[0], c, s, normal)
      result = copyNode(n)
      result.add call
    else:
      let tmp = c.getTemp(s, n[0].typ, n.info)
      var m = c.genCopyNoCheck(tmp, n[0], attachedAsgn)
      m.add p(n[0], c, s, normal)
      c.finishCopy(m, n[0], isFromSink = false)
      result = newTree(nkStmtList, c.genWasMoved(tmp), m)
      var toDisarm = n[0]
      if toDisarm.kind == nkStmtListExpr: toDisarm = toDisarm.lastSon
      if toDisarm.kind == nkSym and toDisarm.sym.owner == c.owner:
        result.add c.genWasMoved(toDisarm)
      result.add newTree(nkRaiseStmt, tmp)
  else:
    result = copyNode(n)
    if n[0].kind != nkEmpty:
      result.add p(n[0], c, s, sinkArg)
    else:
      result.add copyNode(n[0])
  s.needsTry = true

proc p(n: PNode; c: var Con; s: var Scope; mode: ProcessMode; tmpFlags = {sfSingleUsedTemp}; inReturn = false): PNode =
  if n.kind in {nkStmtList, nkStmtListExpr, nkBlockStmt, nkBlockExpr, nkIfStmt,
                nkIfExpr, nkCaseStmt, nkWhen, nkWhileStmt, nkParForStmt, nkTryStmt, nkPragmaBlock}:
    template process(child, s): untyped = p(child, c, s, mode)
    handleNestedTempl(n, process, tmpFlags = tmpFlags)
  elif mode == sinkArg:
    if n.containsConstSeq:
      # const sequences are not mutable and so we need to pass a copy to the
      # sink parameter (bug #11524). Note that the string implementation is
      # different and can deal with 'const string sunk into var'.
      result = passCopyToSink(n, c, s)
    elif n.kind in {nkBracket, nkObjConstr, nkTupleConstr, nkClosure, nkNilLit} +
         nkCallKinds + nkLiterals:
      if n.kind in nkCallKinds and n[0].kind == nkSym:
        if n[0].sym.magic == mEnsureMove:
          inc c.inEnsureMove
          result = p(n[1], c, s, sinkArg)
          dec c.inEnsureMove
        else:
          result = p(n, c, s, consumed)
      else:
        result = p(n, c, s, consumed)
    elif ((n.kind == nkSym and isSinkParam(n.sym)) or isAnalysableFieldAccess(n, c.owner)) and
        isLastRead(n, c, s) and not (n.kind == nkSym and isCursor(n)):
      # Sinked params can be consumed only once. We need to reset the memory
      # to disable the destructor which we have not elided
      result = destructiveMoveVar(n, c, s)
    elif n.kind in {nkHiddenSubConv, nkHiddenStdConv, nkConv}:
      result = copyTree(n)
      if n.typ.skipTypes(abstractInst-{tyOwned}).kind != tyOwned and
          n[1].typ.skipTypes(abstractInst-{tyOwned}).kind == tyOwned:
        # allow conversions from owned to unowned via this little hack:
        let nTyp = n[1].typ
        n[1].typ = n.typ
        result[1] = p(n[1], c, s, sinkArg)
        result[1].typ = nTyp
      else:
        result[1] = p(n[1], c, s, sinkArg)
    elif n.kind in {nkObjDownConv, nkObjUpConv}:
      result = copyTree(n)
      result[0] = p(n[0], c, s, sinkArg)
    elif n.typ == nil:
      # 'raise X' can be part of a 'case' expression. Deal with it here:
      result = p(n, c, s, normal)
    else:
      # copy objects that are not temporary but passed to a 'sink' parameter
      result = passCopyToSink(n, c, s)
  else:
    case n.kind
    of nkBracket, nkTupleConstr, nkClosure, nkCurly:
      # Let C(x) be the construction, 'x' the vector of arguments.
      # C(x) either owns 'x' or it doesn't.
      # If C(x) owns its data, we must consume C(x).
      # If it doesn't own the data, it's harmful to destroy it (double frees etc).
      # We have the freedom to choose whether it owns it or not so we are smart about it
      # and we say, "if passed to a sink we demand C(x) to own its data"
      # otherwise we say "C(x) is just some temporary storage, it doesn't own anything,
      # don't destroy it"
      # but if C(x) is a ref it MUST own its data since we must destroy it
      # so then we have no choice but to use 'sinkArg'.
      let m = if mode == normal: normal
              else: sinkArg

      result = copyTree(n)
      for i in ord(n.kind == nkClosure)..<n.len:
        if n[i].kind == nkExprColonExpr:
          result[i][1] = p(n[i][1], c, s, m)
        elif n[i].kind == nkRange:
          result[i][0] = p(n[i][0], c, s, m)
          result[i][1] = p(n[i][1], c, s, m)
        else:
          result[i] = p(n[i], c, s, m)
    of nkObjConstr:
      # see also the remark about `nkTupleConstr`.
      let t = n.typ.skipTypes(abstractInst)
      let isRefConstr = t.kind == tyRef
      let m = if isRefConstr: sinkArg
              elif mode == normal: normal
              else: sinkArg

      result = copyTree(n)
      for i in 1..<n.len:
        if n[i].kind == nkExprColonExpr:
          let field = lookupFieldAgain(t, n[i][0].sym)
          if field != nil and sfCursor in field.flags:
            result[i][1] = p(n[i][1], c, s, normal)
          else:
            result[i][1] = p(n[i][1], c, s, m)
        else:
          result[i] = p(n[i], c, s, m)
      if mode == normal and (isRefConstr or (hasDestructor(c, t) and
        getAttachedOp(c.graph, t, attachedDestructor) != nil and
        sfOverridden in getAttachedOp(c.graph, t, attachedDestructor).flags)):
        result = ensureDestruction(result, n, c, s)
    of nkCallKinds:
      if n[0].kind == nkSym and n[0].sym.magic == mEnsureMove:
        inc c.inEnsureMove
        result = p(n[1], c, s, sinkArg)
        dec c.inEnsureMove
        return

      let inSpawn = c.inSpawn
      if n[0].kind == nkSym and n[0].sym.magic == mSpawn:
        c.inSpawn.inc
      elif c.inSpawn > 0:
        c.inSpawn.dec

      let parameters = n[0].typ
      let L = if parameters != nil: parameters.len else: 0

      when false:
        var isDangerous = false
        if n[0].kind == nkSym and n[0].sym.magic in {mOr, mAnd}:
          inc c.inDangerousBranch
          isDangerous = true

      result = shallowCopy(n)
      for i in 1..<n.len:
        if i < L and isCompileTimeOnly(parameters[i]):
          result[i] = n[i]
        elif i < L and (isSinkTypeForParam(parameters[i]) or inSpawn > 0):
          result[i] = p(n[i], c, s, sinkArg)
        else:
          result[i] = p(n[i], c, s, normal)

      when false:
        if isDangerous:
          dec c.inDangerousBranch

      if n[0].kind == nkSym and n[0].sym.magic in {mNew, mNewFinalize}:
        result[0] = copyTree(n[0])
        if c.graph.config.selectedGC in {gcHooks, gcArc, gcAtomicArc, gcOrc}:
          let destroyOld = c.genDestroy(result[1])
          result = newTree(nkStmtList, destroyOld, result)
      else:
        result[0] = p(n[0], c, s, normal)
      if canRaise(n[0]): s.needsTry = true
      if mode == normal:
        result = ensureDestruction(result, n, c, s)
    of nkDiscardStmt: # Small optimization
      result = shallowCopy(n)
      if n[0].kind != nkEmpty:
        result[0] = p(n[0], c, s, normal)
      else:
        result[0] = copyNode(n[0])
    of nkVarSection, nkLetSection:
      # transform; var x = y to  var x; x op y  where op is a move or copy
      result = newNodeI(nkStmtList, n.info)
      for it in n:
        var ri = it[^1]
        if it.kind == nkVarTuple and hasDestructor(c, ri.typ):
          for i in 0..<it.len-2:
            if it[i].kind == nkSym: s.locals.add it[i].sym
          let x = lowerTupleUnpacking(c.graph, it, c.idgen, c.owner)
          result.add p(x, c, s, consumed)
        elif it.kind == nkIdentDefs and hasDestructor(c, skipPragmaExpr(it[0]).typ):
          for j in 0..<it.len-2:
            let v = skipPragmaExpr(it[j])
            if v.kind == nkSym:
              if sfCompileTime in v.sym.flags: continue
              s.locals.add v.sym
              pVarTopLevel(v, c, s, result)
            if ri.kind != nkEmpty:
              result.add moveOrCopy(v, ri, c, s, if v.kind == nkSym: {IsDecl} else: {})
            elif ri.kind == nkEmpty and c.inLoop > 0:
              let skipInit = v.kind == nkDotExpr and # Closure var
                             sfNoInit in v[1].sym.flags
              if not skipInit:
                result.add moveOrCopy(v, genDefaultCall(v.typ, c, v.info), c, s, if v.kind == nkSym: {IsDecl} else: {})
        else: # keep the var but transform 'ri':
          var v = copyNode(n)
          var itCopy = copyNode(it)
          for j in 0..<it.len-1:
            itCopy.add it[j]
          var flags = {sfSingleUsedTemp}
          if it.kind == nkIdentDefs and it.len == 3 and it[0].kind == nkSym and
                                        sfGlobal in it[0].sym.flags:
            flags.incl sfGlobal
          itCopy.add p(it[^1], c, s, normal, tmpFlags = flags)
          v.add itCopy
          result.add v
    of nkAsgn, nkFastAsgn, nkSinkAsgn:
      if hasDestructor(c, n[0].typ) and n[1].kind notin {nkProcDef, nkDo, nkLambda}:
        if n[0].kind in {nkDotExpr, nkCheckedFieldExpr}:
          cycleCheck(n, c)
        assert n[1].kind notin {nkAsgn, nkFastAsgn, nkSinkAsgn}
        var flags = if n.kind == nkSinkAsgn: {IsExplicitSink} else: {}
        if inReturn:
          flags.incl(IsReturn)
        result = moveOrCopy(p(n[0], c, s, mode), n[1], c, s, flags)
      elif isDiscriminantField(n[0]):
        result = c.genDiscriminantAsgn(s, n)
      else:
        result = copyNode(n)
        result.add p(n[0], c, s, mode)
        result.add p(n[1], c, s, consumed)
    of nkRaiseStmt:
      result = pRaiseStmt(n, c, s)
    of nkWhileStmt:
      internalError(c.graph.config, n.info, "nkWhileStmt should have been handled earlier")
      result = n
    of nkNone..nkNilLit, nkTypeSection, nkProcDef, nkConverterDef,
       nkMethodDef, nkIteratorDef, nkMacroDef, nkTemplateDef, nkLambda, nkDo,
       nkFuncDef, nkConstSection, nkConstDef, nkIncludeStmt, nkImportStmt,
       nkExportStmt, nkPragma, nkCommentStmt, nkBreakState,
       nkTypeOfExpr, nkMixinStmt, nkBindStmt:
      result = n

    of nkStringToCString, nkCStringToString, nkChckRangeF, nkChckRange64, nkChckRange:
      result = shallowCopy(n)
      for i in 0 ..< n.len:
        result[i] = p(n[i], c, s, normal)
      if n.typ != nil and hasDestructor(c, n.typ):
        if mode == normal:
          result = ensureDestruction(result, n, c, s)

    of nkHiddenSubConv, nkHiddenStdConv, nkConv:
      # we have an "ownership invariance" for all constructors C(x).
      # See the comment for nkBracket construction. If the caller wants
      # to own 'C(x)', it really wants to own 'x' too. If it doesn't,
      # we need to destroy 'x' but the function call handling ensures that
      # already.
      result = copyTree(n)
      if n.typ.skipTypes(abstractInst-{tyOwned}).kind != tyOwned and
          n[1].typ.skipTypes(abstractInst-{tyOwned}).kind == tyOwned:
        # allow conversions from owned to unowned via this little hack:
        let nTyp = n[1].typ
        n[1].typ = n.typ
        result[1] = p(n[1], c, s, mode)
        result[1].typ = nTyp
      else:
        result[1] = p(n[1], c, s, mode)

    of nkObjDownConv, nkObjUpConv:
      result = copyTree(n)
      result[0] = p(n[0], c, s, mode)

    of nkDotExpr:
      result = shallowCopy(n)
      result[0] = p(n[0], c, s, normal)
      for i in 1 ..< n.len:
        result[i] = n[i]
      if mode == sinkArg and hasDestructor(c, n.typ):
        if isAnalysableFieldAccess(n, c.owner) and isLastRead(n, c, s):
          s.wasMoved.add c.genWasMoved(n)
        else:
          result = passCopyToSink(result, c, s)

    of nkBracketExpr, nkAddr, nkHiddenAddr, nkDerefExpr, nkHiddenDeref:
      result = shallowCopy(n)
      for i in 0 ..< n.len:
        result[i] = p(n[i], c, s, normal)
      if mode == sinkArg and hasDestructor(c, n.typ):
        if isAnalysableFieldAccess(n, c.owner) and isLastRead(n, c, s):
          # consider 'a[(g; destroy(g); 3)]', we want to say 'wasMoved(a[3])'
          # without the junk, hence 'c.genWasMoved(n)'
          # and not 'c.genWasMoved(result)':
          s.wasMoved.add c.genWasMoved(n)
        else:
          result = passCopyToSink(result, c, s)

    of nkDefer, nkRange:
      result = shallowCopy(n)
      for i in 0 ..< n.len:
        result[i] = p(n[i], c, s, normal)

    of nkBreakStmt:
      s.needsTry = true
      result = n
    of nkReturnStmt:
      result = shallowCopy(n)
      for i in 0..<n.len:
        result[i] = p(n[i], c, s, mode, inReturn=true)
      s.needsTry = true
    of nkCast:
      result = shallowCopy(n)
      result[0] = n[0]
      result[1] = p(n[1], c, s, mode)
    of nkCheckedFieldExpr:
      result = shallowCopy(n)
      result[0] = p(n[0], c, s, mode)
      for i in 1..<n.len:
        result[i] = n[i]
    of nkGotoState, nkState, nkAsmStmt:
      result = n
    else:
      result = nil
      internalError(c.graph.config, n.info, "cannot inject destructors to node kind: " & $n.kind)

proc sameLocation*(a, b: PNode): bool =
  proc sameConstant(a, b: PNode): bool =
    a.kind in nkLiterals and b.kind in nkLiterals and a.intVal == b.intVal

  const nkEndPoint = {nkSym, nkDotExpr, nkCheckedFieldExpr, nkBracketExpr}
  if a.kind in nkEndPoint and b.kind in nkEndPoint:
    if a.kind == b.kind:
      case a.kind
      of nkSym: a.sym == b.sym
      of nkDotExpr, nkCheckedFieldExpr: sameLocation(a[0], b[0]) and sameLocation(a[1], b[1])
      of nkBracketExpr: sameLocation(a[0], b[0]) and sameConstant(a[1], b[1])
      else: false
    else: false
  else:
    case a.kind
    of nkSym, nkDotExpr, nkCheckedFieldExpr, nkBracketExpr:
      # Reached an endpoint, flip to recurse the other side.
      sameLocation(b, a)
    of nkAddr, nkHiddenAddr, nkDerefExpr, nkHiddenDeref:
      # We don't need to check addr/deref levels or differentiate between the two,
      # since pointers don't have hooks :) (e.g: var p: ptr pointer; p[] = addr p)
      sameLocation(a[0], b)
    of nkObjDownConv, nkObjUpConv: sameLocation(a[0], b)
    of nkHiddenStdConv, nkHiddenSubConv: sameLocation(a[1], b)
    else: false

proc genFieldAccessSideEffects(c: var Con; s: var Scope; dest, ri: PNode; flags: set[MoveOrCopyFlag] = {}): PNode =
  # with side effects
  var temp = newSym(skLet, getIdent(c.graph.cache, "bracketTmp"), c.idgen, c.owner, ri[1].info)
  temp.typ = ri[1].typ
  var v = newNodeI(nkLetSection, ri[1].info)
  let tempAsNode = newSymNode(temp)

  var vpart = newNodeI(nkIdentDefs, tempAsNode.info, 3)
  vpart[0] = tempAsNode
  vpart[1] = newNodeI(nkEmpty, tempAsNode.info)
  vpart[2] = ri[1]
  v.add(vpart)

  var newAccess = copyNode(ri)
  newAccess.add ri[0]
  newAccess.add tempAsNode

  var snk = c.genSink(s, dest, newAccess, flags)
  result = newTree(nkStmtList, v, snk, c.genWasMoved(newAccess))

proc moveOrCopy(dest, ri: PNode; c: var Con; s: var Scope, flags: set[MoveOrCopyFlag] = {}): PNode =
  var ri = ri
  var isEnsureMove = 0
  if ri.kind in nkCallKinds and ri[0].kind == nkSym and ri[0].sym.magic == mEnsureMove:
    ri = ri[1]
    isEnsureMove = 1
  if sameLocation(dest, ri):
    # rule (self-assignment-removal):
    result = newNodeI(nkEmpty, dest.info)
  elif isCursor(dest) or dest.typ.kind in {tyOpenArray, tyVarargs}:
    # hoisted openArray parameters might end up here
    # openArray types don't have a lifted assignment operation (it's empty)
    # bug #22132
    case ri.kind:
    of nkStmtListExpr, nkBlockExpr, nkIfExpr, nkCaseStmt, nkTryStmt:
      template process(child, s): untyped = moveOrCopy(dest, child, c, s, flags)
      # We know the result will be a stmt so we use that fact to optimize
      handleNestedTempl(ri, process, willProduceStmt = true)
    else:
      result = newTree(nkFastAsgn, dest, p(ri, c, s, normal))
  else:
    let ri2 = if ri.kind == nkWhen: ri[1][0] else: ri
    case ri2.kind
    of nkCallKinds:
      result = c.genSink(s, dest, p(ri, c, s, consumed), flags)
    of nkBracketExpr:
      if isUnpackedTuple(ri[0]):
        # unpacking of tuple: take over the elements
        result = c.genSink(s, dest, p(ri, c, s, consumed), flags)
      elif isAnalysableFieldAccess(ri, c.owner) and isLastRead(ri, c, s):
        if aliases(dest, ri) == no:
          # Rule 3: `=sink`(x, z); wasMoved(z)
          if isAtom(ri[1]):
            var snk = c.genSink(s, dest, ri, flags)
            result = newTree(nkStmtList, snk, c.genWasMoved(ri))
          else:
            result = genFieldAccessSideEffects(c, s, dest, ri, flags)
        else:
          result = c.genSink(s, dest, destructiveMoveVar(ri, c, s), flags)
      else:
        inc c.inEnsureMove, isEnsureMove
        result = c.genCopy(dest, ri, flags)
        dec c.inEnsureMove, isEnsureMove
        result.add p(ri, c, s, consumed)
        c.finishCopy(result, dest, isFromSink = false)
    of nkBracket:
      # array constructor
      if ri.len > 0 and isDangerousSeq(ri.typ):
        inc c.inEnsureMove, isEnsureMove
        result = c.genCopy(dest, ri, flags)
        dec c.inEnsureMove, isEnsureMove
        result.add p(ri, c, s, consumed)
        c.finishCopy(result, dest, isFromSink = false)
      else:
        result = c.genSink(s, dest, p(ri, c, s, consumed), flags)
    of nkObjConstr, nkTupleConstr, nkClosure, nkCharLit..nkNilLit:
      result = c.genSink(s, dest, p(ri, c, s, consumed), flags)
    of nkSym:
      if isSinkParam(ri.sym) and isLastRead(ri, c, s):
        # Rule 3: `=sink`(x, z); wasMoved(z)
        let snk = c.genSink(s, dest, ri, flags)
        result = newTree(nkStmtList, snk, c.genWasMoved(ri))
      elif ri.sym.kind != skParam and ri.sym.owner == c.owner and
          isLastRead(ri, c, s) and canBeMoved(c, dest.typ) and not isCursor(ri) and
          not ({sfGlobal, sfPure} <= ri.sym.flags):
        # Rule 3: `=sink`(x, z); wasMoved(z)
        let snk = c.genSink(s, dest, ri, flags)
        result = newTree(nkStmtList, snk, c.genWasMoved(ri))
      else:
        inc c.inEnsureMove, isEnsureMove
        result = c.genCopy(dest, ri, flags)
        dec c.inEnsureMove, isEnsureMove
        result.add p(ri, c, s, consumed)
        c.finishCopy(result, dest, isFromSink = false)
    of nkHiddenSubConv, nkHiddenStdConv, nkConv, nkObjDownConv, nkObjUpConv, nkCast:
      result = c.genSink(s, dest, p(ri, c, s, sinkArg), flags)
    of nkStmtListExpr, nkBlockExpr, nkIfExpr, nkCaseStmt, nkTryStmt:
      template process(child, s): untyped = moveOrCopy(dest, child, c, s, flags)
      # We know the result will be a stmt so we use that fact to optimize
      handleNestedTempl(ri, process, willProduceStmt = true)
    of nkRaiseStmt:
      result = pRaiseStmt(ri, c, s)
    else:
      if isAnalysableFieldAccess(ri, c.owner) and isLastRead(ri, c, s) and
          canBeMoved(c, dest.typ):
        # Rule 3: `=sink`(x, z); wasMoved(z)
        let snk = c.genSink(s, dest, ri, flags)
        result = newTree(nkStmtList, snk, c.genWasMoved(ri))
      else:
        inc c.inEnsureMove, isEnsureMove
        result = c.genCopy(dest, ri, flags)
        dec c.inEnsureMove, isEnsureMove
        result.add p(ri, c, s, consumed)
        c.finishCopy(result, dest, isFromSink = false)

when false:
  proc computeUninit(c: var Con) =
    if not c.uninitComputed:
      c.uninitComputed = true
      c.uninit = initIntSet()
      var init = initIntSet()
      discard initialized(c.g, pc = 0, init, c.uninit, int.high)

  proc injectDefaultCalls(n: PNode, c: var Con) =
    case n.kind
    of nkVarSection, nkLetSection:
      for it in n:
        if it.kind == nkIdentDefs and it[^1].kind == nkEmpty:
          computeUninit(c)
          for j in 0..<it.len-2:
            let v = skipPragmaExpr(it[j])
            doAssert v.kind == nkSym
            if c.uninit.contains(v.sym.id):
              it[^1] = genDefaultCall(v.sym.typ, c, v.info)
              break
    of nkNone..nkNilLit, nkTypeSection, nkProcDef, nkConverterDef, nkMethodDef,
        nkIteratorDef, nkMacroDef, nkTemplateDef, nkLambda, nkDo, nkFuncDef:
      discard
    else:
      for i in 0..<n.safeLen:
        injectDefaultCalls(n[i], c)

proc injectDestructorCalls*(g: ModuleGraph; idgen: IdGenerator; owner: PSym; n: PNode): PNode =
  when toDebug.len > 0:
    shouldDebug = toDebug == owner.name.s or toDebug == "always"
  if sfGeneratedOp in owner.flags or (owner.kind == skIterator and isInlineIterator(owner.typ)):
    return n
  var c = Con(owner: owner, graph: g, idgen: idgen, body: n, otherUsage: unknownLineInfo)

  if optCursorInference in g.config.options:
    computeCursors(owner, n, g)

  var scope = Scope(body: n)
  let body = p(n, c, scope, normal)

  if owner.kind in {skProc, skFunc, skMethod, skIterator, skConverter}:
    let params = owner.typ.n
    for i in 1..<params.len:
      let t = params[i].sym.typ
      if isSinkTypeForParam(t) and hasDestructor(c, t.skipTypes({tySink})):
        scope.final.add c.genDestroy(params[i])
  #if optNimV2 in c.graph.config.globalOptions:
  #  injectDefaultCalls(n, c)
  result = optimize processScope(c, scope, body)
  dbg:
    echo ">---------transformed-to--------->"
    echo renderTree(result, {renderIds})

  if g.config.arcToExpand.hasKey(owner.name.s):
    echo "--expandArc: ", owner.name.s
    echo renderTree(result, {renderIr, renderNoComments})
    echo "-- end of expandArc ------------------------"
generated by cgit-pink 1.4.1-2-gfad0 (git 2.36.2.497.gbbea4dcf42) at 2025-02-11 08:07:53 +0000