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-rw-r--r--compiler/vm.nim35
-rw-r--r--compiler/vmdef.nim7
-rw-r--r--compiler/vmgen.nim76
3 files changed, 85 insertions, 33 deletions
diff --git a/compiler/vm.nim b/compiler/vm.nim
index 70eb6f828..8fea6b293 100644
--- a/compiler/vm.nim
+++ b/compiler/vm.nim
@@ -68,7 +68,9 @@ proc stackTrace(c: PCtx, tos: PStackFrame, pc: int,
                 msg: TMsgKind, arg = "") =
   msgWriteln("stack trace: (most recent call last)")
   stackTraceAux(c, tos, pc)
-  localError(c.debug[pc], msg, arg)
+  # XXX test if we want 'globalError' for every mode
+  if c.mode == emRepl: globalError(c.debug[pc], msg, arg)
+  else: localError(c.debug[pc], msg, arg)
 
 proc bailOut(c: PCtx; tos: PStackFrame) =
   stackTrace(c, tos, c.exceptionInstr, errUnhandledExceptionX,
@@ -333,6 +335,16 @@ proc compile(c: PCtx, s: PSym): int =
   when debugEchoCode: c.echoCode result
   #c.echoCode
 
+template handleJmpBack() {.dirty.} =
+  if c.loopIterations <= 0:
+    if allowInfiniteLoops in c.features:
+      c.loopIterations = MaxLoopIterations
+    else:
+      msgWriteln("stack trace: (most recent call last)")
+      stackTraceAux(c, tos, pc)
+      globalError(c.debug[pc], errTooManyIterations)
+  dec(c.loopIterations)
+
 proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
   var pc = start
   var tos = tos
@@ -735,6 +747,9 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
           globalError(c.debug[pc], errGenerated, "VM not built with FFI support")
       elif prc.kind != skTemplate:
         let newPc = compile(c, prc)
+        # tricky: a recursion is also a jump back, so we use the same
+        # logic as for loops:
+        if newPc < pc: handleJmpBack()
         #echo "new pc ", newPc, " calling: ", prc.name.s
         var newFrame = PStackFrame(prc: prc, comesFrom: pc, next: tos)
         newSeq(newFrame.slots, prc.offset)
@@ -778,6 +793,10 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
       # jump Bx
       let rbx = instr.regBx - wordExcess - 1 # -1 for the following 'inc pc'
       inc pc, rbx
+    of opcJmpBack:
+      let rbx = instr.regBx - wordExcess - 1 # -1 for the following 'inc pc'
+      inc pc, rbx
+      handleJmpBack()
     of opcBranch:
       # we know the next instruction is a 'fjmp':
       let branch = c.constants[instr.regBx-wordExcess]
@@ -929,17 +948,15 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
     of opcReset:
       internalError(c.debug[pc], "too implement")
     of opcNarrowS:
-      decodeBC(rkInt)
-      let min = -(1 shl (rc-1))
-      let max = (1 shl (rc-1))-1
-      if regs[rb].intVal >= min and regs[rb].intVal <= max:
-        regs[ra].intVal = regs[rb].intVal
-      else:
+      decodeB(rkInt)
+      let min = -(1 shl (rb-1))
+      let max = (1 shl (rb-1))-1
+      if regs[ra].intVal < min or regs[ra].intVal > max:
         stackTrace(c, tos, pc, errGenerated,
           msgKindToString(errUnhandledExceptionX) % "value out of range")
     of opcNarrowU:
-      decodeBC(rkInt)
-      regs[ra].intVal = regs[rb].intVal and ((1'i64 shl rc)-1)
+      decodeB(rkInt)
+      regs[ra].intVal = regs[ra].intVal and ((1'i64 shl rb)-1)
     of opcIsNil:
       decodeB(rkInt)
       regs[ra].intVal = ord(regs[rb].node.kind == nkNilLit)
diff --git a/compiler/vmdef.nim b/compiler/vmdef.nim
index 7725d79b8..90ff8e29f 100644
--- a/compiler/vmdef.nim
+++ b/compiler/vmdef.nim
@@ -16,6 +16,9 @@ const
   byteExcess* = 128 # we use excess-K for immediates
   wordExcess* = 32768
 
+  MaxLoopIterations* = 500_000 # max iterations of all loops
+
+
 type
   TRegister* = range[0..255]
   TDest* = range[-1 .. 255]
@@ -110,6 +113,7 @@ type
     opcTJmp,  # jump Bx if A != 0
     opcFJmp,  # jump Bx if A == 0
     opcJmp,   # jump Bx
+    opcJmpBack, # jump Bx; resulting from a while loop
     opcBranch,  # branch for 'case'
     opcTry,
     opcExcept,
@@ -182,6 +186,7 @@ type
     mode*: TEvalMode
     features*: TSandboxFlags
     traceActive*: bool
+    loopIterations*: int
 
   TPosition* = distinct int
 
@@ -190,7 +195,7 @@ type
 proc newCtx*(module: PSym): PCtx =
   PCtx(code: @[], debug: @[],
     globals: newNode(nkStmtListExpr), constants: newNode(nkStmtList), types: @[],
-    prc: PProc(blocks: @[]), module: module)
+    prc: PProc(blocks: @[]), module: module, loopIterations: MaxLoopIterations)
 
 proc refresh*(c: PCtx, module: PSym) =
   c.module = module
diff --git a/compiler/vmgen.nim b/compiler/vmgen.nim
index 82d1e9ab8..59d3d2495 100644
--- a/compiler/vmgen.nim
+++ b/compiler/vmgen.nim
@@ -92,10 +92,10 @@ proc genLabel(c: PCtx): TPosition =
   result = TPosition(c.code.len)
   #c.jumpTargets.incl(c.code.len)
 
-proc jmpBack(c: PCtx, n: PNode, opc: TOpcode, p = TPosition(0)) =
+proc jmpBack(c: PCtx, n: PNode, p = TPosition(0)) =
   let dist = p.int - c.code.len
   internalAssert(-0x7fff < dist and dist < 0x7fff)
-  gABx(c, n, opc, 0, dist)
+  gABx(c, n, opcJmpBack, 0, dist)
 
 proc patch(c: PCtx, p: TPosition) =
   # patch with current index
@@ -229,20 +229,20 @@ proc genWhile(c: PCtx; n: PNode) =
   withBlock(nil):
     if isTrue(n.sons[0]):
       c.gen(n.sons[1])
-      c.jmpBack(n, opcJmp, L1)
+      c.jmpBack(n, L1)
     elif isNotOpr(n.sons[0]):
       var tmp = c.genx(n.sons[0].sons[1])
       let L2 = c.xjmp(n, opcTJmp, tmp)
       c.freeTemp(tmp)
       c.gen(n.sons[1])
-      c.jmpBack(n, opcJmp, L1)
+      c.jmpBack(n, L1)
       c.patch(L2)
     else:
       var tmp = c.genx(n.sons[0])
       let L2 = c.xjmp(n, opcFJmp, tmp)
       c.freeTemp(tmp)
       c.gen(n.sons[1])
-      c.jmpBack(n, opcJmp, L1)
+      c.jmpBack(n, L1)
       c.patch(L2)
 
 proc genBlock(c: PCtx; n: PNode; dest: var TDest) =
@@ -543,6 +543,30 @@ proc genBinaryABC(c: PCtx; n: PNode; dest: var TDest; opc: TOpcode) =
   c.freeTemp(tmp)
   c.freeTemp(tmp2)
 
+proc genNarrow(c: PCtx; n: PNode; dest: TDest) =
+  let t = skipTypes(n.typ, abstractVar-{tyTypeDesc})
+  # uint is uint64 in the VM, we we only need to mask the result for
+  # other unsigned types:
+  if t.kind in {tyUInt8..tyUInt32}:
+    c.gABC(n, opcNarrowU, dest, TRegister(t.size*8))
+  elif t.kind in {tyInt8..tyInt32}:
+    c.gABC(n, opcNarrowS, dest, TRegister(t.size*8))
+
+proc genNarrowU(c: PCtx; n: PNode; dest: TDest) =
+  let t = skipTypes(n.typ, abstractVar-{tyTypeDesc})
+  # uint is uint64 in the VM, we we only need to mask the result for
+  # other unsigned types:
+  if t.kind in {tyUInt8..tyUInt32, tyInt8..tyInt32}:
+    c.gABC(n, opcNarrowU, dest, TRegister(t.size*8))
+
+proc genBinaryABCnarrow(c: PCtx; n: PNode; dest: var TDest; opc: TOpcode) =
+  genBinaryABC(c, n, dest, opc)
+  genNarrow(c, n, dest)
+
+proc genBinaryABCnarrowU(c: PCtx; n: PNode; dest: var TDest; opc: TOpcode) =
+  genBinaryABC(c, n, dest, opc)
+  genNarrowU(c, n, dest)
+
 proc genSetType(c: PCtx; n: PNode; dest: TRegister) =
   let t = skipTypes(n.typ, abstractInst-{tyTypeDesc})
   if t.kind == tySet:
@@ -604,6 +628,7 @@ proc genAddSubInt(c: PCtx; n: PNode; dest: var TDest; opc: TOpcode) =
     c.freeTemp(tmp)
   else:
     genBinaryABC(c, n, dest, opc)
+  c.genNarrow(n, dest)
 
 proc genConv(c: PCtx; n, arg: PNode; dest: var TDest; opc=opcConv) =  
   let tmp = c.genx(arg)
@@ -644,6 +669,7 @@ proc genMagic(c: PCtx; n: PNode; dest: var TDest) =
       let tmp = c.genx(n.sons[2])
       c.gABC(n, opc, d, d, tmp)
       c.freeTemp(tmp)
+    c.genNarrow(n.sons[1], d)
     c.genAsgnPatch(n.sons[1], d)
     c.freeTemp(d)
   of mOrd, mChr, mArrToSeq: c.gen(n.sons[1], dest)
@@ -678,23 +704,23 @@ proc genMagic(c: PCtx; n: PNode; dest: var TDest) =
     c.freeTemp(d)
     c.freeTemp(tmp)
   of mCard: genCard(c, n, dest)
-  of mMulI, mMulI64: genBinaryABC(c, n, dest, opcMulInt)
-  of mDivI, mDivI64: genBinaryABC(c, n, dest, opcDivInt)
-  of mModI, mModI64: genBinaryABC(c, n, dest, opcModInt)
+  of mMulI, mMulI64: genBinaryABCnarrow(c, n, dest, opcMulInt)
+  of mDivI, mDivI64: genBinaryABCnarrow(c, n, dest, opcDivInt)
+  of mModI, mModI64: genBinaryABCnarrow(c, n, dest, opcModInt)
   of mAddF64: genBinaryABC(c, n, dest, opcAddFloat)
   of mSubF64: genBinaryABC(c, n, dest, opcSubFloat)
   of mMulF64: genBinaryABC(c, n, dest, opcMulFloat)
   of mDivF64: genBinaryABC(c, n, dest, opcDivFloat)
-  of mShrI, mShrI64: genBinaryABC(c, n, dest, opcShrInt)
-  of mShlI, mShlI64: genBinaryABC(c, n, dest, opcShlInt)
-  of mBitandI, mBitandI64: genBinaryABC(c, n, dest, opcBitandInt)
-  of mBitorI, mBitorI64: genBinaryABC(c, n, dest, opcBitorInt)
-  of mBitxorI, mBitxorI64: genBinaryABC(c, n, dest, opcBitxorInt)
-  of mAddU: genBinaryABC(c, n, dest, opcAddu)
-  of mSubU: genBinaryABC(c, n, dest, opcSubu)
-  of mMulU: genBinaryABC(c, n, dest, opcMulu)
-  of mDivU: genBinaryABC(c, n, dest, opcDivu)
-  of mModU: genBinaryABC(c, n, dest, opcModu)
+  of mShrI, mShrI64: genBinaryABCnarrowU(c, n, dest, opcShrInt)
+  of mShlI, mShlI64: genBinaryABCnarrowU(c, n, dest, opcShlInt)
+  of mBitandI, mBitandI64: genBinaryABCnarrowU(c, n, dest, opcBitandInt)
+  of mBitorI, mBitorI64: genBinaryABCnarrowU(c, n, dest, opcBitorInt)
+  of mBitxorI, mBitxorI64: genBinaryABCnarrowU(c, n, dest, opcBitxorInt)
+  of mAddU: genBinaryABCnarrowU(c, n, dest, opcAddu)
+  of mSubU: genBinaryABCnarrowU(c, n, dest, opcSubu)
+  of mMulU: genBinaryABCnarrowU(c, n, dest, opcMulu)
+  of mDivU: genBinaryABCnarrowU(c, n, dest, opcDivu)
+  of mModU: genBinaryABCnarrowU(c, n, dest, opcModu)
   of mEqI, mEqI64, mEqB, mEqEnum, mEqCh:
     genBinaryABC(c, n, dest, opcEqInt)
   of mLeI, mLeI64, mLeEnum, mLeCh, mLeB:
@@ -708,12 +734,16 @@ proc genMagic(c: PCtx; n: PNode; dest: var TDest) =
   of mLtPtr, mLtU, mLtU64: genBinaryABC(c, n, dest, opcLtu)
   of mEqProc, mEqRef, mEqUntracedRef, mEqCString:
     genBinaryABC(c, n, dest, opcEqRef)
-  of mXor: genBinaryABC(c, n, dest, opcXor)
+  of mXor: genBinaryABCnarrowU(c, n, dest, opcXor)
   of mNot: genUnaryABC(c, n, dest, opcNot)
-  of mUnaryMinusI, mUnaryMinusI64: genUnaryABC(c, n, dest, opcUnaryMinusInt)
+  of mUnaryMinusI, mUnaryMinusI64:
+    genUnaryABC(c, n, dest, opcUnaryMinusInt)
+    genNarrow(c, n, dest)
   of mUnaryMinusF64: genUnaryABC(c, n, dest, opcUnaryMinusFloat)
   of mUnaryPlusI, mUnaryPlusI64, mUnaryPlusF64: gen(c, n.sons[1], dest)
-  of mBitnotI, mBitnotI64: genUnaryABC(c, n, dest, opcBitnotInt)
+  of mBitnotI, mBitnotI64: 
+    genUnaryABC(c, n, dest, opcBitnotInt)
+    genNarrowU(c, n, dest)
   of mZe8ToI, mZe8ToI64, mZe16ToI, mZe16ToI64, mZe32ToI64, mZeIToI64,
      mToU8, mToU16, mToU32, mToFloat, mToBiggestFloat, mToInt, 
      mToBiggestInt, mCharToStr, mBoolToStr, mIntToStr, mInt64ToStr, 
@@ -1518,7 +1548,7 @@ proc optimizeJumps(c: PCtx; start: int) =
       var d = i + c.code[i].jmpDiff
       for iters in countdown(maxIterations, 0):
         case c.code[d].opcode
-        of opcJmp:
+        of opcJmp, opcJmpBack:
           d = d + c.code[d].jmpDiff
         of opcTJmp, opcFJmp:
           if c.code[d].regA != reg: break
@@ -1536,7 +1566,7 @@ proc optimizeJumps(c: PCtx; start: int) =
         else: break
       if d != i + c.code[i].jmpDiff:
         c.finalJumpTarget(i, d - i)
-    of opcJmp:
+    of opcJmp, opcJmpBack:
       var d = i + c.code[i].jmpDiff
       var iters = maxIterations
       while c.code[d].opcode == opcJmp and iters > 0: