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Implement overflow/underflow checking for the VM.

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EXetoC
2014-03-31 14:11:21 +02:00
parent aae774a279
commit b919ab790b
1 changed files with 49 additions and 6 deletions
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55
compiler/vm.nim
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@@ -495,18 +495,46 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
else: stackTrace(c, tos, pc, errNilAccess)
of opcAddInt:
decodeBC(rkInt)
regs[ra].intVal = regs[rb].intVal + regs[rc].intVal
let
bVal = regs[rb].intVal
cVal = regs[rc].intVal
sum = bVal +% cVal
if (sum xor bVal) >= 0 or (sum xor cVal) >= 0:
regs[ra].intVal = sum
else:
stackTrace(c, tos, pc, errOverOrUnderflow)
of opcAddImmInt:
decodeBImm(rkInt)
#message(c.debug[pc], warnUser, "came here")
#debug regs[rb].node
regs[ra].intVal = regs[rb].intVal + imm
let
bVal = regs[rb].intVal
cVal = imm
sum = bVal +% cVal
if (sum xor bVal) >= 0 or (sum xor cVal) >= 0:
regs[ra].intVal = sum
else:
stackTrace(c, tos, pc, errOverOrUnderflow)
of opcSubInt:
decodeBC(rkInt)
regs[ra].intVal = regs[rb].intVal - regs[rc].intVal
let
bVal = regs[rb].intVal
cVal = regs[rc].intVal
diff = bVal -% cVal
if (diff xor bVal) >= 0 or (diff xor not cVal) >= 0:
regs[ra].intVal = diff
else:
stackTrace(c, tos, pc, errOverOrUnderflow)
of opcSubImmInt:
decodeBImm(rkInt)
regs[ra].intVal = regs[rb].intVal - imm
let
bVal = regs[rb].intVal
cVal = imm
diff = bVal -% cVal
if (diff xor bVal) >= 0 or (diff xor not cVal) >= 0:
regs[ra].intVal = diff
else:
stackTrace(c, tos, pc, errOverOrUnderflow)
of opcLenSeq:
decodeBImm(rkInt)
#assert regs[rb].kind == nkBracket
@@ -539,7 +567,18 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
regs[ra].intVal = nimsets.cardSet(regs[rb].node)
of opcMulInt:
decodeBC(rkInt)
regs[ra].intVal = regs[rb].intVal * regs[rc].intVal
let
bVal = regs[rb].intVal
cVal = regs[rc].intVal
product = bVal *% cVal
floatProd = toBiggestFloat(bVal) * toBiggestFloat(cVal)
resAsFloat = toBiggestFloat(product)
if resAsFloat == floatProd:
regs[ra].intVal = product
elif 32.0 * abs(resAsFloat - floatProd) <= abs(floatProd):
regs[ra].intVal = product
else:
stackTrace(c, tos, pc, errOverOrUnderflow)
of opcDivInt:
decodeBC(rkInt)
if regs[rc].intVal == 0: stackTrace(c, tos, pc, errConstantDivisionByZero)
@@ -632,7 +671,11 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
of opcUnaryMinusInt:
decodeB(rkInt)
assert regs[rb].kind == rkInt
regs[ra].intVal = -regs[rb].intVal
let val = regs[rb].intVal
if val != int64.low:
regs[ra].intVal = -val
else:
stackTrace(c, tos, pc, errOverOrUnderflow)
of opcUnaryMinusFloat:
decodeB(rkFloat)
assert regs[rb].kind == rkFloat