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gc2stack: Extract static size checking code into helper function.

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This commit is contained in:
David Nadlinger
2013-10-27 16:02:33 +01:00
parent e1a6d8144b
commit 5b9208ef85
1 changed files with 27 additions and 21 deletions
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48
gen/passes/GarbageCollect2Stack.cpp
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@@ -142,6 +142,31 @@ namespace {
virtual ~FunctionInfo() {}
};
static bool isKnownLessThan(Value* Val, uint64_t Limit, const Analysis& A) {
unsigned BitsLimit = Log2_64(Limit);
// LLVM's alloca ueses an i32 for the number of elements.
BitsLimit = std::min(BitsLimit, 32U);
const IntegerType* SizeType =
dyn_cast<IntegerType>(Val->getType());
if (!SizeType)
return false;
unsigned Bits = SizeType->getBitWidth();
if (Bits > BitsLimit) {
APInt Mask = APInt::getLowBitsSet(Bits, BitsLimit);
Mask.flipAllBits();
APInt KnownZero(Bits, 0), KnownOne(Bits, 0);
ComputeMaskedBits(Val, KnownZero, KnownOne, &A.TD);
if ((KnownZero & Mask) != Mask)
return false;
}
return true;
}
class ArrayFI : public FunctionInfo {
Value* arrSize;
int ArrSizeArgNr;
@@ -174,29 +199,10 @@ namespace {
// miscompilations for humongous arrays, but as the value "range"
// (set bits) inference algorithm is rather limited, this is
// useful for experimenting.
if (SizeLimit > 0)
{
if (SizeLimit > 0) {
uint64_t ElemSize = A.TD.getTypeAllocSize(Ty);
unsigned BitsLimit = Log2_64(SizeLimit / ElemSize);
// LLVM's alloca ueses an i32 for the number of elements.
BitsLimit = std::min(BitsLimit, 32U);
const IntegerType* SizeType =
dyn_cast<IntegerType>(arrSize->getType());
if (!SizeType)
if (!isKnownLessThan(arrSize, SizeLimit / ElemSize, A))
return false;
unsigned Bits = SizeType->getBitWidth();
if (Bits > BitsLimit) {
APInt Mask = APInt::getLowBitsSet(Bits, BitsLimit);
Mask.flipAllBits();
APInt KnownZero(Bits, 0), KnownOne(Bits, 0);
ComputeMaskedBits(arrSize, KnownZero, KnownOne, &A.TD);
if ((KnownZero & Mask) != Mask)
return false;
}
}
return true;