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add a new pass to instrument loads and stores for run-time bounds checking

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move EmitGEPOffset from InstCombine to Transforms/Utils/Local.h

(a draft of this) patch reviewed by Andrew, thanks.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157261 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nuno Lopes
2012-05-22 17:19:09 +00:00
parent 23e75da7e0
commit 5c525b59d5
9 changed files with 357 additions and 62 deletions
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lib/Transforms/InstCombine/InstCombineAddSub.cpp
-61
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@@ -420,67 +420,6 @@ Instruction *InstCombiner::visitFAdd(BinaryOperator &I) {
}
/// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
/// code necessary to compute the offset from the base pointer (without adding
/// in the base pointer). Return the result as a signed integer of intptr size.
/// If NoNUW is true, then the NUW flag is not used.
Value *InstCombiner::EmitGEPOffset(User *GEP, bool NoNUW) {
TargetData &TD = *getTargetData();
gep_type_iterator GTI = gep_type_begin(GEP);
Type *IntPtrTy = TD.getIntPtrType(GEP->getContext());
Value *Result = Constant::getNullValue(IntPtrTy);
// If the GEP is inbounds, we know that none of the addressing operations will
// overflow in an unsigned sense.
bool isInBounds = cast<GEPOperator>(GEP)->isInBounds() && !NoNUW;
// Build a mask for high order bits.
unsigned IntPtrWidth = TD.getPointerSizeInBits();
uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end(); i != e;
++i, ++GTI) {
Value *Op = *i;
uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()) & PtrSizeMask;
if (ConstantInt *OpC = dyn_cast<ConstantInt>(Op)) {
if (OpC->isZero()) continue;
// Handle a struct index, which adds its field offset to the pointer.
if (StructType *STy = dyn_cast<StructType>(*GTI)) {
Size = TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
if (Size)
Result = Builder->CreateAdd(Result, ConstantInt::get(IntPtrTy, Size),
GEP->getName()+".offs");
continue;
}
Constant *Scale = ConstantInt::get(IntPtrTy, Size);
Constant *OC =
ConstantExpr::getIntegerCast(OpC, IntPtrTy, true /*SExt*/);
Scale = ConstantExpr::getMul(OC, Scale, isInBounds/*NUW*/);
// Emit an add instruction.
Result = Builder->CreateAdd(Result, Scale, GEP->getName()+".offs");
continue;
}
// Convert to correct type.
if (Op->getType() != IntPtrTy)
Op = Builder->CreateIntCast(Op, IntPtrTy, true, Op->getName()+".c");
if (Size != 1) {
// We'll let instcombine(mul) convert this to a shl if possible.
Op = Builder->CreateMul(Op, ConstantInt::get(IntPtrTy, Size),
GEP->getName()+".idx", isInBounds /*NUW*/);
}
// Emit an add instruction.
Result = Builder->CreateAdd(Op, Result, GEP->getName()+".offs");
}
return Result;
}
/// Optimize pointer differences into the same array into a size. Consider:
/// &A[10] - &A[0]: we should compile this to "10". LHS/RHS are the pointer
/// operands to the ptrtoint instructions for the LHS/RHS of the subtract.