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Re-add strcmp and known size object size checking optimization.

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Passed bootstrap and nightly test run here.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95145 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eric Christopher
2010-02-02 22:10:43 +00:00
parent 7f89fdae34
commit a6a089cd24
4 changed files with 82 additions and 11 deletions
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42
lib/Transforms/InstCombine/InstCombineCalls.cpp
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@ -633,16 +633,40 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
break;
}
case Intrinsic::objectsize: {
ConstantInt *Const = cast<ConstantInt>(II->getOperand(2));
const Type *Ty = CI.getType();
const Type *ReturnTy = CI.getType();
Value *Op1 = II->getOperand(1);
// 0 is maximum number of bytes left, 1 is minimum number of bytes left.
// TODO: actually add these values, the current return values are "don't
// know".
if (Const->getZExtValue() == 0)
return ReplaceInstUsesWith(CI, Constant::getAllOnesValue(Ty));
else
return ReplaceInstUsesWith(CI, ConstantInt::get(Ty, 0));
// If we're a constant expr then we just return the number of bytes
// left in whatever we're indexing. Since it's constant there's no
// need for maximum or minimum bytes.
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op1)) {
// If this isn't a GEP give up.
if (CE->getOpcode() != Instruction::GetElementPtr) return 0;
const PointerType *ObjTy =
reinterpret_cast<const PointerType*>(CE->getOperand(0)->getType());
if (const ArrayType *AT = dyn_cast<ArrayType>(ObjTy->getElementType())) {
// Deal with multi-dimensional arrays
const ArrayType *SAT = AT;
while ((AT = dyn_cast<ArrayType>(AT->getElementType())))
SAT = AT;
size_t numElems = SAT->getNumElements();
// We return the remaining bytes, so grab the size of an element
// in bytes.
size_t sizeofElem = SAT->getElementType()->getPrimitiveSizeInBits() / 8;
ConstantInt *Const =
cast<ConstantInt>(CE->getOperand(CE->getNumOperands() - 1));
size_t indx = Const->getZExtValue();
return ReplaceInstUsesWith(CI,
ConstantInt::get(ReturnTy,
((numElems - indx) * sizeofElem)));
}
}
// TODO: Add more types here.
}
}