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Lower stpcpy_chk when possible.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98274 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eric Christopher
2010-03-11 19:24:34 +00:00
parent 55282267e1
commit 19888ca8b4
4 changed files with 45 additions and 6 deletions
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13
lib/Transforms/InstCombine/InstCombineCalls.cpp
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@@ -838,6 +838,19 @@ Instruction *InstCombiner::tryOptimizeCall(CallInst *CI, const TargetData *TD) {
// Should be similar to strcpy.
if (Name == "__stpcpy_chk") {
ConstantInt *SizeCI = dyn_cast<ConstantInt>(CI->getOperand(3));
if (!SizeCI)
return 0;
// If a) we don't have any length information, or b) we know this will
// fit then just lower to a plain stpcpy. Otherwise we'll keep our
// stpcpy_chk call which may fail at runtime if the size is too long.
// TODO: It might be nice to get a maximum length out of the possible
// string lengths for varying.
if (SizeCI->isAllOnesValue() ||
SizeCI->getZExtValue() >= GetStringLength(CI->getOperand(2))) {
Value *Ret = EmitStpCpy(CI->getOperand(1), CI->getOperand(2), B, TD);
return ReplaceInstUsesWith(*CI, Ret);
}
return 0;
}