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Make strcpy_chk lower to strcpy if we have a safe size.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94783 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eric Christopher
2010-01-29 01:37:11 +00:00
parent 9988ab0496
commit 407e47c21e
2 changed files with 19 additions and 5 deletions
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12
lib/Transforms/Scalar/SimplifyLibCalls.cpp
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@@ -1203,9 +1203,6 @@ struct MemMoveChkOpt : public LibCallOptimization {
struct StrCpyChkOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// These optimizations require TargetData.
if (!TD) return 0;
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
!isa<PointerType>(FT->getParamType(0)) ||
@@ -1217,8 +1214,13 @@ struct StrCpyChkOpt : public LibCallOptimization {
if (!SizeCI)
return 0;
// We don't have any length information, just lower to a plain strcpy.
if (SizeCI->isAllOnesValue())
// If a) we don't have any length information, or b) we know this will
// fit then just lower to a plain strcpy. Otherwise we'll keep our
// strcpy_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)))
return EmitStrCpy(CI->getOperand(1), CI->getOperand(2), B);
return 0;