Make strcpy_chk lower to strcpy if we have a safe size.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94783 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/SimplifyLibCalls.cpp b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
index a49da9c..fc23c42 100644
--- a/lib/Transforms/Scalar/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
@@ -1203,9 +1203,6 @@
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 @@
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;