Lower stpcpy_chk when possible.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98274 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/InstCombine/InstCombineCalls.cpp b/lib/Transforms/InstCombine/InstCombineCalls.cpp
index c62155e..43ff58d 100644
--- a/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -838,6 +838,19 @@
// 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;
}