fix PR4284, a bug in simplifylibcalls handling memcmp. Patch by
Benjamin Kramer!
llvm-svn: 72625
diff --git a/llvm/lib/Transforms/Scalar/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Scalar/SimplifyLibCalls.cpp
index 8c41c72..4b00640 100644
--- a/llvm/lib/Transforms/Scalar/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Scalar/SimplifyLibCalls.cpp
@@ -878,7 +878,7 @@
if (Len == 1) { // memcmp(S1,S2,1) -> *LHS - *RHS
Value *LHSV = B.CreateLoad(CastToCStr(LHS, B), "lhsv");
Value *RHSV = B.CreateLoad(CastToCStr(RHS, B), "rhsv");
- return B.CreateZExt(B.CreateSub(LHSV, RHSV, "chardiff"), CI->getType());
+ return B.CreateSExt(B.CreateSub(LHSV, RHSV, "chardiff"), CI->getType());
}
// memcmp(S1,S2,2) != 0 -> (*(short*)LHS ^ *(short*)RHS) != 0