Only replace fwrite with fputc, if the return value is unused.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146411 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/SimplifyLibCalls.cpp b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
index 075adc0..f3184ec 100644
--- a/lib/Transforms/Scalar/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
@@ -1293,7 +1293,8 @@
return ConstantInt::get(CI->getType(), 0);
// If this is writing one byte, turn it into fputc.
- if (Bytes == 1) { // fwrite(S,1,1,F) -> fputc(S[0],F)
+ // This optimisation is only valid, if the return value is unused.
+ if (Bytes == 1 && CI->use_empty()) { // fwrite(S,1,1,F) -> fputc(S[0],F)
Value *Char = B.CreateLoad(CastToCStr(CI->getArgOperand(0), B), "char");
EmitFPutC(Char, CI->getArgOperand(3), B, TD);
return ConstantInt::get(CI->getType(), 1);