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| author | Joerg Sonnenberger <joerg@bec.de> | 2011-12-12 20:18:31 +0000 |
|---|---|---|
| committer | Joerg Sonnenberger <joerg@bec.de> | 2011-12-12 20:18:31 +0000 |
| commit | 127a669d09e21ddcd525f493c19dc399093bef35 (patch) | |
| tree | 07a16d55d282531b1a1954a39877b486070d58d8 | |
| parent | 4ab406d7fc06b1272d02cd8be46f0c5ebe51a3da (diff) | |
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
| -rw-r--r-- | lib/Transforms/Scalar/SimplifyLibCalls.cpp | 3 | ||||
| -rw-r--r-- | test/Transforms/SimplifyLibCalls/fwrite.ll | 13 |
2 files changed, 15 insertions, 1 deletions
diff --git a/lib/Transforms/Scalar/SimplifyLibCalls.cpp b/lib/Transforms/Scalar/SimplifyLibCalls.cpp index 075adc0187..f3184ecc86 100644 --- a/lib/Transforms/Scalar/SimplifyLibCalls.cpp +++ b/lib/Transforms/Scalar/SimplifyLibCalls.cpp @@ -1293,7 +1293,8 @@ struct FWriteOpt : public LibCallOptimization { 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); diff --git a/test/Transforms/SimplifyLibCalls/fwrite.ll b/test/Transforms/SimplifyLibCalls/fwrite.ll new file mode 100644 index 0000000000..f0f3dcaac6 --- /dev/null +++ b/test/Transforms/SimplifyLibCalls/fwrite.ll @@ -0,0 +1,13 @@ +; RUN: opt < %s -simplify-libcalls -S | FileCheck %s + +%FILE = type { i32 } + +@.str = private unnamed_addr constant [1 x i8] zeroinitializer, align 1 + +define i64 @foo(%FILE* %f) { +; CHECK: %retval = call i64 @fwrite + %retval = call i64 @fwrite(i8* getelementptr inbounds ([1 x i8]* @.str, i64 0, i64 0), i64 1, i64 1, %FILE* %f) + ret i64 %retval +} + +declare i64 @fwrite(i8*, i64, i64, %FILE *) |