forked from OSchip/llvm-project
cb8c009801
There are 2 parts to getting the -fassociative-math command-line flag translated to LLVM FMF:
1. In the driver/frontend, we accept the flag and its 'no' inverse and deal with the
interactions with other flags like -ffast-math -fno-signed-zeros -fno-trapping-math.
This was mostly already done - we just need to translate the flag as a codegen option.
The test file is complicated because there are many potential combinations of flags here.
Note that we are matching gcc's behavior that requires 'nsz' and no-trapping-math.
2. In codegen, we map the codegen option to FMF in the IR builder. This is simple code and
corresponding test.
For the motivating example from PR27372:
float foo(float a, float x) { return ((a + x) - x); }
$ ./clang -O2 27372.c -S -o - -ffast-math -fno-associative-math -emit-llvm | egrep 'fadd|fsub'
%add = fadd nnan ninf nsz arcp contract float %0, %1
%sub = fsub nnan ninf nsz arcp contract float %add, %2
So 'reassoc' is off as expected (and so is the new 'afn' but that's a different patch).
This case now works as expected end-to-end although the underlying logic is still wrong:
$ ./clang -O2 27372.c -S -o - -ffast-math -fno-associative-math | grep xmm
addss %xmm1, %xmm0
subss %xmm1, %xmm0
We're not done because the case where 'reassoc' is set is ignored by optimizer passes. Example:
$ ./clang -O2 27372.c -S -o - -fassociative-math -fno-signed-zeros -fno-trapping-math -emit-llvm | grep fadd
%add = fadd reassoc float %0, %1
$ ./clang -O2 27372.c -S -o - -fassociative-math -fno-signed-zeros -fno-trapping-math | grep xmm
addss %xmm1, %xmm0
subss %xmm1, %xmm0
Differential Revision: https://reviews.llvm.org/D39812
llvm-svn: 320920
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| .. | ||
| Rewrite | ||
| ASTConsumers.cpp | ||
| ASTMerge.cpp | ||
| ASTUnit.cpp | ||
| CMakeLists.txt | ||
| CacheTokens.cpp | ||
| ChainedDiagnosticConsumer.cpp | ||
| ChainedIncludesSource.cpp | ||
| CodeGenOptions.cpp | ||
| CompilerInstance.cpp | ||
| CompilerInvocation.cpp | ||
| CreateInvocationFromCommandLine.cpp | ||
| DependencyFile.cpp | ||
| DependencyGraph.cpp | ||
| DiagnosticRenderer.cpp | ||
| FrontendAction.cpp | ||
| FrontendActions.cpp | ||
| FrontendOptions.cpp | ||
| HeaderIncludeGen.cpp | ||
| InitHeaderSearch.cpp | ||
| InitPreprocessor.cpp | ||
| LangStandards.cpp | ||
| LayoutOverrideSource.cpp | ||
| LogDiagnosticPrinter.cpp | ||
| ModuleDependencyCollector.cpp | ||
| MultiplexConsumer.cpp | ||
| PCHContainerOperations.cpp | ||
| PrecompiledPreamble.cpp | ||
| PrintPreprocessedOutput.cpp | ||
| SerializedDiagnosticPrinter.cpp | ||
| SerializedDiagnosticReader.cpp | ||
| TestModuleFileExtension.cpp | ||
| TestModuleFileExtension.h | ||
| TextDiagnostic.cpp | ||
| TextDiagnosticBuffer.cpp | ||
| TextDiagnosticPrinter.cpp | ||
| VerifyDiagnosticConsumer.cpp | ||