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Given the following C code llvm currently generates suboptimal code for x86-64: __m128 bss4( const __m128 *ptr, size_t i, size_t j ) { float f = ptr[i][j]; return (__m128) { f, f, f, f }; } ================================================= define <4 x float> @_Z4bss4PKDv4_fmm(<4 x float>* nocapture readonly %ptr, i64 %i, i64 %j) #0 { %a1 = getelementptr inbounds <4 x float>* %ptr, i64 %i %a2 = load <4 x float>* %a1, align 16, !tbaa !1 %a3 = trunc i64 %j to i32 %a4 = extractelement <4 x float> %a2, i32 %a3 %a5 = insertelement <4 x float> undef, float %a4, i32 0 %a6 = insertelement <4 x float> %a5, float %a4, i32 1 %a7 = insertelement <4 x float> %a6, float %a4, i32 2 %a8 = insertelement <4 x float> %a7, float %a4, i32 3 ret <4 x float> %a8 } ================================================= shlq $4, %rsi addq %rdi, %rsi movslq %edx, %rax vbroadcastss (%rsi,%rax,4), %xmm0 retq ================================================= The movslq is uneeded, but is present because of the trunc to i32 and then sext back to i64 that the backend adds for vbroadcastss. We can't remove it because it changes the meaning. The IR that clang generates is already suboptimal. What clang really should emit is: %a4 = extractelement <4 x float> %a2, i64 %j This patch makes that legal. A separate patch will teach clang to do it. Differential Revision: http://reviews.llvm.org/D3519 llvm-svn: 207801 |
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_static | ||
_templates | ||
_themes/llvm-theme | ||
CommandGuide | ||
HistoricalNotes | ||
TableGen | ||
tutorial | ||
AliasAnalysis.rst | ||
Atomics.rst | ||
BitCodeFormat.rst | ||
BlockFrequencyTerminology.rst | ||
BranchWeightMetadata.rst | ||
Bugpoint.rst | ||
CMake.rst | ||
CMakeLists.txt | ||
CodeGenerator.rst | ||
CodingStandards.rst | ||
CommandLine.rst | ||
CompilerWriterInfo.rst | ||
conf.py | ||
DebuggingJITedCode.rst | ||
DeveloperPolicy.rst | ||
doxygen.cfg.in | ||
doxygen.css | ||
doxygen.footer | ||
doxygen.header | ||
doxygen.intro | ||
Dummy.html | ||
ExceptionHandling.rst | ||
ExtendedIntegerResults.txt | ||
ExtendingLLVM.rst | ||
Extensions.rst | ||
FAQ.rst | ||
GarbageCollection.rst | ||
gcc-loops.png | ||
GetElementPtr.rst | ||
GettingStarted.rst | ||
GettingStartedVS.rst | ||
GoldPlugin.rst | ||
HowToAddABuilder.rst | ||
HowToBuildOnARM.rst | ||
HowToCrossCompileLLVM.rst | ||
HowToReleaseLLVM.rst | ||
HowToSetUpLLVMStyleRTTI.rst | ||
HowToSubmitABug.rst | ||
HowToUseAttributes.rst | ||
HowToUseInstrMappings.rst | ||
InAlloca.rst | ||
index.rst | ||
LangRef.rst | ||
Lexicon.rst | ||
LinkTimeOptimization.rst | ||
linpack-pc.png | ||
LLVMBuild.rst | ||
LLVMBuild.txt | ||
make.bat | ||
Makefile | ||
Makefile.sphinx | ||
MakefileGuide.rst | ||
MarkedUpDisassembly.rst | ||
MCJIT-creation.png | ||
MCJIT-dyld-load.png | ||
MCJIT-engine-builder.png | ||
MCJIT-load-object.png | ||
MCJIT-load.png | ||
MCJIT-resolve-relocations.png | ||
MCJITDesignAndImplementation.rst | ||
NVPTXUsage.rst | ||
Packaging.rst | ||
Passes.rst | ||
Phabricator.rst | ||
ProgrammersManual.rst | ||
Projects.rst | ||
re_format.7 | ||
README.txt | ||
ReleaseNotes.rst | ||
ReleaseProcess.rst | ||
SegmentedStacks.rst | ||
SourceLevelDebugging.rst | ||
SphinxQuickstartTemplate.rst | ||
StackMaps.rst | ||
SystemLibrary.rst | ||
TableGenFundamentals.rst | ||
TestingGuide.rst | ||
TestSuiteMakefileGuide.rst | ||
Vectorizers.rst | ||
WritingAnLLVMBackend.rst | ||
WritingAnLLVMPass.rst | ||
yaml2obj.rst | ||
YamlIO.rst |
LLVM Documentation ================== LLVM's documentation is written in reStructuredText, a lightweight plaintext markup language (file extension `.rst`). While the reStructuredText documentation should be quite readable in source form, it is mostly meant to be processed by the Sphinx documentation generation system to create HTML pages which are hosted on <http://llvm.org/docs/> and updated after every commit. Manpage output is also supported, see below. If you instead would like to generate and view the HTML locally, install Sphinx <http://sphinx-doc.org/> and then do: cd docs/ make -f Makefile.sphinx $BROWSER _build/html/index.html The mapping between reStructuredText files and generated documentation is `docs/Foo.rst` <-> `_build/html/Foo.html` <-> `http://llvm.org/docs/Foo.html`. If you are interested in writing new documentation, you will want to read `SphinxQuickstartTemplate.rst` which will get you writing documentation very fast and includes examples of the most important reStructuredText markup syntax. Manpage Output =============== Building the manpages is similar to building the HTML documentation. The primary difference is to use the `man` makefile target, instead of the default (which is `html`). Sphinx then produces the man pages in the directory `_build/man/`. cd docs/ make -f Makefile.sphinx man man -l _build/man/FileCheck.1 The correspondence between .rst files and man pages is `docs/CommandGuide/Foo.rst` <-> `_build/man/Foo.1`. These .rst files are also included during HTML generation so they are also viewable online (as noted above) at e.g. `http://llvm.org/docs/CommandGuide/Foo.html`. Checking links ============== The reachibility of external links in the documentation can be checked by running: cd docs/ make -f Makefile.sphinx linkcheck