hanchenye-llvm-project/llvm/docs
Michael J. Spencer 1f10c5ea94 [IR] Make {extract,insert}element accept an index of any integer type.
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
2014-05-01 22:12:39 +00:00
..
CommandGuide [docs] Fix some links 2014-04-07 22:46:40 +00:00
HistoricalNotes
TableGen [docs] VCS contains a record of authorship 2014-04-08 21:12:56 +00:00
_static
_templates
_themes/llvm-theme
tutorial [docs] Clean up some more llvm-gcc stuff 2014-02-19 00:12:34 +00:00
AliasAnalysis.rst [docs] Fix up some links to the preferred style. 2014-04-08 21:06:22 +00:00
Atomics.rst
BitCodeFormat.rst Remove the linker_private and linker_private_weak linkages. 2014-03-13 23:18:37 +00:00
BlockFrequencyTerminology.rst blockfreq: Document BlockFrequencyInfo terminology 2014-04-11 23:21:07 +00:00
BranchWeightMetadata.rst blockfreq: Document BlockFrequencyInfo terminology 2014-04-11 23:21:07 +00:00
Bugpoint.rst [docs] Fix up some links to the preferred style. 2014-04-08 21:06:22 +00:00
CMake.rst Document recently added sphinx documentation options in 2014-04-29 16:13:27 +00:00
CMakeLists.txt Added Sphinx documentation generation to CMake build system. 2014-04-18 21:45:25 +00:00
CodeGenerator.rst [docs] Fix up some links to the preferred style. 2014-04-08 21:06:22 +00:00
CodingStandards.rst C++11: Compatibility with (C++03 => MSVC) 2014-04-17 18:02:36 +00:00
CommandLine.rst Correct word hyphenations 2013-12-05 05:44:44 +00:00
CompilerWriterInfo.rst Fix some doc and comment typos 2014-04-09 14:47:27 +00:00
DebuggingJITedCode.rst
DeveloperPolicy.rst [docs] Clean up some more llvm-gcc stuff 2014-02-19 00:12:34 +00:00
Dummy.html
ExceptionHandling.rst Exception handling docs: Clarify how the llvm.eh.* intrinsics are used 2014-03-28 17:08:57 +00:00
ExtendedIntegerResults.txt
ExtendingLLVM.rst
Extensions.rst ARM: support stack probe emission for Windows on ARM 2014-04-30 07:05:07 +00:00
FAQ.rst remove an old entry whose link is broken anyway 2014-03-02 06:37:03 +00:00
GarbageCollection.rst Remove projects/sample. 2014-03-12 22:40:22 +00:00
GetElementPtr.rst [docs] Clean up some more llvm-gcc stuff 2014-02-19 00:12:34 +00:00
GettingStarted.rst Remove projects/sample. 2014-03-12 22:40:22 +00:00
GettingStartedVS.rst [docs] Fix up some links to the preferred style. 2014-04-08 21:06:22 +00:00
GoldPlugin.rst Update the LTO GoldPlugin documentation 2013-12-02 07:15:33 +00:00
HowToAddABuilder.rst
HowToBuildOnARM.rst Adding some info about stability of ARM boards 2013-11-15 08:42:14 +00:00
HowToCrossCompileLLVM.rst
HowToReleaseLLVM.rst [docs] Fix some Sphinx warnings. 2014-03-02 00:21:42 +00:00
HowToSetUpLLVMStyleRTTI.rst [C++11] Replace LLVM-style type traits with C++11 standard ones. 2014-03-07 14:42:25 +00:00
HowToSubmitABug.rst [docs] Nuke some references to llvm-gcc 2014-02-18 23:56:43 +00:00
HowToUseAttributes.rst
HowToUseInstrMappings.rst
InAlloca.rst inalloca: *Really* fix the docs 2014-03-27 01:38:48 +00:00
LLVMBuild.rst [docs] Fix some links 2014-04-07 22:46:40 +00:00
LLVMBuild.txt
LangRef.rst [IR] Make {extract,insert}element accept an index of any integer type. 2014-05-01 22:12:39 +00:00
Lexicon.rst
LinkTimeOptimization.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
Makefile
Makefile.sphinx
MakefileGuide.rst Remove projects/sample. 2014-03-12 22:40:22 +00:00
MarkedUpDisassembly.rst
NVPTXUsage.rst Fix documentation typos 2013-12-20 00:33:39 +00:00
Packaging.rst
Passes.rst Remove -simplify-libcalls pass form Passes documentation 2014-04-18 21:19:06 +00:00
Phabricator.rst Make docs point to new domain. 2014-04-07 10:21:33 +00:00
ProgrammersManual.rst Update post-r203364 http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20140303/207915.html 2014-05-01 12:33:26 +00:00
Projects.rst Remove projects/sample. 2014-03-12 22:40:22 +00:00
README.txt [docs] Add a note to docs/README.txt 2014-04-22 21:47:53 +00:00
ReleaseNotes.rst Update release notes with EHABI current behaviour 2014-03-24 11:02:38 +00:00
ReleaseProcess.rst
SegmentedStacks.rst Move the segmented stack switch to a function attribute 2014-04-10 22:58:43 +00:00
SourceLevelDebugging.rst Switch the type field in DIVariable and DIGlobalVariable over to DITypeRefs. 2014-03-18 02:34:58 +00:00
SphinxQuickstartTemplate.rst
StackMaps.rst Stack map docs. Remove some stray markup. 2014-04-03 07:08:21 +00:00
SystemLibrary.rst
TableGenFundamentals.rst Recover TableGen/LangRef, make it official 2014-04-01 09:51:49 +00:00
TestSuiteMakefileGuide.rst
TestingGuide.rst Cleanup docs about lit substitutions 2014-02-15 08:35:56 +00:00
Vectorizers.rst Fix whitespace in vectorizer example 2014-03-12 23:58:07 +00:00
WritingAnLLVMBackend.rst [docs] Fix some links 2014-04-07 22:46:40 +00:00
WritingAnLLVMPass.rst fix RST reference in Writing an LLVM Pass 2013-10-30 17:09:32 +00:00
YamlIO.rst YAMLIO: Allow scalars to dictate quotation rules 2014-04-10 07:37:33 +00:00
conf.py Update the copyright credits -- Happy new year 2014! 2014-01-01 08:27:31 +00:00
doxygen.cfg.in [docs] Teach CMake docs build how to generate Qt Creator help/documentation files. 2014-03-07 19:19:28 +00:00
doxygen.css
doxygen.footer Update the copyright credits -- Happy new year 2014! 2014-01-01 08:27:31 +00:00
doxygen.header
doxygen.intro
gcc-loops.png
index.rst blockfreq: Document BlockFrequencyInfo terminology 2014-04-11 23:21:07 +00:00
linpack-pc.png
make.bat
re_format.7
yaml2obj.rst Object: rename ARMV7 to ARMNT 2014-03-11 03:08:37 +00:00

README.txt

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