mirror of
https://github.com/RPCS3/llvm-mirror.git
synced 2024-11-25 20:23:11 +01:00
e5fbe2c41d
Summary:
In LLVM, 't' selects a floating-point/SIMD register and only supports
32-bit values. This is appropriately documented in the LLVM Language
Reference Manual. However, this behaviour diverges from that of GCC, where
't' selects the s0-s31 registers and its qX and dX variants depending on
additional operand modifiers (q/P).
For example, the following C code:
#include <arm_neon.h>
float32x4_t a, b, x;
asm("vadd.f32 %0, %1, %2" : "=t" (x) : "t" (a), "t" (b))
results in the following assembly if compiled with GCC:
vadd.f32 s0, s0, s1
whereas LLVM will show "error: couldn't allocate output register for
constraint 't'", since a, b, x are 128-bit variables, not 32-bit.
This patch extends the use of 't' to mean that of GCC, thus allowing
selection of the lower Q vector regs and their D/S variants. For example,
the earlier code will now compile as:
vadd.f32 q0, q0, q1
This behaviour still differs from that of GCC but I think it is actually
more correct, since LLVM picks up the right register type based on the
datatype of x, while GCC would need an extra operand modifier to achieve
the same result, as follows:
asm("vadd.f32 %q0, %q1, %q2" : "=t" (x) : "t" (a), "t" (b))
Since this is only an extension of functionality, existing code should not
be affected by this change. Note that operand modifiers q/P are already
supported by LLVM, so this patch should suffice to support inline
assembly with constraint 't' originally built for GCC.
Reviewers: grosbach, rengolin
Reviewed By: rengolin
Subscribers: rogfer01, efriedma, olista01, aemerson, javed.absar, eraman, kristof.beyls, llvm-commits
Differential Revision: https://reviews.llvm.org/D42962
llvm-svn: 325244
|
||
|---|---|---|
| .. | ||
| _ocamldoc | ||
| _static | ||
| _templates | ||
| _themes/llvm-theme | ||
| CommandGuide | ||
| Frontend | ||
| HistoricalNotes | ||
| PDB | ||
| Proposals | ||
| TableGen | ||
| tutorial | ||
| AdvancedBuilds.rst | ||
| AliasAnalysis.rst | ||
| AMDGPUUsage.rst | ||
| ARM-BE-bitcastfail.png | ||
| ARM-BE-bitcastsuccess.png | ||
| ARM-BE-ld1.png | ||
| ARM-BE-ldr.png | ||
| Atomics.rst | ||
| Benchmarking.rst | ||
| BigEndianNEON.rst | ||
| BitCodeFormat.rst | ||
| BlockFrequencyTerminology.rst | ||
| BranchWeightMetadata.rst | ||
| Bugpoint.rst | ||
| CFIVerify.rst | ||
| CMake.rst | ||
| CMakeLists.txt | ||
| CMakePrimer.rst | ||
| CodeGenerator.rst | ||
| CodeOfConduct.rst | ||
| CodingStandards.rst | ||
| CommandLine.rst | ||
| CompileCudaWithLLVM.rst | ||
| CompilerWriterInfo.rst | ||
| conf.py | ||
| Contributing.rst | ||
| Coroutines.rst | ||
| CoverageMappingFormat.rst | ||
| DebuggingJITedCode.rst | ||
| DeveloperPolicy.rst | ||
| Docker.rst | ||
| doxygen-mainpage.dox | ||
| doxygen.cfg.in | ||
| ExceptionHandling.rst | ||
| ExtendedIntegerResults.txt | ||
| ExtendingLLVM.rst | ||
| Extensions.rst | ||
| FAQ.rst | ||
| FaultMaps.rst | ||
| FuzzingLLVM.rst | ||
| GarbageCollection.rst | ||
| gcc-loops.png | ||
| GetElementPtr.rst | ||
| GettingStarted.rst | ||
| GettingStartedVS.rst | ||
| GlobalISel.rst | ||
| GoldPlugin.rst | ||
| HowToAddABuilder.rst | ||
| HowToBuildOnARM.rst | ||
| HowToCrossCompileBuiltinsOnArm.rst | ||
| HowToCrossCompileLLVM.rst | ||
| HowToReleaseLLVM.rst | ||
| HowToSetUpLLVMStyleRTTI.rst | ||
| HowToSubmitABug.rst | ||
| HowToUseAttributes.rst | ||
| HowToUseInstrMappings.rst | ||
| InAlloca.rst | ||
| index.rst | ||
| LangRef.rst | ||
| Lexicon.rst | ||
| LibFuzzer.rst | ||
| LinkTimeOptimization.rst | ||
| linpack-pc.png | ||
| LLVMBuild.rst | ||
| LLVMBuild.txt | ||
| make.bat | ||
| Makefile.sphinx | ||
| 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 | ||
| MemorySSA.rst | ||
| MergeFunctions.rst | ||
| MIRLangRef.rst | ||
| NVPTXUsage.rst | ||
| OptBisect.rst | ||
| Packaging.rst | ||
| Passes.rst | ||
| Phabricator.rst | ||
| ProgrammersManual.rst | ||
| Projects.rst | ||
| re_format.7 | ||
| README.txt | ||
| ReleaseNotes.rst | ||
| ReleaseProcess.rst | ||
| ReportingGuide.rst | ||
| ScudoHardenedAllocator.rst | ||
| SegmentedStacks.rst | ||
| SourceLevelDebugging.rst | ||
| SphinxQuickstartTemplate.rst | ||
| StackMaps.rst | ||
| Statepoints.rst | ||
| SystemLibrary.rst | ||
| TableGenFundamentals.rst | ||
| TestingGuide.rst | ||
| TestSuiteMakefileGuide.rst | ||
| TypeMetadata.rst | ||
| Vectorizers.rst | ||
| WritingAnLLVMBackend.rst | ||
| WritingAnLLVMPass.rst | ||
| XRay.rst | ||
| XRayExample.rst | ||
| XRayFDRFormat.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 <build-dir>
cmake -DLLVM_ENABLE_SPHINX=true -DSPHINX_OUTPUT_HTML=true <src-dir>
make -j3 docs-llvm-html
$BROWSER <build-dir>/docs//html/index.html
The mapping between reStructuredText files and generated documentation is
`docs/Foo.rst` <-> `<build-dir>/docs//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-dir>/docs/man/`.
cd <build-dir>
cmake -DLLVM_ENABLE_SPHINX=true -DSPHINX_OUTPUT_MAN=true <src-dir>
make -j3 docs-llvm-man
man -l >build-dir>/docs/man/FileCheck.1
The correspondence between .rst files and man pages is
`docs/CommandGuide/Foo.rst` <-> `<build-dir>/docs//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 reachability of external links in the documentation can be checked by
running:
cd docs/
make -f Makefile.sphinx linkcheck
Doxygen page Output
==============
Install doxygen <http://www.stack.nl/~dimitri/doxygen/download.html> and dot2tex <https://dot2tex.readthedocs.io/en/latest>.
cd <build-dir>
cmake -DLLVM_ENABLE_DOXYGEN=On <llvm-top-src-dir>
make doxygen-llvm # for LLVM docs
make doxygen-clang # for clang docs
It will generate html in
<build-dir>/docs/doxygen/html # for LLVM docs
<build-dir>/tools/clang/docs/doxygen/html # for clang docs