forked from OSchip/llvm-project
a89d751fb4
This patch adds support for the fptoui.sat and fptosi.sat intrinsics, which provide basically the same functionality as the existing fptoui and fptosi instructions, but will saturate (or return 0 for NaN) on values unrepresentable in the target type, instead of returning poison. Related mailing list discussion can be found at: https://groups.google.com/d/msg/llvm-dev/cgDFaBmCnDQ/CZAIMj4IBAAJ The intrinsics have overloaded source and result type and support vector operands: i32 @llvm.fptoui.sat.i32.f32(float %f) i100 @llvm.fptoui.sat.i100.f64(double %f) <4 x i32> @llvm.fptoui.sat.v4i32.v4f16(half %f) // etc On the SelectionDAG layer two new ISD opcodes are added, FP_TO_UINT_SAT and FP_TO_SINT_SAT. These opcodes have two operands and one result. The second operand is an integer constant specifying the scalar saturation width. The idea here is that initially the second operand and the scalar width of the result type are the same, but they may change during type legalization. For example: i19 @llvm.fptsi.sat.i19.f32(float %f) // builds i19 fp_to_sint_sat f, 19 // type legalizes (through integer result promotion) i32 fp_to_sint_sat f, 19 I went for this approach, because saturated conversion does not compose well. There is no good way of "adjusting" a saturating conversion to i32 into one to i19 short of saturating twice. Specifying the saturation width separately allows directly saturating to the correct width. There are two baseline expansions for the fp_to_xint_sat opcodes. If the integer bounds can be exactly represented in the float type and fminnum/fmaxnum are legal, we can expand to something like: f = fmaxnum f, FP(MIN) f = fminnum f, FP(MAX) i = fptoxi f i = select f uo f, 0, i # unnecessary if unsigned as 0 = MIN If the bounds cannot be exactly represented, we expand to something like this instead: i = fptoxi f i = select f ult FP(MIN), MIN, i i = select f ogt FP(MAX), MAX, i i = select f uo f, 0, i # unnecessary if unsigned as 0 = MIN It should be noted that this expansion assumes a non-trapping fptoxi. Initial tests are for AArch64, x86_64 and ARM. This exercises all of the scalar and vector legalization. ARM is included to test float softening. Original patch by @nikic and @ebevhan (based on D54696). Differential Revision: https://reviews.llvm.org/D54749 |
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| .. | ||
| AMDGPU | ||
| CommandGuide | ||
| DependenceGraphs | ||
| Frontend | ||
| GlobalISel | ||
| HistoricalNotes | ||
| PDB | ||
| Proposals | ||
| TableGen | ||
| _ocamldoc | ||
| _static | ||
| _templates | ||
| _themes/llvm-theme | ||
| tutorial | ||
| AMDGPUDwarfExtensionsForHeterogeneousDebugging.rst | ||
| AMDGPUInstructionNotation.rst | ||
| AMDGPUInstructionSyntax.rst | ||
| AMDGPUModifierSyntax.rst | ||
| AMDGPUOperandSyntax.rst | ||
| AMDGPUUsage.rst | ||
| ARM-BE-bitcastfail.png | ||
| ARM-BE-bitcastsuccess.png | ||
| ARM-BE-ld1.png | ||
| ARM-BE-ldr.png | ||
| AddingConstrainedIntrinsics.rst | ||
| AdvancedBuilds.rst | ||
| AliasAnalysis.rst | ||
| Atomics.rst | ||
| Benchmarking.rst | ||
| BigEndianNEON.rst | ||
| BitCodeFormat.rst | ||
| BlockFrequencyTerminology.rst | ||
| BranchWeightMetadata.rst | ||
| BugLifeCycle.rst | ||
| Bugpoint.rst | ||
| BugpointRedesign.md | ||
| BuildingADistribution.rst | ||
| CFIVerify.rst | ||
| CMake.rst | ||
| CMakeLists.txt | ||
| CMakePrimer.rst | ||
| CodeGenerator.rst | ||
| CodeOfConduct.rst | ||
| CodeReview.rst | ||
| CodingStandards.rst | ||
| CommandLine.rst | ||
| CompileCudaWithLLVM.rst | ||
| CompilerWriterInfo.rst | ||
| Contributing.rst | ||
| Coroutines.rst | ||
| CoverageMappingFormat.rst | ||
| DebuggingJITedCode.rst | ||
| DeveloperPolicy.rst | ||
| Docker.rst | ||
| ExceptionHandling.rst | ||
| ExtendedIntegerResults.txt | ||
| ExtendingLLVM.rst | ||
| Extensions.rst | ||
| FAQ.rst | ||
| FaultMaps.rst | ||
| FuzzingLLVM.rst | ||
| GarbageCollection.rst | ||
| GetElementPtr.rst | ||
| GettingInvolved.rst | ||
| GettingStarted.rst | ||
| GettingStartedTutorials.rst | ||
| GettingStartedVS.rst | ||
| GitBisecting.rst | ||
| GoldPlugin.rst | ||
| GwpAsan.rst | ||
| HowToAddABuilder.rst | ||
| HowToBuildOnARM.rst | ||
| HowToBuildWithPGO.rst | ||
| HowToCrossCompileBuiltinsOnArm.rst | ||
| HowToCrossCompileLLVM.rst | ||
| HowToReleaseLLVM.rst | ||
| HowToSetUpLLVMStyleRTTI.rst | ||
| HowToSubmitABug.rst | ||
| HowToUpdateDebugInfo.rst | ||
| HowToUseAttributes.rst | ||
| HowToUseInstrMappings.rst | ||
| InAlloca.rst | ||
| LangRef.rst | ||
| Lexicon.rst | ||
| LibFuzzer.rst | ||
| LinkTimeOptimization.rst | ||
| LoopTerminology.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 | ||
| MIRLangRef.rst | ||
| Makefile.sphinx | ||
| MarkdownQuickstartTemplate.md | ||
| MarkedUpDisassembly.rst | ||
| MeetupGuidelines.rst | ||
| MemTagSanitizer.rst | ||
| MemorySSA.rst | ||
| MergeFunctions.rst | ||
| NVPTXUsage.rst | ||
| ORCv2.rst | ||
| OptBisect.rst | ||
| Packaging.rst | ||
| Passes.rst | ||
| Phabricator.rst | ||
| ProgrammersManual.rst | ||
| Projects.rst | ||
| README.txt | ||
| Reference.rst | ||
| ReleaseNotes.rst | ||
| ReleaseProcess.rst | ||
| Remarks.rst | ||
| ReportingGuide.rst | ||
| ScudoHardenedAllocator.rst | ||
| Security.rst | ||
| SegmentedStacks.rst | ||
| SourceLevelDebugging.rst | ||
| SpeculativeLoadHardening.md | ||
| SphinxQuickstartTemplate.rst | ||
| StackMaps.rst | ||
| StackSafetyAnalysis.rst | ||
| Statepoints.rst | ||
| SupportLibrary.rst | ||
| SupportPolicy.rst | ||
| SystemLibrary.rst | ||
| TableGenFundamentals.rst | ||
| TestSuiteGuide.md | ||
| TestSuiteMakefileGuide.rst | ||
| TestingGuide.rst | ||
| TransformMetadata.rst | ||
| TypeMetadata.rst | ||
| UserGuides.rst | ||
| Vectorizers.rst | ||
| WritingAnLLVMBackend.rst | ||
| WritingAnLLVMNewPMPass.rst | ||
| WritingAnLLVMPass.rst | ||
| XRay.rst | ||
| XRayExample.rst | ||
| XRayFDRFormat.rst | ||
| YamlIO.rst | ||
| conf.py | ||
| doxygen-mainpage.dox | ||
| doxygen.cfg.in | ||
| epilogue-vectorization-cfg.png | ||
| gcc-loops.png | ||
| index.rst | ||
| linpack-pc.png | ||
| llvm-objdump.1 | ||
| loop-guard.svg | ||
| loop-irreducible.svg | ||
| loop-merge.svg | ||
| loop-nested.svg | ||
| loop-nonmaximal.svg | ||
| loop-separate.svg | ||
| loop-single.svg | ||
| loop-terminology-guarded-loop.png | ||
| loop-terminology-initial-loop.png | ||
| loop-terminology-rotated-loop.png | ||
| loop-terminology.svg | ||
| make.bat | ||
| re_format.7 | ||
| speculative_load_hardening_microbenchmarks.png | ||
| yaml2obj.rst | ||
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 <https://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` <-> `https://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.
`https://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