llvm/docs
Peter Collingbourne f159a1182e hwasan: Add a tag_offset DWARF attribute to instrumented stack variables.
The goal is to improve hwasan's error reporting for stack use-after-return by
recording enough information to allow the specific variable that was accessed
to be identified based on the pointer's tag. Currently we record the PC and
lower bits of SP for each stack frame we create (which will eventually be
enough to derive the base tag used by the stack frame) but that's not enough
to determine the specific tag for each variable, which is the stack frame's
base tag XOR a value (the "tag offset") that is unique for each variable in
a function.

In IR, the tag offset is most naturally represented as part of a location
expression on the llvm.dbg.declare instruction. However, the presence of the
tag offset in the variable's actual location expression is likely to confuse
debuggers which won't know about tag offsets, and moreover the tag offset
is not required for a debugger to determine the location of the variable on
the stack, so at the DWARF level it is represented as an attribute so that
it will be ignored by debuggers that don't know about it.

Differential Revision: https://reviews.llvm.org/D63119

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@363635 91177308-0d34-0410-b5e6-96231b3b80d8
2019-06-17 23:39:41 +00:00
..
_ocamldoc
_static Fix some typos in the doc 2016-08-28 20:29:18 +00:00
_templates
_themes/llvm-theme
AMDGPU [AMDGPU][MC][DOC] Updated AMD GPU assembler description. 2018-12-28 11:48:23 +00:00
CommandGuide [docs][llvm-dwarfdump] Make the --show-parents and --show-children help text and docs more consistent and correct 2019-06-14 13:00:09 +00:00
Frontend
HistoricalNotes
PDB Try to unbreak sphinx bot after r359714 2019-05-01 20:00:45 +00:00
Proposals [Documentation] Proposal to change variable names 2019-03-28 14:42:21 +00:00
TableGen [docs] Fix TableGen/LangRef typos 2019-06-13 18:42:30 +00:00
tutorial Fix missing arguments in tutorial 2019-04-12 08:23:28 +00:00
AddingConstrainedIntrinsics.rst Fix sphinx documentation warning. 2019-04-11 17:30:03 +00:00
AdvancedBuilds.rst Use backquotes to avoid a sphinx unexpected error: 2018-12-16 14:19:39 +00:00
AliasAnalysis.rst [doc] Removed obsolete -count-aa from AliasAnalysis documentation 2018-04-23 13:45:28 +00:00
AMDGPUInstructionNotation.rst [AMDGPU][MC][DOC] Updated AMD GPU assembler description. 2018-12-28 11:48:23 +00:00
AMDGPUInstructionSyntax.rst [AMDGPU][MC][DOC] A fix for build failure in r349370 2018-12-17 18:53:10 +00:00
AMDGPUModifierSyntax.rst [AMDGPU][MC][DOC] Updated AMD GPU assembler description. 2018-12-28 11:48:23 +00:00
AMDGPUOperandSyntax.rst [AMDGPU][MC][GFX8+][DISASSEMBLER] Corrected 1/2pi value for 64-bit operands 2019-01-18 15:17:17 +00:00
AMDGPUUsage.rst [AMDGPU] gfx10 documentation update. NFC. 2019-06-13 22:18:47 +00:00
ARM-BE-bitcastfail.png
ARM-BE-bitcastsuccess.png
ARM-BE-ld1.png
ARM-BE-ldr.png
Atomics.rst [docs][AtomicExpandPass] Document the alternate lowering strategy for part-word atomicrmw/cmpxchg 2018-11-30 09:23:24 +00:00
Benchmarking.rst Add some tips on benchmarking. 2017-05-24 16:39:12 +00:00
BigEndianNEON.rst
BitCodeFormat.rst Add the ShadowCallStack attribute 2018-04-03 20:10:40 +00:00
BlockFrequencyTerminology.rst
BranchWeightMetadata.rst [TI removal] Remove discussion of TerminatorInst from the LLVM 2018-10-18 07:40:24 +00:00
BugLifeCycle.rst Introduce bug life cycle documentation. 2018-11-07 08:49:36 +00:00
Bugpoint.rst Rename DEBUG macro to LLVM_DEBUG. 2018-05-14 12:53:11 +00:00
BuildingADistribution.rst [docs] Add new document on building distributions 2019-05-21 16:29:31 +00:00
CFIVerify.rst [cfi-verify] Abort on unsupported targets 2018-07-16 15:26:44 +00:00
CMake.rst [Docs] Modernize references to macOS 2019-05-30 16:46:22 +00:00
CMakeLists.txt [dsymutil][doc] Improve wording in manpage and rename file. 2017-11-02 18:44:54 +00:00
CMakePrimer.rst [docs] In the CMake primer, correct the description of the ARGV/ARGN variables. 2017-08-24 05:38:39 +00:00
CodeGenerator.rst [Docs] fix formatting for bullet list; NFC 2019-05-22 00:48:47 +00:00
CodeOfConduct.rst
CodingStandards.rst Update the coding standards with the new file header. 2019-01-19 11:53:58 +00:00
CommandLine.rst [docs] Put DefaultOption bullet in alphabetical order. 2019-04-26 15:22:21 +00:00
CompileCudaWithLLVM.rst Adjust documentation for git migration. 2019-01-29 16:37:27 +00:00
CompilerWriterInfo.rst [Docs] Modernize references to macOS 2019-05-30 16:46:22 +00:00
conf.py [docs] Add support for Markdown documentation when creating man pages 2019-05-03 05:11:48 +00:00
Contributing.rst [Docs] Add LLVM for Grad Students to Contributing page. 2018-03-02 14:35:02 +00:00
Coroutines.rst [coroutines] Add support for llvm.coro.noop intrinsics 2018-04-02 16:55:12 +00:00
CoverageMappingFormat.rst [Coverage] Use gap regions to select better line exec counts 2017-09-18 23:37:28 +00:00
DebuggingJITedCode.rst [Docs] Modernize references to macOS 2019-05-30 16:46:22 +00:00
DeveloperPolicy.rst DeveloperPolicy: update toolchain with sample RFC / patch 2019-01-31 23:18:11 +00:00
Docker.rst [build] Rename clang-headers to clang-resource-headers 2019-03-04 21:19:53 +00:00
doxygen-mainpage.dox
doxygen.cfg.in [Docs] Increase Doxygen cache size 2019-05-22 00:56:42 +00:00
ExceptionHandling.rst [NFC] fix trivial typos in documents and comments 2018-04-12 05:53:20 +00:00
ExtendedIntegerResults.txt
ExtendingLLVM.rst Note ImmArg in documentation for adding intrinsics 2019-03-14 13:46:17 +00:00
Extensions.rst Add IR support, ELF section and user documentation for partitioning feature. 2019-05-29 03:29:01 +00:00
FAQ.rst fix some typos in the doc 2016-07-28 09:28:58 +00:00
FaultMaps.rst Fix the docs build 2017-02-07 20:36:03 +00:00
FuzzingLLVM.rst [docs] Try to clarify the FuzzingLLVM docs 2018-08-16 21:55:09 +00:00
GarbageCollection.rst [GC docs] Update the gcroot documentation to reflect recent simplifcations to GCStrategy configurability 2018-11-12 20:30:50 +00:00
gcc-loops.png
GetElementPtr.rst [DOC] Fix load instructions' syntax, function definition. 2019-06-12 11:24:22 +00:00
GettingStarted.rst [docs] Add 'git llvm revert' to getting started guide 2019-06-10 17:00:49 +00:00
GettingStartedVS.rst [MC] Fix regression tests on Windows when git “core.autocrlf” is set to true. 2017-11-17 21:59:43 +00:00
GlobalISel.rst [globalisel] Update the legalizer documentation 2019-05-01 16:52:29 +00:00
GoldPlugin.rst [docs][gold] Fix a typo 2018-08-21 21:00:54 +00:00
HowToAddABuilder.rst Added more info on silent master to the doc. 2017-07-05 20:45:44 +00:00
HowToBuildOnARM.rst
HowToBuildWithPGO.rst HowToBuildWithPGO.rst: Fix a few details in the manual steps 2018-12-05 08:35:30 +00:00
HowToCrossCompileBuiltinsOnArm.rst [docs] Improve HowToCrossCompilerBuiltinsOnArm 2018-12-18 12:40:19 +00:00
HowToCrossCompileLLVM.rst
HowToReleaseLLVM.rst docs: Fix formatting in HowToReleaseLLVM 2017-09-19 03:27:26 +00:00
HowToSetUpLLVMStyleRTTI.rst
HowToSubmitABug.rst [docs] Prevent O0 optnone for opt input 2019-01-29 22:17:51 +00:00
HowToUseAttributes.rst Fix RST docs AttributeList heading underline 2017-03-21 17:05:00 +00:00
HowToUseInstrMappings.rst [docs] Fixing Sphinx warnings to unclog the buildbot 2016-07-20 12:16:38 +00:00
InAlloca.rst [docs] Fixing Sphinx warnings to unclog the buildbot 2016-07-20 12:16:38 +00:00
index.rst [docs] Add new document on building distributions 2019-05-21 16:29:31 +00:00
LangRef.rst hwasan: Add a tag_offset DWARF attribute to instrumented stack variables. 2019-06-17 23:39:41 +00:00
Lexicon.rst Update the coding standards and developer policy documentation surrounding whitespace. 2018-08-10 17:26:07 +00:00
LibFuzzer.rst [libFuzzer] document -len_control 2019-03-18 22:20:47 +00:00
LinkTimeOptimization.rst [docs] Typos and whitespace fixed in LTO docs. 2016-11-29 18:00:31 +00:00
linpack-pc.png
llvm-objdump.1 Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
LLVMBuild.rst Fix LLVMBuild.txt typo. NFC 2017-04-03 18:21:50 +00:00
LLVMBuild.txt Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
make.bat
Makefile.sphinx
MarkdownQuickstartTemplate.md [docs] Reinstate r337730 - Add support for Markdown documentation in 2018-08-06 00:38:31 +00:00
MarkedUpDisassembly.rst [docs] Fixing Sphinx warnings to unclog the buildbot 2016-07-20 12:16:38 +00:00
MCJIT-creation.png
MCJIT-dyld-load.png
MCJIT-engine-builder.png
MCJIT-load-object.png
MCJIT-load.png
MCJIT-resolve-relocations.png
MCJITDesignAndImplementation.rst
MeetupGuidelines.rst Add guidelines/recommendations for organizers of LLVM Socials 2019-05-14 07:20:58 +00:00
MemorySSA.rst [NFC] fix trivial typos in comments and documents 2018-01-26 08:15:29 +00:00
MergeFunctions.rst Updating MergeFunctions.rst 2018-08-18 20:17:19 +00:00
MIRLangRef.rst MIR: Add method to stop after specific runs of passes 2018-12-04 17:45:12 +00:00
NVPTXUsage.rst [CodeGen] Unify MBB reference format in both MIR and debug output 2017-12-04 17:18:51 +00:00
OptBisect.rst [Docs] Remove hard tab character from code block in optbisect documentation 2018-07-27 06:54:13 +00:00
ORCv2DesignAndImplementation.rst Fix sphinx warning about missing footnote. 2019-05-30 09:40:35 +00:00
Packaging.rst
Passes.rst [Unroll/UnrollAndJam/Vectorizer/Distribute] Add followup loop attributes. 2018-12-12 17:32:52 +00:00
Phabricator.rst Update GettingStarted guide to recommend that people use the new 2019-01-14 22:27:32 +00:00
ProgrammersManual.rst [Docs] Modernize references to macOS 2019-05-30 16:46:22 +00:00
Projects.rst
re_format.7
README.txt [NFC] Test commit, whitespace change 2019-06-06 22:07:14 +00:00
ReleaseNotes.rst Reapply: IR: add optional type to 'byval' function parameters 2019-05-30 18:48:23 +00:00
ReleaseProcess.rst [docs] Make ReleaseProcess.rst 80 column. NFCI 2018-01-18 14:57:55 +00:00
ReportingGuide.rst
ScudoHardenedAllocator.rst [docs] Scudo: document error messages & their potential cause 2019-01-22 16:43:45 +00:00
SegmentedStacks.rst [docs] Fixing Sphinx warnings to unclog the buildbot 2016-07-20 12:16:38 +00:00
SourceLevelDebugging.rst [llvm-readobj] Change -long-option to --long-option in tests. NFC 2019-05-01 05:27:20 +00:00
speculative_load_hardening_microbenchmarks.png [x86/SLH] Add the design document for Speculative Load Hardening, 2018-07-18 14:05:14 +00:00
SpeculativeLoadHardening.md [docs] Fix a couple spelling errors. 2019-01-28 23:03:41 +00:00
SphinxQuickstartTemplate.rst
StackMaps.rst [docs] Clarify ELF section naming for StackMaps and fix a typo 2018-11-08 17:20:35 +00:00
StackSafetyAnalysis.rst Remove trailing empty line 2018-11-26 23:17:52 +00:00
Statepoints.rst [docs][statepoints] Reformulate open issues list 2018-11-09 17:09:16 +00:00
SupportLibrary.rst [Docs] [Support] Correct a missed reference and use up to date .inc examples. 2018-09-21 01:53:51 +00:00
SystemLibrary.rst [Docs] [Support] System Library to Support Library transition along with minor corrections to reflect it. 2018-09-18 18:05:38 +00:00
TableGenFundamentals.rst
TestingGuide.rst [Docs] Modernize references to macOS 2019-05-30 16:46:22 +00:00
TestSuiteGuide.md Adjust documentation for git migration. 2019-01-29 16:37:27 +00:00
TestSuiteMakefileGuide.rst Adjust documentation for git migration. 2019-01-29 16:37:27 +00:00
TransformMetadata.rst [Unroll/UnrollAndJam/Vectorizer/Distribute] Add followup loop attributes. 2018-12-12 17:32:52 +00:00
TypeMetadata.rst Update GettingStarted guide to recommend that people use the new 2019-01-14 22:27:32 +00:00
Vectorizers.rst Update GettingStarted guide to recommend that people use the new 2019-01-14 22:27:32 +00:00
WritingAnLLVMBackend.rst [Docs] Fix typo in scheduler model documentation. enumemation->enumeration 2017-12-10 09:14:35 +00:00
WritingAnLLVMPass.rst [Docs] Modernize references to macOS 2019-05-30 16:46:22 +00:00
XRay.rst [Docs] Update of Xray page 2018-07-26 04:44:31 +00:00
XRayExample.rst [XRay][docs] Fix option name 2019-03-12 13:44:42 +00:00
XRayFDRFormat.rst Tidy some language in the xray documentation. 2018-05-27 09:19:03 +00:00
yaml2obj.rst
YamlIO.rst [Docs] Fix LLVM_YAML_IS_DOCUMENT_LIST_VECTOR 2018-07-23 14:17:43 +00:00

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