# Reference

LLVM and API reference documentation.

```{contents}
:local:
```

```{toctree}
:hidden:

HowToUseAttributes
CommandGuide/index
CommandGuide/llvm-reduce
OptBisect
SymbolizerMarkupFormat
PDB/index
GarbageCollection
Statepoints
LibFuzzer
FuzzingLLVM
LangRef
UndefinedBehavior
InAlloca
BitCodeFormat
MIRLangRef
GlobalISel/index
ConvergentOperations
TestingGuide
TestSuiteGuide
GwpAsan
XRay
XRayExample
FaultMaps
Atomics
ExceptionHandling
Extensions
HowToSetUpLLVMStyleRTTI
BlockFrequencyTerminology
BranchWeightMetadata
GetElementPtr
ScudoHardenedAllocator
MemoryModelRelaxationAnnotations
MemTagSanitizer
DependenceGraphs/index
SpeculativeLoadHardening
SegmentedStacks
MarkedUpDisassembly
StackMaps
Coroutines
PointerAuth
YamlIO
ConvergenceAndUniformity
MLGO
ContentAddressableStorage
CIBestPractices
AIToolPolicy
CalleeTypeMetadata
CallGraphSection
InterfaceExportAnnotations
PCSectionsMetadata
QualGroup
Security
SecurityTransparencyReports
SystemLibrary
TransformMetadata
TypeMetadata
XRayFDRFormat
```

## API Reference

[Doxygen generated documentation](https://llvm.org/doxygen/)
:   ([classes](https://llvm.org/doxygen/inherits.html))

{doc}`HowToUseAttributes`
:   Answers some questions about the new Attributes infrastructure.

## LLVM Reference

### Command Line Utilities

{doc}`LLVM Command Guide <CommandGuide/index>`
:   A reference manual for the LLVM command line utilities ("man" pages for LLVM
    tools).

{doc}`llvm-reduce <CommandGuide/llvm-reduce>`
:   Automatic bug finder and test-case reducer description and usage
    information.

{doc}`OptBisect`
:   A command line option for debugging optimization-induced failures.

{doc}`SymbolizerMarkupFormat`
:   A reference for the log symbolizer markup accepted by `llvm-symbolizer`.

{doc}`The Microsoft PDB File Format <PDB/index>`
:   A detailed description of the Microsoft PDB (Program Database) file format.

### Garbage Collection

{doc}`GarbageCollection`
:   The interfaces source-language compilers should use for compiling GC'd
    programs.

{doc}`Statepoints`
:   This describes a set of experimental extensions for garbage
    collection support.

### LibFuzzer

{doc}`LibFuzzer`
:   A library for writing in-process guided fuzzers.

{doc}`FuzzingLLVM`
:   Information on writing and using Fuzzers to find bugs in LLVM.

### LLVM IR

{doc}`LLVM Language Reference Manual <LangRef>`
:   Defines the LLVM intermediate representation and the assembly form of the
    different nodes.

{doc}`Undefined Behavior (UB) <UndefinedBehavior>`
:   A guide on what UB/undef/poison are and when to use each one.

{doc}`InAlloca`
:   Description of the `inalloca` argument attribute.

{doc}`BitCodeFormat`
:   This describes the file format and encoding used for LLVM "bc" files.

{doc}`Machine IR (MIR) Format Reference Manual <MIRLangRef>`
:   A reference manual for the MIR serialization format, which is used to test
    LLVM's code generation passes.

{doc}`GlobalISel/index`
:   This describes the prototype instruction selection replacement, GlobalISel.

{doc}`ConvergentOperations`
:   Description of `convergent` operation semantics and related intrinsics.

### Testing and Debugging

{doc}`LLVM Testing Infrastructure Guide <TestingGuide>`
:   A reference manual for using the LLVM testing infrastructure.

{doc}`TestSuiteGuide`
:   Describes how to compile and run the test-suite benchmarks.


{doc}`GwpAsan`
:   A sampled heap memory error detection toolkit designed for production use.

### XRay

{doc}`XRay`
:   High-level documentation of how to use XRay in LLVM.

{doc}`XRayExample`
:   An example of how to debug an application with XRay.

### Additional Topics

{doc}`FaultMaps`
:   LLVM support for folding control flow into faulting machine instructions.

{doc}`Atomics`
:   Information about LLVM's concurrency model.

{doc}`ExceptionHandling`
:   This document describes the design and implementation of exception handling
    in LLVM.

{doc}`Extensions`
:   LLVM-specific extensions to tools and formats LLVM seeks compatibility with.

{doc}`HowToSetUpLLVMStyleRTTI`
:   How to make `isa<>`, `dyn_cast<>`, etc. available for clients of your
    class hierarchy.

{doc}`BlockFrequencyTerminology`
:   Provides information about terminology used in the `BlockFrequencyInfo`
    analysis pass.

{doc}`BranchWeightMetadata`
:   Provides information about Branch Prediction Information.

{doc}`GetElementPtr`
:   Answers to some very frequent questions about LLVM's most frequently
    misunderstood instruction.

{doc}`ScudoHardenedAllocator`
:   A library that implements a security-hardened `malloc()`.

{doc}`MemoryModelRelaxationAnnotations`
:   Target-defined relaxation to LLVM's concurrency model.

{doc}`MemTagSanitizer`
:   Security hardening for production code aiming to mitigate memory
    related vulnerabilities. Based on the Armv8.5-A Memory Tagging Extension.

{doc}`Dependence Graphs <DependenceGraphs/index>`
:   A description of the design of the various dependence graphs such as
    the DDG (Data Dependence Graph).

{doc}`SpeculativeLoadHardening`
:   A description of the Speculative Load Hardening mitigation for Spectre v1.

{doc}`SegmentedStacks`
:   This document describes segmented stacks and how they are used in LLVM.

{doc}`MarkedUpDisassembly`
:   This document describes the optional rich disassembly output syntax.

{doc}`StackMaps`
:   LLVM support for mapping instruction addresses to the location of
    values and allowing code to be patched.

{doc}`Coroutines`
:   LLVM support for coroutines.

{doc}`PointerAuth`
:   A description of pointer authentication, its LLVM IR representation, and its
    support in the backend.

{doc}`YamlIO`
:   A reference guide for using LLVM's YAML I/O library.

{doc}`ConvergenceAndUniformity`
:   A description of uniformity analysis in the presence of irreducible
    control flow, and its implementation.

{doc}`MLGO`
:   Facilities for ML-Guided Optimization, such as collecting IR corpora from a
    build, interfacing with ML models, an exposing features for training.

{doc}`ContentAddressableStorage`
:   A reference guide for using LLVM's CAS library.

{doc}`CIBestPractices`
:   A list of guidelines and best practices to use when working on LLVM's
    CI systems.