LLVM  8.0.0svn
llvm::Use Class Reference

A Use represents the edge between a Value definition and its users. More...

#include "llvm/IR/Use.h"

## Classes

struct  PrevPointerTraits
Pointer traits for the Prev PointerIntPair. More...

struct  UserRefPointerTraits
Pointer traits for the UserRef PointerIntPair. More...

## Public Types

using UserRef = PointerIntPair< User *, 1, unsigned, UserRefPointerTraits >

## Public Member Functions

Use (const Use &U)=delete

void swap (Use &RHS)
Provide a fast substitute to std::swap<Use> that also works with less standard-compliant compilers. More...

operator Value * () const

Valueget () const

Returns the User that contains this Use. More...

void set (Value *Val)

Valueoperator= (Value *RHS)

const Useoperator= (const Use &RHS)

Valueoperator-> ()

const Valueoperator-> () const

UsegetNext () const

unsigned getOperandNo () const
Return the operand # of this use in its User. More...

## Static Public Member Functions

static UseinitTags (Use *Start, Use *Stop)
Initializes the waymarking tags on an array of Uses. More...

static void zap (Use *Start, const Use *Stop, bool del=false)
Destroys Use operands when the number of operands of a User changes. More...

class Value

## Detailed Description

A Use represents the edge between a Value definition and its users.

This is notionally a two-dimensional linked list. It supports traversing all of the uses for a particular value definition. It also supports jumping directly to the used value when we arrive from the User's operands, and jumping directly to the User when we arrive from the Value's uses.

The pointer to the used Value is explicit, and the pointer to the User is implicit. The implicit pointer is found via a waymarking algorithm described in the programmer's manual:

http://www.llvm.org/docs/ProgrammersManual.html#the-waymarking-algorithm

This is essentially the single most memory intensive object in LLVM because of the number of uses in the system. At the same time, the constant time operations it allows are essential to many optimizations having reasonable time complexity.

Definition at line 56 of file Use.h.

## ◆ UserRef

 using llvm::Use::UserRef = PointerIntPair

Definition at line 78 of file Use.h.

## ◆ Use()

 llvm::Use::Use ( const Use & U )
delete

## ◆ get()

 Value* llvm::Use::get ( ) const
inline

Definition at line 108 of file Use.h.

## ◆ getNext()

 Use* llvm::Use::getNext ( ) const
inline

Definition at line 124 of file Use.h.

References getOperandNo(), and initTags().

## ◆ getOperandNo()

 unsigned llvm::Use::getOperandNo ( ) const

Return the operand # of this use in its User.

Definition at line 48 of file Use.cpp.

References getUser(), and llvm::User::op_begin().

## ◆ getUser()

 User * llvm::Use::getUser ( ) const

Returns the User that contains this Use.

For an instruction operand, for example, this will return the instruction.

Definition at line 41 of file Use.cpp.

## ◆ initTags()

 Use * llvm::Use::initTags ( Use * Start, Use * Stop )
static

Initializes the waymarking tags on an array of Uses.

This sets up the array of Uses such that getUser() can find the User from any of those Uses.

Definition at line 57 of file Use.cpp.

Referenced by getNext().

## ◆ operator Value *()

 llvm::Use::operator Value * ( ) const
inline

Definition at line 107 of file Use.h.

## ◆ operator->() [1/2]

 Value* llvm::Use::operator-> ( )
inline

Definition at line 121 of file Use.h.

## ◆ operator->() [2/2]

 const Value* llvm::Use::operator-> ( ) const
inline

Definition at line 122 of file Use.h.

## ◆ operator=() [1/2]

 Value * llvm::Use::operator= ( Value * RHS )
inline

Definition at line 677 of file Value.h.

Referenced by get().

## ◆ operator=() [2/2]

 const Use & llvm::Use::operator= ( const Use & RHS )
inline

Definition at line 682 of file Value.h.

## ◆ set()

 void llvm::Use::set ( Value * Val )
inline

## ◆ swap()

 void llvm::Use::swap ( Use & RHS )

Provide a fast substitute to std::swap<Use> that also works with less standard-compliant compilers.

Definition at line 17 of file Use.cpp.

## ◆ zap()

 void llvm::Use::zap ( Use * Start, const Use * Stop, bool del = false )
static

Destroys Use operands when the number of operands of a User changes.

Definition at line 87 of file Use.cpp.

Referenced by llvm::User::growHungoffUses(), and llvm::User::operator delete().

## ◆ Value

 friend class Value
friend

Definition at line 105 of file Use.h.

The documentation for this class was generated from the following files: