llvm::Dependence

Synopsis

Declared in <llvm/Analysis/DependenceAnalysis.h>

class Dependence;

Description

It contains minimal information and is used in the very common situation where the compiler is unable to determine anything beyond the existence of a dependence; that is, it represents a confused dependence (see also FullDependence). In most cases (for output, flow, and anti dependences), the dependence implies an ordering, where the source must precede the destination; in contrast, input dependences are unordered.

When a dependence graph is built, each Dependence will be a member of the set of predecessor edges for its destination instruction and a set if successor edges for its source instruction. These sets are represented as singly-linked lists, with the "next" fields stored in the dependence itelf.

Types

Name	Description
`DVEntry`	One level of a dependence distance/direction vector.

Member Functions

Name	Description
`Dependence` [constructor]	Construct a dependence from `Source` to `Destination` under `A.`
`~Dependence` [destructor] [virtual]	Destroy this dependence.
`dump`	dump - For debugging purposes, dumps a dependence to OS.
`dumpImp`	dumpImp - For debugging purposes. Dumps a dependence to OS with or without considering the SameSD levels.
`getDirection` [virtual]	getDirection - Returns the direction associated with a particular common or SameSD level.
`getDistance` [virtual]	getDistance - Returns the distance (or NULL) associated with a particular common or SameSD level.
`getDst`	getDst - Returns the destination instruction for this dependence.
`getLevels` [virtual]	getLevels - Returns the number of common loops surrounding the source and destination of the dependence.
`getNextPredecessor`	getNextPredecessor - Returns the value of the NextPredecessor field.
`getNextSuccessor`	getNextSuccessor - Returns the value of the NextSuccessor field.
`getRuntimeAssumptions`	getRuntimeAssumptions - Returns the runtime assumptions under which this Dependence relation is valid.
`getSameSDLevels` [virtual]	getSameSDLevels - Returns the number of separate SameSD loops surrounding the source and destination of the dependence.
`getSrc`	getSrc - Returns the source instruction for this dependence.
`inSameSDLoops` [virtual]	inSameSDLoops - Returns true if this level is an SameSD level, i.e., performed across two separate loop nests that have the Same Iteration and Depth.
`isAnti`	isAnti - Returns true if this is an anti dependence.
`isConfused` [virtual]	isConfused - Returns true if this dependence is confused (the compiler understands nothing and makes worst-case assumptions).
`isDirectionNegative` [virtual]	Check if the direction vector is negative. A negative direction vector means Src and Dst are reversed in the actual program.
`isFlow`	isFlow - Returns true if this is a flow (aka true) dependence.
`isInput`	isInput - Returns true if this is an input dependence.
`isLoopIndependent` [virtual]	isLoopIndependent - Returns true if this is a loop-independent dependence.
`isOrdered`	isOrdered - Returns true if dependence is Output, Flow, or Anti
`isOutput`	isOutput - Returns true if this is an output dependence.
`isScalar` [virtual]	Return true if a particular regular or SameSD level is scalar.
`isUnordered`	isUnordered - Returns true if dependence is Input
`negate` [virtual]	Negate the dependence by swapping the source and destination.
`normalize` [virtual]	Normalize a negative direction vector to make it non-negative.
`setNextPredecessor`	setNextPredecessor - Sets the value of the NextPredecessor field.
`setNextSuccessor`	setNextSuccessor - Sets the value of the NextSuccessor field.

Protected Member Functions

Name	Description
`Dependence` [constructor]	Move-construct this dependence, transferring ownership of linked state.
`operator=`	Move-assign this dependence, transferring ownership of linked state.

Protected Data Members

Name	Description
`Dst`	Destination instruction of this dependence.
`Src`	Source instruction of this dependence.

Friends

Name	Description
`llvm::DependenceInfo`	DependenceInfo - This class is the main dependence-analysis driver.

Derived Classes

Name	Description
`FullDependence`	Detailed dependence between two memory references in a function.