Minimal dependence between two memory references in a function.
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 |
One level of a dependence distance/direction vector. |
Member Functions
Name |
Description |
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Construct a dependence from |
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Destroy this dependence. |
dump ‐ For debugging purposes, dumps a dependence to OS. |
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dumpImp ‐ For debugging purposes. Dumps a dependence to OS with or without considering the SameSD levels. |
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getDirection ‐ Returns the direction associated with a particular common or SameSD level. |
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getDistance ‐ Returns the distance (or NULL) associated with a particular common or SameSD level. |
getDst ‐ Returns the destination instruction for this dependence. |
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getLevels ‐ Returns the number of common loops surrounding the source and destination of the dependence. |
getNextPredecessor ‐ Returns the value of the NextPredecessor field. |
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getNextSuccessor ‐ Returns the value of the NextSuccessor field. |
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getRuntimeAssumptions ‐ Returns the runtime assumptions under which this Dependence relation is valid. |
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getSameSDLevels ‐ Returns the number of separate SameSD loops surrounding the source and destination of the dependence. |
getSrc ‐ Returns the source instruction for this dependence. |
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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 ‐ Returns true if this is an anti dependence. |
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isConfused ‐ Returns true if this dependence is confused (the compiler understands nothing and makes worst‐case assumptions). |
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Check if the direction vector is negative. A negative direction vector means Src and Dst are reversed in the actual program. |
isFlow ‐ Returns true if this is a flow (aka true) dependence. |
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isInput ‐ Returns true if this is an input dependence. |
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isLoopIndependent ‐ Returns true if this is a loop‐independent dependence. |
isOrdered ‐ Returns true if dependence is Output, Flow, or Anti |
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isOutput ‐ Returns true if this is an output dependence. |
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Return true if a particular regular or SameSD level is scalar. |
isUnordered ‐ Returns true if dependence is Input |
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Negate the dependence by swapping the source and destination. |
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Normalize a negative direction vector to make it non‐negative. |
setNextPredecessor ‐ Sets the value of the NextPredecessor field. |
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setNextSuccessor ‐ Sets the value of the NextSuccessor field. |
Protected Member Functions
Name |
Description |
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Move‐construct this dependence, transferring ownership of linked state. |
Move‐assign this dependence, transferring ownership of linked state. |
Protected Data Members
Friends
Name |
Description |
DependenceInfo ‐ This class is the main dependence‐analysis driver. |
Derived Classes
Name |
Description |
Detailed dependence between two memory references in a function. |
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