LLVM  10.0.0svn
llvm::MemorySSAWalker Class Referenceabstract

This is the generic walker interface for walkers of MemorySSA. More...

#include "llvm/Analysis/MemorySSA.h"

Inheritance diagram for llvm::MemorySSAWalker:
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Collaboration diagram for llvm::MemorySSAWalker:
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## Public Types

using MemoryAccessSet = SmallVector< MemoryAccess *, 8 >

## Public Member Functions

MemorySSAWalker (MemorySSA *)

virtual ~MemorySSAWalker ()=default

MemoryAccessgetClobberingMemoryAccess (const Instruction *I)
Given a memory Mod/Ref/ModRef'ing instruction, calling this will give you the nearest dominating MemoryAccess that Mod's the location the instruction accesses (by skipping any def which AA can prove does not alias the location(s) accessed by the instruction given). More...

virtual MemoryAccessgetClobberingMemoryAccess (MemoryAccess *)=0
Does the same thing as getClobberingMemoryAccess(const Instruction *I), but takes a MemoryAccess instead of an Instruction. More...

virtual MemoryAccessgetClobberingMemoryAccess (MemoryAccess *, const MemoryLocation &)=0
Given a potentially clobbering memory access and a new location, calling this will give you the nearest dominating clobbering MemoryAccess (by skipping non-aliasing def links). More...

virtual void invalidateInfo (MemoryAccess *)
Given a memory access, invalidate anything this walker knows about that access. More...

MemorySSAMSSA

class MemorySSA

## Detailed Description

This is the generic walker interface for walkers of MemorySSA.

Walkers are used to be able to further disambiguate the def-use chains MemorySSA gives you, or otherwise produce better info than MemorySSA gives you. In particular, while the def-use chains provide basic information, and are guaranteed to give, for example, the nearest may-aliasing MemoryDef for a MemoryUse as AliasAnalysis considers it, a user mant want better or other information. In particular, they may want to use SCEV info to further disambiguate memory accesses, or they may want the nearest dominating may-aliasing MemoryDef for a call or a store. This API enables a standardized interface to getting and using that info.

Definition at line 996 of file MemorySSA.h.

## ◆ MemoryAccessSet

 using llvm::MemorySSAWalker::MemoryAccessSet = SmallVector

Definition at line 1001 of file MemorySSA.h.

## ◆ MemorySSAWalker()

 MemorySSAWalker::MemorySSAWalker ( MemorySSA * M )

Definition at line 2310 of file MemorySSA.cpp.

## ◆ ~MemorySSAWalker()

 virtual llvm::MemorySSAWalker::~MemorySSAWalker ( )
virtualdefault

## ◆ getClobberingMemoryAccess() [1/3]

 MemoryAccess* llvm::MemorySSAWalker::getClobberingMemoryAccess ( const Instruction * I )
inline

Given a memory Mod/Ref/ModRef'ing instruction, calling this will give you the nearest dominating MemoryAccess that Mod's the location the instruction accesses (by skipping any def which AA can prove does not alias the location(s) accessed by the instruction given).

Note that this will return a single access, and it must dominate the Instruction, so if an operand of a MemoryPhi node Mod's the instruction, this will return the MemoryPhi, not the operand. This means that given: if (a) { 1 = MemoryDef(liveOnEntry) store a } else { 2 = MemoryDef(liveOnEntry) store b } 3 = MemoryPhi(2, 1) MemoryUse(3) load a

calling this API on load(a) will return the MemoryPhi, not the MemoryDef in the if (a) branch.

Definition at line 1025 of file MemorySSA.h.

References assert().

Referenced by llvm::canSinkOrHoistInst(), and pointerInvalidatedByLoopWithMSSA().

## ◆ getClobberingMemoryAccess() [2/3]

 virtual MemoryAccess* llvm::MemorySSAWalker::getClobberingMemoryAccess ( MemoryAccess * )
pure virtual

Does the same thing as getClobberingMemoryAccess(const Instruction *I), but takes a MemoryAccess instead of an Instruction.

Implemented in llvm::DoNothingMemorySSAWalker.

## ◆ getClobberingMemoryAccess() [3/3]

 virtual MemoryAccess* llvm::MemorySSAWalker::getClobberingMemoryAccess ( MemoryAccess * , const MemoryLocation & )
pure virtual

Given a potentially clobbering memory access and a new location, calling this will give you the nearest dominating clobbering MemoryAccess (by skipping non-aliasing def links).

This version of the function is mainly used to disambiguate phi translated pointers, where the value of a pointer may have changed from the initial memory access. Note that this expects to be handed either a MemoryUse, or an already potentially clobbering access. Unlike the above API, if given a MemoryDef that clobbers the pointer as the starting access, it will return that MemoryDef, whereas the above would return the clobber starting from the use side of the memory def.

Implemented in llvm::DoNothingMemorySSAWalker.

## ◆ invalidateInfo()

 virtual void llvm::MemorySSAWalker::invalidateInfo ( MemoryAccess * )
inlinevirtual

Given a memory access, invalidate anything this walker knows about that access.

This API is used by walkers that store information to perform basic cache invalidation. This will be called by MemorySSA at appropriate times for the walker it uses or returns.

Definition at line 1054 of file MemorySSA.h.

Referenced by llvm::MemorySSA::removeFromLookups().

## ◆ MemorySSA

 friend class MemorySSA
friend

Definition at line 1057 of file MemorySSA.h.

## ◆ MSSA

 MemorySSA* llvm::MemorySSAWalker::MSSA
protected

Definition at line 1059 of file MemorySSA.h.

Referenced by MemorySSAWalker().

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