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llvm::AliasAnalysis Class Reference

#include <AliasAnalysis.h>

Collaboration diagram for llvm::AliasAnalysis:

Collaboration graph
[legend]
List of all members.

Public Types

enum  AliasResult { NoAlias = 0, MayAlias = 1, MustAlias = 2 }
enum  ModRefResult { NoModRef = 0, Ref = 1, Mod = 2, ModRef = 3 }

Public Member Functions

 AliasAnalysis ()
virtual ~AliasAnalysis ()
const TargetDatagetTargetData () const
virtual AliasResult alias (const Value *V1, unsigned V1Size, const Value *V2, unsigned V2Size)
virtual void getMustAliases (Value *P, std::vector< Value * > &RetVals)
virtual bool pointsToConstantMemory (const Value *P)
virtual bool doesNotAccessMemory (Function *F)
virtual bool onlyReadsMemory (Function *F)
virtual ModRefResult getModRefInfo (CallSite CS, Value *P, unsigned Size)
virtual ModRefResult getModRefInfo (CallSite CS1, CallSite CS2)
virtual bool hasNoModRefInfoForCalls () const
ModRefResult getModRefInfo (LoadInst *L, Value *P, unsigned Size)
 Convenience functions...
ModRefResult getModRefInfo (StoreInst *S, Value *P, unsigned Size)
ModRefResult getModRefInfo (CallInst *C, Value *P, unsigned Size)
ModRefResult getModRefInfo (InvokeInst *I, Value *P, unsigned Size)
ModRefResult getModRefInfo (Instruction *I, Value *P, unsigned Size)
bool canBasicBlockModify (const BasicBlock &BB, const Value *P, unsigned Size)
bool canInstructionRangeModify (const Instruction &I1, const Instruction &I2, const Value *Ptr, unsigned Size)
virtual void deleteValue (Value *V)
virtual void copyValue (Value *From, Value *To)
void replaceWithNewValue (Value *Old, Value *New)

Protected Member Functions

void InitializeAliasAnalysis (Pass *P)
virtual void getAnalysisUsage (AnalysisUsage &AU) const

Protected Attributes

const TargetDataTD
AliasAnalysisAA

Detailed Description

Definition at line 42 of file AliasAnalysis.h.


Member Enumeration Documentation

enum llvm::AliasAnalysis::AliasResult
 

Alias analysis result - Either we know for sure that it does not alias, we know for sure it must alias, or we don't know anything: The two pointers _might_ alias. This enum is designed so you can do things like: if (AA.alias(P1, P2)) { ... } to check to see if two pointers might alias.

Enumerator:
NoAlias 
MayAlias 
MustAlias 

Definition at line 79 of file AliasAnalysis.h.

enum llvm::AliasAnalysis::ModRefResult
 

ModRefResult - Represent the result of a mod/ref query. Mod and Ref are bits which may be or'd together.

Enumerator:
NoModRef 
Ref 
Mod 
ModRef 

Definition at line 135 of file AliasAnalysis.h.


Constructor & Destructor Documentation

llvm::AliasAnalysis::AliasAnalysis  )  [inline]
 

Definition at line 60 of file AliasAnalysis.h.

AliasAnalysis::~AliasAnalysis  )  [virtual]
 

Definition at line 140 of file AliasAnalysis.cpp.


Member Function Documentation

AliasAnalysis::AliasResult AliasAnalysis::alias const Value V1,
unsigned  V1Size,
const Value V2,
unsigned  V2Size
[virtual]
 

alias - The main low level interface to the alias analysis implementation. Returns a Result indicating whether the two pointers are aliased to each other. This is the interface that must be implemented by specific alias analysis implementations.

Definition at line 44 of file AliasAnalysis.cpp.

References AA, and alias().

Referenced by alias(), getModRefInfo(), and llvm::AliasSet::mergeSetIn().

bool AliasAnalysis::canBasicBlockModify const BasicBlock BB,
const Value P,
unsigned  Size
 

canBasicBlockModify - Return true if it is possible for execution of the specified basic block to modify the value pointed to by Ptr.

Definition at line 161 of file AliasAnalysis.cpp.

References llvm::BasicBlock::back(), canInstructionRangeModify(), and llvm::BasicBlock::front().

Referenced by isPathTransparentTo().

bool AliasAnalysis::canInstructionRangeModify const Instruction I1,
const Instruction I2,
const Value Ptr,
unsigned  Size
 

canInstructionRangeModify - Return true if it is possible for the execution of the specified instructions to modify the value pointed to by Ptr. The instructions to consider are all of the instructions in the range of [I1,I2] INCLUSIVE. I1 and I2 must be in the same basic block.

Definition at line 171 of file AliasAnalysis.cpp.

References E, getModRefInfo(), llvm::Instruction::getParent(), I, and Mod.

Referenced by canBasicBlockModify().

void AliasAnalysis::copyValue Value From,
Value To
[virtual]
 

copyValue - This method should be used whenever a preexisting value in the program is copied or cloned, introducing a new value. Note that analysis implementations should tolerate clients that use this method to introduce the same value multiple times: if the analysis already knows about a value, it should ignore the request.

Definition at line 80 of file AliasAnalysis.cpp.

References AA, and copyValue().

Referenced by llvm::AliasSetTracker::copyValue(), copyValue(), and replaceWithNewValue().

void AliasAnalysis::deleteValue Value V  )  [virtual]
 

deleteValue - This method should be called whenever an LLVM Value is deleted from the program, for example when an instruction is found to be redundant and is eliminated.

Definition at line 75 of file AliasAnalysis.cpp.

References AA, and deleteValue().

Referenced by llvm::AliasSetTracker::deleteValue(), deleteValue(), and replaceWithNewValue().

bool AliasAnalysis::doesNotAccessMemory Function F  )  [virtual]
 

doesNotAccessMemory - If the specified function is known to never read or write memory, return true. If the function only reads from known-constant memory, it is also legal to return true. Functions that unwind the stack are not legal for this predicate.

Many optimizations (such as CSE and LICM) can be performed on calls to it, without worrying about aliasing properties, and many functions have this property (e.g. 'sin' and 'cos').

This property corresponds to the GCC 'const' attribute.

Definition at line 60 of file AliasAnalysis.cpp.

References AA, and doesNotAccessMemory().

Referenced by llvm::AliasSetTracker::add(), doesNotAccessMemory(), getModRefInfo(), onlyReadsMemory(), and llvm::AliasSetTracker::remove().

void AliasAnalysis::getAnalysisUsage AnalysisUsage AU  )  const [protected, virtual]
 

Definition at line 153 of file AliasAnalysis.cpp.

References llvm::AnalysisUsage::addRequired().

ModRefResult llvm::AliasAnalysis::getModRefInfo Instruction I,
Value P,
unsigned  Size
[inline]
 

Definition at line 172 of file AliasAnalysis.h.

References llvm::Instruction::Call, getModRefInfo(), llvm::Instruction::getOpcode(), llvm::Instruction::Load, NoModRef, and llvm::ISD::Store.

ModRefResult llvm::AliasAnalysis::getModRefInfo InvokeInst I,
Value P,
unsigned  Size
[inline]
 

Definition at line 169 of file AliasAnalysis.h.

References getModRefInfo().

ModRefResult llvm::AliasAnalysis::getModRefInfo CallInst C,
Value P,
unsigned  Size
[inline]
 

Definition at line 166 of file AliasAnalysis.h.

References getModRefInfo().

AliasAnalysis::ModRefResult AliasAnalysis::getModRefInfo StoreInst S,
Value P,
unsigned  Size
 

Definition at line 104 of file AliasAnalysis.cpp.

References alias(), llvm::User::getOperand(), llvm::Value::getType(), llvm::TargetData::getTypeSize(), Mod, NoModRef, pointsToConstantMemory(), and TD.

AliasAnalysis::ModRefResult AliasAnalysis::getModRefInfo LoadInst L,
Value P,
unsigned  Size
 

Convenience functions...

Definition at line 98 of file AliasAnalysis.cpp.

References alias(), llvm::User::getOperand(), llvm::Value::getType(), llvm::TargetData::getTypeSize(), NoModRef, Ref, and TD.

AliasAnalysis::ModRefResult AliasAnalysis::getModRefInfo CallSite  CS1,
CallSite  CS2
[virtual]
 

getModRefInfo - Return information about whether two call sites may refer to the same set of memory locations. This function returns NoModRef if the two calls refer to disjoint memory locations, Ref if CS1 reads memory written by CS2, Mod if CS1 writes to memory read or written by CS2, or ModRef if CS1 might read or write memory accessed by CS2.

Definition at line 86 of file AliasAnalysis.cpp.

References AA, and getModRefInfo().

AliasAnalysis::ModRefResult AliasAnalysis::getModRefInfo CallSite  CS,
Value P,
unsigned  Size
[virtual]
 

getModRefInfo (for call sites) - Return whether information about whether a particular call site modifies or reads the memory specified by the pointer.

Definition at line 117 of file AliasAnalysis.cpp.

References AA, doesNotAccessMemory(), F, llvm::CallSite::getCalledFunction(), getModRefInfo(), Mod, ModRef, NoModRef, onlyReadsMemory(), pointsToConstantMemory(), and Ref.

Referenced by canInstructionRangeModify(), and getModRefInfo().

void AliasAnalysis::getMustAliases Value P,
std::vector< Value * > &  RetVals
[virtual]
 

getMustAliases - If there are any pointers known that must alias this pointer, return them now. This allows alias-set based alias analyses to perform a form a value numbering (which is exposed by load-vn). If an alias analysis supports this, it should ADD any must aliased pointers to the specified vector.

Definition at line 50 of file AliasAnalysis.cpp.

References AA, and getMustAliases().

Referenced by getMustAliases().

const TargetData& llvm::AliasAnalysis::getTargetData  )  const [inline]
 

getTargetData - Every alias analysis implementation depends on the size of data items in the current Target. This provides a uniform way to handle it.

Definition at line 67 of file AliasAnalysis.h.

References TD.

Referenced by llvm::AliasSetTracker::add(), and llvm::AliasSetTracker::remove().

bool AliasAnalysis::hasNoModRefInfoForCalls  )  const [virtual]
 

hasNoModRefInfoForCalls - Return true if the analysis has no mod/ref information for pairs of function calls (other than "pure" and "const" functions). This can be used by clients to avoid many pointless queries. Remember that if you override this and chain to another analysis, you must make sure that it doesn't have mod/ref info either.

Definition at line 70 of file AliasAnalysis.cpp.

References AA, and hasNoModRefInfoForCalls().

Referenced by hasNoModRefInfoForCalls().

void AliasAnalysis::InitializeAliasAnalysis Pass P  )  [protected]
 

InitializeAliasAnalysis - Subclasses must call this method to initialize the AliasAnalysis interface before any other methods are called. This is typically called by the run* methods of these subclasses. This may be called multiple times.

Definition at line 145 of file AliasAnalysis.cpp.

References AA, llvm::Pass::getAnalysis(), and TD.

bool AliasAnalysis::onlyReadsMemory Function F  )  [virtual]
 

onlyReadsMemory - If the specified function is known to only read from non-volatile memory (or not access memory at all), return true. Functions that unwind the stack are not legal for this predicate.

This property allows many common optimizations to be performed in the absence of interfering store instructions, such as CSE of strlen calls.

This property corresponds to the GCC 'pure' attribute.

Definition at line 65 of file AliasAnalysis.cpp.

References AA, doesNotAccessMemory(), and onlyReadsMemory().

Referenced by getModRefInfo(), and onlyReadsMemory().

bool AliasAnalysis::pointsToConstantMemory const Value P  )  [virtual]
 

pointsToConstantMemory - If the specified pointer is known to point into constant global memory, return true. This allows disambiguation of store instructions from constant pointers.

Definition at line 55 of file AliasAnalysis.cpp.

References AA, and pointsToConstantMemory().

Referenced by getModRefInfo(), and pointsToConstantMemory().

void llvm::AliasAnalysis::replaceWithNewValue Value Old,
Value New
[inline]
 

replaceWithNewValue - This method is the obvious combination of the two above, and it provided as a helper to simplify client code.

Definition at line 223 of file AliasAnalysis.h.

References copyValue(), and deleteValue().


Member Data Documentation

AliasAnalysis* llvm::AliasAnalysis::AA [protected]
 

Definition at line 45 of file AliasAnalysis.h.

Referenced by alias(), copyValue(), deleteValue(), doesNotAccessMemory(), getModRefInfo(), getMustAliases(), hasNoModRefInfoForCalls(), InitializeAliasAnalysis(), onlyReadsMemory(), and pointsToConstantMemory().

const TargetData* llvm::AliasAnalysis::TD [protected]
 

Definition at line 44 of file AliasAnalysis.h.

Referenced by getModRefInfo(), getTargetData(), and InitializeAliasAnalysis().


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