llvm::AliasAnalysis Class Reference

#include <AliasAnalysis.h>

Inheritance diagram for llvm::AliasAnalysis:

Collaboration diagram for llvm::AliasAnalysis:

List of all members.

Public Types

enum AliasResult { NoAlias = 0, MayAlias = 1, MustAlias = 2 }

enum ModRefResult { NoModRef = 0, Ref = 1, Mod = 2, ModRef = 3 }

enum ModRefBehavior {
DoesNotAccessMemory, AccessesArguments, AccessesArgumentsAndGlobals, OnlyReadsMemory,
UnknownModRefBehavior
}

Public Member Functions

AliasAnalysis ()

virtual ~AliasAnalysis ()

const TargetData & getTargetData () 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)

ModRefBehavior getModRefBehavior (CallSite CS, std::vector< PointerAccessInfo > *Info=0)

getModRefBehavior - Return the behavior when calling the given call site.

ModRefBehavior getModRefBehavior (Function *F, std::vector< PointerAccessInfo > *Info=0)

bool doesNotAccessMemory (CallSite CS)

bool doesNotAccessMemory (Function *F)

bool onlyReadsMemory (CallSite CS)

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 (VAArgInst *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)

Static Public Attributes

static char ID = 0

Protected Member Functions

void InitializeAliasAnalysis (Pass *P)

virtual void getAnalysisUsage (AnalysisUsage &AU) const

virtual ModRefBehavior getModRefBehavior (Function *F, CallSite CS, std::vector< PointerAccessInfo > *Info=0)

Protected Attributes

const TargetData * TD

AliasAnalysis * AA

Classes

struct PointerAccessInfo

Detailed Description

Definition at line 46 of file AliasAnalysis.h.

Member Enumeration Documentation

enum llvm::AliasAnalysis::AliasResult

Alias Queries... 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 84 of file AliasAnalysis.h.

enum llvm::AliasAnalysis::ModRefResult

Simple mod/ref information... 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 115 of file AliasAnalysis.h.

enum llvm::AliasAnalysis::ModRefBehavior

ModRefBehavior - Summary of how a function affects memory in the program. Loads from constant globals are not considered memory accesses for this interface. Also, functions may freely modify stack space local to their invocation without having to report it through these interfaces.

Enumerator:

DoesNotAccessMemory
AccessesArguments
AccessesArgumentsAndGlobals
OnlyReadsMemory
UnknownModRefBehavior

Definition at line 122 of file AliasAnalysis.h.

Constructor & Destructor Documentation

llvm::AliasAnalysis::AliasAnalysis ( ) [inline]

Definition at line 65 of file AliasAnalysis.h.

AliasAnalysis::~AliasAnalysis ( ) [virtual]

Definition at line 164 of file AliasAnalysis.cpp.

Member Function Documentation

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.

InitializeAliasAnalysis - Subclasses must call this method to initialize the AliasAnalysis interface before any other methods are called.

Definition at line 169 of file AliasAnalysis.cpp.

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

Referenced by llvm::LibCallAliasAnalysis::runOnFunction().

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

getAnalysisUsage - All alias analysis implementations should invoke this directly (using AliasAnalysis::getAnalysisUsage(AU)) to make sure that TargetData is required by the pass.

Reimplemented in llvm::LibCallAliasAnalysis.

Definition at line 177 of file AliasAnalysis.cpp.

References llvm::AnalysisUsage::addRequired().

Referenced by llvm::LibCallAliasAnalysis::getAnalysisUsage().

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 72 of file AliasAnalysis.h.

References TD.

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

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 45 of file AliasAnalysis.cpp.

References AA, and alias().

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

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 51 of file AliasAnalysis.cpp.

References AA, and getMustAliases().

Referenced by getMustAliases().

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 56 of file AliasAnalysis.cpp.

References AA, and pointsToConstantMemory().

Referenced by getModRefInfo(), and pointsToConstantMemory().

AliasAnalysis::ModRefBehavior AliasAnalysis::getModRefBehavior	(	CallSite	CS,
		std::vector< PointerAccessInfo > *	Info = `0`
	)

getModRefBehavior - Return the behavior when calling the given call site.

Definition at line 115 of file AliasAnalysis.cpp.

References DoesNotAccessMemory, llvm::CallSite::doesNotAccessMemory(), F, llvm::CallSite::getCalledFunction(), OnlyReadsMemory, llvm::CallSite::onlyReadsMemory(), and UnknownModRefBehavior.

Referenced by doesNotAccessMemory(), getModRefBehavior(), getModRefInfo(), and onlyReadsMemory().

AliasAnalysis::ModRefBehavior AliasAnalysis::getModRefBehavior	(	Function *	F,
		std::vector< PointerAccessInfo > *	Info = `0`
	)

getModRefBehavior - Return the behavior when calling the given function. For use when the call site is not known.

Definition at line 129 of file AliasAnalysis.cpp.

References DoesNotAccessMemory, llvm::Function::doesNotAccessMemory(), getModRefBehavior(), OnlyReadsMemory, and llvm::Function::onlyReadsMemory().

bool llvm::AliasAnalysis::doesNotAccessMemory ( CallSite CS ) [inline]

doesNotAccessMemory - If the specified call is known to never read or write memory, return true. If the call only reads from known-constant memory, it is also legal to return true. Calls that unwind the stack are legal for this predicate.

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

This property corresponds to the GCC 'const' attribute.

Definition at line 209 of file AliasAnalysis.h.

References DoesNotAccessMemory, and getModRefBehavior().

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

bool llvm::AliasAnalysis::doesNotAccessMemory ( Function * F ) [inline]

doesNotAccessMemory - If the specified function is known to never read or write memory, return true. For use when the call site is not known.

Definition at line 216 of file AliasAnalysis.h.

References DoesNotAccessMemory, and getModRefBehavior().

bool llvm::AliasAnalysis::onlyReadsMemory ( CallSite CS ) [inline]

onlyReadsMemory - If the specified call is known to only read from non-volatile memory (or not access memory at all), return true. Calls that unwind the stack are 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 229 of file AliasAnalysis.h.

References DoesNotAccessMemory, getModRefBehavior(), and OnlyReadsMemory.

Referenced by llvm::MemoryDependenceAnalysis::getDependency(), and llvm::MemoryDependenceAnalysis::getNonLocalCallDependency().

bool llvm::AliasAnalysis::onlyReadsMemory ( Function * F ) [inline]

onlyReadsMemory - If the specified function is known to only read from non-volatile memory (or not access memory at all), return true. For use when the call site is not known.

Definition at line 238 of file AliasAnalysis.h.

References DoesNotAccessMemory, getModRefBehavior(), and OnlyReadsMemory.

AliasAnalysis::ModRefResult AliasAnalysis::getModRefInfo	(	CallSite	CS,
		Value *	P,
		unsigned	Size
	)			`[virtual]`

getModRefInfo - Return information about whether or not an instruction may read or write memory specified by the pointer operand. An instruction that doesn't read or write memory may be trivially LICM'd for example. getModRefInfo (for call sites) - Return whether information about whether a particular call site modifies or reads the memory specified by the pointer.

Reimplemented in llvm::LibCallAliasAnalysis.

Definition at line 141 of file AliasAnalysis.cpp.

References AA, DoesNotAccessMemory, getModRefBehavior(), getModRefInfo(), Mod, ModRef, NoModRef, OnlyReadsMemory, pointsToConstantMemory(), and Ref.

Referenced by canInstructionRangeModify(), llvm::FindAvailableLoadedValue(), llvm::LibCallAliasAnalysis::getModRefInfo(), and getModRefInfo().

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.

Reimplemented in llvm::LibCallAliasAnalysis.

Definition at line 84 of file AliasAnalysis.cpp.

References AA, and getModRefInfo().

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.

Reimplemented in llvm::LibCallAliasAnalysis.

Definition at line 68 of file AliasAnalysis.cpp.

References AA, and hasNoModRefInfoForCalls().

Referenced by hasNoModRefInfoForCalls().

AliasAnalysis::ModRefBehavior AliasAnalysis::getModRefBehavior	(	Function *	F,
		CallSite	CS,
		std::vector< PointerAccessInfo > *	Info = `0`
	)			`[protected, virtual]`

getModRefBehavior - Return the behavior of the specified function if called from the specified call site. The call site may be null in which case the most generic behavior of this function should be returned.

Definition at line 62 of file AliasAnalysis.cpp.

References AA, and getModRefBehavior().

AliasAnalysis::ModRefResult AliasAnalysis::getModRefInfo	(	LoadInst *	L,
		Value *	P,
		unsigned	Size
	)

Convenience functions...

Definition at line 96 of file AliasAnalysis.cpp.

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

AliasAnalysis::ModRefResult AliasAnalysis::getModRefInfo	(	StoreInst *	S,
		Value *	P,
		unsigned	Size
	)

Definition at line 102 of file AliasAnalysis.cpp.

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

ModRefResult llvm::AliasAnalysis::getModRefInfo	(	CallInst *	C,
		Value *	P,
		unsigned	Size
	)			`[inline]`

Definition at line 281 of file AliasAnalysis.h.

References getModRefInfo().

ModRefResult llvm::AliasAnalysis::getModRefInfo	(	InvokeInst *	I,
		Value *	P,
		unsigned	Size
	)			`[inline]`

Definition at line 284 of file AliasAnalysis.h.

References getModRefInfo().

ModRefResult llvm::AliasAnalysis::getModRefInfo	(	VAArgInst *	I,
		Value *	P,
		unsigned	Size
	)			`[inline]`

Definition at line 287 of file AliasAnalysis.h.

References ModRef.

ModRefResult llvm::AliasAnalysis::getModRefInfo	(	Instruction *	I,
		Value *	P,
		unsigned	Size
	)			`[inline]`

Definition at line 290 of file AliasAnalysis.h.

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

bool AliasAnalysis::canBasicBlockModify	(	const BasicBlock &	BB,
		const Value *	Ptr,
		unsigned	Size
	)

Higher level methods for querying mod/ref information. canBasicBlockModify - Return true if it is possible for execution of the specified basic block to modify the value pointed to by Ptr.

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 185 of file AliasAnalysis.cpp.

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

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 195 of file AliasAnalysis.cpp.

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

Referenced by canBasicBlockModify().

void AliasAnalysis::deleteValue ( Value * V ) [virtual]

Methods that clients should call when they transform the program to allow alias analyses to update their internal data structures. Note that these methods may be called on any instruction, regardless of whether or not they have pointer-analysis implications. 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 73 of file AliasAnalysis.cpp.

References AA, and deleteValue().

Referenced by llvm::AliasSetTracker::deleteValue(), deleteValue(), FindPHIToPartitionLoops(), llvm::MemoryDependenceAnalysis::removeInstruction(), replaceWithNewValue(), and llvm::SplitBlockPredecessors().

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 78 of file AliasAnalysis.cpp.

References AA, and copyValue().

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

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 342 of file AliasAnalysis.h.

References copyValue(), and deleteValue().

Member Data Documentation

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

Definition at line 48 of file AliasAnalysis.h.

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

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

Definition at line 49 of file AliasAnalysis.h.

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

char AliasAnalysis::ID = 0 [static]

Reimplemented in llvm::LibCallAliasAnalysis.

Definition at line 64 of file AliasAnalysis.h.

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


Public Types
enum	AliasResult { NoAlias = 0, MayAlias = 1, MustAlias = 2 }
enum	ModRefResult { NoModRef = 0, Ref = 1, Mod = 2, ModRef = 3 }
enum	ModRefBehavior { DoesNotAccessMemory, AccessesArguments, AccessesArgumentsAndGlobals, OnlyReadsMemory, UnknownModRefBehavior }
Public Member Functions
	AliasAnalysis ()
virtual	~AliasAnalysis ()
const TargetData &	getTargetData () 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)
ModRefBehavior	getModRefBehavior (CallSite CS, std::vector< PointerAccessInfo > *Info=0)
	getModRefBehavior - Return the behavior when calling the given call site.
ModRefBehavior	getModRefBehavior (Function F, std::vector< PointerAccessInfo > Info=0)
bool	doesNotAccessMemory (CallSite CS)
bool	doesNotAccessMemory (Function *F)
bool	onlyReadsMemory (CallSite CS)
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 (VAArgInst 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)
Static Public Attributes
static char	ID = 0
Protected Member Functions
void	InitializeAliasAnalysis (Pass *P)
virtual void	getAnalysisUsage (AnalysisUsage &AU) const
virtual ModRefBehavior	getModRefBehavior (Function F, CallSite CS, std::vector< PointerAccessInfo > Info=0)
Protected Attributes
const TargetData *	TD
AliasAnalysis *	AA
Classes
struct	PointerAccessInfo