//===- llvm/Analysis/AliasAnalysis.h - Alias Analysis Interface -*- C++ -*-===//
//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
// This file defines the generic AliasAnalysis interface, which is used as the
// common interface used by all clients of alias analysis information, and
-// implemented by all alias analysis implementations.
+// implemented by all alias analysis implementations. Mod/Ref information is
+// also captured by this interface.
//
// Implementations of this interface must implement the various virtual methods,
// which automatically provides functionality for the entire suite of client
// APIs.
//
+// This API represents memory as a (Pointer, Size) pair. The Pointer component
+// specifies the base memory address of the region, the Size specifies how large
+// of an area is being queried, or UnknownSize if the size is not known.
+// Pointers that point to two completely different objects in memory never
+// alias, regardless of the value of the Size component.
+//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_ALIAS_ANALYSIS_H
#define LLVM_ANALYSIS_ALIAS_ANALYSIS_H
-class Value;
-class CallInst;
-class InvokeInst;
-class BasicBlock;
-class Instruction;
-
-struct AliasAnalysis {
-
- // 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.
- //
- enum Result { NoAlias = 0, MayAlias = 1, MustAlias = 2 };
-
- // 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.
- //
- virtual Result alias(const Value *V1, const Value *V2) const = 0;
-
- // canCallModify - Return a Result that indicates whether the specified
- // function call can modify the memory location pointed to by Ptr.
- //
- virtual Result canCallModify(const CallInst &CI, const Value *Ptr) const = 0;
-
- // canInvokeModify - Return a Result that indicates whether the specified
- // function invoke can modify the memory location pointed to by Ptr.
- //
- virtual Result canInvokeModify(const InvokeInst &I, const Value *Ptr) const=0;
-
- // canBasicBlockModify - Return true if it is possible for execution of the
- // specified basic block to modify the value pointed to by Ptr.
- //
- bool canBasicBlockModify(const BasicBlock &BB, const Value *Ptr) const;
-
- // 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.
- //
- bool canInstructionRangeModify(const Instruction &I1, const Instruction &I2,
- const Value *Ptr) const;
+#include "llvm/Support/CallSite.h"
+#include <vector>
+
+namespace llvm {
+
+class LoadInst;
+class StoreInst;
+class VAArgInst;
+class TargetData;
+class Pass;
+class AnalysisUsage;
+
+class AliasAnalysis {
+protected:
+ const TargetData *TD;
+
+private:
+ AliasAnalysis *AA; // Previous Alias Analysis to chain to.
+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.
+ ///
+ void InitializeAliasAnalysis(Pass *P);
+
+ /// getAnalysisUsage - All alias analysis implementations should invoke this
+ /// directly (using AliasAnalysis::getAnalysisUsage(AU)).
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const;
+
+public:
+ static char ID; // Class identification, replacement for typeinfo
+ AliasAnalysis() : TD(0), AA(0) {}
virtual ~AliasAnalysis(); // We want to be subclassed
+
+ /// UnknownSize - This is a special value which can be used with the
+ /// size arguments in alias queries to indicate that the caller does not
+ /// know the sizes of the potential memory references.
+ static uint64_t const UnknownSize = ~UINT64_C(0);
+
+ /// getTargetData - Return a pointer to the current TargetData object, or
+ /// null if no TargetData object is available.
+ ///
+ const TargetData *getTargetData() const { return TD; }
+
+ /// getTypeStoreSize - Return the TargetData store size for the given type,
+ /// if known, or a conservative value otherwise.
+ ///
+ uint64_t getTypeStoreSize(const Type *Ty);
+
+ //===--------------------------------------------------------------------===//
+ /// Alias Queries...
+ ///
+
+ /// Location - A description of a memory location.
+ struct Location {
+ /// Ptr - The address of the start of the location.
+ const Value *Ptr;
+ /// Size - The size of the location.
+ uint64_t Size;
+ /// TBAATag - The metadata node which describes the TBAA type of
+ /// the location, or null if there is no (unique) tag.
+ const MDNode *TBAATag;
+
+ explicit Location(const Value *P = 0,
+ uint64_t S = UnknownSize,
+ const MDNode *N = 0)
+ : Ptr(P), Size(S), TBAATag(N) {}
+
+ Location getWithNewPtr(const Value *NewPtr) const {
+ Location Copy(*this);
+ Copy.Ptr = NewPtr;
+ return Copy;
+ }
+
+ Location getWithoutTBAATag() const {
+ Location Copy(*this);
+ Copy.TBAATag = 0;
+ return Copy;
+ }
+ };
+
+ /// 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.
+ ///
+ /// See docs/AliasAnalysis.html for more information on the specific meanings
+ /// of these values.
+ ///
+ enum AliasResult { NoAlias = 0, MayAlias = 1, MustAlias = 2 };
+
+ /// 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.
+ virtual AliasResult alias(const Location &LocA, const Location &LocB);
+
+ /// alias - A convenience wrapper.
+ AliasResult alias(const Value *V1, uint64_t V1Size,
+ const Value *V2, uint64_t V2Size) {
+ return alias(Location(V1, V1Size), Location(V2, V2Size));
+ }
+
+ /// alias - A convenience wrapper.
+ AliasResult alias(const Value *V1, const Value *V2) {
+ return alias(V1, UnknownSize, V2, UnknownSize);
+ }
+
+ /// isNoAlias - A trivial helper function to check to see if the specified
+ /// pointers are no-alias.
+ bool isNoAlias(const Location &LocA, const Location &LocB) {
+ return alias(LocA, LocB) == NoAlias;
+ }
+
+ /// isNoAlias - A convenience wrapper.
+ bool isNoAlias(const Value *V1, uint64_t V1Size,
+ const Value *V2, uint64_t V2Size) {
+ return isNoAlias(Location(V1, V1Size), Location(V2, V2Size));
+ }
+
+ /// pointsToConstantMemory - If the specified memory location is known to be
+ /// constant, return true. This allows disambiguation of store
+ /// instructions from constant pointers.
+ ///
+ virtual bool pointsToConstantMemory(const Location &Loc);
+
+ /// pointsToConstantMemory - A convenient wrapper.
+ bool pointsToConstantMemory(const Value *P) {
+ return pointsToConstantMemory(Location(P));
+ }
+
+ //===--------------------------------------------------------------------===//
+ /// Simple mod/ref information...
+ ///
+
+ /// ModRefResult - Represent the result of a mod/ref query. Mod and Ref are
+ /// bits which may be or'd together.
+ ///
+ enum ModRefResult { NoModRef = 0, Ref = 1, Mod = 2, ModRef = 3 };
+
+
+ /// 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.
+ enum ModRefBehavior {
+ // DoesNotAccessMemory - This function does not perform any non-local loads
+ // or stores to memory.
+ //
+ // This property corresponds to the GCC 'const' attribute.
+ DoesNotAccessMemory,
+
+ // AccessesArguments - This function accesses function arguments in well
+ // known (possibly volatile) ways, but does not access any other memory.
+ AccessesArguments,
+
+ // AccessesArgumentsAndGlobals - This function has accesses function
+ // arguments and global variables well known (possibly volatile) ways, but
+ // does not access any other memory.
+ AccessesArgumentsAndGlobals,
+
+ // OnlyReadsMemory - This function does not perform any non-local stores or
+ // volatile loads, but may read from any memory location.
+ //
+ // This property corresponds to the GCC 'pure' attribute.
+ OnlyReadsMemory,
+
+ // UnknownModRefBehavior - This indicates that the function could not be
+ // classified into one of the behaviors above.
+ UnknownModRefBehavior
+ };
+
+ /// getModRefBehavior - Return the behavior when calling the given call site.
+ virtual ModRefBehavior getModRefBehavior(ImmutableCallSite CS);
+
+ /// getModRefBehavior - Return the behavior when calling the given function.
+ /// For use when the call site is not known.
+ virtual ModRefBehavior getModRefBehavior(const Function *F);
+
+ /// getIntrinsicModRefBehavior - Return the modref behavior of the intrinsic
+ /// with the given id. Most clients won't need this, because the regular
+ /// getModRefBehavior incorporates this information.
+ static ModRefBehavior getIntrinsicModRefBehavior(unsigned iid);
+
+ /// 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.
+ ///
+ bool doesNotAccessMemory(ImmutableCallSite CS) {
+ return getModRefBehavior(CS) == DoesNotAccessMemory;
+ }
+
+ /// doesNotAccessMemory - If the specified function is known to never read or
+ /// write memory, return true. For use when the call site is not known.
+ ///
+ bool doesNotAccessMemory(const Function *F) {
+ return getModRefBehavior(F) == DoesNotAccessMemory;
+ }
+
+ /// 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.
+ ///
+ bool onlyReadsMemory(ImmutableCallSite CS) {
+ ModRefBehavior MRB = getModRefBehavior(CS);
+ return MRB == DoesNotAccessMemory || MRB == OnlyReadsMemory;
+ }
+
+ /// 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.
+ ///
+ bool onlyReadsMemory(const Function *F) {
+ ModRefBehavior MRB = getModRefBehavior(F);
+ return MRB == DoesNotAccessMemory || MRB == OnlyReadsMemory;
+ }
+
+
+ /// getModRefInfo - Return information about whether or not an instruction may
+ /// read or write the specified memory location. An instruction
+ /// that doesn't read or write memory may be trivially LICM'd for example.
+ ModRefResult getModRefInfo(const Instruction *I,
+ const Location &Loc) {
+ switch (I->getOpcode()) {
+ case Instruction::VAArg: return getModRefInfo((const VAArgInst*)I, Loc);
+ case Instruction::Load: return getModRefInfo((const LoadInst*)I, Loc);
+ case Instruction::Store: return getModRefInfo((const StoreInst*)I, Loc);
+ case Instruction::Call: return getModRefInfo((const CallInst*)I, Loc);
+ case Instruction::Invoke: return getModRefInfo((const InvokeInst*)I,Loc);
+ default: return NoModRef;
+ }
+ }
+
+ /// getModRefInfo - A convenience wrapper.
+ ModRefResult getModRefInfo(const Instruction *I,
+ const Value *P, uint64_t Size) {
+ return getModRefInfo(I, Location(P, Size));
+ }
+
+ /// getModRefInfo (for call sites) - Return whether information about whether
+ /// a particular call site modifies or reads the specified memory location.
+ virtual ModRefResult getModRefInfo(ImmutableCallSite CS,
+ const Location &Loc);
+
+ /// getModRefInfo (for call sites) - A convenience wrapper.
+ ModRefResult getModRefInfo(ImmutableCallSite CS,
+ const Value *P, uint64_t Size) {
+ return getModRefInfo(CS, Location(P, Size));
+ }
+
+ /// getModRefInfo (for calls) - Return whether information about whether
+ /// a particular call modifies or reads the specified memory location.
+ ModRefResult getModRefInfo(const CallInst *C, const Location &Loc) {
+ return getModRefInfo(ImmutableCallSite(C), Loc);
+ }
+
+ /// getModRefInfo (for calls) - A convenience wrapper.
+ ModRefResult getModRefInfo(const CallInst *C, const Value *P, uint64_t Size) {
+ return getModRefInfo(C, Location(P, Size));
+ }
+
+ /// getModRefInfo (for invokes) - Return whether information about whether
+ /// a particular invoke modifies or reads the specified memory location.
+ ModRefResult getModRefInfo(const InvokeInst *I,
+ const Location &Loc) {
+ return getModRefInfo(ImmutableCallSite(I), Loc);
+ }
+
+ /// getModRefInfo (for invokes) - A convenience wrapper.
+ ModRefResult getModRefInfo(const InvokeInst *I,
+ const Value *P, uint64_t Size) {
+ return getModRefInfo(I, Location(P, Size));
+ }
+
+ /// getModRefInfo (for loads) - Return whether information about whether
+ /// a particular load modifies or reads the specified memory location.
+ ModRefResult getModRefInfo(const LoadInst *L, const Location &Loc);
+
+ /// getModRefInfo (for loads) - A convenience wrapper.
+ ModRefResult getModRefInfo(const LoadInst *L, const Value *P, uint64_t Size) {
+ return getModRefInfo(L, Location(P, Size));
+ }
+
+ /// getModRefInfo (for stores) - Return whether information about whether
+ /// a particular store modifies or reads the specified memory location.
+ ModRefResult getModRefInfo(const StoreInst *S, const Location &Loc);
+
+ /// getModRefInfo (for stores) - A convenience wrapper.
+ ModRefResult getModRefInfo(const StoreInst *S, const Value *P, uint64_t Size) {
+ return getModRefInfo(S, Location(P, Size));
+ }
+
+ /// getModRefInfo (for va_args) - Return whether information about whether
+ /// a particular va_arg modifies or reads the specified memory location.
+ ModRefResult getModRefInfo(const VAArgInst* I, const Location &Loc);
+
+ /// getModRefInfo (for va_args) - A convenience wrapper.
+ ModRefResult getModRefInfo(const VAArgInst* I, const Value* P, uint64_t Size) {
+ return getModRefInfo(I, Location(P, Size));
+ }
+
+ /// getModRefInfo - Return information about whether two call sites may refer
+ /// to the same set of memory locations. See
+ /// http://llvm.org/docs/AliasAnalysis.html#ModRefInfo
+ /// for details.
+ virtual ModRefResult getModRefInfo(ImmutableCallSite CS1,
+ ImmutableCallSite CS2);
+
+ //===--------------------------------------------------------------------===//
+ /// 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.
+ bool canBasicBlockModify(const BasicBlock &BB, const Location &Loc);
+
+ /// canBasicBlockModify - A convenience wrapper.
+ bool canBasicBlockModify(const BasicBlock &BB, const Value *P, uint64_t Size){
+ return canBasicBlockModify(BB, Location(P, 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.
+ bool canInstructionRangeModify(const Instruction &I1, const Instruction &I2,
+ const Location &Loc);
+
+ /// canInstructionRangeModify - A convenience wrapper.
+ bool canInstructionRangeModify(const Instruction &I1, const Instruction &I2,
+ const Value *Ptr, uint64_t Size) {
+ return canInstructionRangeModify(I1, I2, Location(Ptr, Size));
+ }
+
+ //===--------------------------------------------------------------------===//
+ /// 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.
+ ///
+ virtual void deleteValue(Value *V);
+
+ /// 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.
+ ///
+ virtual void copyValue(Value *From, Value *To);
+
+ /// replaceWithNewValue - This method is the obvious combination of the two
+ /// above, and it provided as a helper to simplify client code.
+ ///
+ void replaceWithNewValue(Value *Old, Value *New) {
+ copyValue(Old, New);
+ deleteValue(Old);
+ }
};
+/// isNoAliasCall - Return true if this pointer is returned by a noalias
+/// function.
+bool isNoAliasCall(const Value *V);
+
+/// isIdentifiedObject - Return true if this pointer refers to a distinct and
+/// identifiable object. This returns true for:
+/// Global Variables and Functions (but not Global Aliases)
+/// Allocas and Mallocs
+/// ByVal and NoAlias Arguments
+/// NoAlias returns
+///
+bool isIdentifiedObject(const Value *V);
+
+} // End llvm namespace
+
#endif
projects / oota-llvm.git / blobdiff