//
// 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. If Size is 0, two pointers only alias if they
-// are exactly equal. If size is greater than zero, but small, the two pointers
-// alias if the areas pointed to overlap. If the size is very large (ie, ~0U),
-// then the two pointers alias if they may be pointing to components of the same
-// memory object. Pointers that point to two completely different objects in
-// memory never alias, regardless of the value of the Size component.
+// 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.
//
//===----------------------------------------------------------------------===//
#define LLVM_ANALYSIS_ALIAS_ANALYSIS_H
#include "llvm/Support/CallSite.h"
-#include "llvm/System/IncludeFile.h"
#include <vector>
namespace llvm {
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
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.
///
/// getTypeStoreSize - Return the TargetData store size for the given type,
/// if known, or a conservative value otherwise.
///
- unsigned getTypeStoreSize(const Type *Ty);
+ 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 maximum size of the location, or UnknownSize if the size is
+ /// not known. Note that an unknown size does not mean the pointer aliases
+ /// the entire virtual address space, because there are restrictions on
+ /// stepping out of one object and into another.
+ /// See http://llvm.org/docs/LangRef.html#pointeraliasing
+ uint64_t Size;
+ /// TBAATag - The metadata node which describes the TBAA type of
+ /// the location, or null if there is no known 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 Value *V1, unsigned V1Size,
- const Value *V2, unsigned V2Size);
+ /// Returns an AliasResult 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 Value *V1, unsigned V1Size,
- const Value *V2, unsigned V2Size) {
- return alias(V1, V1Size, V2, V2Size) == NoAlias;
+ bool isNoAlias(const Location &LocA, const Location &LocB) {
+ return alias(LocA, LocB) == NoAlias;
}
- /// pointsToConstantMemory - If the specified pointer is known to point into
- /// constant global memory, return true. This allows disambiguation of store
- /// instructions from constant pointers.
- ///
- virtual bool pointsToConstantMemory(const Value *P);
+ /// 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. If OrLocal is true and the
+ /// specified memory location is known to be "local" (derived from
+ /// an alloca), return true. Otherwise return false.
+ virtual bool pointsToConstantMemory(const Location &Loc,
+ bool OrLocal = false);
+
+ /// pointsToConstantMemory - A convenient wrapper.
+ bool pointsToConstantMemory(const Value *P, bool OrLocal = false) {
+ return pointsToConstantMemory(Location(P), OrLocal);
+ }
//===--------------------------------------------------------------------===//
/// Simple mod/ref information...
///
enum ModRefResult { NoModRef = 0, Ref = 1, Mod = 2, ModRef = 3 };
+ /// These values define additional bits used to define the
+ /// ModRefBehavior values.
+ enum { Nowhere = 0, ArgumentPointees = 4, Anywhere = 8 | ArgumentPointees };
/// 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.
- //
- // Clients may use the Info parameter of getModRefBehavior to get specific
- // information about how pointer arguments are used.
- AccessesArguments,
-
- // AccessesArgumentsAndGlobals - This function has accesses function
- // arguments and global variables well known (possibly volatile) ways, but
- // does not access any other memory.
- //
- // Clients may use the Info parameter of getModRefBehavior to get specific
- // information about how pointer arguments are used.
- 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
- };
+ /// DoesNotAccessMemory - This function does not perform any non-local loads
+ /// or stores to memory.
+ ///
+ /// This property corresponds to the GCC 'const' attribute.
+ /// This property corresponds to the LLVM IR 'readnone' attribute.
+ /// This property corresponds to the IntrNoMem LLVM intrinsic flag.
+ DoesNotAccessMemory = Nowhere | NoModRef,
+
+ /// AccessesArgumentsReadonly - This function loads through function
+ /// arguments and does not perform any non-local stores or volatile
+ /// loads.
+ ///
+ /// This property corresponds to the IntrReadArgMem LLVM intrinsic flag.
+ AccessesArgumentsReadonly = ArgumentPointees | Ref,
- /// PointerAccessInfo - This struct is used to return results for pointers,
- /// globals, and the return value of a function.
- struct PointerAccessInfo {
- /// V - The value this record corresponds to. This may be an Argument for
- /// the function, a GlobalVariable, or null, corresponding to the return
- /// value for the function.
- Value *V;
+ /// AccessesArguments - This function accesses function arguments in well
+ /// known (possibly volatile) ways, but does not access any other memory.
+ ///
+ /// This property corresponds to the IntrReadWriteArgMem LLVM intrinsic flag.
+ AccessesArguments = ArgumentPointees | ModRef,
- /// ModRefInfo - Whether the pointer is loaded or stored to/from.
+ /// OnlyReadsMemory - This function does not perform any non-local stores or
+ /// volatile loads, but may read from any memory location.
///
- ModRefResult ModRefInfo;
+ /// This property corresponds to the GCC 'pure' attribute.
+ /// This property corresponds to the LLVM IR 'readonly' attribute.
+ /// This property corresponds to the IntrReadMem LLVM intrinsic flag.
+ OnlyReadsMemory = Anywhere | Ref,
+
+ /// UnknownModRefBehavior - This indicates that the function could not be
+ /// classified into one of the behaviors above.
+ UnknownModRefBehavior = Anywhere | ModRef
};
/// getModRefBehavior - Return the behavior when calling the given call site.
- virtual ModRefBehavior getModRefBehavior(CallSite CS,
- std::vector<PointerAccessInfo> *Info = 0);
+ 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(Function *F,
- std::vector<PointerAccessInfo> *Info = 0);
-
- /// getModRefBehavior - Return the modref behavior of the intrinsic with the
- /// given id.
- static ModRefBehavior getModRefBehavior(unsigned iid);
+ virtual ModRefBehavior getModRefBehavior(const Function *F);
/// doesNotAccessMemory - If the specified call is known to never read or
/// write memory, return true. If the call only reads from known-constant
///
/// This property corresponds to the GCC 'const' attribute.
///
- bool doesNotAccessMemory(CallSite CS) {
+ 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(Function *F) {
+ bool doesNotAccessMemory(const Function *F) {
return getModRefBehavior(F) == DoesNotAccessMemory;
}
///
/// This property corresponds to the GCC 'pure' attribute.
///
- bool onlyReadsMemory(CallSite CS) {
- ModRefBehavior MRB = getModRefBehavior(CS);
- return MRB == DoesNotAccessMemory || MRB == OnlyReadsMemory;
+ bool onlyReadsMemory(ImmutableCallSite CS) {
+ return onlyReadsMemory(getModRefBehavior(CS));
}
/// 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(Function *F) {
- ModRefBehavior MRB = getModRefBehavior(F);
- return MRB == DoesNotAccessMemory || MRB == OnlyReadsMemory;
+ bool onlyReadsMemory(const Function *F) {
+ return onlyReadsMemory(getModRefBehavior(F));
+ }
+
+ /// onlyReadsMemory - Return true if functions with the specified behavior are
+ /// known to only read from non-volatile memory (or not access memory at all).
+ ///
+ static bool onlyReadsMemory(ModRefBehavior MRB) {
+ return !(MRB & Mod);
}
+ /// onlyAccessesArgPointees - Return true if functions with the specified
+ /// behavior are known to read at most from objects pointed to by their
+ /// pointer-typed arguments (with arbitrary offsets).
+ ///
+ static bool onlyAccessesArgPointees(ModRefBehavior MRB) {
+ return !(MRB & Anywhere & ~ArgumentPointees);
+ }
/// getModRefInfo - Return information about whether or not an instruction may
- /// read or write memory specified by the pointer operand. An instruction
+ /// 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 memory specified by the
- /// pointer.
- ///
- virtual ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size);
+ /// 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 - 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.
- ///
- virtual ModRefResult getModRefInfo(CallSite CS1, CallSite CS2);
+ /// 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);
+ }
-public:
- /// Convenience functions...
- ModRefResult getModRefInfo(LoadInst *L, Value *P, unsigned Size);
- ModRefResult getModRefInfo(StoreInst *S, Value *P, unsigned Size);
- ModRefResult getModRefInfo(CallInst *C, Value *P, unsigned Size) {
- return getModRefInfo(CallSite(C), P, Size);
+ /// getModRefInfo (for calls) - A convenience wrapper.
+ ModRefResult getModRefInfo(const CallInst *C, const Value *P, uint64_t Size) {
+ return getModRefInfo(C, Location(P, Size));
}
- ModRefResult getModRefInfo(InvokeInst *I, Value *P, unsigned Size) {
- return getModRefInfo(CallSite(I), 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);
}
- ModRefResult getModRefInfo(VAArgInst* I, Value* P, unsigned Size) {
- return AliasAnalysis::ModRef;
+
+ /// getModRefInfo (for invokes) - A convenience wrapper.
+ ModRefResult getModRefInfo(const InvokeInst *I,
+ const Value *P, uint64_t Size) {
+ return getModRefInfo(I, Location(P, Size));
}
- ModRefResult getModRefInfo(Instruction *I, Value *P, unsigned Size) {
- switch (I->getOpcode()) {
- case Instruction::VAArg: return getModRefInfo((VAArgInst*)I, P, Size);
- case Instruction::Load: return getModRefInfo((LoadInst*)I, P, Size);
- case Instruction::Store: return getModRefInfo((StoreInst*)I, P, Size);
- case Instruction::Call: return getModRefInfo((CallInst*)I, P, Size);
- case Instruction::Invoke: return getModRefInfo((InvokeInst*)I, P, Size);
- default: return NoModRef;
- }
+
+ /// 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 Value *P, unsigned Size);
+ 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 Value *Ptr, unsigned Size);
+ 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
/// identifiable object. This returns true for:
/// Global Variables and Functions (but not Global Aliases)
/// Allocas and Mallocs
-/// ByVal and NoAlias Arguments, if Interprocedural is false
-/// NoAlias returns, if Interprocedural is false
+/// ByVal and NoAlias Arguments
+/// NoAlias returns
///
-bool isIdentifiedObject(const Value *V, bool Interprocedural = false);
+bool isIdentifiedObject(const Value *V);
} // End llvm namespace
-// Because of the way .a files work, we must force the BasicAA implementation to
-// be pulled in if the AliasAnalysis header is included. Otherwise we run
-// the risk of AliasAnalysis being used, but the default implementation not
-// being linked into the tool that uses it.
-FORCE_DEFINING_FILE_TO_BE_LINKED(AliasAnalysis)
-FORCE_DEFINING_FILE_TO_BE_LINKED(BasicAliasAnalysis)
-
#endif
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