//===- llvm/Analysis/AliasAnalysis.h - Alias Analysis Interface -*- C++ -*-===//
-//
+//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and 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
#define LLVM_ANALYSIS_ALIAS_ANALYSIS_H
#include "llvm/Support/CallSite.h"
-#include "llvm/Pass.h" // Need this for IncludeFile
+#include "llvm/System/IncludeFile.h"
+#include <vector>
namespace llvm {
class LoadInst;
class StoreInst;
+class VAArgInst;
class TargetData;
+class Pass;
+class AnalysisUsage;
class AliasAnalysis {
protected:
/// called multiple times.
///
void InitializeAliasAnalysis(Pass *P);
-
+
// getAnalysisUsage - All alias analysis implementations should invoke this
// directly (using AliasAnalysis::getAnalysisUsage(AU)) to make sure that
// TargetData is required by the pass.
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
///
virtual bool pointsToConstantMemory(const Value *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
+ // non-volatile and well known ways, but does not access any other memory.
+ //
+ // Clients may call getArgumentAccesses to get specific information about
+ // how pointer arguments are used.
+ AccessesArguments,
+
+ // AccessesArgumentsAndGlobals - This function has accesses function
+ // arguments and global variables in non-volatile and well-known ways, but
+ // does not access any other memory.
+ //
+ // Clients may call getArgumentAccesses to get specific information about
+ // how pointer arguments and globals 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
+ };
+
+ /// 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;
+
+ /// ModRefInfo - Whether the pointer is loaded or stored to/from.
+ ///
+ ModRefResult ModRefInfo;
+
+ /// AccessType - Specific fine-grained access information for the argument.
+ /// If none of these classifications is general enough, the
+ /// getModRefBehavior method should not return AccessesArguments*. If a
+ /// record is not returned for a particular argument, the argument is never
+ /// dead and never dereferenced.
+ enum AccessType {
+ /// ScalarAccess - The pointer is dereferenced.
+ ///
+ ScalarAccess,
+
+ /// ArrayAccess - The pointer is indexed through as an array of elements.
+ ///
+ ArrayAccess,
+
+ /// ElementAccess ?? P->F only?
+
+ /// CallsThrough - Indirect calls are made through the specified function
+ /// pointer.
+ CallsThrough
+ };
+ };
+
+ /// 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.
+ virtual ModRefBehavior getModRefBehavior(Function *F, CallSite CS,
+ std::vector<PointerAccessInfo> *Info = 0);
+
/// 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
///
/// This property corresponds to the GCC 'const' attribute.
///
- virtual bool doesNotAccessMemory(Function *F);
+ bool doesNotAccessMemory(Function *F) {
+ return getModRefBehavior(F, CallSite()) == DoesNotAccessMemory;
+ }
/// onlyReadsMemory - If the specified function is known to only read from
/// non-volatile memory (or not access memory at all), return true. Functions
///
/// This property corresponds to the GCC 'pure' attribute.
///
- virtual bool onlyReadsMemory(Function *F);
-
+ bool onlyReadsMemory(Function *F) {
+ /// FIXME: If the analysis returns more precise info, we can reduce it to
+ /// this.
+ ModRefBehavior MRB = getModRefBehavior(F, CallSite());
+ return MRB == DoesNotAccessMemory || MRB == OnlyReadsMemory;
+ }
- //===--------------------------------------------------------------------===//
- /// 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 };
/// getModRefInfo - Return information about whether or not an instruction may
/// read or write memory specified by the pointer operand. An instruction
ModRefResult getModRefInfo(InvokeInst *I, Value *P, unsigned Size) {
return getModRefInfo(CallSite(I), P, Size);
}
+ ModRefResult getModRefInfo(VAArgInst* I, Value* P, unsigned Size) {
+ return AliasAnalysis::Mod;
+ }
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);
}
};
+} // 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.
-//
-extern void BasicAAStub();
-static IncludeFile HDR_INCLUDE_BASICAA_CPP((void*)&BasicAAStub);
-
-} // End llvm namespace
+FORCE_DEFINING_FILE_TO_BE_LINKED(AliasAnalysis)
+FORCE_DEFINING_FILE_TO_BE_LINKED(BasicAliasAnalysis)
#endif