llvm-6502/lib/Analysis/AliasAnalysis.cpp
Reid Spencer 4f1bd9e996 For PR780:
1. Fix the macros in IncludeFile.h to put everything in the llvm namespace
2. Replace the previous explicit mechanism in all the .h and .cpp files
   with the macros in IncludeFile.h
This gets us a consistent mechanism throughout LLVM for ensuring linkage.
Next step is to make sure its used in enough places.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28715 91177308-0d34-0410-b5e6-96231b3b80d8
2006-06-07 22:00:26 +00:00

192 lines
7.5 KiB
C++

//===- AliasAnalysis.cpp - Generic Alias Analysis Interface Implementation -==//
//
// 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 implements the generic AliasAnalysis interface which is used as the
// common interface used by all clients and implementations of alias analysis.
//
// This file also implements the default version of the AliasAnalysis interface
// that is to be used when no other implementation is specified. This does some
// simple tests that detect obvious cases: two different global pointers cannot
// alias, a global cannot alias a malloc, two different mallocs cannot alias,
// etc.
//
// This alias analysis implementation really isn't very good for anything, but
// it is very fast, and makes a nice clean default implementation. Because it
// handles lots of little corner cases, other, more complex, alias analysis
// implementations may choose to rely on this pass to resolve these simple and
// easy cases.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Pass.h"
#include "llvm/BasicBlock.h"
#include "llvm/Instructions.h"
#include "llvm/Type.h"
#include "llvm/Target/TargetData.h"
#include <iostream>
using namespace llvm;
// Register the AliasAnalysis interface, providing a nice name to refer to.
namespace {
RegisterAnalysisGroup<AliasAnalysis> Z("Alias Analysis");
}
//===----------------------------------------------------------------------===//
// Default chaining methods
//===----------------------------------------------------------------------===//
AliasAnalysis::AliasResult
AliasAnalysis::alias(const Value *V1, unsigned V1Size,
const Value *V2, unsigned V2Size) {
assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
return AA->alias(V1, V1Size, V2, V2Size);
}
void AliasAnalysis::getMustAliases(Value *P, std::vector<Value*> &RetVals) {
assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
return AA->getMustAliases(P, RetVals);
}
bool AliasAnalysis::pointsToConstantMemory(const Value *P) {
assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
return AA->pointsToConstantMemory(P);
}
AliasAnalysis::ModRefBehavior
AliasAnalysis::getModRefBehavior(Function *F, CallSite CS,
std::vector<PointerAccessInfo> *Info) {
assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
return AA->getModRefBehavior(F, CS, Info);
}
bool AliasAnalysis::hasNoModRefInfoForCalls() const {
assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
return AA->hasNoModRefInfoForCalls();
}
void AliasAnalysis::deleteValue(Value *V) {
assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
AA->deleteValue(V);
}
void AliasAnalysis::copyValue(Value *From, Value *To) {
assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
AA->copyValue(From, To);
}
AliasAnalysis::ModRefResult
AliasAnalysis::getModRefInfo(CallSite CS1, CallSite CS2) {
// FIXME: we can do better.
assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
return AA->getModRefInfo(CS1, CS2);
}
//===----------------------------------------------------------------------===//
// AliasAnalysis non-virtual helper method implementation
//===----------------------------------------------------------------------===//
AliasAnalysis::ModRefResult
AliasAnalysis::getModRefInfo(LoadInst *L, Value *P, unsigned Size) {
return alias(L->getOperand(0), TD->getTypeSize(L->getType()),
P, Size) ? Ref : NoModRef;
}
AliasAnalysis::ModRefResult
AliasAnalysis::getModRefInfo(StoreInst *S, Value *P, unsigned Size) {
// If the stored address cannot alias the pointer in question, then the
// pointer cannot be modified by the store.
if (!alias(S->getOperand(1), TD->getTypeSize(S->getOperand(0)->getType()),
P, Size))
return NoModRef;
// If the pointer is a pointer to constant memory, then it could not have been
// modified by this store.
return pointsToConstantMemory(P) ? NoModRef : Mod;
}
AliasAnalysis::ModRefResult
AliasAnalysis::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
ModRefResult Mask = ModRef;
if (Function *F = CS.getCalledFunction()) {
ModRefBehavior MRB = getModRefBehavior(F, CallSite());
if (MRB == OnlyReadsMemory)
Mask = Ref;
else if (MRB == DoesNotAccessMemory)
return NoModRef;
}
if (!AA) return Mask;
// If P points to a constant memory location, the call definitely could not
// modify the memory location.
if ((Mask & Mod) && AA->pointsToConstantMemory(P))
Mask = ModRefResult(Mask & ~Mod);
return ModRefResult(Mask & AA->getModRefInfo(CS, P, Size));
}
// AliasAnalysis destructor: DO NOT move this to the header file for
// AliasAnalysis or else clients of the AliasAnalysis class may not depend on
// the AliasAnalysis.o file in the current .a file, causing alias analysis
// support to not be included in the tool correctly!
//
AliasAnalysis::~AliasAnalysis() {}
/// setTargetData - Subclasses must call this method to initialize the
/// AliasAnalysis interface before any other methods are called.
///
void AliasAnalysis::InitializeAliasAnalysis(Pass *P) {
TD = &P->getAnalysis<TargetData>();
AA = &P->getAnalysis<AliasAnalysis>();
}
// getAnalysisUsage - All alias analysis implementations should invoke this
// directly (using AliasAnalysis::getAnalysisUsage(AU)) to make sure that
// TargetData is required by the pass.
void AliasAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<TargetData>(); // All AA's need TargetData.
AU.addRequired<AliasAnalysis>(); // All AA's chain
}
/// canBasicBlockModify - Return true if it is possible for execution of the
/// specified basic block to modify the value pointed to by Ptr.
///
bool AliasAnalysis::canBasicBlockModify(const BasicBlock &BB,
const Value *Ptr, unsigned Size) {
return canInstructionRangeModify(BB.front(), BB.back(), Ptr, 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 AliasAnalysis::canInstructionRangeModify(const Instruction &I1,
const Instruction &I2,
const Value *Ptr, unsigned Size) {
assert(I1.getParent() == I2.getParent() &&
"Instructions not in same basic block!");
BasicBlock::iterator I = const_cast<Instruction*>(&I1);
BasicBlock::iterator E = const_cast<Instruction*>(&I2);
++E; // Convert from inclusive to exclusive range.
for (; I != E; ++I) // Check every instruction in range
if (getModRefInfo(I, const_cast<Value*>(Ptr), Size) & Mod)
return true;
return false;
}
// Because of the way .a files work, we must force the BasicAA implementation to
// be pulled in if the AliasAnalysis classes are pulled in. Otherwise we run
// the risk of AliasAnalysis being used, but the default implementation not
// being linked into the tool that uses it.
DEFINING_FILE_FOR(AliasAnalysis)