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//===- AliasDebugger.cpp - Simple Alias Analysis Use Checker --------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This simple pass checks alias analysis users to ensure that if they
// create a new value, they do not query AA without informing it of the value.
// It acts as a shim over any other AA pass you want.
//
// Yes keeping track of every value in the program is expensive, but this is
// a debugging pass.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/Passes.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Module.h"
#include "llvm/Pass.h"
#include <set>
using namespace llvm;
namespace {
class AliasDebugger : public ModulePass, public AliasAnalysis {
//What we do is simple. Keep track of every value the AA could
//know about, and verify that queries are one of those.
//A query to a value that didn't exist when the AA was created
//means someone forgot to update the AA when creating new values
std::set<const Value*> Vals;
public:
static char ID; // Class identification, replacement for typeinfo
AliasDebugger() : ModulePass(ID) {
initializeAliasDebuggerPass(*PassRegistry::getPassRegistry());
}
bool runOnModule(Module &M) override {
InitializeAliasAnalysis(this, &M.getDataLayout()); // set up super class
for(Module::global_iterator I = M.global_begin(),
E = M.global_end(); I != E; ++I) {
Vals.insert(&*I);
for (User::const_op_iterator OI = I->op_begin(),
OE = I->op_end(); OI != OE; ++OI)
Vals.insert(*OI);
}
for(Module::iterator I = M.begin(),
E = M.end(); I != E; ++I){
Vals.insert(&*I);
if(!I->isDeclaration()) {
for (Function::arg_iterator AI = I->arg_begin(), AE = I->arg_end();
AI != AE; ++AI)
Vals.insert(&*AI);
for (Function::const_iterator FI = I->begin(), FE = I->end();
FI != FE; ++FI)
for (BasicBlock::const_iterator BI = FI->begin(), BE = FI->end();
BI != BE; ++BI) {
Vals.insert(&*BI);
for (User::const_op_iterator OI = BI->op_begin(),
OE = BI->op_end(); OI != OE; ++OI)
Vals.insert(*OI);
}
}
}
return false;
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AliasAnalysis::getAnalysisUsage(AU);
AU.setPreservesAll(); // Does not transform code
}
/// getAdjustedAnalysisPointer - This method is used when a pass implements
/// an analysis interface through multiple inheritance. If needed, it
/// should override this to adjust the this pointer as needed for the
/// specified pass info.
void *getAdjustedAnalysisPointer(AnalysisID PI) override {
if (PI == &AliasAnalysis::ID)
return (AliasAnalysis*)this;
return this;
}
//------------------------------------------------
// Implement the AliasAnalysis API
//
AliasResult alias(const Location &LocA, const Location &LocB) override {
assert(Vals.find(LocA.Ptr) != Vals.end() &&
"Never seen value in AA before");
assert(Vals.find(LocB.Ptr) != Vals.end() &&
"Never seen value in AA before");
return AliasAnalysis::alias(LocA, LocB);
}
ModRefResult getModRefInfo(ImmutableCallSite CS,
const Location &Loc) override {
assert(Vals.find(Loc.Ptr) != Vals.end() && "Never seen value in AA before");
return AliasAnalysis::getModRefInfo(CS, Loc);
}
ModRefResult getModRefInfo(ImmutableCallSite CS1,
ImmutableCallSite CS2) override {
return AliasAnalysis::getModRefInfo(CS1,CS2);
}
bool pointsToConstantMemory(const Location &Loc, bool OrLocal) override {
assert(Vals.find(Loc.Ptr) != Vals.end() && "Never seen value in AA before");
return AliasAnalysis::pointsToConstantMemory(Loc, OrLocal);
}
void deleteValue(Value *V) override {
assert(Vals.find(V) != Vals.end() && "Never seen value in AA before");
AliasAnalysis::deleteValue(V);
}
void copyValue(Value *From, Value *To) override {
Vals.insert(To);
AliasAnalysis::copyValue(From, To);
}
};
}
char AliasDebugger::ID = 0;
INITIALIZE_AG_PASS(AliasDebugger, AliasAnalysis, "debug-aa",
"AA use debugger", false, true, false)
Pass *llvm::createAliasDebugger() { return new AliasDebugger(); }
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