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