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+//===- AliasAnalysisEvaluator.cpp - Alias Analysis Accuracy Evaluator -----===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements a simple N^2 alias analysis accuracy evaluator.
+// Basically, for each function in the program, it simply queries to see how the
+// alias analysis implementation answers alias queries between each pair of
+// pointers in the function.
+//
+// This is inspired and adapted from code by: Naveen Neelakantam, Francesco
+// Spadini, and Wojciech Stryjewski.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/Passes.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Assembly/Writer.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/InstIterator.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+
+static cl::opt<bool> PrintAll("print-all-alias-modref-info", cl::ReallyHidden);
+
+static cl::opt<bool> PrintNoAlias("print-no-aliases", cl::ReallyHidden);
+static cl::opt<bool> PrintMayAlias("print-may-aliases", cl::ReallyHidden);
+static cl::opt<bool> PrintPartialAlias("print-partial-aliases", cl::ReallyHidden);
+static cl::opt<bool> PrintMustAlias("print-must-aliases", cl::ReallyHidden);
+
+static cl::opt<bool> PrintNoModRef("print-no-modref", cl::ReallyHidden);
+static cl::opt<bool> PrintMod("print-mod", cl::ReallyHidden);
+static cl::opt<bool> PrintRef("print-ref", cl::ReallyHidden);
+static cl::opt<bool> PrintModRef("print-modref", cl::ReallyHidden);
+
+static cl::opt<bool> EvalTBAA("evaluate-tbaa", cl::ReallyHidden);
+
+namespace {
+ class AAEval : public FunctionPass {
+ unsigned NoAlias, MayAlias, PartialAlias, MustAlias;
+ unsigned NoModRef, Mod, Ref, ModRef;
+
+ public:
+ static char ID; // Pass identification, replacement for typeid
+ AAEval() : FunctionPass(ID) {
+ initializeAAEvalPass(*PassRegistry::getPassRegistry());
+ }
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<AliasAnalysis>();
+ AU.setPreservesAll();
+ }
+
+ bool doInitialization(Module &M) {
+ NoAlias = MayAlias = PartialAlias = MustAlias = 0;
+ NoModRef = Mod = Ref = ModRef = 0;
+
+ if (PrintAll) {
+ PrintNoAlias = PrintMayAlias = true;
+ PrintPartialAlias = PrintMustAlias = true;
+ PrintNoModRef = PrintMod = PrintRef = PrintModRef = true;
+ }
+ return false;
+ }
+
+ bool runOnFunction(Function &F);
+ bool doFinalization(Module &M);
+ };
+}
+
+char AAEval::ID = 0;
+INITIALIZE_PASS_BEGIN(AAEval, "aa-eval",
+ "Exhaustive Alias Analysis Precision Evaluator", false, true)
+INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
+INITIALIZE_PASS_END(AAEval, "aa-eval",
+ "Exhaustive Alias Analysis Precision Evaluator", false, true)
+
+FunctionPass *llvm::createAAEvalPass() { return new AAEval(); }
+
+static void PrintResults(const char *Msg, bool P, const Value *V1,
+ const Value *V2, const Module *M) {
+ if (P) {
+ std::string o1, o2;
+ {
+ raw_string_ostream os1(o1), os2(o2);
+ WriteAsOperand(os1, V1, true, M);
+ WriteAsOperand(os2, V2, true, M);
+ }
+
+ if (o2 < o1)
+ std::swap(o1, o2);
+ errs() << " " << Msg << ":\t"
+ << o1 << ", "
+ << o2 << "\n";
+ }
+}
+
+static inline void
+PrintModRefResults(const char *Msg, bool P, Instruction *I, Value *Ptr,
+ Module *M) {
+ if (P) {
+ errs() << " " << Msg << ": Ptr: ";
+ WriteAsOperand(errs(), Ptr, true, M);
+ errs() << "\t<->" << *I << '\n';
+ }
+}
+
+static inline void
+PrintModRefResults(const char *Msg, bool P, CallSite CSA, CallSite CSB,
+ Module *M) {
+ if (P) {
+ errs() << " " << Msg << ": " << *CSA.getInstruction()
+ << " <-> " << *CSB.getInstruction() << '\n';
+ }
+}
+
+static inline void
+PrintLoadStoreResults(const char *Msg, bool P, const Value *V1,
+ const Value *V2, const Module *M) {
+ if (P) {
+ errs() << " " << Msg << ": " << *V1
+ << " <-> " << *V2 << '\n';
+ }
+}
+
+static inline bool isInterestingPointer(Value *V) {
+ return V->getType()->isPointerTy()
+ && !isa<ConstantPointerNull>(V);
+}
+
+bool AAEval::runOnFunction(Function &F) {
+ AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
+
+ SetVector<Value *> Pointers;
+ SetVector<CallSite> CallSites;
+ SetVector<Value *> Loads;
+ SetVector<Value *> Stores;
+
+ for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I)
+ if (I->getType()->isPointerTy()) // Add all pointer arguments.
+ Pointers.insert(I);
+
+ for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
+ if (I->getType()->isPointerTy()) // Add all pointer instructions.
+ Pointers.insert(&*I);
+ if (EvalTBAA && isa<LoadInst>(&*I))
+ Loads.insert(&*I);
+ if (EvalTBAA && isa<StoreInst>(&*I))
+ Stores.insert(&*I);
+ Instruction &Inst = *I;
+ if (CallSite CS = cast<Value>(&Inst)) {
+ Value *Callee = CS.getCalledValue();
+ // Skip actual functions for direct function calls.
+ if (!isa<Function>(Callee) && isInterestingPointer(Callee))
+ Pointers.insert(Callee);
+ // Consider formals.
+ for (CallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end();
+ AI != AE; ++AI)
+ if (isInterestingPointer(*AI))
+ Pointers.insert(*AI);
+ CallSites.insert(CS);
+ } else {
+ // Consider all operands.
+ for (Instruction::op_iterator OI = Inst.op_begin(), OE = Inst.op_end();
+ OI != OE; ++OI)
+ if (isInterestingPointer(*OI))
+ Pointers.insert(*OI);
+ }
+ }
+
+ if (PrintNoAlias || PrintMayAlias || PrintPartialAlias || PrintMustAlias ||
+ PrintNoModRef || PrintMod || PrintRef || PrintModRef)
+ errs() << "Function: " << F.getName() << ": " << Pointers.size()
+ << " pointers, " << CallSites.size() << " call sites\n";
+
+ // iterate over the worklist, and run the full (n^2)/2 disambiguations
+ for (SetVector<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end();
+ I1 != E; ++I1) {
+ uint64_t I1Size = AliasAnalysis::UnknownSize;
+ Type *I1ElTy = cast<PointerType>((*I1)->getType())->getElementType();
+ if (I1ElTy->isSized()) I1Size = AA.getTypeStoreSize(I1ElTy);
+
+ for (SetVector<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2) {
+ uint64_t I2Size = AliasAnalysis::UnknownSize;
+ Type *I2ElTy =cast<PointerType>((*I2)->getType())->getElementType();
+ if (I2ElTy->isSized()) I2Size = AA.getTypeStoreSize(I2ElTy);
+
+ switch (AA.alias(*I1, I1Size, *I2, I2Size)) {
+ case AliasAnalysis::NoAlias:
+ PrintResults("NoAlias", PrintNoAlias, *I1, *I2, F.getParent());
+ ++NoAlias; break;
+ case AliasAnalysis::MayAlias:
+ PrintResults("MayAlias", PrintMayAlias, *I1, *I2, F.getParent());
+ ++MayAlias; break;
+ case AliasAnalysis::PartialAlias:
+ PrintResults("PartialAlias", PrintPartialAlias, *I1, *I2,
+ F.getParent());
+ ++PartialAlias; break;
+ case AliasAnalysis::MustAlias:
+ PrintResults("MustAlias", PrintMustAlias, *I1, *I2, F.getParent());
+ ++MustAlias; break;
+ }
+ }
+ }
+
+ if (EvalTBAA) {
+ // iterate over all pairs of load, store
+ for (SetVector<Value *>::iterator I1 = Loads.begin(), E = Loads.end();
+ I1 != E; ++I1) {
+ for (SetVector<Value *>::iterator I2 = Stores.begin(), E2 = Stores.end();
+ I2 != E2; ++I2) {
+ switch (AA.alias(AA.getLocation(cast<LoadInst>(*I1)),
+ AA.getLocation(cast<StoreInst>(*I2)))) {
+ case AliasAnalysis::NoAlias:
+ PrintLoadStoreResults("NoAlias", PrintNoAlias, *I1, *I2,
+ F.getParent());
+ ++NoAlias; break;
+ case AliasAnalysis::MayAlias:
+ PrintLoadStoreResults("MayAlias", PrintMayAlias, *I1, *I2,
+ F.getParent());
+ ++MayAlias; break;
+ case AliasAnalysis::PartialAlias:
+ PrintLoadStoreResults("PartialAlias", PrintPartialAlias, *I1, *I2,
+ F.getParent());
+ ++PartialAlias; break;
+ case AliasAnalysis::MustAlias:
+ PrintLoadStoreResults("MustAlias", PrintMustAlias, *I1, *I2,
+ F.getParent());
+ ++MustAlias; break;
+ }
+ }
+ }
+
+ // iterate over all pairs of store, store
+ for (SetVector<Value *>::iterator I1 = Stores.begin(), E = Stores.end();
+ I1 != E; ++I1) {
+ for (SetVector<Value *>::iterator I2 = Stores.begin(); I2 != I1; ++I2) {
+ switch (AA.alias(AA.getLocation(cast<StoreInst>(*I1)),
+ AA.getLocation(cast<StoreInst>(*I2)))) {
+ case AliasAnalysis::NoAlias:
+ PrintLoadStoreResults("NoAlias", PrintNoAlias, *I1, *I2,
+ F.getParent());
+ ++NoAlias; break;
+ case AliasAnalysis::MayAlias:
+ PrintLoadStoreResults("MayAlias", PrintMayAlias, *I1, *I2,
+ F.getParent());
+ ++MayAlias; break;
+ case AliasAnalysis::PartialAlias:
+ PrintLoadStoreResults("PartialAlias", PrintPartialAlias, *I1, *I2,
+ F.getParent());
+ ++PartialAlias; break;
+ case AliasAnalysis::MustAlias:
+ PrintLoadStoreResults("MustAlias", PrintMustAlias, *I1, *I2,
+ F.getParent());
+ ++MustAlias; break;
+ }
+ }
+ }
+ }
+
+ // Mod/ref alias analysis: compare all pairs of calls and values
+ for (SetVector<CallSite>::iterator C = CallSites.begin(),
+ Ce = CallSites.end(); C != Ce; ++C) {
+ Instruction *I = C->getInstruction();
+
+ for (SetVector<Value *>::iterator V = Pointers.begin(), Ve = Pointers.end();
+ V != Ve; ++V) {
+ uint64_t Size = AliasAnalysis::UnknownSize;
+ Type *ElTy = cast<PointerType>((*V)->getType())->getElementType();
+ if (ElTy->isSized()) Size = AA.getTypeStoreSize(ElTy);
+
+ switch (AA.getModRefInfo(*C, *V, Size)) {
+ case AliasAnalysis::NoModRef:
+ PrintModRefResults("NoModRef", PrintNoModRef, I, *V, F.getParent());
+ ++NoModRef; break;
+ case AliasAnalysis::Mod:
+ PrintModRefResults("Just Mod", PrintMod, I, *V, F.getParent());
+ ++Mod; break;
+ case AliasAnalysis::Ref:
+ PrintModRefResults("Just Ref", PrintRef, I, *V, F.getParent());
+ ++Ref; break;
+ case AliasAnalysis::ModRef:
+ PrintModRefResults("Both ModRef", PrintModRef, I, *V, F.getParent());
+ ++ModRef; break;
+ }
+ }
+ }
+
+ // Mod/ref alias analysis: compare all pairs of calls
+ for (SetVector<CallSite>::iterator C = CallSites.begin(),
+ Ce = CallSites.end(); C != Ce; ++C) {
+ for (SetVector<CallSite>::iterator D = CallSites.begin(); D != Ce; ++D) {
+ if (D == C)
+ continue;
+ switch (AA.getModRefInfo(*C, *D)) {
+ case AliasAnalysis::NoModRef:
+ PrintModRefResults("NoModRef", PrintNoModRef, *C, *D, F.getParent());
+ ++NoModRef; break;
+ case AliasAnalysis::Mod:
+ PrintModRefResults("Just Mod", PrintMod, *C, *D, F.getParent());
+ ++Mod; break;
+ case AliasAnalysis::Ref:
+ PrintModRefResults("Just Ref", PrintRef, *C, *D, F.getParent());
+ ++Ref; break;
+ case AliasAnalysis::ModRef:
+ PrintModRefResults("Both ModRef", PrintModRef, *C, *D, F.getParent());
+ ++ModRef; break;
+ }
+ }
+ }
+
+ return false;
+}
+
+static void PrintPercent(unsigned Num, unsigned Sum) {
+ errs() << "(" << Num*100ULL/Sum << "."
+ << ((Num*1000ULL/Sum) % 10) << "%)\n";
+}
+
+bool AAEval::doFinalization(Module &M) {
+ unsigned AliasSum = NoAlias + MayAlias + PartialAlias + MustAlias;
+ errs() << "===== Alias Analysis Evaluator Report =====\n";
+ if (AliasSum == 0) {
+ errs() << " Alias Analysis Evaluator Summary: No pointers!\n";
+ } else {
+ errs() << " " << AliasSum << " Total Alias Queries Performed\n";
+ errs() << " " << NoAlias << " no alias responses ";
+ PrintPercent(NoAlias, AliasSum);
+ errs() << " " << MayAlias << " may alias responses ";
+ PrintPercent(MayAlias, AliasSum);
+ errs() << " " << PartialAlias << " partial alias responses ";
+ PrintPercent(PartialAlias, AliasSum);
+ errs() << " " << MustAlias << " must alias responses ";
+ PrintPercent(MustAlias, AliasSum);
+ errs() << " Alias Analysis Evaluator Pointer Alias Summary: "
+ << NoAlias*100/AliasSum << "%/" << MayAlias*100/AliasSum << "%/"
+ << PartialAlias*100/AliasSum << "%/"
+ << MustAlias*100/AliasSum << "%\n";
+ }
+
+ // Display the summary for mod/ref analysis
+ unsigned ModRefSum = NoModRef + Mod + Ref + ModRef;
+ if (ModRefSum == 0) {
+ errs() << " Alias Analysis Mod/Ref Evaluator Summary: no mod/ref!\n";
+ } else {
+ errs() << " " << ModRefSum << " Total ModRef Queries Performed\n";
+ errs() << " " << NoModRef << " no mod/ref responses ";
+ PrintPercent(NoModRef, ModRefSum);
+ errs() << " " << Mod << " mod responses ";
+ PrintPercent(Mod, ModRefSum);
+ errs() << " " << Ref << " ref responses ";
+ PrintPercent(Ref, ModRefSum);
+ errs() << " " << ModRef << " mod & ref responses ";
+ PrintPercent(ModRef, ModRefSum);
+ errs() << " Alias Analysis Evaluator Mod/Ref Summary: "
+ << NoModRef*100/ModRefSum << "%/" << Mod*100/ModRefSum << "%/"
+ << Ref*100/ModRefSum << "%/" << ModRef*100/ModRefSum << "%\n";
+ }
+
+ return false;
+}