1//===- AliasAnalysisEvaluator.cpp - Alias Analysis Accuracy Evaluator -----===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "llvm/Analysis/AliasAnalysisEvaluator.h"
10#include "llvm/ADT/SetVector.h"
11#include "llvm/Analysis/AliasAnalysis.h"
12#include "llvm/IR/DataLayout.h"
13#include "llvm/IR/Function.h"
14#include "llvm/IR/InstIterator.h"
15#include "llvm/IR/Instructions.h"
16#include "llvm/IR/Module.h"
17#include "llvm/InitializePasses.h"
18#include "llvm/Pass.h"
19#include "llvm/Support/CommandLine.h"
20#include "llvm/Support/raw_ostream.h"
21using namespace llvm;
22
23static cl::opt<bool> PrintAll("print-all-alias-modref-info", cl::ReallyHidden);
24
25static cl::opt<bool> PrintNoAlias("print-no-aliases", cl::ReallyHidden);
26static cl::opt<bool> PrintMayAlias("print-may-aliases", cl::ReallyHidden);
27static cl::opt<bool> PrintPartialAlias("print-partial-aliases", cl::ReallyHidden);
28static cl::opt<bool> PrintMustAlias("print-must-aliases", cl::ReallyHidden);
29
30static cl::opt<bool> PrintNoModRef("print-no-modref", cl::ReallyHidden);
31static cl::opt<bool> PrintRef("print-ref", cl::ReallyHidden);
32static cl::opt<bool> PrintMod("print-mod", cl::ReallyHidden);
33static cl::opt<bool> PrintModRef("print-modref", cl::ReallyHidden);
34
35static cl::opt<bool> EvalAAMD("evaluate-aa-metadata", cl::ReallyHidden);
36
37static void PrintResults(AliasResult AR, bool P,
38                         std::pair<const Value *, Type *> Loc1,
39                         std::pair<const Value *, Type *> Loc2,
40                         const Module *M) {
41  if (PrintAll || P) {
42    Type *Ty1 = Loc1.second, *Ty2 = Loc2.second;
43    unsigned AS1 = Loc1.first->getType()->getPointerAddressSpace();
44    unsigned AS2 = Loc2.first->getType()->getPointerAddressSpace();
45    std::string o1, o2;
46    {
47      raw_string_ostream os1(o1), os2(o2);
48      Loc1.first->printAsOperand(os1, false, M);
49      Loc2.first->printAsOperand(os2, false, M);
50    }
51
52    if (o2 < o1) {
53      std::swap(o1, o2);
54      std::swap(Ty1, Ty2);
55      std::swap(AS1, AS2);
56      // Change offset sign for the local AR, for printing only.
57      AR.swap();
58    }
59    errs() << "  " << AR << ":\t";
60    Ty1->print(errs(), false, /* NoDetails */ true);
61    if (AS1 != 0)
62      errs() << " addrspace(" << AS1 << ")";
63    errs() << "* " << o1 << ", ";
64    Ty2->print(errs(), false, /* NoDetails */ true);
65    if (AS2 != 0)
66      errs() << " addrspace(" << AS2 << ")";
67    errs() << "* " << o2 << "\n";
68  }
69}
70
71static inline void PrintModRefResults(
72    const char *Msg, bool P, Instruction *I,
73    std::pair<const Value *, Type *> Loc, Module *M) {
74  if (PrintAll || P) {
75    errs() << "  " << Msg << ":  Ptr: ";
76    Loc.second->print(errs(), false, /* NoDetails */ true);
77    errs() << "* ";
78    Loc.first->printAsOperand(errs(), false, M);
79    errs() << "\t<->" << *I << '\n';
80  }
81}
82
83static inline void PrintModRefResults(const char *Msg, bool P, CallBase *CallA,
84                                      CallBase *CallB, Module *M) {
85  if (PrintAll || P) {
86    errs() << "  " << Msg << ": " << *CallA << " <-> " << *CallB << '\n';
87  }
88}
89
90static inline void PrintLoadStoreResults(AliasResult AR, bool P,
91                                         const Value *V1, const Value *V2,
92                                         const Module *M) {
93  if (PrintAll || P) {
94    errs() << "  " << AR << ": " << *V1 << " <-> " << *V2 << '\n';
95  }
96}
97
98PreservedAnalyses AAEvaluator::run(Function &F, FunctionAnalysisManager &AM) {
99  runInternal(F, AM.getResult<AAManager>(F));
100  return PreservedAnalyses::all();
101}
102
103void AAEvaluator::runInternal(Function &F, AAResults &AA) {
104  const DataLayout &DL = F.getParent()->getDataLayout();
105
106  ++FunctionCount;
107
108  SetVector<std::pair<const Value *, Type *>> Pointers;
109  SmallSetVector<CallBase *, 16> Calls;
110  SetVector<Value *> Loads;
111  SetVector<Value *> Stores;
112
113  for (Instruction &Inst : instructions(F)) {
114    if (auto *LI = dyn_cast<LoadInst>(&Inst)) {
115      Pointers.insert({LI->getPointerOperand(), LI->getType()});
116      Loads.insert(LI);
117    } else if (auto *SI = dyn_cast<StoreInst>(&Inst)) {
118      Pointers.insert({SI->getPointerOperand(),
119                       SI->getValueOperand()->getType()});
120      Stores.insert(SI);
121    } else if (auto *CB = dyn_cast<CallBase>(&Inst))
122      Calls.insert(CB);
123  }
124
125  if (PrintAll || PrintNoAlias || PrintMayAlias || PrintPartialAlias ||
126      PrintMustAlias || PrintNoModRef || PrintMod || PrintRef || PrintModRef)
127    errs() << "Function: " << F.getName() << ": " << Pointers.size()
128           << " pointers, " << Calls.size() << " call sites\n";
129
130  // iterate over the worklist, and run the full (n^2)/2 disambiguations
131  for (auto I1 = Pointers.begin(), E = Pointers.end(); I1 != E; ++I1) {
132    LocationSize Size1 = LocationSize::precise(DL.getTypeStoreSize(I1->second));
133    for (auto I2 = Pointers.begin(); I2 != I1; ++I2) {
134      LocationSize Size2 =
135          LocationSize::precise(DL.getTypeStoreSize(I2->second));
136      AliasResult AR = AA.alias(I1->first, Size1, I2->first, Size2);
137      switch (AR) {
138      case AliasResult::NoAlias:
139        PrintResults(AR, PrintNoAlias, *I1, *I2, F.getParent());
140        ++NoAliasCount;
141        break;
142      case AliasResult::MayAlias:
143        PrintResults(AR, PrintMayAlias, *I1, *I2, F.getParent());
144        ++MayAliasCount;
145        break;
146      case AliasResult::PartialAlias:
147        PrintResults(AR, PrintPartialAlias, *I1, *I2, F.getParent());
148        ++PartialAliasCount;
149        break;
150      case AliasResult::MustAlias:
151        PrintResults(AR, PrintMustAlias, *I1, *I2, F.getParent());
152        ++MustAliasCount;
153        break;
154      }
155    }
156  }
157
158  if (EvalAAMD) {
159    // iterate over all pairs of load, store
160    for (Value *Load : Loads) {
161      for (Value *Store : Stores) {
162        AliasResult AR = AA.alias(MemoryLocation::get(cast<LoadInst>(Load)),
163                                  MemoryLocation::get(cast<StoreInst>(Store)));
164        switch (AR) {
165        case AliasResult::NoAlias:
166          PrintLoadStoreResults(AR, PrintNoAlias, Load, Store, F.getParent());
167          ++NoAliasCount;
168          break;
169        case AliasResult::MayAlias:
170          PrintLoadStoreResults(AR, PrintMayAlias, Load, Store, F.getParent());
171          ++MayAliasCount;
172          break;
173        case AliasResult::PartialAlias:
174          PrintLoadStoreResults(AR, PrintPartialAlias, Load, Store, F.getParent());
175          ++PartialAliasCount;
176          break;
177        case AliasResult::MustAlias:
178          PrintLoadStoreResults(AR, PrintMustAlias, Load, Store, F.getParent());
179          ++MustAliasCount;
180          break;
181        }
182      }
183    }
184
185    // iterate over all pairs of store, store
186    for (SetVector<Value *>::iterator I1 = Stores.begin(), E = Stores.end();
187         I1 != E; ++I1) {
188      for (SetVector<Value *>::iterator I2 = Stores.begin(); I2 != I1; ++I2) {
189        AliasResult AR = AA.alias(MemoryLocation::get(cast<StoreInst>(*I1)),
190                                  MemoryLocation::get(cast<StoreInst>(*I2)));
191        switch (AR) {
192        case AliasResult::NoAlias:
193          PrintLoadStoreResults(AR, PrintNoAlias, *I1, *I2, F.getParent());
194          ++NoAliasCount;
195          break;
196        case AliasResult::MayAlias:
197          PrintLoadStoreResults(AR, PrintMayAlias, *I1, *I2, F.getParent());
198          ++MayAliasCount;
199          break;
200        case AliasResult::PartialAlias:
201          PrintLoadStoreResults(AR, PrintPartialAlias, *I1, *I2, F.getParent());
202          ++PartialAliasCount;
203          break;
204        case AliasResult::MustAlias:
205          PrintLoadStoreResults(AR, PrintMustAlias, *I1, *I2, F.getParent());
206          ++MustAliasCount;
207          break;
208        }
209      }
210    }
211  }
212
213  // Mod/ref alias analysis: compare all pairs of calls and values
214  for (CallBase *Call : Calls) {
215    for (const auto &Pointer : Pointers) {
216      LocationSize Size =
217          LocationSize::precise(DL.getTypeStoreSize(Pointer.second));
218      switch (AA.getModRefInfo(Call, Pointer.first, Size)) {
219      case ModRefInfo::NoModRef:
220        PrintModRefResults("NoModRef", PrintNoModRef, Call, Pointer,
221                           F.getParent());
222        ++NoModRefCount;
223        break;
224      case ModRefInfo::Mod:
225        PrintModRefResults("Just Mod", PrintMod, Call, Pointer, F.getParent());
226        ++ModCount;
227        break;
228      case ModRefInfo::Ref:
229        PrintModRefResults("Just Ref", PrintRef, Call, Pointer, F.getParent());
230        ++RefCount;
231        break;
232      case ModRefInfo::ModRef:
233        PrintModRefResults("Both ModRef", PrintModRef, Call, Pointer,
234                           F.getParent());
235        ++ModRefCount;
236        break;
237      }
238    }
239  }
240
241  // Mod/ref alias analysis: compare all pairs of calls
242  for (CallBase *CallA : Calls) {
243    for (CallBase *CallB : Calls) {
244      if (CallA == CallB)
245        continue;
246      switch (AA.getModRefInfo(CallA, CallB)) {
247      case ModRefInfo::NoModRef:
248        PrintModRefResults("NoModRef", PrintNoModRef, CallA, CallB,
249                           F.getParent());
250        ++NoModRefCount;
251        break;
252      case ModRefInfo::Mod:
253        PrintModRefResults("Just Mod", PrintMod, CallA, CallB, F.getParent());
254        ++ModCount;
255        break;
256      case ModRefInfo::Ref:
257        PrintModRefResults("Just Ref", PrintRef, CallA, CallB, F.getParent());
258        ++RefCount;
259        break;
260      case ModRefInfo::ModRef:
261        PrintModRefResults("Both ModRef", PrintModRef, CallA, CallB,
262                           F.getParent());
263        ++ModRefCount;
264        break;
265      }
266    }
267  }
268}
269
270static void PrintPercent(int64_t Num, int64_t Sum) {
271  errs() << "(" << Num * 100LL / Sum << "." << ((Num * 1000LL / Sum) % 10)
272         << "%)\n";
273}
274
275AAEvaluator::~AAEvaluator() {
276  if (FunctionCount == 0)
277    return;
278
279  int64_t AliasSum =
280      NoAliasCount + MayAliasCount + PartialAliasCount + MustAliasCount;
281  errs() << "===== Alias Analysis Evaluator Report =====\n";
282  if (AliasSum == 0) {
283    errs() << "  Alias Analysis Evaluator Summary: No pointers!\n";
284  } else {
285    errs() << "  " << AliasSum << " Total Alias Queries Performed\n";
286    errs() << "  " << NoAliasCount << " no alias responses ";
287    PrintPercent(NoAliasCount, AliasSum);
288    errs() << "  " << MayAliasCount << " may alias responses ";
289    PrintPercent(MayAliasCount, AliasSum);
290    errs() << "  " << PartialAliasCount << " partial alias responses ";
291    PrintPercent(PartialAliasCount, AliasSum);
292    errs() << "  " << MustAliasCount << " must alias responses ";
293    PrintPercent(MustAliasCount, AliasSum);
294    errs() << "  Alias Analysis Evaluator Pointer Alias Summary: "
295           << NoAliasCount * 100 / AliasSum << "%/"
296           << MayAliasCount * 100 / AliasSum << "%/"
297           << PartialAliasCount * 100 / AliasSum << "%/"
298           << MustAliasCount * 100 / AliasSum << "%\n";
299  }
300
301  // Display the summary for mod/ref analysis
302  int64_t ModRefSum = NoModRefCount + RefCount + ModCount + ModRefCount;
303  if (ModRefSum == 0) {
304    errs() << "  Alias Analysis Mod/Ref Evaluator Summary: no "
305              "mod/ref!\n";
306  } else {
307    errs() << "  " << ModRefSum << " Total ModRef Queries Performed\n";
308    errs() << "  " << NoModRefCount << " no mod/ref responses ";
309    PrintPercent(NoModRefCount, ModRefSum);
310    errs() << "  " << ModCount << " mod responses ";
311    PrintPercent(ModCount, ModRefSum);
312    errs() << "  " << RefCount << " ref responses ";
313    PrintPercent(RefCount, ModRefSum);
314    errs() << "  " << ModRefCount << " mod & ref responses ";
315    PrintPercent(ModRefCount, ModRefSum);
316    errs() << "  Alias Analysis Evaluator Mod/Ref Summary: "
317           << NoModRefCount * 100 / ModRefSum << "%/"
318           << ModCount * 100 / ModRefSum << "%/" << RefCount * 100 / ModRefSum
319           << "%/" << ModRefCount * 100 / ModRefSum << "%\n";
320  }
321}
322
323namespace llvm {
324class AAEvalLegacyPass : public FunctionPass {
325  std::unique_ptr<AAEvaluator> P;
326
327public:
328  static char ID; // Pass identification, replacement for typeid
329  AAEvalLegacyPass() : FunctionPass(ID) {
330    initializeAAEvalLegacyPassPass(*PassRegistry::getPassRegistry());
331  }
332
333  void getAnalysisUsage(AnalysisUsage &AU) const override {
334    AU.addRequired<AAResultsWrapperPass>();
335    AU.setPreservesAll();
336  }
337
338  bool doInitialization(Module &M) override {
339    P.reset(new AAEvaluator());
340    return false;
341  }
342
343  bool runOnFunction(Function &F) override {
344    P->runInternal(F, getAnalysis<AAResultsWrapperPass>().getAAResults());
345    return false;
346  }
347  bool doFinalization(Module &M) override {
348    P.reset();
349    return false;
350  }
351};
352}
353
354char AAEvalLegacyPass::ID = 0;
355INITIALIZE_PASS_BEGIN(AAEvalLegacyPass, "aa-eval",
356                      "Exhaustive Alias Analysis Precision Evaluator", false,
357                      true)
358INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
359INITIALIZE_PASS_END(AAEvalLegacyPass, "aa-eval",
360                    "Exhaustive Alias Analysis Precision Evaluator", false,
361                    true)
362
363FunctionPass *llvm::createAAEvalPass() { return new AAEvalLegacyPass(); }
364