llvm/tools/verify-uselistorder/verify-uselistorder.cpp

   1 //===- verify-uselistorder.cpp - The LLVM Modular Optimizer ---------------===//
   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 // Verify that use-list order can be serialized correctly.  After reading the
  10 // provided IR, this tool shuffles the use-lists and then writes and reads to a
  11 // separate Module whose use-list orders are compared to the original.
  12 //
  13 // The shuffles are deterministic, but guarantee that use-lists will change.
  14 // The algorithm per iteration is as follows:
  15 //
  16 //  1. Seed the random number generator.  The seed is different for each
  17 //     shuffle.  Shuffle 0 uses default+0, shuffle 1 uses default+1, and so on.
  18 //
  19 //  2. Visit every Value in a deterministic order.
  20 //
  21 //  3. Assign a random number to each Use in the Value's use-list in order.
  22 //
  23 //  4. If the numbers are already in order, reassign numbers until they aren't.
  24 //
  25 //  5. Sort the use-list using Value::sortUseList(), which is a stable sort.
  26 //
  27 //===----------------------------------------------------------------------===//
  28
  29 #include "llvm/ADT/DenseMap.h"
  30 #include "llvm/ADT/DenseSet.h"
  31 #include "llvm/AsmParser/Parser.h"
  32 #include "llvm/Bitcode/BitcodeReader.h"
  33 #include "llvm/Bitcode/BitcodeWriter.h"
  34 #include "llvm/IR/LLVMContext.h"
  35 #include "llvm/IR/Module.h"
  36 #include "llvm/IR/UseListOrder.h"
  37 #include "llvm/IR/Verifier.h"
  38 #include "llvm/IRReader/IRReader.h"
  39 #include "llvm/Support/CommandLine.h"
  40 #include "llvm/Support/Debug.h"
  41 #include "llvm/Support/ErrorHandling.h"
  42 #include "llvm/Support/FileSystem.h"
  43 #include "llvm/Support/FileUtilities.h"
  44 #include "llvm/Support/InitLLVM.h"
  45 #include "llvm/Support/MemoryBuffer.h"
  46 #include "llvm/Support/SourceMgr.h"
  47 #include "llvm/Support/SystemUtils.h"
  48 #include "llvm/Support/raw_ostream.h"
  49 #include <random>
  50 #include <vector>
  51
  52 using namespace llvm;
  53
  54 #define DEBUG_TYPE "uselistorder"
  55
  56 static cl::OptionCategory Cat("verify-uselistorder Options");
  57
  58 static cl::opt<std::string> InputFilename(cl::Positional,
  59                                           cl::desc("<input bitcode file>"),
  60                                           cl::init("-"),
  61                                           cl::value_desc("filename"));
  62
  63 static cl::opt<bool> SaveTemps("save-temps", cl::desc("Save temp files"),
  64                                cl::cat(Cat));
  65
  66 static cl::opt<unsigned>
  67     NumShuffles("num-shuffles",
  68                 cl::desc("Number of times to shuffle and verify use-lists"),
  69                 cl::init(1), cl::cat(Cat));
  70
  71 extern cl::opt<cl::boolOrDefault> PreserveInputDbgFormat;
  72
  73 namespace {
  74
  75 struct TempFile {
  76   std::string Filename;
  77   FileRemover Remover;
  78   bool init(const std::string &Ext);
  79   bool writeBitcode(const Module &M) const;
  80   bool writeAssembly(const Module &M) const;
  81   std::unique_ptr<Module> readBitcode(LLVMContext &Context) const;
  82   std::unique_ptr<Module> readAssembly(LLVMContext &Context) const;
  83 };
  84
  85 struct ValueMapping {
  86   DenseMap<const Value *, unsigned> IDs;
  87   std::vector<const Value *> Values;
  88
  89   /// Construct a value mapping for module.
  90   ///
  91   /// Creates mapping from every value in \c M to an ID.  This mapping includes
  92   /// un-referencable values.
  93   ///
  94   /// Every \a Value that gets serialized in some way should be represented
  95   /// here.  The order needs to be deterministic, but it's unnecessary to match
  96   /// the value-ids in the bitcode writer.
  97   ///
  98   /// All constants that are referenced by other values are included in the
  99   /// mapping, but others -- which wouldn't be serialized -- are not.
 100   ValueMapping(const Module &M);
 101
 102   /// Map a value.
 103   ///
 104   /// Maps a value.  If it's a constant, maps all of its operands first.
 105   void map(const Value *V);
 106   unsigned lookup(const Value *V) const { return IDs.lookup(V); }
 107 };
 108
 109 } // end namespace
 110
 111 bool TempFile::init(const std::string &Ext) {
 112   SmallVector<char, 64> Vector;
 113   LLVM_DEBUG(dbgs() << " - create-temp-file\n");
 114   if (auto EC = sys::fs::createTemporaryFile("uselistorder", Ext, Vector)) {
 115     errs() << "verify-uselistorder: error: " << EC.message() << "\n";
 116     return true;
 117   }
 118   assert(!Vector.empty());
 119
 120   Filename.assign(Vector.data(), Vector.data() + Vector.size());
 121   Remover.setFile(Filename, !SaveTemps);
 122   if (SaveTemps)
 123     outs() << " - filename = " << Filename << "\n";
 124   return false;
 125 }
 126
 127 bool TempFile::writeBitcode(const Module &M) const {
 128   LLVM_DEBUG(dbgs() << " - write bitcode\n");
 129   std::error_code EC;
 130   raw_fd_ostream OS(Filename, EC, sys::fs::OF_None);
 131   if (EC) {
 132     errs() << "verify-uselistorder: error: " << EC.message() << "\n";
 133     return true;
 134   }
 135
 136   WriteBitcodeToFile(M, OS, /* ShouldPreserveUseListOrder */ true);
 137   return false;
 138 }
 139
 140 bool TempFile::writeAssembly(const Module &M) const {
 141   LLVM_DEBUG(dbgs() << " - write assembly\n");
 142   std::error_code EC;
 143   raw_fd_ostream OS(Filename, EC, sys::fs::OF_TextWithCRLF);
 144   if (EC) {
 145     errs() << "verify-uselistorder: error: " << EC.message() << "\n";
 146     return true;
 147   }
 148
 149   M.print(OS, nullptr, /* ShouldPreserveUseListOrder */ true);
 150   return false;
 151 }
 152
 153 std::unique_ptr<Module> TempFile::readBitcode(LLVMContext &Context) const {
 154   LLVM_DEBUG(dbgs() << " - read bitcode\n");
 155   ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOr =
 156       MemoryBuffer::getFile(Filename);
 157   if (!BufferOr) {
 158     errs() << "verify-uselistorder: error: " << BufferOr.getError().message()
 159            << "\n";
 160     return nullptr;
 161   }
 162
 163   MemoryBuffer *Buffer = BufferOr.get().get();
 164   Expected<std::unique_ptr<Module>> ModuleOr =
 165       parseBitcodeFile(Buffer->getMemBufferRef(), Context);
 166   if (!ModuleOr) {
 167     logAllUnhandledErrors(ModuleOr.takeError(), errs(),
 168                           "verify-uselistorder: error: ");
 169     return nullptr;
 170   }
 171
 172   return std::move(ModuleOr.get());
 173 }
 174
 175 std::unique_ptr<Module> TempFile::readAssembly(LLVMContext &Context) const {
 176   LLVM_DEBUG(dbgs() << " - read assembly\n");
 177   SMDiagnostic Err;
 178   std::unique_ptr<Module> M = parseAssemblyFile(Filename, Err, Context);
 179   if (!M)
 180     Err.print("verify-uselistorder", errs());
 181   return M;
 182 }
 183
 184 ValueMapping::ValueMapping(const Module &M) {
 185   // Every value should be mapped, including things like void instructions and
 186   // basic blocks that are kept out of the ValueEnumerator.
 187   //
 188   // The current mapping order makes it easier to debug the tables.  It happens
 189   // to be similar to the ID mapping when writing ValueEnumerator, but they
 190   // aren't (and needn't be) in sync.
 191
 192   // Globals.
 193   for (const GlobalVariable &G : M.globals())
 194     map(&G);
 195   for (const GlobalAlias &A : M.aliases())
 196     map(&A);
 197   for (const GlobalIFunc &IF : M.ifuncs())
 198     map(&IF);
 199   for (const Function &F : M)
 200     map(&F);
 201
 202   // Constants used by globals.
 203   for (const GlobalVariable &G : M.globals())
 204     if (G.hasInitializer())
 205       map(G.getInitializer());
 206   for (const GlobalAlias &A : M.aliases())
 207     map(A.getAliasee());
 208   for (const GlobalIFunc &IF : M.ifuncs())
 209     map(IF.getResolver());
 210   for (const Function &F : M)
 211     for (Value *Op : F.operands())
 212       map(Op);
 213
 214   // Function bodies.
 215   for (const Function &F : M) {
 216     for (const Argument &A : F.args())
 217       map(&A);
 218     for (const BasicBlock &BB : F)
 219       map(&BB);
 220     for (const BasicBlock &BB : F)
 221       for (const Instruction &I : BB)
 222         map(&I);
 223
 224     // Constants used by instructions.
 225     for (const BasicBlock &BB : F) {
 226       for (const Instruction &I : BB) {
 227         for (const DbgVariableRecord &DVR :
 228              filterDbgVars(I.getDbgRecordRange())) {
 229           for (Value *Op : DVR.location_ops())
 230             map(Op);
 231           if (DVR.isDbgAssign())
 232             map(DVR.getAddress());
 233         }
 234         for (const Value *Op : I.operands()) {
 235           // Look through a metadata wrapper.
 236           if (const auto *MAV = dyn_cast<MetadataAsValue>(Op))
 237             if (const auto *VAM = dyn_cast<ValueAsMetadata>(MAV->getMetadata()))
 238               Op = VAM->getValue();
 239
 240           if ((isa<Constant>(Op) && !isa<GlobalValue>(*Op)) ||
 241               isa<InlineAsm>(Op))
 242             map(Op);
 243         }
 244       }
 245     }
 246   }
 247 }
 248
 249 void ValueMapping::map(const Value *V) {
 250   if (IDs.lookup(V))
 251     return;
 252
 253   if (auto *C = dyn_cast<Constant>(V))
 254     if (!isa<GlobalValue>(C))
 255       for (const Value *Op : C->operands())
 256         map(Op);
 257
 258   Values.push_back(V);
 259   IDs[V] = Values.size();
 260 }
 261
 262 #ifndef NDEBUG
 263 static void dumpMapping(const ValueMapping &VM) {
 264   dbgs() << "value-mapping (size = " << VM.Values.size() << "):\n";
 265   for (unsigned I = 0, E = VM.Values.size(); I != E; ++I) {
 266     dbgs() << " - id = " << I << ", value = ";
 267     VM.Values[I]->dump();
 268   }
 269 }
 270
 271 static void debugValue(const ValueMapping &M, unsigned I, StringRef Desc) {
 272   const Value *V = M.Values[I];
 273   dbgs() << " - " << Desc << " value = ";
 274   V->dump();
 275   for (const Use &U : V->uses()) {
 276     dbgs() << "   => use: op = " << U.getOperandNo()
 277            << ", user-id = " << M.IDs.lookup(U.getUser()) << ", user = ";
 278     U.getUser()->dump();
 279   }
 280 }
 281
 282 static void debugUserMismatch(const ValueMapping &L, const ValueMapping &R,
 283                               unsigned I) {
 284   dbgs() << " - fail: user mismatch: ID = " << I << "\n";
 285   debugValue(L, I, "LHS");
 286   debugValue(R, I, "RHS");
 287
 288   dbgs() << "\nlhs-";
 289   dumpMapping(L);
 290   dbgs() << "\nrhs-";
 291   dumpMapping(R);
 292 }
 293
 294 static void debugSizeMismatch(const ValueMapping &L, const ValueMapping &R) {
 295   dbgs() << " - fail: map size: " << L.Values.size()
 296          << " != " << R.Values.size() << "\n";
 297   dbgs() << "\nlhs-";
 298   dumpMapping(L);
 299   dbgs() << "\nrhs-";
 300   dumpMapping(R);
 301 }
 302 #endif
 303
 304 static bool matches(const ValueMapping &LM, const ValueMapping &RM) {
 305   LLVM_DEBUG(dbgs() << "compare value maps\n");
 306   if (LM.Values.size() != RM.Values.size()) {
 307     LLVM_DEBUG(debugSizeMismatch(LM, RM));
 308     return false;
 309   }
 310
 311   // This mapping doesn't include dangling constant users, since those don't
 312   // get serialized.  However, checking if users are constant and calling
 313   // isConstantUsed() on every one is very expensive.  Instead, just check if
 314   // the user is mapped.
 315   auto skipUnmappedUsers =
 316       [&](Value::const_use_iterator &U, Value::const_use_iterator E,
 317           const ValueMapping &M) {
 318     while (U != E && !M.lookup(U->getUser()))
 319       ++U;
 320   };
 321
 322   // Iterate through all values, and check that both mappings have the same
 323   // users.
 324   for (unsigned I = 0, E = LM.Values.size(); I != E; ++I) {
 325     const Value *L = LM.Values[I];
 326     const Value *R = RM.Values[I];
 327     auto LU = L->use_begin(), LE = L->use_end();
 328     auto RU = R->use_begin(), RE = R->use_end();
 329     skipUnmappedUsers(LU, LE, LM);
 330     skipUnmappedUsers(RU, RE, RM);
 331
 332     while (LU != LE) {
 333       if (RU == RE) {
 334         LLVM_DEBUG(debugUserMismatch(LM, RM, I));
 335         return false;
 336       }
 337       if (LM.lookup(LU->getUser()) != RM.lookup(RU->getUser())) {
 338         LLVM_DEBUG(debugUserMismatch(LM, RM, I));
 339         return false;
 340       }
 341       if (LU->getOperandNo() != RU->getOperandNo()) {
 342         LLVM_DEBUG(debugUserMismatch(LM, RM, I));
 343         return false;
 344       }
 345       skipUnmappedUsers(++LU, LE, LM);
 346       skipUnmappedUsers(++RU, RE, RM);
 347     }
 348     if (RU != RE) {
 349       LLVM_DEBUG(debugUserMismatch(LM, RM, I));
 350       return false;
 351     }
 352   }
 353
 354   return true;
 355 }
 356
 357 static void verifyAfterRoundTrip(const Module &M,
 358                                  std::unique_ptr<Module> OtherM) {
 359   if (!OtherM)
 360     report_fatal_error("parsing failed");
 361   if (verifyModule(*OtherM, &errs()))
 362     report_fatal_error("verification failed");
 363   if (!matches(ValueMapping(M), ValueMapping(*OtherM)))
 364     report_fatal_error("use-list order changed");
 365 }
 366
 367 static void verifyBitcodeUseListOrder(const Module &M) {
 368   TempFile F;
 369   if (F.init("bc"))
 370     report_fatal_error("failed to initialize bitcode file");
 371
 372   if (F.writeBitcode(M))
 373     report_fatal_error("failed to write bitcode");
 374
 375   LLVMContext Context;
 376   verifyAfterRoundTrip(M, F.readBitcode(Context));
 377 }
 378
 379 static void verifyAssemblyUseListOrder(const Module &M) {
 380   TempFile F;
 381   if (F.init("ll"))
 382     report_fatal_error("failed to initialize assembly file");
 383
 384   if (F.writeAssembly(M))
 385     report_fatal_error("failed to write assembly");
 386
 387   LLVMContext Context;
 388   verifyAfterRoundTrip(M, F.readAssembly(Context));
 389 }
 390
 391 static void verifyUseListOrder(const Module &M) {
 392   outs() << "verify bitcode\n";
 393   verifyBitcodeUseListOrder(M);
 394   outs() << "verify assembly\n";
 395   verifyAssemblyUseListOrder(M);
 396 }
 397
 398 static void shuffleValueUseLists(Value *V, std::minstd_rand0 &Gen,
 399                                  DenseSet<Value *> &Seen) {
 400   if (!Seen.insert(V).second)
 401     return;
 402
 403   if (auto *C = dyn_cast<Constant>(V))
 404     if (!isa<GlobalValue>(C))
 405       for (Value *Op : C->operands())
 406         shuffleValueUseLists(Op, Gen, Seen);
 407
 408   if (V->use_empty() || std::next(V->use_begin()) == V->use_end())
 409     // Nothing to shuffle for 0 or 1 users.
 410     return;
 411
 412   // Generate random numbers between 10 and 99, which will line up nicely in
 413   // debug output.  We're not worried about collisions here.
 414   LLVM_DEBUG(dbgs() << "V = "; V->dump());
 415   std::uniform_int_distribution<short> Dist(10, 99);
 416   SmallDenseMap<const Use *, short, 16> Order;
 417   auto compareUses =
 418       [&Order](const Use &L, const Use &R) { return Order[&L] < Order[&R]; };
 419   do {
 420     for (const Use &U : V->uses()) {
 421       auto I = Dist(Gen);
 422       Order[&U] = I;
 423       LLVM_DEBUG(dbgs() << " - order: " << I << ", op = " << U.getOperandNo()
 424                         << ", U = ";
 425                  U.getUser()->dump());
 426     }
 427   } while (std::is_sorted(V->use_begin(), V->use_end(), compareUses));
 428
 429   LLVM_DEBUG(dbgs() << " => shuffle\n");
 430   V->sortUseList(compareUses);
 431
 432   LLVM_DEBUG({
 433     for (const Use &U : V->uses()) {
 434       dbgs() << " - order: " << Order.lookup(&U)
 435              << ", op = " << U.getOperandNo() << ", U = ";
 436       U.getUser()->dump();
 437     }
 438   });
 439 }
 440
 441 static void reverseValueUseLists(Value *V, DenseSet<Value *> &Seen) {
 442   if (!Seen.insert(V).second)
 443     return;
 444
 445   if (auto *C = dyn_cast<Constant>(V))
 446     if (!isa<GlobalValue>(C))
 447       for (Value *Op : C->operands())
 448         reverseValueUseLists(Op, Seen);
 449
 450   if (V->use_empty() || std::next(V->use_begin()) == V->use_end())
 451     // Nothing to shuffle for 0 or 1 users.
 452     return;
 453
 454   LLVM_DEBUG({
 455     dbgs() << "V = ";
 456     V->dump();
 457     for (const Use &U : V->uses()) {
 458       dbgs() << " - order: op = " << U.getOperandNo() << ", U = ";
 459       U.getUser()->dump();
 460     }
 461     dbgs() << " => reverse\n";
 462   });
 463
 464   V->reverseUseList();
 465
 466   LLVM_DEBUG({
 467     for (const Use &U : V->uses()) {
 468       dbgs() << " - order: op = " << U.getOperandNo() << ", U = ";
 469       U.getUser()->dump();
 470     }
 471   });
 472 }
 473
 474 template <class Changer>
 475 static void changeUseLists(Module &M, Changer changeValueUseList) {
 476   // Visit every value that would be serialized to an IR file.
 477   //
 478   // Globals.
 479   for (GlobalVariable &G : M.globals())
 480     changeValueUseList(&G);
 481   for (GlobalAlias &A : M.aliases())
 482     changeValueUseList(&A);
 483   for (GlobalIFunc &IF : M.ifuncs())
 484     changeValueUseList(&IF);
 485   for (Function &F : M)
 486     changeValueUseList(&F);
 487
 488   // Constants used by globals.
 489   for (GlobalVariable &G : M.globals())
 490     if (G.hasInitializer())
 491       changeValueUseList(G.getInitializer());
 492   for (GlobalAlias &A : M.aliases())
 493     changeValueUseList(A.getAliasee());
 494   for (GlobalIFunc &IF : M.ifuncs())
 495     changeValueUseList(IF.getResolver());
 496   for (Function &F : M)
 497     for (Value *Op : F.operands())
 498       changeValueUseList(Op);
 499
 500   // Function bodies.
 501   for (Function &F : M) {
 502     for (Argument &A : F.args())
 503       changeValueUseList(&A);
 504     for (BasicBlock &BB : F)
 505       changeValueUseList(&BB);
 506     for (BasicBlock &BB : F)
 507       for (Instruction &I : BB)
 508         changeValueUseList(&I);
 509
 510     // Constants used by instructions.
 511     for (BasicBlock &BB : F)
 512       for (Instruction &I : BB)
 513         for (Value *Op : I.operands()) {
 514           // Look through a metadata wrapper.
 515           if (auto *MAV = dyn_cast<MetadataAsValue>(Op))
 516             if (auto *VAM = dyn_cast<ValueAsMetadata>(MAV->getMetadata()))
 517               Op = VAM->getValue();
 518           if ((isa<Constant>(Op) && !isa<GlobalValue>(*Op)) ||
 519               isa<InlineAsm>(Op))
 520             changeValueUseList(Op);
 521         }
 522   }
 523
 524   if (verifyModule(M, &errs()))
 525     report_fatal_error("verification failed");
 526 }
 527
 528 static void shuffleUseLists(Module &M, unsigned SeedOffset) {
 529   std::minstd_rand0 Gen(std::minstd_rand0::default_seed + SeedOffset);
 530   DenseSet<Value *> Seen;
 531   changeUseLists(M, [&](Value *V) { shuffleValueUseLists(V, Gen, Seen); });
 532   LLVM_DEBUG(dbgs() << "\n");
 533 }
 534
 535 static void reverseUseLists(Module &M) {
 536   DenseSet<Value *> Seen;
 537   changeUseLists(M, [&](Value *V) { reverseValueUseLists(V, Seen); });
 538   LLVM_DEBUG(dbgs() << "\n");
 539 }
 540
 541 int main(int argc, char **argv) {
 542   PreserveInputDbgFormat = cl::boolOrDefault::BOU_TRUE;
 543   InitLLVM X(argc, argv);
 544
 545   // Enable debug stream buffering.
 546   EnableDebugBuffering = true;
 547
 548   cl::HideUnrelatedOptions(Cat);
 549   cl::ParseCommandLineOptions(argc, argv,
 550                               "llvm tool to verify use-list order\n");
 551
 552   LLVMContext Context;
 553   SMDiagnostic Err;
 554
 555   // Load the input module...
 556   std::unique_ptr<Module> M = parseIRFile(InputFilename, Err, Context);
 557
 558   if (!M) {
 559     Err.print(argv[0], errs());
 560     return 1;
 561   }
 562   if (verifyModule(*M, &errs())) {
 563     errs() << argv[0] << ": " << InputFilename
 564            << ": error: input module is broken!\n";
 565     return 1;
 566   }
 567
 568   // Verify the use lists now and after reversing them.
 569   outs() << "*** verify-uselistorder ***\n";
 570   verifyUseListOrder(*M);
 571   outs() << "reverse\n";
 572   reverseUseLists(*M);
 573   verifyUseListOrder(*M);
 574
 575   for (unsigned I = 0, E = NumShuffles; I != E; ++I) {
 576     outs() << "\n";
 577
 578     // Shuffle with a different (deterministic) seed each time.
 579     outs() << "shuffle (" << I + 1 << " of " << E << ")\n";
 580     shuffleUseLists(*M, I);
 581
 582     // Verify again before and after reversing.
 583     verifyUseListOrder(*M);
 584     outs() << "reverse\n";
 585     reverseUseLists(*M);
 586     verifyUseListOrder(*M);
 587   }
 588
 589   return 0;
 590 }