1 //===- verify-uselistorder.cpp - The LLVM Modular Optimizer ---------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // Verify that use-list order can be serialized correctly. After reading the
11 // provided IR, this tool shuffles the use-lists and then writes and reads to a
12 // separate Module whose use-list orders are compared to the original.
13 //
14 // The shuffles are deterministic, but guarantee that use-lists will change.
15 // The algorithm per iteration is as follows:
16 //
17 // 1. Seed the random number generator. The seed is different for each
18 // shuffle. Shuffle 0 uses default+0, shuffle 1 uses default+1, and so on.
19 //
20 // 2. Visit every Value in a deterministic order.
21 //
22 // 3. Assign a random number to each Use in the Value's use-list in order.
23 //
24 // 4. If the numbers are already in order, reassign numbers until they aren't.
25 //
26 // 5. Sort the use-list using Value::sortUseList(), which is a stable sort.
27 //
28 //===----------------------------------------------------------------------===//
29
30 #include "llvm/ADT/DenseMap.h"
31 #include "llvm/ADT/DenseSet.h"
32 #include "llvm/AsmParser/Parser.h"
33 #include "llvm/Bitcode/ReaderWriter.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/ManagedStatic.h"
45 #include "llvm/Support/MemoryBuffer.h"
46 #include "llvm/Support/PrettyStackTrace.h"
47 #include "llvm/Support/Signals.h"
48 #include "llvm/Support/SourceMgr.h"
49 #include "llvm/Support/SystemUtils.h"
50 #include <random>
51 #include <vector>
52
53 using namespace llvm;
54
55 #define DEBUG_TYPE "use-list-order"
56
57 static cl::opt<std::string> InputFilename(cl::Positional,
58 cl::desc("<input bitcode file>"),
59 cl::init("-"),
60 cl::value_desc("filename"));
61
62 static cl::opt<bool> SaveTemps("save-temps", cl::desc("Save temp files"),
63 cl::init(false));
64
65 static cl::opt<unsigned>
66 NumShuffles("num-shuffles",
67 cl::desc("Number of times to shuffle and verify use-lists"),
68 cl::init(1));
69
70 namespace {
71
72 struct TempFile {
73 std::string Filename;
74 FileRemover Remover;
75 bool init(const std::string &Ext);
76 bool writeBitcode(const Module &M) const;
77 bool writeAssembly(const Module &M) const;
78 std::unique_ptr<Module> readBitcode(LLVMContext &Context) const;
79 std::unique_ptr<Module> readAssembly(LLVMContext &Context) const;
80 };
81
82 struct ValueMapping {
83 DenseMap<const Value *, unsigned> IDs;
84 std::vector<const Value *> Values;
85
86 /// \brief Construct a value mapping for module.
87 ///
88 /// Creates mapping from every value in \c M to an ID. This mapping includes
89 /// un-referencable values.
90 ///
91 /// Every \a Value that gets serialized in some way should be represented
92 /// here. The order needs to be deterministic, but it's unnecessary to match
93 /// the value-ids in the bitcode writer.
94 ///
95 /// All constants that are referenced by other values are included in the
96 /// mapping, but others -- which wouldn't be serialized -- are not.
97 ValueMapping(const Module &M);
98
99 /// \brief Map a value.
100 ///
101 /// Maps a value. If it's a constant, maps all of its operands first.
102 void map(const Value *V);
lookup__anon40f559f20111::ValueMapping103 unsigned lookup(const Value *V) const { return IDs.lookup(V); }
104 };
105
106 } // end namespace
107
init(const std::string & Ext)108 bool TempFile::init(const std::string &Ext) {
109 SmallVector<char, 64> Vector;
110 DEBUG(dbgs() << " - create-temp-file\n");
111 if (auto EC = sys::fs::createTemporaryFile("use-list-order", Ext, Vector)) {
112 (void)EC;
113 DEBUG(dbgs() << "error: " << EC.message() << "\n");
114 return true;
115 }
116 assert(!Vector.empty());
117
118 Filename.assign(Vector.data(), Vector.data() + Vector.size());
119 Remover.setFile(Filename, !SaveTemps);
120 DEBUG(dbgs() << " - filename = " << Filename << "\n");
121 return false;
122 }
123
writeBitcode(const Module & M) const124 bool TempFile::writeBitcode(const Module &M) const {
125 DEBUG(dbgs() << " - write bitcode\n");
126 std::error_code EC;
127 raw_fd_ostream OS(Filename, EC, sys::fs::F_None);
128 if (EC) {
129 DEBUG(dbgs() << "error: " << EC.message() << "\n");
130 return true;
131 }
132
133 WriteBitcodeToFile(&M, OS);
134 return false;
135 }
136
writeAssembly(const Module & M) const137 bool TempFile::writeAssembly(const Module &M) const {
138 DEBUG(dbgs() << " - write assembly\n");
139 std::error_code EC;
140 raw_fd_ostream OS(Filename, EC, sys::fs::F_Text);
141 if (EC) {
142 DEBUG(dbgs() << "error: " << EC.message() << "\n");
143 return true;
144 }
145
146 OS << M;
147 return false;
148 }
149
readBitcode(LLVMContext & Context) const150 std::unique_ptr<Module> TempFile::readBitcode(LLVMContext &Context) const {
151 DEBUG(dbgs() << " - read bitcode\n");
152 ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOr =
153 MemoryBuffer::getFile(Filename);
154 if (!BufferOr) {
155 DEBUG(dbgs() << "error: " << BufferOr.getError().message() << "\n");
156 return nullptr;
157 }
158
159 MemoryBuffer *Buffer = BufferOr.get().get();
160 ErrorOr<Module *> ModuleOr =
161 parseBitcodeFile(Buffer->getMemBufferRef(), Context);
162 if (!ModuleOr) {
163 DEBUG(dbgs() << "error: " << ModuleOr.getError().message() << "\n");
164 return nullptr;
165 }
166 return std::unique_ptr<Module>(ModuleOr.get());
167 }
168
readAssembly(LLVMContext & Context) const169 std::unique_ptr<Module> TempFile::readAssembly(LLVMContext &Context) const {
170 DEBUG(dbgs() << " - read assembly\n");
171 SMDiagnostic Err;
172 std::unique_ptr<Module> M = parseAssemblyFile(Filename, Err, Context);
173 if (!M.get())
174 DEBUG(dbgs() << "error: "; Err.print("verify-use-list-order", dbgs()));
175 return M;
176 }
177
ValueMapping(const Module & M)178 ValueMapping::ValueMapping(const Module &M) {
179 // Every value should be mapped, including things like void instructions and
180 // basic blocks that are kept out of the ValueEnumerator.
181 //
182 // The current mapping order makes it easier to debug the tables. It happens
183 // to be similar to the ID mapping when writing ValueEnumerator, but they
184 // aren't (and needn't be) in sync.
185
186 // Globals.
187 for (const GlobalVariable &G : M.globals())
188 map(&G);
189 for (const GlobalAlias &A : M.aliases())
190 map(&A);
191 for (const Function &F : M)
192 map(&F);
193
194 // Constants used by globals.
195 for (const GlobalVariable &G : M.globals())
196 if (G.hasInitializer())
197 map(G.getInitializer());
198 for (const GlobalAlias &A : M.aliases())
199 map(A.getAliasee());
200 for (const Function &F : M) {
201 if (F.hasPrefixData())
202 map(F.getPrefixData());
203 if (F.hasPrologueData())
204 map(F.getPrologueData());
205 }
206
207 // Function bodies.
208 for (const Function &F : M) {
209 for (const Argument &A : F.args())
210 map(&A);
211 for (const BasicBlock &BB : F)
212 map(&BB);
213 for (const BasicBlock &BB : F)
214 for (const Instruction &I : BB)
215 map(&I);
216
217 // Constants used by instructions.
218 for (const BasicBlock &BB : F)
219 for (const Instruction &I : BB)
220 for (const Value *Op : I.operands())
221 if ((isa<Constant>(Op) && !isa<GlobalValue>(*Op)) ||
222 isa<InlineAsm>(Op))
223 map(Op);
224 }
225 }
226
map(const Value * V)227 void ValueMapping::map(const Value *V) {
228 if (IDs.lookup(V))
229 return;
230
231 if (auto *C = dyn_cast<Constant>(V))
232 if (!isa<GlobalValue>(C))
233 for (const Value *Op : C->operands())
234 map(Op);
235
236 Values.push_back(V);
237 IDs[V] = Values.size();
238 }
239
240 #ifndef NDEBUG
dumpMapping(const ValueMapping & VM)241 static void dumpMapping(const ValueMapping &VM) {
242 dbgs() << "value-mapping (size = " << VM.Values.size() << "):\n";
243 for (unsigned I = 0, E = VM.Values.size(); I != E; ++I) {
244 dbgs() << " - id = " << I << ", value = ";
245 VM.Values[I]->dump();
246 }
247 }
248
debugValue(const ValueMapping & M,unsigned I,StringRef Desc)249 static void debugValue(const ValueMapping &M, unsigned I, StringRef Desc) {
250 const Value *V = M.Values[I];
251 dbgs() << " - " << Desc << " value = ";
252 V->dump();
253 for (const Use &U : V->uses()) {
254 dbgs() << " => use: op = " << U.getOperandNo()
255 << ", user-id = " << M.IDs.lookup(U.getUser()) << ", user = ";
256 U.getUser()->dump();
257 }
258 }
259
debugUserMismatch(const ValueMapping & L,const ValueMapping & R,unsigned I)260 static void debugUserMismatch(const ValueMapping &L, const ValueMapping &R,
261 unsigned I) {
262 dbgs() << " - fail: user mismatch: ID = " << I << "\n";
263 debugValue(L, I, "LHS");
264 debugValue(R, I, "RHS");
265
266 dbgs() << "\nlhs-";
267 dumpMapping(L);
268 dbgs() << "\nrhs-";
269 dumpMapping(R);
270 }
271
debugSizeMismatch(const ValueMapping & L,const ValueMapping & R)272 static void debugSizeMismatch(const ValueMapping &L, const ValueMapping &R) {
273 dbgs() << " - fail: map size: " << L.Values.size()
274 << " != " << R.Values.size() << "\n";
275 dbgs() << "\nlhs-";
276 dumpMapping(L);
277 dbgs() << "\nrhs-";
278 dumpMapping(R);
279 }
280 #endif
281
matches(const ValueMapping & LM,const ValueMapping & RM)282 static bool matches(const ValueMapping &LM, const ValueMapping &RM) {
283 DEBUG(dbgs() << "compare value maps\n");
284 if (LM.Values.size() != RM.Values.size()) {
285 DEBUG(debugSizeMismatch(LM, RM));
286 return false;
287 }
288
289 // This mapping doesn't include dangling constant users, since those don't
290 // get serialized. However, checking if users are constant and calling
291 // isConstantUsed() on every one is very expensive. Instead, just check if
292 // the user is mapped.
293 auto skipUnmappedUsers =
294 [&](Value::const_use_iterator &U, Value::const_use_iterator E,
295 const ValueMapping &M) {
296 while (U != E && !M.lookup(U->getUser()))
297 ++U;
298 };
299
300 // Iterate through all values, and check that both mappings have the same
301 // users.
302 for (unsigned I = 0, E = LM.Values.size(); I != E; ++I) {
303 const Value *L = LM.Values[I];
304 const Value *R = RM.Values[I];
305 auto LU = L->use_begin(), LE = L->use_end();
306 auto RU = R->use_begin(), RE = R->use_end();
307 skipUnmappedUsers(LU, LE, LM);
308 skipUnmappedUsers(RU, RE, RM);
309
310 while (LU != LE) {
311 if (RU == RE) {
312 DEBUG(debugUserMismatch(LM, RM, I));
313 return false;
314 }
315 if (LM.lookup(LU->getUser()) != RM.lookup(RU->getUser())) {
316 DEBUG(debugUserMismatch(LM, RM, I));
317 return false;
318 }
319 if (LU->getOperandNo() != RU->getOperandNo()) {
320 DEBUG(debugUserMismatch(LM, RM, I));
321 return false;
322 }
323 skipUnmappedUsers(++LU, LE, LM);
324 skipUnmappedUsers(++RU, RE, RM);
325 }
326 if (RU != RE) {
327 DEBUG(debugUserMismatch(LM, RM, I));
328 return false;
329 }
330 }
331
332 return true;
333 }
334
verifyAfterRoundTrip(const Module & M,std::unique_ptr<Module> OtherM)335 static void verifyAfterRoundTrip(const Module &M,
336 std::unique_ptr<Module> OtherM) {
337 if (!OtherM)
338 report_fatal_error("parsing failed");
339 if (verifyModule(*OtherM, &errs()))
340 report_fatal_error("verification failed");
341 if (!matches(ValueMapping(M), ValueMapping(*OtherM)))
342 report_fatal_error("use-list order changed");
343 }
verifyBitcodeUseListOrder(const Module & M)344 static void verifyBitcodeUseListOrder(const Module &M) {
345 errs() << "*** verify-use-list-order: bitcode ***\n";
346 TempFile F;
347 if (F.init("bc"))
348 report_fatal_error("failed to initialize bitcode file");
349
350 if (F.writeBitcode(M))
351 report_fatal_error("failed to write bitcode");
352
353 LLVMContext Context;
354 verifyAfterRoundTrip(M, F.readBitcode(Context));
355 }
356
verifyAssemblyUseListOrder(const Module & M)357 static void verifyAssemblyUseListOrder(const Module &M) {
358 errs() << "*** verify-use-list-order: assembly ***\n";
359 TempFile F;
360 if (F.init("ll"))
361 report_fatal_error("failed to initialize assembly file");
362
363 if (F.writeAssembly(M))
364 report_fatal_error("failed to write assembly");
365
366 LLVMContext Context;
367 verifyAfterRoundTrip(M, F.readAssembly(Context));
368 }
369
verifyUseListOrder(const Module & M)370 static void verifyUseListOrder(const Module &M) {
371 verifyBitcodeUseListOrder(M);
372 verifyAssemblyUseListOrder(M);
373 }
374
shuffleValueUseLists(Value * V,std::minstd_rand0 & Gen,DenseSet<Value * > & Seen)375 static void shuffleValueUseLists(Value *V, std::minstd_rand0 &Gen,
376 DenseSet<Value *> &Seen) {
377 if (!Seen.insert(V).second)
378 return;
379
380 if (auto *C = dyn_cast<Constant>(V))
381 if (!isa<GlobalValue>(C))
382 for (Value *Op : C->operands())
383 shuffleValueUseLists(Op, Gen, Seen);
384
385 if (V->use_empty() || std::next(V->use_begin()) == V->use_end())
386 // Nothing to shuffle for 0 or 1 users.
387 return;
388
389 // Generate random numbers between 10 and 99, which will line up nicely in
390 // debug output. We're not worried about collisons here.
391 DEBUG(dbgs() << "V = "; V->dump());
392 std::uniform_int_distribution<short> Dist(10, 99);
393 SmallDenseMap<const Use *, short, 16> Order;
394 auto compareUses =
395 [&Order](const Use &L, const Use &R) { return Order[&L] < Order[&R]; };
396 do {
397 for (const Use &U : V->uses()) {
398 auto I = Dist(Gen);
399 Order[&U] = I;
400 DEBUG(dbgs() << " - order: " << I << ", op = " << U.getOperandNo()
401 << ", U = ";
402 U.getUser()->dump());
403 }
404 } while (std::is_sorted(V->use_begin(), V->use_end(), compareUses));
405
406 DEBUG(dbgs() << " => shuffle\n");
407 V->sortUseList(compareUses);
408
409 DEBUG({
410 for (const Use &U : V->uses()) {
411 dbgs() << " - order: " << Order.lookup(&U)
412 << ", op = " << U.getOperandNo() << ", U = ";
413 U.getUser()->dump();
414 }
415 });
416 }
417
reverseValueUseLists(Value * V,DenseSet<Value * > & Seen)418 static void reverseValueUseLists(Value *V, DenseSet<Value *> &Seen) {
419 if (!Seen.insert(V).second)
420 return;
421
422 if (auto *C = dyn_cast<Constant>(V))
423 if (!isa<GlobalValue>(C))
424 for (Value *Op : C->operands())
425 reverseValueUseLists(Op, Seen);
426
427 if (V->use_empty() || std::next(V->use_begin()) == V->use_end())
428 // Nothing to shuffle for 0 or 1 users.
429 return;
430
431 DEBUG({
432 dbgs() << "V = ";
433 V->dump();
434 for (const Use &U : V->uses()) {
435 dbgs() << " - order: op = " << U.getOperandNo() << ", U = ";
436 U.getUser()->dump();
437 }
438 dbgs() << " => reverse\n";
439 });
440
441 V->reverseUseList();
442
443 DEBUG({
444 for (const Use &U : V->uses()) {
445 dbgs() << " - order: op = " << U.getOperandNo() << ", U = ";
446 U.getUser()->dump();
447 }
448 });
449 }
450
451 template <class Changer>
changeUseLists(Module & M,Changer changeValueUseList)452 static void changeUseLists(Module &M, Changer changeValueUseList) {
453 // Visit every value that would be serialized to an IR file.
454 //
455 // Globals.
456 for (GlobalVariable &G : M.globals())
457 changeValueUseList(&G);
458 for (GlobalAlias &A : M.aliases())
459 changeValueUseList(&A);
460 for (Function &F : M)
461 changeValueUseList(&F);
462
463 // Constants used by globals.
464 for (GlobalVariable &G : M.globals())
465 if (G.hasInitializer())
466 changeValueUseList(G.getInitializer());
467 for (GlobalAlias &A : M.aliases())
468 changeValueUseList(A.getAliasee());
469 for (Function &F : M) {
470 if (F.hasPrefixData())
471 changeValueUseList(F.getPrefixData());
472 if (F.hasPrologueData())
473 changeValueUseList(F.getPrologueData());
474 }
475
476 // Function bodies.
477 for (Function &F : M) {
478 for (Argument &A : F.args())
479 changeValueUseList(&A);
480 for (BasicBlock &BB : F)
481 changeValueUseList(&BB);
482 for (BasicBlock &BB : F)
483 for (Instruction &I : BB)
484 changeValueUseList(&I);
485
486 // Constants used by instructions.
487 for (BasicBlock &BB : F)
488 for (Instruction &I : BB)
489 for (Value *Op : I.operands())
490 if ((isa<Constant>(Op) && !isa<GlobalValue>(*Op)) ||
491 isa<InlineAsm>(Op))
492 changeValueUseList(Op);
493 }
494
495 if (verifyModule(M, &errs()))
496 report_fatal_error("verification failed");
497 }
498
shuffleUseLists(Module & M,unsigned SeedOffset)499 static void shuffleUseLists(Module &M, unsigned SeedOffset) {
500 errs() << "*** shuffle-use-lists ***\n";
501 std::minstd_rand0 Gen(std::minstd_rand0::default_seed + SeedOffset);
502 DenseSet<Value *> Seen;
503 changeUseLists(M, [&](Value *V) { shuffleValueUseLists(V, Gen, Seen); });
504 DEBUG(dbgs() << "\n");
505 }
506
reverseUseLists(Module & M)507 static void reverseUseLists(Module &M) {
508 errs() << "*** reverse-use-lists ***\n";
509 DenseSet<Value *> Seen;
510 changeUseLists(M, [&](Value *V) { reverseValueUseLists(V, Seen); });
511 DEBUG(dbgs() << "\n");
512 }
513
main(int argc,char ** argv)514 int main(int argc, char **argv) {
515 sys::PrintStackTraceOnErrorSignal();
516 llvm::PrettyStackTraceProgram X(argc, argv);
517
518 // Enable debug stream buffering.
519 EnableDebugBuffering = true;
520
521 llvm_shutdown_obj Y; // Call llvm_shutdown() on exit.
522 LLVMContext &Context = getGlobalContext();
523
524 cl::ParseCommandLineOptions(argc, argv,
525 "llvm tool to verify use-list order\n");
526
527 SMDiagnostic Err;
528
529 // Load the input module...
530 std::unique_ptr<Module> M = parseIRFile(InputFilename, Err, Context);
531
532 if (!M.get()) {
533 Err.print(argv[0], errs());
534 return 1;
535 }
536 if (verifyModule(*M, &errs()))
537 report_fatal_error("verification failed");
538
539 errs() << "*** verify-use-list-order ***\n";
540 // Can't verify if order isn't preserved.
541 if (!shouldPreserveBitcodeUseListOrder()) {
542 errs() << "warning: forcing -preserve-bc-use-list-order\n";
543 setPreserveBitcodeUseListOrder(true);
544 }
545 if (!shouldPreserveAssemblyUseListOrder()) {
546 errs() << "warning: forcing -preserve-ll-use-list-order\n";
547 setPreserveAssemblyUseListOrder(true);
548 }
549
550 // Verify the use lists now and after reversing them.
551 verifyUseListOrder(*M);
552 reverseUseLists(*M);
553 verifyUseListOrder(*M);
554
555 for (unsigned I = 0, E = NumShuffles; I != E; ++I) {
556 errs() << "*** shuffle iteration: " << I + 1 << " of " << E << " ***\n";
557
558 // Shuffle with a different (deterministic) seed each time.
559 shuffleUseLists(*M, I);
560
561 // Verify again before and after reversing.
562 verifyUseListOrder(*M);
563 reverseUseLists(*M);
564 verifyUseListOrder(*M);
565 }
566
567 return 0;
568 }
569