1//===- Miscompilation.cpp - Debug program miscompilations -----------------===//
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// This file implements optimizer and code generation miscompilation debugging
10// support.
11//
12//===----------------------------------------------------------------------===//
13
14#include "BugDriver.h"
15#include "ListReducer.h"
16#include "ToolRunner.h"
17#include "llvm/Config/config.h" // for HAVE_LINK_R
18#include "llvm/IR/Constants.h"
19#include "llvm/IR/DerivedTypes.h"
20#include "llvm/IR/Instructions.h"
21#include "llvm/IR/Module.h"
22#include "llvm/IR/Verifier.h"
23#include "llvm/Linker/Linker.h"
24#include "llvm/Pass.h"
25#include "llvm/Support/CommandLine.h"
26#include "llvm/Support/FileUtilities.h"
27#include "llvm/Transforms/Utils/Cloning.h"
28
29using namespace llvm;
30
31namespace llvm {
32extern cl::opt<std::string> OutputPrefix;
33extern cl::list<std::string> InputArgv;
34} // end namespace llvm
35
36namespace {
37static llvm::cl::opt<bool> DisableLoopExtraction(
38 "disable-loop-extraction",
39 cl::desc("Don't extract loops when searching for miscompilations"),
40 cl::init(Val: false));
41static llvm::cl::opt<bool> DisableBlockExtraction(
42 "disable-block-extraction",
43 cl::desc("Don't extract blocks when searching for miscompilations"),
44 cl::init(Val: false));
45
46class ReduceMiscompilingPasses : public ListReducer<std::string> {
47 BugDriver &BD;
48
49public:
50 ReduceMiscompilingPasses(BugDriver &bd) : BD(bd) {}
51
52 Expected<TestResult> doTest(std::vector<std::string> &Prefix,
53 std::vector<std::string> &Suffix) override;
54};
55} // end anonymous namespace
56
57/// TestResult - After passes have been split into a test group and a control
58/// group, see if they still break the program.
59///
60Expected<ReduceMiscompilingPasses::TestResult>
61ReduceMiscompilingPasses::doTest(std::vector<std::string> &Prefix,
62 std::vector<std::string> &Suffix) {
63 // First, run the program with just the Suffix passes. If it is still broken
64 // with JUST the kept passes, discard the prefix passes.
65 outs() << "Checking to see if '" << getPassesString(Passes: Suffix)
66 << "' compiles correctly: ";
67
68 std::string BitcodeResult;
69 if (BD.runPasses(Program&: BD.getProgram(), PassesToRun: Suffix, OutputFilename&: BitcodeResult, DeleteOutput: false /*delete*/,
70 Quiet: true /*quiet*/)) {
71 errs() << " Error running this sequence of passes"
72 << " on the input program!\n";
73 BD.setPassesToRun(Suffix);
74 BD.EmitProgressBitcode(M: BD.getProgram(), ID: "pass-error", NoFlyer: false);
75 // TODO: This should propagate the error instead of exiting.
76 if (Error E = BD.debugOptimizerCrash())
77 exit(status: 1);
78 exit(status: 0);
79 }
80
81 // Check to see if the finished program matches the reference output...
82 Expected<bool> Diff = BD.diffProgram(Program: BD.getProgram(), BitcodeFile: BitcodeResult, SharedObj: "",
83 RemoveBitcode: true /*delete bitcode*/);
84 if (Error E = Diff.takeError())
85 return std::move(E);
86 if (*Diff) {
87 outs() << " nope.\n";
88 if (Suffix.empty()) {
89 errs() << BD.getToolName() << ": I'm confused: the test fails when "
90 << "no passes are run, nondeterministic program?\n";
91 exit(status: 1);
92 }
93 return KeepSuffix; // Miscompilation detected!
94 }
95 outs() << " yup.\n"; // No miscompilation!
96
97 if (Prefix.empty())
98 return NoFailure;
99
100 // Next, see if the program is broken if we run the "prefix" passes first,
101 // then separately run the "kept" passes.
102 outs() << "Checking to see if '" << getPassesString(Passes: Prefix)
103 << "' compiles correctly: ";
104
105 // If it is not broken with the kept passes, it's possible that the prefix
106 // passes must be run before the kept passes to break it. If the program
107 // WORKS after the prefix passes, but then fails if running the prefix AND
108 // kept passes, we can update our bitcode file to include the result of the
109 // prefix passes, then discard the prefix passes.
110 //
111 if (BD.runPasses(Program&: BD.getProgram(), PassesToRun: Prefix, OutputFilename&: BitcodeResult, DeleteOutput: false /*delete*/,
112 Quiet: true /*quiet*/)) {
113 errs() << " Error running this sequence of passes"
114 << " on the input program!\n";
115 BD.setPassesToRun(Prefix);
116 BD.EmitProgressBitcode(M: BD.getProgram(), ID: "pass-error", NoFlyer: false);
117 // TODO: This should propagate the error instead of exiting.
118 if (Error E = BD.debugOptimizerCrash())
119 exit(status: 1);
120 exit(status: 0);
121 }
122
123 // If the prefix maintains the predicate by itself, only keep the prefix!
124 Diff = BD.diffProgram(Program: BD.getProgram(), BitcodeFile: BitcodeResult, SharedObj: "", RemoveBitcode: false);
125 if (Error E = Diff.takeError())
126 return std::move(E);
127 if (*Diff) {
128 outs() << " nope.\n";
129 sys::fs::remove(path: BitcodeResult);
130 return KeepPrefix;
131 }
132 outs() << " yup.\n"; // No miscompilation!
133
134 // Ok, so now we know that the prefix passes work, try running the suffix
135 // passes on the result of the prefix passes.
136 //
137 std::unique_ptr<Module> PrefixOutput =
138 parseInputFile(InputFilename: BitcodeResult, ctxt&: BD.getContext());
139 if (!PrefixOutput) {
140 errs() << BD.getToolName() << ": Error reading bitcode file '"
141 << BitcodeResult << "'!\n";
142 exit(status: 1);
143 }
144 sys::fs::remove(path: BitcodeResult);
145
146 // Don't check if there are no passes in the suffix.
147 if (Suffix.empty())
148 return NoFailure;
149
150 outs() << "Checking to see if '" << getPassesString(Passes: Suffix)
151 << "' passes compile correctly after the '" << getPassesString(Passes: Prefix)
152 << "' passes: ";
153
154 std::unique_ptr<Module> OriginalInput =
155 BD.swapProgramIn(M: std::move(PrefixOutput));
156 if (BD.runPasses(Program&: BD.getProgram(), PassesToRun: Suffix, OutputFilename&: BitcodeResult, DeleteOutput: false /*delete*/,
157 Quiet: true /*quiet*/)) {
158 errs() << " Error running this sequence of passes"
159 << " on the input program!\n";
160 BD.setPassesToRun(Suffix);
161 BD.EmitProgressBitcode(M: BD.getProgram(), ID: "pass-error", NoFlyer: false);
162 // TODO: This should propagate the error instead of exiting.
163 if (Error E = BD.debugOptimizerCrash())
164 exit(status: 1);
165 exit(status: 0);
166 }
167
168 // Run the result...
169 Diff = BD.diffProgram(Program: BD.getProgram(), BitcodeFile: BitcodeResult, SharedObj: "",
170 RemoveBitcode: true /*delete bitcode*/);
171 if (Error E = Diff.takeError())
172 return std::move(E);
173 if (*Diff) {
174 outs() << " nope.\n";
175 return KeepSuffix;
176 }
177
178 // Otherwise, we must not be running the bad pass anymore.
179 outs() << " yup.\n"; // No miscompilation!
180 // Restore orig program & free test.
181 BD.setNewProgram(std::move(OriginalInput));
182 return NoFailure;
183}
184
185namespace {
186class ReduceMiscompilingFunctions : public ListReducer<Function *> {
187 BugDriver &BD;
188 Expected<bool> (*TestFn)(BugDriver &, std::unique_ptr<Module>,
189 std::unique_ptr<Module>);
190
191public:
192 ReduceMiscompilingFunctions(BugDriver &bd,
193 Expected<bool> (*F)(BugDriver &,
194 std::unique_ptr<Module>,
195 std::unique_ptr<Module>))
196 : BD(bd), TestFn(F) {}
197
198 Expected<TestResult> doTest(std::vector<Function *> &Prefix,
199 std::vector<Function *> &Suffix) override {
200 if (!Suffix.empty()) {
201 Expected<bool> Ret = TestFuncs(Prefix: Suffix);
202 if (Error E = Ret.takeError())
203 return std::move(E);
204 if (*Ret)
205 return KeepSuffix;
206 }
207 if (!Prefix.empty()) {
208 Expected<bool> Ret = TestFuncs(Prefix);
209 if (Error E = Ret.takeError())
210 return std::move(E);
211 if (*Ret)
212 return KeepPrefix;
213 }
214 return NoFailure;
215 }
216
217 Expected<bool> TestFuncs(const std::vector<Function *> &Prefix);
218};
219} // end anonymous namespace
220
221/// Given two modules, link them together and run the program, checking to see
222/// if the program matches the diff. If there is an error, return NULL. If not,
223/// return the merged module. The Broken argument will be set to true if the
224/// output is different. If the DeleteInputs argument is set to true then this
225/// function deletes both input modules before it returns.
226///
227static Expected<std::unique_ptr<Module>> testMergedProgram(const BugDriver &BD,
228 const Module &M1,
229 const Module &M2,
230 bool &Broken) {
231 // Resulting merge of M1 and M2.
232 auto Merged = CloneModule(M: M1);
233 if (Linker::linkModules(Dest&: *Merged, Src: CloneModule(M: M2)))
234 // TODO: Shouldn't we thread the error up instead of exiting?
235 exit(status: 1);
236
237 // Execute the program.
238 Expected<bool> Diff = BD.diffProgram(Program: *Merged, BitcodeFile: "", SharedObj: "", RemoveBitcode: false);
239 if (Error E = Diff.takeError())
240 return std::move(E);
241 Broken = *Diff;
242 return std::move(Merged);
243}
244
245/// split functions in a Module into two groups: those that are under
246/// consideration for miscompilation vs. those that are not, and test
247/// accordingly. Each group of functions becomes a separate Module.
248Expected<bool>
249ReduceMiscompilingFunctions::TestFuncs(const std::vector<Function *> &Funcs) {
250 // Test to see if the function is misoptimized if we ONLY run it on the
251 // functions listed in Funcs.
252 outs() << "Checking to see if the program is misoptimized when "
253 << (Funcs.size() == 1 ? "this function is" : "these functions are")
254 << " run through the pass"
255 << (BD.getPassesToRun().size() == 1 ? "" : "es") << ":";
256 PrintFunctionList(Funcs);
257 outs() << '\n';
258
259 // Create a clone for two reasons:
260 // * If the optimization passes delete any function, the deleted function
261 // will be in the clone and Funcs will still point to valid memory
262 // * If the optimization passes use interprocedural information to break
263 // a function, we want to continue with the original function. Otherwise
264 // we can conclude that a function triggers the bug when in fact one
265 // needs a larger set of original functions to do so.
266 ValueToValueMapTy VMap;
267 std::unique_ptr<Module> Clone = CloneModule(M: BD.getProgram(), VMap);
268 std::unique_ptr<Module> Orig = BD.swapProgramIn(M: std::move(Clone));
269
270 std::vector<Function *> FuncsOnClone;
271 for (unsigned i = 0, e = Funcs.size(); i != e; ++i) {
272 Function *F = cast<Function>(Val&: VMap[Funcs[i]]);
273 FuncsOnClone.push_back(x: F);
274 }
275
276 // Split the module into the two halves of the program we want.
277 VMap.clear();
278 std::unique_ptr<Module> ToNotOptimize = CloneModule(M: BD.getProgram(), VMap);
279 std::unique_ptr<Module> ToOptimize =
280 SplitFunctionsOutOfModule(M: ToNotOptimize.get(), F: FuncsOnClone, VMap);
281
282 Expected<bool> Broken =
283 TestFn(BD, std::move(ToOptimize), std::move(ToNotOptimize));
284
285 BD.setNewProgram(std::move(Orig));
286
287 return Broken;
288}
289
290/// Give anonymous global values names.
291static void DisambiguateGlobalSymbols(Module &M) {
292 for (Module::global_iterator I = M.global_begin(), E = M.global_end(); I != E;
293 ++I)
294 if (!I->hasName())
295 I->setName("anon_global");
296 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
297 if (!I->hasName())
298 I->setName("anon_fn");
299}
300
301/// Given a reduced list of functions that still exposed the bug, check to see
302/// if we can extract the loops in the region without obscuring the bug. If so,
303/// it reduces the amount of code identified.
304///
305static Expected<bool>
306ExtractLoops(BugDriver &BD,
307 Expected<bool> (*TestFn)(BugDriver &, std::unique_ptr<Module>,
308 std::unique_ptr<Module>),
309 std::vector<Function *> &MiscompiledFunctions) {
310 bool MadeChange = false;
311 while (true) {
312 if (BugpointIsInterrupted)
313 return MadeChange;
314
315 ValueToValueMapTy VMap;
316 std::unique_ptr<Module> ToNotOptimize = CloneModule(M: BD.getProgram(), VMap);
317 std::unique_ptr<Module> ToOptimize = SplitFunctionsOutOfModule(
318 M: ToNotOptimize.get(), F: MiscompiledFunctions, VMap);
319 std::unique_ptr<Module> ToOptimizeLoopExtracted =
320 BD.extractLoop(M: ToOptimize.get());
321 if (!ToOptimizeLoopExtracted)
322 // If the loop extractor crashed or if there were no extractible loops,
323 // then this chapter of our odyssey is over with.
324 return MadeChange;
325
326 errs() << "Extracted a loop from the breaking portion of the program.\n";
327
328 // Bugpoint is intentionally not very trusting of LLVM transformations. In
329 // particular, we're not going to assume that the loop extractor works, so
330 // we're going to test the newly loop extracted program to make sure nothing
331 // has broken. If something broke, then we'll inform the user and stop
332 // extraction.
333 AbstractInterpreter *AI = BD.switchToSafeInterpreter();
334 bool Failure;
335 Expected<std::unique_ptr<Module>> New = testMergedProgram(
336 BD, M1: *ToOptimizeLoopExtracted, M2: *ToNotOptimize, Broken&: Failure);
337 if (Error E = New.takeError())
338 return std::move(E);
339 if (!*New)
340 return false;
341
342 // Delete the original and set the new program.
343 std::unique_ptr<Module> Old = BD.swapProgramIn(M: std::move(*New));
344 for (unsigned i = 0, e = MiscompiledFunctions.size(); i != e; ++i)
345 MiscompiledFunctions[i] = cast<Function>(Val&: VMap[MiscompiledFunctions[i]]);
346
347 if (Failure) {
348 BD.switchToInterpreter(AI);
349
350 // Merged program doesn't work anymore!
351 errs() << " *** ERROR: Loop extraction broke the program. :("
352 << " Please report a bug!\n";
353 errs() << " Continuing on with un-loop-extracted version.\n";
354
355 BD.writeProgramToFile(Filename: OutputPrefix + "-loop-extract-fail-tno.bc",
356 M: *ToNotOptimize);
357 BD.writeProgramToFile(Filename: OutputPrefix + "-loop-extract-fail-to.bc",
358 M: *ToOptimize);
359 BD.writeProgramToFile(Filename: OutputPrefix + "-loop-extract-fail-to-le.bc",
360 M: *ToOptimizeLoopExtracted);
361
362 errs() << "Please submit the " << OutputPrefix
363 << "-loop-extract-fail-*.bc files.\n";
364 return MadeChange;
365 }
366 BD.switchToInterpreter(AI);
367
368 outs() << " Testing after loop extraction:\n";
369 // Clone modules, the tester function will free them.
370 std::unique_ptr<Module> TOLEBackup =
371 CloneModule(M: *ToOptimizeLoopExtracted, VMap);
372 std::unique_ptr<Module> TNOBackup = CloneModule(M: *ToNotOptimize, VMap);
373
374 for (unsigned i = 0, e = MiscompiledFunctions.size(); i != e; ++i)
375 MiscompiledFunctions[i] = cast<Function>(Val&: VMap[MiscompiledFunctions[i]]);
376
377 Expected<bool> Result = TestFn(BD, std::move(ToOptimizeLoopExtracted),
378 std::move(ToNotOptimize));
379 if (Error E = Result.takeError())
380 return std::move(E);
381
382 ToOptimizeLoopExtracted = std::move(TOLEBackup);
383 ToNotOptimize = std::move(TNOBackup);
384
385 if (!*Result) {
386 outs() << "*** Loop extraction masked the problem. Undoing.\n";
387 // If the program is not still broken, then loop extraction did something
388 // that masked the error. Stop loop extraction now.
389
390 std::vector<std::pair<std::string, FunctionType *>> MisCompFunctions;
391 for (Function *F : MiscompiledFunctions) {
392 MisCompFunctions.emplace_back(args: std::string(F->getName()),
393 args: F->getFunctionType());
394 }
395
396 if (Linker::linkModules(Dest&: *ToNotOptimize,
397 Src: std::move(ToOptimizeLoopExtracted)))
398 exit(status: 1);
399
400 MiscompiledFunctions.clear();
401 for (unsigned i = 0, e = MisCompFunctions.size(); i != e; ++i) {
402 Function *NewF = ToNotOptimize->getFunction(Name: MisCompFunctions[i].first);
403
404 assert(NewF && "Function not found??");
405 MiscompiledFunctions.push_back(x: NewF);
406 }
407
408 BD.setNewProgram(std::move(ToNotOptimize));
409 return MadeChange;
410 }
411
412 outs() << "*** Loop extraction successful!\n";
413
414 std::vector<std::pair<std::string, FunctionType *>> MisCompFunctions;
415 for (Module::iterator I = ToOptimizeLoopExtracted->begin(),
416 E = ToOptimizeLoopExtracted->end();
417 I != E; ++I)
418 if (!I->isDeclaration())
419 MisCompFunctions.emplace_back(args: std::string(I->getName()),
420 args: I->getFunctionType());
421
422 // Okay, great! Now we know that we extracted a loop and that loop
423 // extraction both didn't break the program, and didn't mask the problem.
424 // Replace the current program with the loop extracted version, and try to
425 // extract another loop.
426 if (Linker::linkModules(Dest&: *ToNotOptimize, Src: std::move(ToOptimizeLoopExtracted)))
427 exit(status: 1);
428
429 // All of the Function*'s in the MiscompiledFunctions list are in the old
430 // module. Update this list to include all of the functions in the
431 // optimized and loop extracted module.
432 MiscompiledFunctions.clear();
433 for (unsigned i = 0, e = MisCompFunctions.size(); i != e; ++i) {
434 Function *NewF = ToNotOptimize->getFunction(Name: MisCompFunctions[i].first);
435
436 assert(NewF && "Function not found??");
437 MiscompiledFunctions.push_back(x: NewF);
438 }
439
440 BD.setNewProgram(std::move(ToNotOptimize));
441 MadeChange = true;
442 }
443}
444
445namespace {
446class ReduceMiscompiledBlocks : public ListReducer<BasicBlock *> {
447 BugDriver &BD;
448 Expected<bool> (*TestFn)(BugDriver &, std::unique_ptr<Module>,
449 std::unique_ptr<Module>);
450 std::vector<Function *> FunctionsBeingTested;
451
452public:
453 ReduceMiscompiledBlocks(BugDriver &bd,
454 Expected<bool> (*F)(BugDriver &,
455 std::unique_ptr<Module>,
456 std::unique_ptr<Module>),
457 const std::vector<Function *> &Fns)
458 : BD(bd), TestFn(F), FunctionsBeingTested(Fns) {}
459
460 Expected<TestResult> doTest(std::vector<BasicBlock *> &Prefix,
461 std::vector<BasicBlock *> &Suffix) override {
462 if (!Suffix.empty()) {
463 Expected<bool> Ret = TestFuncs(BBs: Suffix);
464 if (Error E = Ret.takeError())
465 return std::move(E);
466 if (*Ret)
467 return KeepSuffix;
468 }
469 if (!Prefix.empty()) {
470 Expected<bool> Ret = TestFuncs(BBs: Prefix);
471 if (Error E = Ret.takeError())
472 return std::move(E);
473 if (*Ret)
474 return KeepPrefix;
475 }
476 return NoFailure;
477 }
478
479 Expected<bool> TestFuncs(const std::vector<BasicBlock *> &BBs);
480};
481} // end anonymous namespace
482
483/// TestFuncs - Extract all blocks for the miscompiled functions except for the
484/// specified blocks. If the problem still exists, return true.
485///
486Expected<bool>
487ReduceMiscompiledBlocks::TestFuncs(const std::vector<BasicBlock *> &BBs) {
488 // Test to see if the function is misoptimized if we ONLY run it on the
489 // functions listed in Funcs.
490 outs() << "Checking to see if the program is misoptimized when all ";
491 if (!BBs.empty()) {
492 outs() << "but these " << BBs.size() << " blocks are extracted: ";
493 for (unsigned i = 0, e = BBs.size() < 10 ? BBs.size() : 10; i != e; ++i)
494 outs() << BBs[i]->getName() << " ";
495 if (BBs.size() > 10)
496 outs() << "...";
497 } else {
498 outs() << "blocks are extracted.";
499 }
500 outs() << '\n';
501
502 // Split the module into the two halves of the program we want.
503 ValueToValueMapTy VMap;
504 std::unique_ptr<Module> Clone = CloneModule(M: BD.getProgram(), VMap);
505 std::unique_ptr<Module> Orig = BD.swapProgramIn(M: std::move(Clone));
506 std::vector<Function *> FuncsOnClone;
507 std::vector<BasicBlock *> BBsOnClone;
508 for (unsigned i = 0, e = FunctionsBeingTested.size(); i != e; ++i) {
509 Function *F = cast<Function>(Val&: VMap[FunctionsBeingTested[i]]);
510 FuncsOnClone.push_back(x: F);
511 }
512 for (unsigned i = 0, e = BBs.size(); i != e; ++i) {
513 BasicBlock *BB = cast<BasicBlock>(Val&: VMap[BBs[i]]);
514 BBsOnClone.push_back(x: BB);
515 }
516 VMap.clear();
517
518 std::unique_ptr<Module> ToNotOptimize = CloneModule(M: BD.getProgram(), VMap);
519 std::unique_ptr<Module> ToOptimize =
520 SplitFunctionsOutOfModule(M: ToNotOptimize.get(), F: FuncsOnClone, VMap);
521
522 // Try the extraction. If it doesn't work, then the block extractor crashed
523 // or something, in which case bugpoint can't chase down this possibility.
524 if (std::unique_ptr<Module> New =
525 BD.extractMappedBlocksFromModule(BBs: BBsOnClone, M: ToOptimize.get())) {
526 Expected<bool> Ret = TestFn(BD, std::move(New), std::move(ToNotOptimize));
527 BD.setNewProgram(std::move(Orig));
528 return Ret;
529 }
530 BD.setNewProgram(std::move(Orig));
531 return false;
532}
533
534/// Given a reduced list of functions that still expose the bug, extract as many
535/// basic blocks from the region as possible without obscuring the bug.
536///
537static Expected<bool>
538ExtractBlocks(BugDriver &BD,
539 Expected<bool> (*TestFn)(BugDriver &, std::unique_ptr<Module>,
540 std::unique_ptr<Module>),
541 std::vector<Function *> &MiscompiledFunctions) {
542 if (BugpointIsInterrupted)
543 return false;
544
545 std::vector<BasicBlock *> Blocks;
546 for (unsigned i = 0, e = MiscompiledFunctions.size(); i != e; ++i)
547 for (BasicBlock &BB : *MiscompiledFunctions[i])
548 Blocks.push_back(x: &BB);
549
550 // Use the list reducer to identify blocks that can be extracted without
551 // obscuring the bug. The Blocks list will end up containing blocks that must
552 // be retained from the original program.
553 unsigned OldSize = Blocks.size();
554
555 // Check to see if all blocks are extractible first.
556 Expected<bool> Ret = ReduceMiscompiledBlocks(BD, TestFn, MiscompiledFunctions)
557 .TestFuncs(BBs: std::vector<BasicBlock *>());
558 if (Error E = Ret.takeError())
559 return std::move(E);
560 if (*Ret) {
561 Blocks.clear();
562 } else {
563 Expected<bool> Ret =
564 ReduceMiscompiledBlocks(BD, TestFn, MiscompiledFunctions)
565 .reduceList(TheList&: Blocks);
566 if (Error E = Ret.takeError())
567 return std::move(E);
568 if (Blocks.size() == OldSize)
569 return false;
570 }
571
572 ValueToValueMapTy VMap;
573 std::unique_ptr<Module> ProgClone = CloneModule(M: BD.getProgram(), VMap);
574 std::unique_ptr<Module> ToExtract =
575 SplitFunctionsOutOfModule(M: ProgClone.get(), F: MiscompiledFunctions, VMap);
576 std::unique_ptr<Module> Extracted =
577 BD.extractMappedBlocksFromModule(BBs: Blocks, M: ToExtract.get());
578 if (!Extracted) {
579 // Weird, extraction should have worked.
580 errs() << "Nondeterministic problem extracting blocks??\n";
581 return false;
582 }
583
584 // Otherwise, block extraction succeeded. Link the two program fragments back
585 // together.
586
587 std::vector<std::pair<std::string, FunctionType *>> MisCompFunctions;
588 for (Module::iterator I = Extracted->begin(), E = Extracted->end(); I != E;
589 ++I)
590 if (!I->isDeclaration())
591 MisCompFunctions.emplace_back(args: std::string(I->getName()),
592 args: I->getFunctionType());
593
594 if (Linker::linkModules(Dest&: *ProgClone, Src: std::move(Extracted)))
595 exit(status: 1);
596
597 // Update the list of miscompiled functions.
598 MiscompiledFunctions.clear();
599
600 for (unsigned i = 0, e = MisCompFunctions.size(); i != e; ++i) {
601 Function *NewF = ProgClone->getFunction(Name: MisCompFunctions[i].first);
602 assert(NewF && "Function not found??");
603 MiscompiledFunctions.push_back(x: NewF);
604 }
605
606 // Set the new program and delete the old one.
607 BD.setNewProgram(std::move(ProgClone));
608
609 return true;
610}
611
612/// This is a generic driver to narrow down miscompilations, either in an
613/// optimization or a code generator.
614///
615static Expected<std::vector<Function *>> DebugAMiscompilation(
616 BugDriver &BD,
617 Expected<bool> (*TestFn)(BugDriver &, std::unique_ptr<Module>,
618 std::unique_ptr<Module>)) {
619 // Okay, now that we have reduced the list of passes which are causing the
620 // failure, see if we can pin down which functions are being
621 // miscompiled... first build a list of all of the non-external functions in
622 // the program.
623 std::vector<Function *> MiscompiledFunctions;
624 Module &Prog = BD.getProgram();
625 for (Function &F : Prog)
626 if (!F.isDeclaration())
627 MiscompiledFunctions.push_back(x: &F);
628
629 // Do the reduction...
630 if (!BugpointIsInterrupted) {
631 Expected<bool> Ret = ReduceMiscompilingFunctions(BD, TestFn)
632 .reduceList(TheList&: MiscompiledFunctions);
633 if (Error E = Ret.takeError()) {
634 errs() << "\n***Cannot reduce functions: ";
635 return std::move(E);
636 }
637 }
638 outs() << "\n*** The following function"
639 << (MiscompiledFunctions.size() == 1 ? " is" : "s are")
640 << " being miscompiled: ";
641 PrintFunctionList(Funcs: MiscompiledFunctions);
642 outs() << '\n';
643
644 // See if we can rip any loops out of the miscompiled functions and still
645 // trigger the problem.
646
647 if (!BugpointIsInterrupted && !DisableLoopExtraction) {
648 Expected<bool> Ret = ExtractLoops(BD, TestFn, MiscompiledFunctions);
649 if (Error E = Ret.takeError())
650 return std::move(E);
651 if (*Ret) {
652 // Okay, we extracted some loops and the problem still appears. See if
653 // we can eliminate some of the created functions from being candidates.
654 DisambiguateGlobalSymbols(M&: BD.getProgram());
655
656 // Do the reduction...
657 if (!BugpointIsInterrupted)
658 Ret = ReduceMiscompilingFunctions(BD, TestFn)
659 .reduceList(TheList&: MiscompiledFunctions);
660 if (Error E = Ret.takeError())
661 return std::move(E);
662
663 outs() << "\n*** The following function"
664 << (MiscompiledFunctions.size() == 1 ? " is" : "s are")
665 << " being miscompiled: ";
666 PrintFunctionList(Funcs: MiscompiledFunctions);
667 outs() << '\n';
668 }
669 }
670
671 if (!BugpointIsInterrupted && !DisableBlockExtraction) {
672 Expected<bool> Ret = ExtractBlocks(BD, TestFn, MiscompiledFunctions);
673 if (Error E = Ret.takeError())
674 return std::move(E);
675 if (*Ret) {
676 // Okay, we extracted some blocks and the problem still appears. See if
677 // we can eliminate some of the created functions from being candidates.
678 DisambiguateGlobalSymbols(M&: BD.getProgram());
679
680 // Do the reduction...
681 Ret = ReduceMiscompilingFunctions(BD, TestFn)
682 .reduceList(TheList&: MiscompiledFunctions);
683 if (Error E = Ret.takeError())
684 return std::move(E);
685
686 outs() << "\n*** The following function"
687 << (MiscompiledFunctions.size() == 1 ? " is" : "s are")
688 << " being miscompiled: ";
689 PrintFunctionList(Funcs: MiscompiledFunctions);
690 outs() << '\n';
691 }
692 }
693
694 return MiscompiledFunctions;
695}
696
697/// This is the predicate function used to check to see if the "Test" portion of
698/// the program is misoptimized. If so, return true. In any case, both module
699/// arguments are deleted.
700///
701static Expected<bool> TestOptimizer(BugDriver &BD, std::unique_ptr<Module> Test,
702 std::unique_ptr<Module> Safe) {
703 // Run the optimization passes on ToOptimize, producing a transformed version
704 // of the functions being tested.
705 outs() << " Optimizing functions being tested: ";
706 std::unique_ptr<Module> Optimized =
707 BD.runPassesOn(M: Test.get(), Passes: BD.getPassesToRun());
708 if (!Optimized) {
709 errs() << " Error running this sequence of passes"
710 << " on the input program!\n";
711 BD.EmitProgressBitcode(M: *Test, ID: "pass-error", NoFlyer: false);
712 BD.setNewProgram(std::move(Test));
713 if (Error E = BD.debugOptimizerCrash())
714 return std::move(E);
715 return false;
716 }
717 outs() << "done.\n";
718
719 outs() << " Checking to see if the merged program executes correctly: ";
720 bool Broken;
721 auto Result = testMergedProgram(BD, M1: *Optimized, M2: *Safe, Broken);
722 if (Error E = Result.takeError())
723 return std::move(E);
724 if (auto New = std::move(*Result)) {
725 outs() << (Broken ? " nope.\n" : " yup.\n");
726 // Delete the original and set the new program.
727 BD.setNewProgram(std::move(New));
728 }
729 return Broken;
730}
731
732/// debugMiscompilation - This method is used when the passes selected are not
733/// crashing, but the generated output is semantically different from the
734/// input.
735///
736Error BugDriver::debugMiscompilation() {
737 // Make sure something was miscompiled...
738 if (!BugpointIsInterrupted) {
739 Expected<bool> Result =
740 ReduceMiscompilingPasses(*this).reduceList(TheList&: PassesToRun);
741 if (Error E = Result.takeError())
742 return E;
743 if (!*Result)
744 return make_error<StringError>(
745 Args: "*** Optimized program matches reference output! No problem"
746 " detected...\nbugpoint can't help you with your problem!\n",
747 Args: inconvertibleErrorCode());
748 }
749
750 outs() << "\n*** Found miscompiling pass"
751 << (getPassesToRun().size() == 1 ? "" : "es") << ": "
752 << getPassesString(Passes: getPassesToRun()) << '\n';
753 EmitProgressBitcode(M: *Program, ID: "passinput");
754
755 Expected<std::vector<Function *>> MiscompiledFunctions =
756 DebugAMiscompilation(BD&: *this, TestFn: TestOptimizer);
757 if (Error E = MiscompiledFunctions.takeError())
758 return E;
759
760 // Output a bunch of bitcode files for the user...
761 outs() << "Outputting reduced bitcode files which expose the problem:\n";
762 ValueToValueMapTy VMap;
763 Module *ToNotOptimize = CloneModule(M: getProgram(), VMap).release();
764 Module *ToOptimize =
765 SplitFunctionsOutOfModule(M: ToNotOptimize, F: *MiscompiledFunctions, VMap)
766 .release();
767
768 outs() << " Non-optimized portion: ";
769 EmitProgressBitcode(M: *ToNotOptimize, ID: "tonotoptimize", NoFlyer: true);
770 delete ToNotOptimize; // Delete hacked module.
771
772 outs() << " Portion that is input to optimizer: ";
773 EmitProgressBitcode(M: *ToOptimize, ID: "tooptimize");
774 delete ToOptimize; // Delete hacked module.
775
776 return Error::success();
777}
778
779/// Get the specified modules ready for code generator testing.
780///
781static std::unique_ptr<Module>
782CleanupAndPrepareModules(BugDriver &BD, std::unique_ptr<Module> Test,
783 Module *Safe) {
784 // Clean up the modules, removing extra cruft that we don't need anymore...
785 Test = BD.performFinalCleanups(M: std::move(Test));
786
787 // If we are executing the JIT, we have several nasty issues to take care of.
788 if (!BD.isExecutingJIT())
789 return Test;
790
791 // First, if the main function is in the Safe module, we must add a stub to
792 // the Test module to call into it. Thus, we create a new function `main'
793 // which just calls the old one.
794 if (Function *oldMain = Safe->getFunction(Name: "main"))
795 if (!oldMain->isDeclaration()) {
796 // Rename it
797 oldMain->setName("llvm_bugpoint_old_main");
798 // Create a NEW `main' function with same type in the test module.
799 Function *newMain =
800 Function::Create(Ty: oldMain->getFunctionType(),
801 Linkage: GlobalValue::ExternalLinkage, N: "main", M: Test.get());
802 // Create an `oldmain' prototype in the test module, which will
803 // corresponds to the real main function in the same module.
804 Function *oldMainProto = Function::Create(Ty: oldMain->getFunctionType(),
805 Linkage: GlobalValue::ExternalLinkage,
806 N: oldMain->getName(), M: Test.get());
807 // Set up and remember the argument list for the main function.
808 std::vector<Value *> args;
809 for (Function::arg_iterator I = newMain->arg_begin(),
810 E = newMain->arg_end(),
811 OI = oldMain->arg_begin();
812 I != E; ++I, ++OI) {
813 I->setName(OI->getName()); // Copy argument names from oldMain
814 args.push_back(x: &*I);
815 }
816
817 // Call the old main function and return its result
818 BasicBlock *BB = BasicBlock::Create(Context&: Safe->getContext(), Name: "entry", Parent: newMain);
819 CallInst *call = CallInst::Create(Func: oldMainProto, Args: args, NameStr: "", InsertBefore: BB);
820
821 // If the type of old function wasn't void, return value of call
822 ReturnInst::Create(C&: Safe->getContext(), retVal: call, InsertBefore: BB);
823 }
824
825 // The second nasty issue we must deal with in the JIT is that the Safe
826 // module cannot directly reference any functions defined in the test
827 // module. Instead, we use a JIT API call to dynamically resolve the
828 // symbol.
829
830 // Add the resolver to the Safe module.
831 // Prototype: void *getPointerToNamedFunction(const char* Name)
832 FunctionCallee resolverFunc = Safe->getOrInsertFunction(
833 Name: "getPointerToNamedFunction", RetTy: PointerType::getUnqual(C&: Safe->getContext()),
834 Args: PointerType::getUnqual(C&: Safe->getContext()));
835
836 // Use the function we just added to get addresses of functions we need.
837 for (Module::iterator F = Safe->begin(), E = Safe->end(); F != E; ++F) {
838 if (F->isDeclaration() && !F->use_empty() &&
839 &*F != resolverFunc.getCallee() &&
840 !F->isIntrinsic() /* ignore intrinsics */) {
841 Function *TestFn = Test->getFunction(Name: F->getName());
842
843 // Don't forward functions which are external in the test module too.
844 if (TestFn && !TestFn->isDeclaration()) {
845 // 1. Add a string constant with its name to the global file
846 Constant *InitArray =
847 ConstantDataArray::getString(Context&: F->getContext(), Initializer: F->getName());
848 GlobalVariable *funcName = new GlobalVariable(
849 *Safe, InitArray->getType(), true /*isConstant*/,
850 GlobalValue::InternalLinkage, InitArray, F->getName() + "_name");
851
852 // 2. Use `GetElementPtr *funcName, 0, 0' to convert the string to an
853 // sbyte* so it matches the signature of the resolver function.
854
855 // GetElementPtr *funcName, ulong 0, ulong 0
856 std::vector<Constant *> GEPargs(
857 2, Constant::getNullValue(Ty: Type::getInt32Ty(C&: F->getContext())));
858 Value *GEP = ConstantExpr::getGetElementPtr(Ty: InitArray->getType(),
859 C: funcName, IdxList: GEPargs);
860 std::vector<Value *> ResolverArgs;
861 ResolverArgs.push_back(x: GEP);
862
863 // Rewrite uses of F in global initializers, etc. to uses of a wrapper
864 // function that dynamically resolves the calls to F via our JIT API
865 if (!F->use_empty()) {
866 // Create a new global to hold the cached function pointer.
867 Constant *NullPtr = ConstantPointerNull::get(T: F->getType());
868 GlobalVariable *Cache = new GlobalVariable(
869 *F->getParent(), F->getType(), false,
870 GlobalValue::InternalLinkage, NullPtr, F->getName() + ".fpcache");
871
872 // Construct a new stub function that will re-route calls to F
873 FunctionType *FuncTy = F->getFunctionType();
874 Function *FuncWrapper =
875 Function::Create(Ty: FuncTy, Linkage: GlobalValue::InternalLinkage,
876 N: F->getName() + "_wrapper", M: F->getParent());
877 BasicBlock *EntryBB =
878 BasicBlock::Create(Context&: F->getContext(), Name: "entry", Parent: FuncWrapper);
879 BasicBlock *DoCallBB =
880 BasicBlock::Create(Context&: F->getContext(), Name: "usecache", Parent: FuncWrapper);
881 BasicBlock *LookupBB =
882 BasicBlock::Create(Context&: F->getContext(), Name: "lookupfp", Parent: FuncWrapper);
883
884 // Check to see if we already looked up the value.
885 Value *CachedVal =
886 new LoadInst(F->getType(), Cache, "fpcache", EntryBB);
887 Value *IsNull = new ICmpInst(EntryBB, ICmpInst::ICMP_EQ, CachedVal,
888 NullPtr, "isNull");
889 BranchInst::Create(IfTrue: LookupBB, IfFalse: DoCallBB, Cond: IsNull, InsertBefore: EntryBB);
890
891 // Resolve the call to function F via the JIT API:
892 //
893 // call resolver(GetElementPtr...)
894 CallInst *Resolver = CallInst::Create(Func: resolverFunc, Args: ResolverArgs,
895 NameStr: "resolver", InsertBefore: LookupBB);
896
897 // Save the value in our cache.
898 new StoreInst(Resolver, Cache, LookupBB);
899 BranchInst::Create(IfTrue: DoCallBB, InsertBefore: LookupBB);
900
901 PHINode *FuncPtr =
902 PHINode::Create(Ty: NullPtr->getType(), NumReservedValues: 2, NameStr: "fp", InsertBefore: DoCallBB);
903 FuncPtr->addIncoming(V: Resolver, BB: LookupBB);
904 FuncPtr->addIncoming(V: CachedVal, BB: EntryBB);
905
906 // Save the argument list.
907 std::vector<Value *> Args;
908 for (Argument &A : FuncWrapper->args())
909 Args.push_back(x: &A);
910
911 // Pass on the arguments to the real function, return its result
912 if (F->getReturnType()->isVoidTy()) {
913 CallInst::Create(Ty: FuncTy, Func: FuncPtr, Args, NameStr: "", InsertBefore: DoCallBB);
914 ReturnInst::Create(C&: F->getContext(), InsertAtEnd: DoCallBB);
915 } else {
916 CallInst *Call =
917 CallInst::Create(Ty: FuncTy, Func: FuncPtr, Args, NameStr: "retval", InsertBefore: DoCallBB);
918 ReturnInst::Create(C&: F->getContext(), retVal: Call, InsertBefore: DoCallBB);
919 }
920
921 // Use the wrapper function instead of the old function
922 F->replaceAllUsesWith(V: FuncWrapper);
923 }
924 }
925 }
926 }
927
928 if (verifyModule(M: *Test) || verifyModule(M: *Safe)) {
929 errs() << "Bugpoint has a bug, which corrupted a module!!\n";
930 abort();
931 }
932
933 return Test;
934}
935
936/// This is the predicate function used to check to see if the "Test" portion of
937/// the program is miscompiled by the code generator under test. If so, return
938/// true. In any case, both module arguments are deleted.
939///
940static Expected<bool> TestCodeGenerator(BugDriver &BD,
941 std::unique_ptr<Module> Test,
942 std::unique_ptr<Module> Safe) {
943 Test = CleanupAndPrepareModules(BD, Test: std::move(Test), Safe: Safe.get());
944
945 SmallString<128> TestModuleBC;
946 int TestModuleFD;
947 std::error_code EC = sys::fs::createTemporaryFile(Prefix: "bugpoint.test", Suffix: "bc",
948 ResultFD&: TestModuleFD, ResultPath&: TestModuleBC);
949 if (EC) {
950 errs() << BD.getToolName()
951 << "Error making unique filename: " << EC.message() << "\n";
952 exit(status: 1);
953 }
954 if (BD.writeProgramToFile(Filename: std::string(TestModuleBC), FD: TestModuleFD, M: *Test)) {
955 errs() << "Error writing bitcode to `" << TestModuleBC.str()
956 << "'\nExiting.";
957 exit(status: 1);
958 }
959
960 FileRemover TestModuleBCRemover(TestModuleBC.str(), !SaveTemps);
961
962 // Make the shared library
963 SmallString<128> SafeModuleBC;
964 int SafeModuleFD;
965 EC = sys::fs::createTemporaryFile(Prefix: "bugpoint.safe", Suffix: "bc", ResultFD&: SafeModuleFD,
966 ResultPath&: SafeModuleBC);
967 if (EC) {
968 errs() << BD.getToolName()
969 << "Error making unique filename: " << EC.message() << "\n";
970 exit(status: 1);
971 }
972
973 if (BD.writeProgramToFile(Filename: std::string(SafeModuleBC), FD: SafeModuleFD, M: *Safe)) {
974 errs() << "Error writing bitcode to `" << SafeModuleBC << "'\nExiting.";
975 exit(status: 1);
976 }
977
978 FileRemover SafeModuleBCRemover(SafeModuleBC.str(), !SaveTemps);
979
980 Expected<std::string> SharedObject =
981 BD.compileSharedObject(BitcodeFile: std::string(SafeModuleBC));
982 if (Error E = SharedObject.takeError())
983 return std::move(E);
984
985 FileRemover SharedObjectRemover(*SharedObject, !SaveTemps);
986
987 // Run the code generator on the `Test' code, loading the shared library.
988 // The function returns whether or not the new output differs from reference.
989 Expected<bool> Result = BD.diffProgram(
990 Program: BD.getProgram(), BitcodeFile: std::string(TestModuleBC), SharedObj: *SharedObject, RemoveBitcode: false);
991 if (Error E = Result.takeError())
992 return std::move(E);
993
994 if (*Result)
995 errs() << ": still failing!\n";
996 else
997 errs() << ": didn't fail.\n";
998
999 return Result;
1000}
1001
1002/// debugCodeGenerator - debug errors in LLC, LLI, or CBE.
1003///
1004Error BugDriver::debugCodeGenerator() {
1005 if ((void *)SafeInterpreter == (void *)Interpreter) {
1006 Expected<std::string> Result =
1007 executeProgramSafely(Program: *Program, OutputFile: "bugpoint.safe.out");
1008 if (Result) {
1009 outs() << "\n*** The \"safe\" i.e. 'known good' backend cannot match "
1010 << "the reference diff. This may be due to a\n front-end "
1011 << "bug or a bug in the original program, but this can also "
1012 << "happen if bugpoint isn't running the program with the "
1013 << "right flags or input.\n I left the result of executing "
1014 << "the program with the \"safe\" backend in this file for "
1015 << "you: '" << *Result << "'.\n";
1016 }
1017 return Error::success();
1018 }
1019
1020 DisambiguateGlobalSymbols(M&: *Program);
1021
1022 Expected<std::vector<Function *>> Funcs =
1023 DebugAMiscompilation(BD&: *this, TestFn: TestCodeGenerator);
1024 if (Error E = Funcs.takeError())
1025 return E;
1026
1027 // Split the module into the two halves of the program we want.
1028 ValueToValueMapTy VMap;
1029 std::unique_ptr<Module> ToNotCodeGen = CloneModule(M: getProgram(), VMap);
1030 std::unique_ptr<Module> ToCodeGen =
1031 SplitFunctionsOutOfModule(M: ToNotCodeGen.get(), F: *Funcs, VMap);
1032
1033 // Condition the modules
1034 ToCodeGen =
1035 CleanupAndPrepareModules(BD&: *this, Test: std::move(ToCodeGen), Safe: ToNotCodeGen.get());
1036
1037 SmallString<128> TestModuleBC;
1038 int TestModuleFD;
1039 std::error_code EC = sys::fs::createTemporaryFile(Prefix: "bugpoint.test", Suffix: "bc",
1040 ResultFD&: TestModuleFD, ResultPath&: TestModuleBC);
1041 if (EC) {
1042 errs() << getToolName() << "Error making unique filename: " << EC.message()
1043 << "\n";
1044 exit(status: 1);
1045 }
1046
1047 if (writeProgramToFile(Filename: std::string(TestModuleBC), FD: TestModuleFD, M: *ToCodeGen)) {
1048 errs() << "Error writing bitcode to `" << TestModuleBC << "'\nExiting.";
1049 exit(status: 1);
1050 }
1051
1052 // Make the shared library
1053 SmallString<128> SafeModuleBC;
1054 int SafeModuleFD;
1055 EC = sys::fs::createTemporaryFile(Prefix: "bugpoint.safe", Suffix: "bc", ResultFD&: SafeModuleFD,
1056 ResultPath&: SafeModuleBC);
1057 if (EC) {
1058 errs() << getToolName() << "Error making unique filename: " << EC.message()
1059 << "\n";
1060 exit(status: 1);
1061 }
1062
1063 if (writeProgramToFile(Filename: std::string(SafeModuleBC), FD: SafeModuleFD,
1064 M: *ToNotCodeGen)) {
1065 errs() << "Error writing bitcode to `" << SafeModuleBC << "'\nExiting.";
1066 exit(status: 1);
1067 }
1068 Expected<std::string> SharedObject =
1069 compileSharedObject(BitcodeFile: std::string(SafeModuleBC));
1070 if (Error E = SharedObject.takeError())
1071 return E;
1072
1073 outs() << "You can reproduce the problem with the command line: \n";
1074 if (isExecutingJIT()) {
1075 outs() << " lli -load " << *SharedObject << " " << TestModuleBC;
1076 } else {
1077 outs() << " llc " << TestModuleBC << " -o " << TestModuleBC << ".s\n";
1078 outs() << " cc " << *SharedObject << " " << TestModuleBC.str() << ".s -o "
1079 << TestModuleBC << ".exe\n";
1080 outs() << " ./" << TestModuleBC << ".exe";
1081 }
1082 for (unsigned i = 0, e = InputArgv.size(); i != e; ++i)
1083 outs() << " " << InputArgv[i];
1084 outs() << '\n';
1085 outs() << "The shared object was created with:\n llc -march=c "
1086 << SafeModuleBC.str() << " -o temporary.c\n"
1087 << " cc -xc temporary.c -O2 -o " << *SharedObject;
1088 if (TargetTriple.getArch() == Triple::sparc)
1089 outs() << " -G"; // Compile a shared library, `-G' for Sparc
1090 else
1091 outs() << " -fPIC -shared"; // `-shared' for Linux/X86, maybe others
1092
1093 outs() << " -fno-strict-aliasing\n";
1094
1095 return Error::success();
1096}
1097