1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
|
//===- Miscompilation.cpp - Debug program miscompilations -----------------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements optimizer and code generation miscompilation debugging
// support.
//
//===----------------------------------------------------------------------===//
#include "BugDriver.h"
#include "ListReducer.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
#include "llvm/Linker.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/Analysis/Verifier.h"
#include "llvm/Support/Mangler.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileUtilities.h"
#include "llvm/Config/config.h" // for HAVE_LINK_R
using namespace llvm;
namespace llvm {
extern cl::list<std::string> InputArgv;
}
namespace {
static llvm::cl::opt<bool>
DisableLoopExtraction("disable-loop-extraction",
cl::desc("Don't extract loops when searching for miscompilations"),
cl::init(false));
class ReduceMiscompilingPasses : public ListReducer<const PassInfo*> {
BugDriver &BD;
public:
ReduceMiscompilingPasses(BugDriver &bd) : BD(bd) {}
virtual TestResult doTest(std::vector<const PassInfo*> &Prefix,
std::vector<const PassInfo*> &Suffix);
};
}
/// TestResult - After passes have been split into a test group and a control
/// group, see if they still break the program.
///
ReduceMiscompilingPasses::TestResult
ReduceMiscompilingPasses::doTest(std::vector<const PassInfo*> &Prefix,
std::vector<const PassInfo*> &Suffix) {
// First, run the program with just the Suffix passes. If it is still broken
// with JUST the kept passes, discard the prefix passes.
std::cout << "Checking to see if '" << getPassesString(Suffix)
<< "' compile correctly: ";
std::string BitcodeResult;
if (BD.runPasses(Suffix, BitcodeResult, false/*delete*/, true/*quiet*/)) {
std::cerr << " Error running this sequence of passes"
<< " on the input program!\n";
BD.setPassesToRun(Suffix);
BD.EmitProgressBitcode("pass-error", false);
exit(BD.debugOptimizerCrash());
}
// Check to see if the finished program matches the reference output...
if (BD.diffProgram(BitcodeResult, "", true /*delete bitcode*/)) {
std::cout << " nope.\n";
if (Suffix.empty()) {
std::cerr << BD.getToolName() << ": I'm confused: the test fails when "
<< "no passes are run, nondeterministic program?\n";
exit(1);
}
return KeepSuffix; // Miscompilation detected!
}
std::cout << " yup.\n"; // No miscompilation!
if (Prefix.empty()) return NoFailure;
// Next, see if the program is broken if we run the "prefix" passes first,
// then separately run the "kept" passes.
std::cout << "Checking to see if '" << getPassesString(Prefix)
<< "' compile correctly: ";
// If it is not broken with the kept passes, it's possible that the prefix
// passes must be run before the kept passes to break it. If the program
// WORKS after the prefix passes, but then fails if running the prefix AND
// kept passes, we can update our bitcode file to include the result of the
// prefix passes, then discard the prefix passes.
//
if (BD.runPasses(Prefix, BitcodeResult, false/*delete*/, true/*quiet*/)) {
std::cerr << " Error running this sequence of passes"
<< " on the input program!\n";
BD.setPassesToRun(Prefix);
BD.EmitProgressBitcode("pass-error", false);
exit(BD.debugOptimizerCrash());
}
// If the prefix maintains the predicate by itself, only keep the prefix!
if (BD.diffProgram(BitcodeResult)) {
std::cout << " nope.\n";
sys::Path(BitcodeResult).eraseFromDisk();
return KeepPrefix;
}
std::cout << " yup.\n"; // No miscompilation!
// Ok, so now we know that the prefix passes work, try running the suffix
// passes on the result of the prefix passes.
//
Module *PrefixOutput = ParseInputFile(BitcodeResult);
if (PrefixOutput == 0) {
std::cerr << BD.getToolName() << ": Error reading bitcode file '"
<< BitcodeResult << "'!\n";
exit(1);
}
sys::Path(BitcodeResult).eraseFromDisk(); // No longer need the file on disk
// Don't check if there are no passes in the suffix.
if (Suffix.empty())
return NoFailure;
std::cout << "Checking to see if '" << getPassesString(Suffix)
<< "' passes compile correctly after the '"
<< getPassesString(Prefix) << "' passes: ";
Module *OriginalInput = BD.swapProgramIn(PrefixOutput);
if (BD.runPasses(Suffix, BitcodeResult, false/*delete*/, true/*quiet*/)) {
std::cerr << " Error running this sequence of passes"
<< " on the input program!\n";
BD.setPassesToRun(Suffix);
BD.EmitProgressBitcode("pass-error", false);
exit(BD.debugOptimizerCrash());
}
// Run the result...
if (BD.diffProgram(BitcodeResult, "", true/*delete bitcode*/)) {
std::cout << " nope.\n";
delete OriginalInput; // We pruned down the original input...
return KeepSuffix;
}
// Otherwise, we must not be running the bad pass anymore.
std::cout << " yup.\n"; // No miscompilation!
delete BD.swapProgramIn(OriginalInput); // Restore orig program & free test
return NoFailure;
}
namespace {
class ReduceMiscompilingFunctions : public ListReducer<Function*> {
BugDriver &BD;
bool (*TestFn)(BugDriver &, Module *, Module *);
public:
ReduceMiscompilingFunctions(BugDriver &bd,
bool (*F)(BugDriver &, Module *, Module *))
: BD(bd), TestFn(F) {}
virtual TestResult doTest(std::vector<Function*> &Prefix,
std::vector<Function*> &Suffix) {
if (!Suffix.empty() && TestFuncs(Suffix))
return KeepSuffix;
if (!Prefix.empty() && TestFuncs(Prefix))
return KeepPrefix;
return NoFailure;
}
bool TestFuncs(const std::vector<Function*> &Prefix);
};
}
/// TestMergedProgram - Given two modules, link them together and run the
/// program, checking to see if the program matches the diff. If the diff
/// matches, return false, otherwise return true. If the DeleteInputs argument
/// is set to true then this function deletes both input modules before it
/// returns.
///
static bool TestMergedProgram(BugDriver &BD, Module *M1, Module *M2,
bool DeleteInputs) {
// Link the two portions of the program back to together.
std::string ErrorMsg;
if (!DeleteInputs) {
M1 = CloneModule(M1);
M2 = CloneModule(M2);
}
if (Linker::LinkModules(M1, M2, &ErrorMsg)) {
std::cerr << BD.getToolName() << ": Error linking modules together:"
<< ErrorMsg << '\n';
exit(1);
}
delete M2; // We are done with this module.
Module *OldProgram = BD.swapProgramIn(M1);
// Execute the program. If it does not match the expected output, we must
// return true.
bool Broken = BD.diffProgram();
// Delete the linked module & restore the original
BD.swapProgramIn(OldProgram);
delete M1;
return Broken;
}
/// TestFuncs - split functions in a Module into two groups: those that are
/// under consideration for miscompilation vs. those that are not, and test
/// accordingly. Each group of functions becomes a separate Module.
///
bool ReduceMiscompilingFunctions::TestFuncs(const std::vector<Function*>&Funcs){
// Test to see if the function is misoptimized if we ONLY run it on the
// functions listed in Funcs.
std::cout << "Checking to see if the program is misoptimized when "
<< (Funcs.size()==1 ? "this function is" : "these functions are")
<< " run through the pass"
<< (BD.getPassesToRun().size() == 1 ? "" : "es") << ":";
PrintFunctionList(Funcs);
std::cout << '\n';
// Split the module into the two halves of the program we want.
Module *ToNotOptimize = CloneModule(BD.getProgram());
Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize, Funcs);
// Run the predicate, not that the predicate will delete both input modules.
return TestFn(BD, ToOptimize, ToNotOptimize);
}
/// DisambiguateGlobalSymbols - Mangle symbols to guarantee uniqueness by
/// modifying predominantly internal symbols rather than external ones.
///
static void DisambiguateGlobalSymbols(Module *M) {
// Try not to cause collisions by minimizing chances of renaming an
// already-external symbol, so take in external globals and functions as-is.
// The code should work correctly without disambiguation (assuming the same
// mangler is used by the two code generators), but having symbols with the
// same name causes warnings to be emitted by the code generator.
Mangler Mang(*M);
// Agree with the CBE on symbol naming
Mang.markCharUnacceptable('.');
Mang.setPreserveAsmNames(true);
for (Module::global_iterator I = M->global_begin(), E = M->global_end();
I != E; ++I)
I->setName(Mang.getValueName(I));
for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
I->setName(Mang.getValueName(I));
}
/// ExtractLoops - Given a reduced list of functions that still exposed the bug,
/// check to see if we can extract the loops in the region without obscuring the
/// bug. If so, it reduces the amount of code identified.
///
static bool ExtractLoops(BugDriver &BD,
bool (*TestFn)(BugDriver &, Module *, Module *),
std::vector<Function*> &MiscompiledFunctions) {
bool MadeChange = false;
while (1) {
if (BugpointIsInterrupted) return MadeChange;
Module *ToNotOptimize = CloneModule(BD.getProgram());
Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize,
MiscompiledFunctions);
Module *ToOptimizeLoopExtracted = BD.ExtractLoop(ToOptimize);
if (!ToOptimizeLoopExtracted) {
// If the loop extractor crashed or if there were no extractible loops,
// then this chapter of our odyssey is over with.
delete ToNotOptimize;
delete ToOptimize;
return MadeChange;
}
std::cerr << "Extracted a loop from the breaking portion of the program.\n";
// Bugpoint is intentionally not very trusting of LLVM transformations. In
// particular, we're not going to assume that the loop extractor works, so
// we're going to test the newly loop extracted program to make sure nothing
// has broken. If something broke, then we'll inform the user and stop
// extraction.
AbstractInterpreter *AI = BD.switchToCBE();
if (TestMergedProgram(BD, ToOptimizeLoopExtracted, ToNotOptimize, false)) {
BD.switchToInterpreter(AI);
// Merged program doesn't work anymore!
std::cerr << " *** ERROR: Loop extraction broke the program. :("
<< " Please report a bug!\n";
std::cerr << " Continuing on with un-loop-extracted version.\n";
BD.writeProgramToFile("bugpoint-loop-extract-fail-tno.bc", ToNotOptimize);
BD.writeProgramToFile("bugpoint-loop-extract-fail-to.bc", ToOptimize);
BD.writeProgramToFile("bugpoint-loop-extract-fail-to-le.bc",
ToOptimizeLoopExtracted);
std::cerr << "Please submit the bugpoint-loop-extract-fail-*.bc files.\n";
delete ToOptimize;
delete ToNotOptimize;
delete ToOptimizeLoopExtracted;
return MadeChange;
}
delete ToOptimize;
BD.switchToInterpreter(AI);
std::cout << " Testing after loop extraction:\n";
// Clone modules, the tester function will free them.
Module *TOLEBackup = CloneModule(ToOptimizeLoopExtracted);
Module *TNOBackup = CloneModule(ToNotOptimize);
if (!TestFn(BD, ToOptimizeLoopExtracted, ToNotOptimize)) {
std::cout << "*** Loop extraction masked the problem. Undoing.\n";
// If the program is not still broken, then loop extraction did something
// that masked the error. Stop loop extraction now.
delete TOLEBackup;
delete TNOBackup;
return MadeChange;
}
ToOptimizeLoopExtracted = TOLEBackup;
ToNotOptimize = TNOBackup;
std::cout << "*** Loop extraction successful!\n";
std::vector<std::pair<std::string, const FunctionType*> > MisCompFunctions;
for (Module::iterator I = ToOptimizeLoopExtracted->begin(),
E = ToOptimizeLoopExtracted->end(); I != E; ++I)
if (!I->isDeclaration())
MisCompFunctions.push_back(std::make_pair(I->getName(),
I->getFunctionType()));
// Okay, great! Now we know that we extracted a loop and that loop
// extraction both didn't break the program, and didn't mask the problem.
// Replace the current program with the loop extracted version, and try to
// extract another loop.
std::string ErrorMsg;
if (Linker::LinkModules(ToNotOptimize, ToOptimizeLoopExtracted, &ErrorMsg)){
std::cerr << BD.getToolName() << ": Error linking modules together:"
<< ErrorMsg << '\n';
exit(1);
}
delete ToOptimizeLoopExtracted;
// All of the Function*'s in the MiscompiledFunctions list are in the old
// module. Update this list to include all of the functions in the
// optimized and loop extracted module.
MiscompiledFunctions.clear();
for (unsigned i = 0, e = MisCompFunctions.size(); i != e; ++i) {
Function *NewF = ToNotOptimize->getFunction(MisCompFunctions[i].first);
assert(NewF && "Function not found??");
assert(NewF->getFunctionType() == MisCompFunctions[i].second &&
"found wrong function type?");
MiscompiledFunctions.push_back(NewF);
}
BD.setNewProgram(ToNotOptimize);
MadeChange = true;
}
}
namespace {
class ReduceMiscompiledBlocks : public ListReducer<BasicBlock*> {
BugDriver &BD;
bool (*TestFn)(BugDriver &, Module *, Module *);
std::vector<Function*> FunctionsBeingTested;
public:
ReduceMiscompiledBlocks(BugDriver &bd,
bool (*F)(BugDriver &, Module *, Module *),
const std::vector<Function*> &Fns)
: BD(bd), TestFn(F), FunctionsBeingTested(Fns) {}
virtual TestResult doTest(std::vector<BasicBlock*> &Prefix,
std::vector<BasicBlock*> &Suffix) {
if (!Suffix.empty() && TestFuncs(Suffix))
return KeepSuffix;
if (TestFuncs(Prefix))
return KeepPrefix;
return NoFailure;
}
bool TestFuncs(const std::vector<BasicBlock*> &Prefix);
};
}
/// TestFuncs - Extract all blocks for the miscompiled functions except for the
/// specified blocks. If the problem still exists, return true.
///
bool ReduceMiscompiledBlocks::TestFuncs(const std::vector<BasicBlock*> &BBs) {
// Test to see if the function is misoptimized if we ONLY run it on the
// functions listed in Funcs.
std::cout << "Checking to see if the program is misoptimized when all ";
if (!BBs.empty()) {
std::cout << "but these " << BBs.size() << " blocks are extracted: ";
for (unsigned i = 0, e = BBs.size() < 10 ? BBs.size() : 10; i != e; ++i)
std::cout << BBs[i]->getName() << " ";
if (BBs.size() > 10) std::cout << "...";
} else {
std::cout << "blocks are extracted.";
}
std::cout << '\n';
// Split the module into the two halves of the program we want.
Module *ToNotOptimize = CloneModule(BD.getProgram());
Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize,
FunctionsBeingTested);
// Try the extraction. If it doesn't work, then the block extractor crashed
// or something, in which case bugpoint can't chase down this possibility.
if (Module *New = BD.ExtractMappedBlocksFromModule(BBs, ToOptimize)) {
delete ToOptimize;
// Run the predicate, not that the predicate will delete both input modules.
return TestFn(BD, New, ToNotOptimize);
}
delete ToOptimize;
delete ToNotOptimize;
return false;
}
/// ExtractBlocks - Given a reduced list of functions that still expose the bug,
/// extract as many basic blocks from the region as possible without obscuring
/// the bug.
///
static bool ExtractBlocks(BugDriver &BD,
bool (*TestFn)(BugDriver &, Module *, Module *),
std::vector<Function*> &MiscompiledFunctions) {
if (BugpointIsInterrupted) return false;
std::vector<BasicBlock*> Blocks;
for (unsigned i = 0, e = MiscompiledFunctions.size(); i != e; ++i)
for (Function::iterator I = MiscompiledFunctions[i]->begin(),
E = MiscompiledFunctions[i]->end(); I != E; ++I)
Blocks.push_back(I);
// Use the list reducer to identify blocks that can be extracted without
// obscuring the bug. The Blocks list will end up containing blocks that must
// be retained from the original program.
unsigned OldSize = Blocks.size();
// Check to see if all blocks are extractible first.
if (ReduceMiscompiledBlocks(BD, TestFn,
MiscompiledFunctions).TestFuncs(std::vector<BasicBlock*>())) {
Blocks.clear();
} else {
ReduceMiscompiledBlocks(BD, TestFn,MiscompiledFunctions).reduceList(Blocks);
if (Blocks.size() == OldSize)
return false;
}
Module *ProgClone = CloneModule(BD.getProgram());
Module *ToExtract = SplitFunctionsOutOfModule(ProgClone,
MiscompiledFunctions);
Module *Extracted = BD.ExtractMappedBlocksFromModule(Blocks, ToExtract);
if (Extracted == 0) {
// Weird, extraction should have worked.
std::cerr << "Nondeterministic problem extracting blocks??\n";
delete ProgClone;
delete ToExtract;
return false;
}
// Otherwise, block extraction succeeded. Link the two program fragments back
// together.
delete ToExtract;
std::vector<std::pair<std::string, const FunctionType*> > MisCompFunctions;
for (Module::iterator I = Extracted->begin(), E = Extracted->end();
I != E; ++I)
if (!I->isDeclaration())
MisCompFunctions.push_back(std::make_pair(I->getName(),
I->getFunctionType()));
std::string ErrorMsg;
if (Linker::LinkModules(ProgClone, Extracted, &ErrorMsg)) {
std::cerr << BD.getToolName() << ": Error linking modules together:"
<< ErrorMsg << '\n';
exit(1);
}
delete Extracted;
// Set the new program and delete the old one.
BD.setNewProgram(ProgClone);
// Update the list of miscompiled functions.
MiscompiledFunctions.clear();
for (unsigned i = 0, e = MisCompFunctions.size(); i != e; ++i) {
Function *NewF = ProgClone->getFunction(MisCompFunctions[i].first);
assert(NewF && "Function not found??");
assert(NewF->getFunctionType() == MisCompFunctions[i].second &&
"Function has wrong type??");
MiscompiledFunctions.push_back(NewF);
}
return true;
}
/// DebugAMiscompilation - This is a generic driver to narrow down
/// miscompilations, either in an optimization or a code generator.
///
static std::vector<Function*>
DebugAMiscompilation(BugDriver &BD,
bool (*TestFn)(BugDriver &, Module *, Module *)) {
// Okay, now that we have reduced the list of passes which are causing the
// failure, see if we can pin down which functions are being
// miscompiled... first build a list of all of the non-external functions in
// the program.
std::vector<Function*> MiscompiledFunctions;
Module *Prog = BD.getProgram();
for (Module::iterator I = Prog->begin(), E = Prog->end(); I != E; ++I)
if (!I->isDeclaration())
MiscompiledFunctions.push_back(I);
// Do the reduction...
if (!BugpointIsInterrupted)
ReduceMiscompilingFunctions(BD, TestFn).reduceList(MiscompiledFunctions);
std::cout << "\n*** The following function"
<< (MiscompiledFunctions.size() == 1 ? " is" : "s are")
<< " being miscompiled: ";
PrintFunctionList(MiscompiledFunctions);
std::cout << '\n';
// See if we can rip any loops out of the miscompiled functions and still
// trigger the problem.
if (!BugpointIsInterrupted && !DisableLoopExtraction &&
ExtractLoops(BD, TestFn, MiscompiledFunctions)) {
// Okay, we extracted some loops and the problem still appears. See if we
// can eliminate some of the created functions from being candidates.
// Loop extraction can introduce functions with the same name (foo_code).
// Make sure to disambiguate the symbols so that when the program is split
// apart that we can link it back together again.
DisambiguateGlobalSymbols(BD.getProgram());
// Do the reduction...
if (!BugpointIsInterrupted)
ReduceMiscompilingFunctions(BD, TestFn).reduceList(MiscompiledFunctions);
std::cout << "\n*** The following function"
<< (MiscompiledFunctions.size() == 1 ? " is" : "s are")
<< " being miscompiled: ";
PrintFunctionList(MiscompiledFunctions);
std::cout << '\n';
}
if (!BugpointIsInterrupted &&
ExtractBlocks(BD, TestFn, MiscompiledFunctions)) {
// Okay, we extracted some blocks and the problem still appears. See if we
// can eliminate some of the created functions from being candidates.
// Block extraction can introduce functions with the same name (foo_code).
// Make sure to disambiguate the symbols so that when the program is split
// apart that we can link it back together again.
DisambiguateGlobalSymbols(BD.getProgram());
// Do the reduction...
ReduceMiscompilingFunctions(BD, TestFn).reduceList(MiscompiledFunctions);
std::cout << "\n*** The following function"
<< (MiscompiledFunctions.size() == 1 ? " is" : "s are")
<< " being miscompiled: ";
PrintFunctionList(MiscompiledFunctions);
std::cout << '\n';
}
return MiscompiledFunctions;
}
/// TestOptimizer - This is the predicate function used to check to see if the
/// "Test" portion of the program is misoptimized. If so, return true. In any
/// case, both module arguments are deleted.
///
static bool TestOptimizer(BugDriver &BD, Module *Test, Module *Safe) {
// Run the optimization passes on ToOptimize, producing a transformed version
// of the functions being tested.
std::cout << " Optimizing functions being tested: ";
Module *Optimized = BD.runPassesOn(Test, BD.getPassesToRun(),
/*AutoDebugCrashes*/true);
std::cout << "done.\n";
delete Test;
std::cout << " Checking to see if the merged program executes correctly: ";
bool Broken = TestMergedProgram(BD, Optimized, Safe, true);
std::cout << (Broken ? " nope.\n" : " yup.\n");
return Broken;
}
/// debugMiscompilation - This method is used when the passes selected are not
/// crashing, but the generated output is semantically different from the
/// input.
///
bool BugDriver::debugMiscompilation() {
// Make sure something was miscompiled...
if (!BugpointIsInterrupted)
if (!ReduceMiscompilingPasses(*this).reduceList(PassesToRun)) {
std::cerr << "*** Optimized program matches reference output! No problem"
<< " detected...\nbugpoint can't help you with your problem!\n";
return false;
}
std::cout << "\n*** Found miscompiling pass"
<< (getPassesToRun().size() == 1 ? "" : "es") << ": "
<< getPassesString(getPassesToRun()) << '\n';
EmitProgressBitcode("passinput");
std::vector<Function*> MiscompiledFunctions =
DebugAMiscompilation(*this, TestOptimizer);
// Output a bunch of bitcode files for the user...
std::cout << "Outputting reduced bitcode files which expose the problem:\n";
Module *ToNotOptimize = CloneModule(getProgram());
Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize,
MiscompiledFunctions);
std::cout << " Non-optimized portion: ";
ToNotOptimize = swapProgramIn(ToNotOptimize);
EmitProgressBitcode("tonotoptimize", true);
setNewProgram(ToNotOptimize); // Delete hacked module.
std::cout << " Portion that is input to optimizer: ";
ToOptimize = swapProgramIn(ToOptimize);
EmitProgressBitcode("tooptimize");
setNewProgram(ToOptimize); // Delete hacked module.
return false;
}
/// CleanupAndPrepareModules - Get the specified modules ready for code
/// generator testing.
///
static void CleanupAndPrepareModules(BugDriver &BD, Module *&Test,
Module *Safe) {
// Clean up the modules, removing extra cruft that we don't need anymore...
Test = BD.performFinalCleanups(Test);
// If we are executing the JIT, we have several nasty issues to take care of.
if (!BD.isExecutingJIT()) return;
// First, if the main function is in the Safe module, we must add a stub to
// the Test module to call into it. Thus, we create a new function `main'
// which just calls the old one.
if (Function *oldMain = Safe->getFunction("main"))
if (!oldMain->isDeclaration()) {
// Rename it
oldMain->setName("llvm_bugpoint_old_main");
// Create a NEW `main' function with same type in the test module.
Function *newMain = new Function(oldMain->getFunctionType(),
GlobalValue::ExternalLinkage,
"main", Test);
// Create an `oldmain' prototype in the test module, which will
// corresponds to the real main function in the same module.
Function *oldMainProto = new Function(oldMain->getFunctionType(),
GlobalValue::ExternalLinkage,
oldMain->getName(), Test);
// Set up and remember the argument list for the main function.
std::vector<Value*> args;
for (Function::arg_iterator
I = newMain->arg_begin(), E = newMain->arg_end(),
OI = oldMain->arg_begin(); I != E; ++I, ++OI) {
I->setName(OI->getName()); // Copy argument names from oldMain
args.push_back(I);
}
// Call the old main function and return its result
BasicBlock *BB = new BasicBlock("entry", newMain);
CallInst *call = new CallInst(oldMainProto, args.begin(), args.end(),
"", BB);
// If the type of old function wasn't void, return value of call
new ReturnInst(call, BB);
}
// The second nasty issue we must deal with in the JIT is that the Safe
// module cannot directly reference any functions defined in the test
// module. Instead, we use a JIT API call to dynamically resolve the
// symbol.
// Add the resolver to the Safe module.
// Prototype: void *getPointerToNamedFunction(const char* Name)
Constant *resolverFunc =
Safe->getOrInsertFunction("getPointerToNamedFunction",
PointerType::get(Type::Int8Ty),
PointerType::get(Type::Int8Ty), (Type *)0);
// Use the function we just added to get addresses of functions we need.
for (Module::iterator F = Safe->begin(), E = Safe->end(); F != E; ++F) {
if (F->isDeclaration() && !F->use_empty() && &*F != resolverFunc &&
F->getIntrinsicID() == 0 /* ignore intrinsics */) {
Function *TestFn = Test->getFunction(F->getName());
// Don't forward functions which are external in the test module too.
if (TestFn && !TestFn->isDeclaration()) {
// 1. Add a string constant with its name to the global file
Constant *InitArray = ConstantArray::get(F->getName());
GlobalVariable *funcName =
new GlobalVariable(InitArray->getType(), true /*isConstant*/,
GlobalValue::InternalLinkage, InitArray,
F->getName() + "_name", Safe);
// 2. Use `GetElementPtr *funcName, 0, 0' to convert the string to an
// sbyte* so it matches the signature of the resolver function.
// GetElementPtr *funcName, ulong 0, ulong 0
std::vector<Constant*> GEPargs(2,Constant::getNullValue(Type::Int32Ty));
Value *GEP = ConstantExpr::getGetElementPtr(funcName, &GEPargs[0], 2);
std::vector<Value*> ResolverArgs;
ResolverArgs.push_back(GEP);
// Rewrite uses of F in global initializers, etc. to uses of a wrapper
// function that dynamically resolves the calls to F via our JIT API
if (!F->use_empty()) {
// Create a new global to hold the cached function pointer.
Constant *NullPtr = ConstantPointerNull::get(F->getType());
GlobalVariable *Cache =
new GlobalVariable(F->getType(), false,GlobalValue::InternalLinkage,
NullPtr,F->getName()+".fpcache", F->getParent());
// Construct a new stub function that will re-route calls to F
const FunctionType *FuncTy = F->getFunctionType();
Function *FuncWrapper = new Function(FuncTy,
GlobalValue::InternalLinkage,
F->getName() + "_wrapper",
F->getParent());
BasicBlock *EntryBB = new BasicBlock("entry", FuncWrapper);
BasicBlock *DoCallBB = new BasicBlock("usecache", FuncWrapper);
BasicBlock *LookupBB = new BasicBlock("lookupfp", FuncWrapper);
// Check to see if we already looked up the value.
Value *CachedVal = new LoadInst(Cache, "fpcache", EntryBB);
Value *IsNull = new ICmpInst(ICmpInst::ICMP_EQ, CachedVal,
NullPtr, "isNull", EntryBB);
new BranchInst(LookupBB, DoCallBB, IsNull, EntryBB);
// Resolve the call to function F via the JIT API:
//
// call resolver(GetElementPtr...)
CallInst *Resolver = new CallInst(resolverFunc, ResolverArgs.begin(),
ResolverArgs.end(),
"resolver", LookupBB);
// cast the result from the resolver to correctly-typed function
CastInst *CastedResolver = new BitCastInst(Resolver,
PointerType::get(F->getFunctionType()), "resolverCast", LookupBB);
// Save the value in our cache.
new StoreInst(CastedResolver, Cache, LookupBB);
new BranchInst(DoCallBB, LookupBB);
PHINode *FuncPtr = new PHINode(NullPtr->getType(), "fp", DoCallBB);
FuncPtr->addIncoming(CastedResolver, LookupBB);
FuncPtr->addIncoming(CachedVal, EntryBB);
// Save the argument list.
std::vector<Value*> Args;
for (Function::arg_iterator i = FuncWrapper->arg_begin(),
e = FuncWrapper->arg_end(); i != e; ++i)
Args.push_back(i);
// Pass on the arguments to the real function, return its result
if (F->getReturnType() == Type::VoidTy) {
new CallInst(FuncPtr, Args.begin(), Args.end(), "", DoCallBB);
new ReturnInst(DoCallBB);
} else {
CallInst *Call = new CallInst(FuncPtr, Args.begin(), Args.end(),
"retval", DoCallBB);
new ReturnInst(Call, DoCallBB);
}
// Use the wrapper function instead of the old function
F->replaceAllUsesWith(FuncWrapper);
}
}
}
}
if (verifyModule(*Test) || verifyModule(*Safe)) {
std::cerr << "Bugpoint has a bug, which corrupted a module!!\n";
abort();
}
}
/// TestCodeGenerator - This is the predicate function used to check to see if
/// the "Test" portion of the program is miscompiled by the code generator under
/// test. If so, return true. In any case, both module arguments are deleted.
///
static bool TestCodeGenerator(BugDriver &BD, Module *Test, Module *Safe) {
CleanupAndPrepareModules(BD, Test, Safe);
sys::Path TestModuleBC("bugpoint.test.bc");
std::string ErrMsg;
if (TestModuleBC.makeUnique(true, &ErrMsg)) {
std::cerr << BD.getToolName() << "Error making unique filename: "
<< ErrMsg << "\n";
exit(1);
}
if (BD.writeProgramToFile(TestModuleBC.toString(), Test)) {
std::cerr << "Error writing bitcode to `" << TestModuleBC << "'\nExiting.";
exit(1);
}
delete Test;
// Make the shared library
sys::Path SafeModuleBC("bugpoint.safe.bc");
if (SafeModuleBC.makeUnique(true, &ErrMsg)) {
std::cerr << BD.getToolName() << "Error making unique filename: "
<< ErrMsg << "\n";
exit(1);
}
if (BD.writeProgramToFile(SafeModuleBC.toString(), Safe)) {
std::cerr << "Error writing bitcode to `" << SafeModuleBC << "'\nExiting.";
exit(1);
}
std::string SharedObject = BD.compileSharedObject(SafeModuleBC.toString());
delete Safe;
// Run the code generator on the `Test' code, loading the shared library.
// The function returns whether or not the new output differs from reference.
int Result = BD.diffProgram(TestModuleBC.toString(), SharedObject, false);
if (Result)
std::cerr << ": still failing!\n";
else
std::cerr << ": didn't fail.\n";
TestModuleBC.eraseFromDisk();
SafeModuleBC.eraseFromDisk();
sys::Path(SharedObject).eraseFromDisk();
return Result;
}
/// debugCodeGenerator - debug errors in LLC, LLI, or CBE.
///
bool BugDriver::debugCodeGenerator() {
if ((void*)cbe == (void*)Interpreter) {
std::string Result = executeProgramWithCBE("bugpoint.cbe.out");
std::cout << "\n*** The C backend cannot match the reference diff, but it "
<< "is used as the 'known good'\n code generator, so I can't"
<< " debug it. Perhaps you have a front-end problem?\n As a"
<< " sanity check, I left the result of executing the program "
<< "with the C backend\n in this file for you: '"
<< Result << "'.\n";
return true;
}
DisambiguateGlobalSymbols(Program);
std::vector<Function*> Funcs = DebugAMiscompilation(*this, TestCodeGenerator);
// Split the module into the two halves of the program we want.
Module *ToNotCodeGen = CloneModule(getProgram());
Module *ToCodeGen = SplitFunctionsOutOfModule(ToNotCodeGen, Funcs);
// Condition the modules
CleanupAndPrepareModules(*this, ToCodeGen, ToNotCodeGen);
sys::Path TestModuleBC("bugpoint.test.bc");
std::string ErrMsg;
if (TestModuleBC.makeUnique(true, &ErrMsg)) {
std::cerr << getToolName() << "Error making unique filename: "
<< ErrMsg << "\n";
exit(1);
}
if (writeProgramToFile(TestModuleBC.toString(), ToCodeGen)) {
std::cerr << "Error writing bitcode to `" << TestModuleBC << "'\nExiting.";
exit(1);
}
delete ToCodeGen;
// Make the shared library
sys::Path SafeModuleBC("bugpoint.safe.bc");
if (SafeModuleBC.makeUnique(true, &ErrMsg)) {
std::cerr << getToolName() << "Error making unique filename: "
<< ErrMsg << "\n";
exit(1);
}
if (writeProgramToFile(SafeModuleBC.toString(), ToNotCodeGen)) {
std::cerr << "Error writing bitcode to `" << SafeModuleBC << "'\nExiting.";
exit(1);
}
std::string SharedObject = compileSharedObject(SafeModuleBC.toString());
delete ToNotCodeGen;
std::cout << "You can reproduce the problem with the command line: \n";
if (isExecutingJIT()) {
std::cout << " lli -load " << SharedObject << " " << TestModuleBC;
} else {
std::cout << " llc -f " << TestModuleBC << " -o " << TestModuleBC<< ".s\n";
std::cout << " gcc " << SharedObject << " " << TestModuleBC
<< ".s -o " << TestModuleBC << ".exe";
#if defined (HAVE_LINK_R)
std::cout << " -Wl,-R.";
#endif
std::cout << "\n";
std::cout << " " << TestModuleBC << ".exe";
}
for (unsigned i=0, e = InputArgv.size(); i != e; ++i)
std::cout << " " << InputArgv[i];
std::cout << '\n';
std::cout << "The shared object was created with:\n llc -march=c "
<< SafeModuleBC << " -o temporary.c\n"
<< " gcc -xc temporary.c -O2 -o " << SharedObject
#if defined(sparc) || defined(__sparc__) || defined(__sparcv9)
<< " -G" // Compile a shared library, `-G' for Sparc
#else
<< " -shared" // `-shared' for Linux/X86, maybe others
#endif
<< " -fno-strict-aliasing\n";
return false;
}
|