1 //===- Miscompilation.cpp - Debug program miscompilations -----------------===//
3 // This file implements program miscompilation debugging support.
5 //===----------------------------------------------------------------------===//
8 #include "ListReducer.h"
9 #include "llvm/Module.h"
10 #include "llvm/Pass.h"
11 #include "llvm/Transforms/Utils/Cloning.h"
12 #include "llvm/Transforms/Utils/Linker.h"
13 #include "Support/FileUtilities.h"
15 class ReduceMiscompilingPasses : public ListReducer<const PassInfo*> {
18 ReduceMiscompilingPasses(BugDriver &bd) : BD(bd) {}
20 virtual TestResult doTest(std::vector<const PassInfo*> &Prefix,
21 std::vector<const PassInfo*> &Suffix);
24 ReduceMiscompilingPasses::TestResult
25 ReduceMiscompilingPasses::doTest(std::vector<const PassInfo*> &Prefix,
26 std::vector<const PassInfo*> &Suffix) {
27 // First, run the program with just the Suffix passes. If it is still broken
28 // with JUST the kept passes, discard the prefix passes.
29 std::cout << "Checking to see if '" << getPassesString(Suffix)
30 << "' compile correctly: ";
32 std::string BytecodeResult;
33 if (BD.runPasses(Suffix, BytecodeResult, false/*delete*/, true/*quiet*/)) {
34 std::cerr << BD.getToolName() << ": Error running this sequence of passes"
35 << " on the input program!\n";
39 // Check to see if the finished program matches the reference output...
40 if (BD.diffProgram(BytecodeResult, "", true /*delete bytecode*/)) {
41 std::cout << "nope.\n";
42 return KeepSuffix; // Miscompilation detected!
44 std::cout << "yup.\n"; // No miscompilation!
46 if (Prefix.empty()) return NoFailure;
48 // Next, see if the program is broken if we run the "prefix" passes first,
49 // then separately run the "kept" passes.
50 std::cout << "Checking to see if '" << getPassesString(Prefix)
51 << "' compile correctly: ";
53 // If it is not broken with the kept passes, it's possible that the prefix
54 // passes must be run before the kept passes to break it. If the program
55 // WORKS after the prefix passes, but then fails if running the prefix AND
56 // kept passes, we can update our bytecode file to include the result of the
57 // prefix passes, then discard the prefix passes.
59 if (BD.runPasses(Prefix, BytecodeResult, false/*delete*/, true/*quiet*/)) {
60 std::cerr << BD.getToolName() << ": Error running this sequence of passes"
61 << " on the input program!\n";
65 // If the prefix maintains the predicate by itself, only keep the prefix!
66 if (BD.diffProgram(BytecodeResult)) {
67 std::cout << "nope.\n";
68 removeFile(BytecodeResult);
71 std::cout << "yup.\n"; // No miscompilation!
73 // Ok, so now we know that the prefix passes work, try running the suffix
74 // passes on the result of the prefix passes.
76 Module *PrefixOutput = BD.ParseInputFile(BytecodeResult);
77 if (PrefixOutput == 0) {
78 std::cerr << BD.getToolName() << ": Error reading bytecode file '"
79 << BytecodeResult << "'!\n";
82 removeFile(BytecodeResult); // No longer need the file on disk
84 std::cout << "Checking to see if '" << getPassesString(Suffix)
85 << "' passes compile correctly after the '"
86 << getPassesString(Prefix) << "' passes: ";
88 Module *OriginalInput = BD.Program;
89 BD.Program = PrefixOutput;
90 if (BD.runPasses(Suffix, BytecodeResult, false/*delete*/, true/*quiet*/)) {
91 std::cerr << BD.getToolName() << ": Error running this sequence of passes"
92 << " on the input program!\n";
97 if (BD.diffProgram(BytecodeResult, "", true/*delete bytecode*/)) {
98 std::cout << "nope.\n";
99 delete OriginalInput; // We pruned down the original input...
103 // Otherwise, we must not be running the bad pass anymore.
104 std::cout << "yup.\n"; // No miscompilation!
105 BD.Program = OriginalInput; // Restore original program
106 delete PrefixOutput; // Free experiment
110 class ReduceMiscompilingFunctions : public ListReducer<Function*> {
113 ReduceMiscompilingFunctions(BugDriver &bd) : BD(bd) {}
115 virtual TestResult doTest(std::vector<Function*> &Prefix,
116 std::vector<Function*> &Suffix) {
117 if (!Suffix.empty() && TestFuncs(Suffix, false))
119 if (!Prefix.empty() && TestFuncs(Prefix, false))
124 bool TestFuncs(const std::vector<Function*> &Prefix, bool EmitBytecode);
127 bool ReduceMiscompilingFunctions::TestFuncs(const std::vector<Function*> &Funcs,
129 // Test to see if the function is misoptimized if we ONLY run it on the
130 // functions listed in Funcs.
132 std::cout << "Checking to see if the program is misoptimized when these "
133 << "functions are run\nthrough the passes: ";
134 BD.PrintFunctionList(Funcs);
137 std::cout <<"Outputting reduced bytecode files which expose the problem:\n";
140 // First step: clone the module for the two halves of the program we want.
141 Module *ToOptimize = CloneModule(BD.Program);
143 // Second step: Make sure functions & globals are all external so that linkage
144 // between the two modules will work.
145 for (Module::iterator I = ToOptimize->begin(), E = ToOptimize->end();I!=E;++I)
146 I->setLinkage(GlobalValue::ExternalLinkage);
147 for (Module::giterator I = ToOptimize->gbegin(), E = ToOptimize->gend();
149 I->setLinkage(GlobalValue::ExternalLinkage);
151 // Third step: make a clone of the externalized program for the non-optimized
153 Module *ToNotOptimize = CloneModule(ToOptimize);
155 // Fourth step: Remove the test functions from the ToNotOptimize module, and
156 // all of the global variables.
157 for (unsigned i = 0, e = Funcs.size(); i != e; ++i) {
158 Function *TNOF = ToNotOptimize->getFunction(Funcs[i]->getName(),
159 Funcs[i]->getFunctionType());
160 assert(TNOF && "Function doesn't exist in module!");
161 DeleteFunctionBody(TNOF); // Function is now external in this module!
163 for (Module::giterator I = ToNotOptimize->gbegin(), E = ToNotOptimize->gend();
165 I->setInitializer(0); // Delete the initializer to make it external
168 std::cout << " Non-optimized portion: ";
169 std::swap(BD.Program, ToNotOptimize);
170 BD.EmitProgressBytecode("tonotoptimize", true);
171 std::swap(BD.Program, ToNotOptimize);
174 // Fifth step: Remove all functions from the ToOptimize module EXCEPT for the
175 // ones specified in Funcs. We know which ones these are because they are
176 // non-external in ToOptimize, but external in ToNotOptimize.
178 for (Module::iterator I = ToOptimize->begin(), E = ToOptimize->end();I!=E;++I)
179 if (!I->isExternal()) {
180 Function *TNOF = ToNotOptimize->getFunction(I->getName(),
181 I->getFunctionType());
182 assert(TNOF && "Function doesn't exist in ToNotOptimize module??");
183 if (!TNOF->isExternal())
184 DeleteFunctionBody(I);
188 std::cout << " Portion that is input to optimizer: ";
189 std::swap(BD.Program, ToOptimize);
190 BD.EmitProgressBytecode("tooptimize");
191 std::swap(BD.Program, ToOptimize);
194 // Sixth step: Run the optimization passes on ToOptimize, producing a
195 // transformed version of the functions being tested.
196 Module *OldProgram = BD.Program;
197 BD.Program = ToOptimize;
200 std::cout << " Optimizing functions being tested: ";
201 std::string BytecodeResult;
202 if (BD.runPasses(BD.PassesToRun, BytecodeResult, false/*delete*/,
204 std::cerr << BD.getToolName() << ": Error running this sequence of passes"
205 << " on the input program!\n";
210 std::cout << "done.\n";
212 delete BD.Program; // Delete the old "ToOptimize" module
213 BD.Program = BD.ParseInputFile(BytecodeResult);
216 std::cout << " 'tooptimize' after being optimized: ";
217 BD.EmitProgressBytecode("optimized", true);
220 if (BD.Program == 0) {
221 std::cerr << BD.getToolName() << ": Error reading bytecode file '"
222 << BytecodeResult << "'!\n";
225 removeFile(BytecodeResult); // No longer need the file on disk
227 // Seventh step: Link the optimized part of the program back to the
228 // unoptimized part of the program.
230 if (LinkModules(BD.Program, ToNotOptimize, &BytecodeResult)) {
231 std::cerr << BD.getToolName() << ": Error linking modules together:"
232 << BytecodeResult << "\n";
235 delete ToNotOptimize; // We are done with this module...
238 std::cout << " Program as tested: ";
239 BD.EmitProgressBytecode("linked", true);
241 BD.Program = OldProgram;
242 return false; // We don't need to actually execute the program here.
245 std::cout << " Checking to see if the merged program executes correctly: ";
247 // Eighth step: Execute the program. If it does not match the expected
248 // output, then 'Funcs' are being misoptimized!
249 bool Broken = BD.diffProgram();
251 delete BD.Program; // Delete the hacked up program
252 BD.Program = OldProgram; // Restore the original
254 std::cout << (Broken ? "nope.\n" : "yup.\n");
259 /// debugMiscompilation - This method is used when the passes selected are not
260 /// crashing, but the generated output is semantically different from the
263 bool BugDriver::debugMiscompilation() {
264 // Make sure something was miscompiled...
265 if (!ReduceMiscompilingPasses(*this).reduceList(PassesToRun)) {
266 std::cerr << "*** Optimized program matches reference output! No problem "
267 << "detected...\nbugpoint can't help you with your problem!\n";
271 std::cout << "\n*** Found miscompiling pass"
272 << (PassesToRun.size() == 1 ? "" : "es") << ": "
273 << getPassesString(PassesToRun) << "\n";
274 EmitProgressBytecode("passinput");
276 // Okay, now that we have reduced the list of passes which are causing the
277 // failure, see if we can pin down which functions are being
278 // miscompiled... first build a list of all of the non-external functions in
280 std::vector<Function*> MiscompiledFunctions;
281 for (Module::iterator I = Program->begin(), E = Program->end(); I != E; ++I)
282 if (!I->isExternal())
283 MiscompiledFunctions.push_back(I);
285 // Do the reduction...
286 ReduceMiscompilingFunctions(*this).reduceList(MiscompiledFunctions);
288 std::cout << "\n*** The following functions are being miscompiled: ";
289 PrintFunctionList(MiscompiledFunctions);
292 // Output a bunch of bytecode files for the user...
293 ReduceMiscompilingFunctions(*this).TestFuncs(MiscompiledFunctions, true);