forked from OSchip/llvm-project
357 lines
14 KiB
C++
357 lines
14 KiB
C++
//===- Miscompilation.cpp - Debug program miscompilations -----------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements program miscompilation debugging support.
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//
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//===----------------------------------------------------------------------===//
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#include "BugDriver.h"
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#include "ListReducer.h"
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#include "llvm/Module.h"
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#include "llvm/Pass.h"
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#include "llvm/Transforms/Utils/Cloning.h"
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#include "llvm/Transforms/Utils/Linker.h"
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#include "Support/FileUtilities.h"
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using namespace llvm;
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namespace {
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class ReduceMiscompilingPasses : public ListReducer<const PassInfo*> {
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BugDriver &BD;
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public:
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ReduceMiscompilingPasses(BugDriver &bd) : BD(bd) {}
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virtual TestResult doTest(std::vector<const PassInfo*> &Prefix,
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std::vector<const PassInfo*> &Suffix);
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};
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}
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ReduceMiscompilingPasses::TestResult
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ReduceMiscompilingPasses::doTest(std::vector<const PassInfo*> &Prefix,
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std::vector<const PassInfo*> &Suffix) {
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// First, run the program with just the Suffix passes. If it is still broken
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// with JUST the kept passes, discard the prefix passes.
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std::cout << "Checking to see if '" << getPassesString(Suffix)
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<< "' compile correctly: ";
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std::string BytecodeResult;
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if (BD.runPasses(Suffix, BytecodeResult, false/*delete*/, true/*quiet*/)) {
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std::cerr << " Error running this sequence of passes"
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<< " on the input program!\n";
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BD.setPassesToRun(Suffix);
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BD.EmitProgressBytecode("pass-error", false);
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exit(BD.debugOptimizerCrash());
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}
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// Check to see if the finished program matches the reference output...
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if (BD.diffProgram(BytecodeResult, "", true /*delete bytecode*/)) {
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std::cout << "nope.\n";
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return KeepSuffix; // Miscompilation detected!
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}
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std::cout << "yup.\n"; // No miscompilation!
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if (Prefix.empty()) return NoFailure;
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// Next, see if the program is broken if we run the "prefix" passes first,
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// then separately run the "kept" passes.
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std::cout << "Checking to see if '" << getPassesString(Prefix)
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<< "' compile correctly: ";
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// If it is not broken with the kept passes, it's possible that the prefix
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// passes must be run before the kept passes to break it. If the program
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// WORKS after the prefix passes, but then fails if running the prefix AND
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// kept passes, we can update our bytecode file to include the result of the
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// prefix passes, then discard the prefix passes.
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//
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if (BD.runPasses(Prefix, BytecodeResult, false/*delete*/, true/*quiet*/)) {
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std::cerr << " Error running this sequence of passes"
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<< " on the input program!\n";
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BD.setPassesToRun(Prefix);
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BD.EmitProgressBytecode("pass-error", false);
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exit(BD.debugOptimizerCrash());
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}
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// If the prefix maintains the predicate by itself, only keep the prefix!
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if (BD.diffProgram(BytecodeResult)) {
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std::cout << "nope.\n";
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removeFile(BytecodeResult);
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return KeepPrefix;
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}
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std::cout << "yup.\n"; // No miscompilation!
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// Ok, so now we know that the prefix passes work, try running the suffix
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// passes on the result of the prefix passes.
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//
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Module *PrefixOutput = ParseInputFile(BytecodeResult);
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if (PrefixOutput == 0) {
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std::cerr << BD.getToolName() << ": Error reading bytecode file '"
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<< BytecodeResult << "'!\n";
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exit(1);
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}
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removeFile(BytecodeResult); // No longer need the file on disk
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std::cout << "Checking to see if '" << getPassesString(Suffix)
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<< "' passes compile correctly after the '"
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<< getPassesString(Prefix) << "' passes: ";
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Module *OriginalInput = BD.swapProgramIn(PrefixOutput);
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if (BD.runPasses(Suffix, BytecodeResult, false/*delete*/, true/*quiet*/)) {
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std::cerr << " Error running this sequence of passes"
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<< " on the input program!\n";
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BD.setPassesToRun(Suffix);
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BD.EmitProgressBytecode("pass-error", false);
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exit(BD.debugOptimizerCrash());
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}
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// Run the result...
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if (BD.diffProgram(BytecodeResult, "", true/*delete bytecode*/)) {
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std::cout << "nope.\n";
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delete OriginalInput; // We pruned down the original input...
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return KeepSuffix;
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}
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// Otherwise, we must not be running the bad pass anymore.
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std::cout << "yup.\n"; // No miscompilation!
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delete BD.swapProgramIn(OriginalInput); // Restore orig program & free test
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return NoFailure;
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}
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namespace {
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class ReduceMiscompilingFunctions : public ListReducer<Function*> {
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BugDriver &BD;
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public:
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ReduceMiscompilingFunctions(BugDriver &bd) : BD(bd) {}
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virtual TestResult doTest(std::vector<Function*> &Prefix,
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std::vector<Function*> &Suffix) {
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if (!Suffix.empty() && TestFuncs(Suffix))
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return KeepSuffix;
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if (!Prefix.empty() && TestFuncs(Prefix))
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return KeepPrefix;
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return NoFailure;
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}
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bool TestFuncs(const std::vector<Function*> &Prefix);
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};
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}
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/// TestMergedProgram - Given two modules, link them together and run the
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/// program, checking to see if the program matches the diff. If the diff
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/// matches, return false, otherwise return true. If the DeleteInputs argument
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/// is set to true then this function deletes both input modules before it
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/// returns.
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static bool TestMergedProgram(BugDriver &BD, Module *M1, Module *M2,
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bool DeleteInputs) {
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// Link the two portions of the program back to together.
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std::string ErrorMsg;
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if (!DeleteInputs) M1 = CloneModule(M1);
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if (LinkModules(M1, M2, &ErrorMsg)) {
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std::cerr << BD.getToolName() << ": Error linking modules together:"
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<< ErrorMsg << "\n";
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exit(1);
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}
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if (DeleteInputs) delete M2; // We are done with this module...
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Module *OldProgram = BD.swapProgramIn(M1);
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// Execute the program. If it does not match the expected output, we must
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// return true.
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bool Broken = BD.diffProgram();
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// Delete the linked module & restore the original
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BD.swapProgramIn(OldProgram);
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if (DeleteInputs) delete M1;
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return Broken;
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}
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bool ReduceMiscompilingFunctions::TestFuncs(const std::vector<Function*>&Funcs){
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// Test to see if the function is misoptimized if we ONLY run it on the
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// functions listed in Funcs.
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std::cout << "Checking to see if the program is misoptimized when "
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<< (Funcs.size()==1 ? "this function is" : "these functions are")
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<< " run through the pass"
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<< (BD.getPassesToRun().size() == 1 ? "" : "es") << ":";
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PrintFunctionList(Funcs);
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std::cout << "\n";
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// Split the module into the two halves of the program we want.
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Module *ToNotOptimize = CloneModule(BD.getProgram());
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Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize, Funcs);
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// Run the optimization passes on ToOptimize, producing a transformed version
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// of the functions being tested.
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std::cout << " Optimizing functions being tested: ";
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Module *Optimized = BD.runPassesOn(ToOptimize, BD.getPassesToRun(),
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/*AutoDebugCrashes*/true);
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std::cout << "done.\n";
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delete ToOptimize;
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std::cout << " Checking to see if the merged program executes correctly: ";
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bool Broken = TestMergedProgram(BD, Optimized, ToNotOptimize, true);
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std::cout << (Broken ? " nope.\n" : " yup.\n");
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return Broken;
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}
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/// ExtractLoops - Given a reduced list of functions that still exposed the bug,
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/// check to see if we can extract the loops in the region without obscuring the
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/// bug. If so, it reduces the amount of code identified.
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static bool ExtractLoops(BugDriver &BD,
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std::vector<Function*> &MiscompiledFunctions) {
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bool MadeChange = false;
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while (1) {
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Module *ToNotOptimize = CloneModule(BD.getProgram());
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Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize,
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MiscompiledFunctions);
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Module *ToOptimizeLoopExtracted = BD.ExtractLoop(ToOptimize);
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if (!ToOptimizeLoopExtracted) {
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// If the loop extractor crashed or if there were no extractible loops,
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// then this chapter of our odyssey is over with.
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delete ToNotOptimize;
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delete ToOptimize;
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return MadeChange;
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}
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std::cerr << "Extracted a loop from the breaking portion of the program.\n";
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delete ToOptimize;
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// Bugpoint is intentionally not very trusting of LLVM transformations. In
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// particular, we're not going to assume that the loop extractor works, so
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// we're going to test the newly loop extracted program to make sure nothing
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// has broken. If something broke, then we'll inform the user and stop
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// extraction.
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if (TestMergedProgram(BD, ToOptimizeLoopExtracted, ToNotOptimize, false)) {
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// Merged program doesn't work anymore!
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std::cerr << " *** ERROR: Loop extraction broke the program. :("
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<< " Please report a bug!\n";
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std::cerr << " Continuing on with un-loop-extracted version.\n";
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delete ToNotOptimize;
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delete ToOptimizeLoopExtracted;
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return MadeChange;
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}
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// Okay, the loop extractor didn't break the program. Run the series of
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// optimizations on the loop extracted portion and see if THEY still break
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// the program. If so, it was safe to extract these loops!
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std::cout << " Running optimizations on loop extracted portion: ";
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Module *Optimized = BD.runPassesOn(ToOptimizeLoopExtracted,
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BD.getPassesToRun(),
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/*AutoDebugCrashes*/true);
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std::cout << "done.\n";
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std::cout << " Checking to see if the merged program executes correctly: ";
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bool Broken = TestMergedProgram(BD, Optimized, ToNotOptimize, false);
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delete Optimized;
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if (!Broken) {
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std::cout << "yup: loop extraction masked the problem. Undoing.\n";
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// If the program is not still broken, then loop extraction did something
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// that masked the error. Stop loop extraction now.
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delete ToNotOptimize;
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delete ToOptimizeLoopExtracted;
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return MadeChange;
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}
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std::cout << "nope: loop extraction successful!\n";
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// Okay, great! Now we know that we extracted a loop and that loop
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// extraction both didn't break the program, and didn't mask the problem.
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// Replace the current program with the loop extracted version, and try to
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// extract another loop.
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std::string ErrorMsg;
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if (LinkModules(ToNotOptimize, ToOptimizeLoopExtracted, &ErrorMsg)) {
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std::cerr << BD.getToolName() << ": Error linking modules together:"
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<< ErrorMsg << "\n";
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exit(1);
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}
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delete ToOptimizeLoopExtracted;
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// All of the Function*'s in the MiscompiledFunctions list are in the old
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// module. Make sure to update them to point to the corresponding functions
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// in the new module.
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for (unsigned i = 0, e = MiscompiledFunctions.size(); i != e; ++i) {
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Function *OldF = MiscompiledFunctions[i];
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Function *NewF =
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ToNotOptimize->getFunction(OldF->getName(), OldF->getFunctionType());
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MiscompiledFunctions[i] = NewF;
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}
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BD.setNewProgram(ToNotOptimize);
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MadeChange = true;
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}
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}
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/// debugMiscompilation - This method is used when the passes selected are not
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/// crashing, but the generated output is semantically different from the
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/// input.
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///
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bool BugDriver::debugMiscompilation() {
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// Make sure something was miscompiled...
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if (!ReduceMiscompilingPasses(*this).reduceList(PassesToRun)) {
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std::cerr << "*** Optimized program matches reference output! No problem "
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<< "detected...\nbugpoint can't help you with your problem!\n";
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return false;
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}
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std::cout << "\n*** Found miscompiling pass"
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<< (getPassesToRun().size() == 1 ? "" : "es") << ": "
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<< getPassesString(getPassesToRun()) << "\n";
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EmitProgressBytecode("passinput");
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// Okay, now that we have reduced the list of passes which are causing the
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// failure, see if we can pin down which functions are being
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// miscompiled... first build a list of all of the non-external functions in
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// the program.
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std::vector<Function*> MiscompiledFunctions;
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for (Module::iterator I = Program->begin(), E = Program->end(); I != E; ++I)
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if (!I->isExternal())
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MiscompiledFunctions.push_back(I);
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// Do the reduction...
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ReduceMiscompilingFunctions(*this).reduceList(MiscompiledFunctions);
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std::cout << "\n*** The following function"
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<< (MiscompiledFunctions.size() == 1 ? " is" : "s are")
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<< " being miscompiled: ";
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PrintFunctionList(MiscompiledFunctions);
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std::cout << "\n";
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// See if we can rip any loops out of the miscompiled functions and still
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// trigger the problem.
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if (ExtractLoops(*this, MiscompiledFunctions)) {
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// Okay, we extracted some loops and the problem still appears. See if we
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// can eliminate some of the created functions from being candidates.
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// Do the reduction...
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ReduceMiscompilingFunctions(*this).reduceList(MiscompiledFunctions);
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std::cout << "\n*** The following function"
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<< (MiscompiledFunctions.size() == 1 ? " is" : "s are")
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<< " being miscompiled: ";
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PrintFunctionList(MiscompiledFunctions);
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std::cout << "\n";
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}
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// Output a bunch of bytecode files for the user...
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std::cout << "Outputting reduced bytecode files which expose the problem:\n";
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Module *ToNotOptimize = CloneModule(getProgram());
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Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize,
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MiscompiledFunctions);
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std::cout << " Non-optimized portion: ";
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std::swap(Program, ToNotOptimize);
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EmitProgressBytecode("tonotoptimize", true);
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setNewProgram(ToNotOptimize); // Delete hacked module.
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std::cout << " Portion that is input to optimizer: ";
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std::swap(Program, ToOptimize);
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EmitProgressBytecode("tooptimize");
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setNewProgram(ToOptimize); // Delete hacked module.
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return false;
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}
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