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//===- CrashDebugger.cpp - Debug compilation crashes ----------------------===//
//
// This file defines the bugpoint internals that narrow down compilation crashes
//
//===----------------------------------------------------------------------===//
#include "BugDriver.h"
#include "ListReducer.h"
#include "llvm/Constant.h"
#include "llvm/iTerminators.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/PassManager.h"
#include "llvm/SymbolTable.h"
#include "llvm/Type.h"
#include "llvm/Analysis/Verifier.h"
#include "llvm/Bytecode/Writer.h"
#include "llvm/Support/CFG.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "Support/FileUtilities.h"
#include <fstream>
#include <set>
class DebugCrashes : public ListReducer<const PassInfo*> {
BugDriver &BD;
public:
DebugCrashes(BugDriver &bd) : BD(bd) {}
// doTest - Return true iff running the "removed" passes succeeds, and running
// the "Kept" passes fail when run on the output of the "removed" passes. If
// we return true, we update the current module of bugpoint.
//
virtual TestResult doTest(std::vector<const PassInfo*> &Removed,
std::vector<const PassInfo*> &Kept);
};
DebugCrashes::TestResult
DebugCrashes::doTest(std::vector<const PassInfo*> &Prefix,
std::vector<const PassInfo*> &Suffix) {
std::string PrefixOutput;
Module *OrigProgram = 0;
if (!Prefix.empty()) {
std::cout << "Checking to see if these passes crash: "
<< getPassesString(Prefix) << ": ";
if (BD.runPasses(Prefix, PrefixOutput))
return KeepPrefix;
OrigProgram = BD.Program;
BD.Program = BD.ParseInputFile(PrefixOutput);
if (BD.Program == 0) {
std::cerr << BD.getToolName() << ": Error reading bytecode file '"
<< PrefixOutput << "'!\n";
exit(1);
}
removeFile(PrefixOutput);
}
std::cout << "Checking to see if these passes crash: "
<< getPassesString(Suffix) << ": ";
if (BD.runPasses(Suffix)) {
delete OrigProgram; // The suffix crashes alone...
return KeepSuffix;
}
// Nothing failed, restore state...
if (OrigProgram) {
delete BD.Program;
BD.Program = OrigProgram;
}
return NoFailure;
}
class ReduceCrashingFunctions : public ListReducer<Function*> {
BugDriver &BD;
public:
ReduceCrashingFunctions(BugDriver &bd) : BD(bd) {}
virtual TestResult doTest(std::vector<Function*> &Prefix,
std::vector<Function*> &Kept) {
if (!Kept.empty() && TestFuncs(Kept))
return KeepSuffix;
if (!Prefix.empty() && TestFuncs(Prefix))
return KeepPrefix;
return NoFailure;
}
bool TestFuncs(std::vector<Function*> &Prefix);
};
bool ReduceCrashingFunctions::TestFuncs(std::vector<Function*> &Funcs) {
// Clone the program to try hacking it appart...
Module *M = CloneModule(BD.Program);
// Convert list to set for fast lookup...
std::set<Function*> Functions;
for (unsigned i = 0, e = Funcs.size(); i != e; ++i) {
Function *CMF = M->getFunction(Funcs[i]->getName(),
Funcs[i]->getFunctionType());
assert(CMF && "Function not in module?!");
Functions.insert(CMF);
}
std::cout << "Checking for crash with only these functions:";
for (unsigned i = 0, e = Funcs.size(); i != e; ++i)
std::cout << " " << Funcs[i]->getName();
std::cout << ": ";
// Loop over and delete any functions which we aren't supposed to be playing
// with...
for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
if (!I->isExternal() && !Functions.count(I))
DeleteFunctionBody(I);
// Try running the hacked up program...
std::swap(BD.Program, M);
if (BD.runPasses(BD.PassesToRun)) {
delete M; // It crashed, keep the trimmed version...
// Make sure to use function pointers that point into the now-current
// module.
Funcs.assign(Functions.begin(), Functions.end());
return true;
}
delete BD.Program; // It didn't crash, revert...
BD.Program = M;
return false;
}
/// ReduceCrashingBlocks reducer - This works by setting the terminators of all
/// terminators except the specified basic blocks to a 'ret' instruction, then
/// running the simplify-cfg pass. This has the effect of chopping up the CFG
/// really fast which can reduce large functions quickly.
///
class ReduceCrashingBlocks : public ListReducer<BasicBlock*> {
BugDriver &BD;
public:
ReduceCrashingBlocks(BugDriver &bd) : BD(bd) {}
virtual TestResult doTest(std::vector<BasicBlock*> &Prefix,
std::vector<BasicBlock*> &Kept) {
if (!Kept.empty() && TestBlocks(Kept))
return KeepSuffix;
if (!Prefix.empty() && TestBlocks(Prefix))
return KeepPrefix;
return NoFailure;
}
bool TestBlocks(std::vector<BasicBlock*> &Prefix);
};
bool ReduceCrashingBlocks::TestBlocks(std::vector<BasicBlock*> &BBs) {
// Clone the program to try hacking it appart...
Module *M = CloneModule(BD.Program);
// Convert list to set for fast lookup...
std::set<BasicBlock*> Blocks;
for (unsigned i = 0, e = BBs.size(); i != e; ++i) {
// Convert the basic block from the original module to the new module...
Function *F = BBs[i]->getParent();
Function *CMF = M->getFunction(F->getName(), F->getFunctionType());
assert(CMF && "Function not in module?!");
// Get the mapped basic block...
Function::iterator CBI = CMF->begin();
std::advance(CBI, std::distance(F->begin(), Function::iterator(BBs[i])));
Blocks.insert(CBI);
}
std::cout << "Checking for crash with only these blocks:";
for (unsigned i = 0, e = Blocks.size(); i != e; ++i)
std::cout << " " << BBs[i]->getName();
std::cout << ": ";
// Loop over and delete any hack up any blocks that are not listed...
for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
for (Function::iterator BB = I->begin(), E = I->end(); BB != E; ++BB)
if (!Blocks.count(BB) && !isa<ReturnInst>(BB->getTerminator())) {
// Loop over all of the successors of this block, deleting any PHI nodes
// that might include it.
for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
(*SI)->removePredecessor(BB);
// Delete the old terminator instruction...
BB->getInstList().pop_back();
// Add a new return instruction of the appropriate type...
const Type *RetTy = BB->getParent()->getReturnType();
ReturnInst *RI = new ReturnInst(RetTy == Type::VoidTy ? 0 :
Constant::getNullValue(RetTy));
BB->getInstList().push_back(RI);
}
// The CFG Simplifier pass may delete one of the basic blocks we are
// interested in. If it does we need to take the block out of the list. Make
// a "persistent mapping" by turning basic blocks into <function, name> pairs.
// This won't work well if blocks are unnamed, but that is just the risk we
// have to take.
std::vector<std::pair<Function*, std::string> > BlockInfo;
for (std::set<BasicBlock*>::iterator I = Blocks.begin(), E = Blocks.end();
I != E; ++I)
BlockInfo.push_back(std::make_pair((*I)->getParent(), (*I)->getName()));
// Now run the CFG simplify pass on the function...
PassManager Passes;
Passes.add(createCFGSimplificationPass());
Passes.add(createVerifierPass());
Passes.run(*M);
// Try running on the hacked up program...
std::swap(BD.Program, M);
if (BD.runPasses(BD.PassesToRun)) {
delete M; // It crashed, keep the trimmed version...
// Make sure to use basic block pointers that point into the now-current
// module, and that they don't include any deleted blocks.
BBs.clear();
for (unsigned i = 0, e = BlockInfo.size(); i != e; ++i) {
SymbolTable &ST = BlockInfo[i].first->getSymbolTable();
SymbolTable::iterator I = ST.find(Type::LabelTy);
if (I != ST.end() && I->second.count(BlockInfo[i].second))
BBs.push_back(cast<BasicBlock>(I->second[BlockInfo[i].second]));
}
return true;
}
delete BD.Program; // It didn't crash, revert...
BD.Program = M;
return false;
}
/// debugCrash - This method is called when some pass crashes on input. It
/// attempts to prune down the testcase to something reasonable, and figure
/// out exactly which pass is crashing.
///
bool BugDriver::debugCrash() {
bool AnyReduction = false;
std::cout << "\n*** Debugging optimizer crash!\n";
// Reduce the list of passes which causes the optimizer to crash...
unsigned OldSize = PassesToRun.size();
DebugCrashes(*this).reduceList(PassesToRun);
std::cout << "\n*** Found crashing pass"
<< (PassesToRun.size() == 1 ? ": " : "es: ")
<< getPassesString(PassesToRun) << "\n";
EmitProgressBytecode("passinput");
// See if we can get away with nuking all of the global variable initializers
// in the program...
if (Program->gbegin() != Program->gend()) {
Module *M = CloneModule(Program);
bool DeletedInit = false;
for (Module::giterator I = M->gbegin(), E = M->gend(); I != E; ++I)
if (I->hasInitializer()) {
I->setInitializer(0);
I->setLinkage(GlobalValue::ExternalLinkage);
DeletedInit = true;
}
if (!DeletedInit) {
delete M; // No change made...
} else {
// See if the program still causes a crash...
std::cout << "\nChecking to see if we can delete global inits: ";
std::swap(Program, M);
if (runPasses(PassesToRun)) { // Still crashes?
AnyReduction = true;
delete M;
std::cout << "\n*** Able to remove all global initializers!\n";
} else { // No longer crashes?
delete Program; // Restore program.
Program = M;
std::cout << " - Removing all global inits hides problem!\n";
}
}
}
// Now try to reduce the number of functions in the module to something small.
std::vector<Function*> Functions;
for (Module::iterator I = Program->begin(), E = Program->end(); I != E; ++I)
if (!I->isExternal())
Functions.push_back(I);
if (Functions.size() > 1) {
std::cout << "\n*** Attempting to reduce the number of functions "
"in the testcase\n";
OldSize = Functions.size();
ReduceCrashingFunctions(*this).reduceList(Functions);
if (Functions.size() < OldSize) {
EmitProgressBytecode("reduced-function");
AnyReduction = true;
}
}
// Attempt to delete entire basic blocks at a time to speed up
// convergence... this actually works by setting the terminator of the blocks
// to a return instruction then running simplifycfg, which can potentially
// shrinks the code dramatically quickly
//
if (!DisableSimplifyCFG) {
std::vector<BasicBlock*> Blocks;
for (Module::iterator I = Program->begin(), E = Program->end(); I != E; ++I)
for (Function::iterator FI = I->begin(), E = I->end(); FI != E; ++FI)
Blocks.push_back(FI);
ReduceCrashingBlocks(*this).reduceList(Blocks);
}
// FIXME: This should use the list reducer to converge faster by deleting
// larger chunks of instructions at a time!
unsigned Simplification = 4;
do {
--Simplification;
std::cout << "\n*** Attempting to reduce testcase by deleting instruc"
<< "tions: Simplification Level #" << Simplification << "\n";
// Now that we have deleted the functions that are unnecessary for the
// program, try to remove instructions that are not necessary to cause the
// crash. To do this, we loop through all of the instructions in the
// remaining functions, deleting them (replacing any values produced with
// nulls), and then running ADCE and SimplifyCFG. If the transformed input
// still triggers failure, keep deleting until we cannot trigger failure
// anymore.
//
TryAgain:
// Loop over all of the (non-terminator) instructions remaining in the
// function, attempting to delete them.
for (Module::iterator FI = Program->begin(), E = Program->end();
FI != E; ++FI)
if (!FI->isExternal()) {
for (Function::iterator BI = FI->begin(), E = FI->end(); BI != E; ++BI)
for (BasicBlock::iterator I = BI->begin(), E = --BI->end();
I != E; ++I) {
Module *M = deleteInstructionFromProgram(I, Simplification);
// Make the function the current program...
std::swap(Program, M);
// Find out if the pass still crashes on this pass...
std::cout << "Checking instruction '" << I->getName() << "': ";
if (runPasses(PassesToRun)) {
// Yup, it does, we delete the old module, and continue trying to
// reduce the testcase...
delete M;
AnyReduction = true;
goto TryAgain; // I wish I had a multi-level break here!
}
// This pass didn't crash without this instruction, try the next
// one.
delete Program;
Program = M;
}
}
} while (Simplification);
// Try to clean up the testcase by running funcresolve and globaldce...
std::cout << "\n*** Attempting to perform final cleanups: ";
Module *M = performFinalCleanups();
std::swap(Program, M);
// Find out if the pass still crashes on the cleaned up program...
if (runPasses(PassesToRun)) {
// Yup, it does, keep the reduced version...
delete M;
AnyReduction = true;
} else {
delete Program; // Otherwise, restore the original module...
Program = M;
}
if (AnyReduction)
EmitProgressBytecode("reduced-simplified");
return false;
}
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