/// DebugACrash - Given a predicate that determines whether a component crashes
/// on a program, try to destructively reduce the program while still keeping
/// the predicate true.
static bool DebugACrash(BugDriver &BD, bool (*TestFn)(BugDriver &, Module *)) {
// See if we can get away with nuking some of the global variable initializers
// in the program...
if (BD.getProgram()->global_begin() != BD.getProgram()->global_end()) {
// Now try to reduce the number of global variable initializers in the
// module to something small.
Module *M = CloneModule(BD.getProgram());
bool DeletedInit = false;
for (Module::global_iterator I = M->global_begin(), E = M->global_end();
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: ";
if (TestFn(BD, M)) { // Still crashes?
BD.setNewProgram(M);
std::cout << "\n*** Able to remove all global initializers!\n";
} else { // No longer crashes?
std::cout << " - Removing all global inits hides problem!\n";
delete M;
std::vector<GlobalVariable*> GVs;
for (Module::global_iterator I = BD.getProgram()->global_begin(),
E = BD.getProgram()->global_end(); I != E; ++I)
if (I->hasInitializer())
GVs.push_back(I);
if (GVs.size() > 1 && !BugpointIsInterrupted) {
std::cout << "\n*** Attempting to reduce the number of global "
<< "variables in the testcase\n";
unsigned OldSize = GVs.size();
ReduceCrashingGlobalVariables(BD, TestFn).reduceList(GVs);
if (GVs.size() < OldSize)
BD.EmitProgressBytecode("reduced-global-variables");
}
}
}
}
// Now try to reduce the number of functions in the module to something small.
std::vector<Function*> Functions;
for (Module::iterator I = BD.getProgram()->begin(),
E = BD.getProgram()->end(); I != E; ++I)
if (!I->isDeclaration())
Functions.push_back(I);
if (Functions.size() > 1 && !BugpointIsInterrupted) {
std::cout << "\n*** Attempting to reduce the number of functions "
"in the testcase\n";
unsigned OldSize = Functions.size();
ReduceCrashingFunctions(BD, TestFn).reduceList(Functions);
if (Functions.size() < OldSize)
BD.EmitProgressBytecode("reduced-function");
}
// 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 && !BugpointIsInterrupted) {
std::vector<const BasicBlock*> Blocks;
for (Module::const_iterator I = BD.getProgram()->begin(),
E = BD.getProgram()->end(); I != E; ++I)
for (Function::const_iterator FI = I->begin(), E = I->end(); FI !=E; ++FI)
Blocks.push_back(FI);
ReduceCrashingBlocks(BD, TestFn).reduceList(Blocks);
}
// FIXME: This should use the list reducer to converge faster by deleting
// larger chunks of instructions at a time!
unsigned Simplification = 2;
do {
if (BugpointIsInterrupted) break;
--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.
//
unsigned InstructionsToSkipBeforeDeleting = 0;
TryAgain:
// Loop over all of the (non-terminator) instructions remaining in the
// function, attempting to delete them.
unsigned CurInstructionNum = 0;
for (Module::const_iterator FI = BD.getProgram()->begin(),
E = BD.getProgram()->end(); FI != E; ++FI)
if (!FI->isDeclaration())
for (Function::const_iterator BI = FI->begin(), E = FI->end(); BI != E;
++BI)
for (BasicBlock::const_iterator I = BI->begin(), E = --BI->end();
I != E; ++I, ++CurInstructionNum)
if (InstructionsToSkipBeforeDeleting) {
--InstructionsToSkipBeforeDeleting;
} else {
if (BugpointIsInterrupted) goto ExitLoops;
std::cout << "Checking instruction '" << I->getName() << "': ";
Module *M = BD.deleteInstructionFromProgram(I, Simplification);
// Find out if the pass still crashes on this pass...
if (TestFn(BD, M)) {
// Yup, it does, we delete the old module, and continue trying
// to reduce the testcase...
BD.setNewProgram(M);
InstructionsToSkipBeforeDeleting = CurInstructionNum;
goto TryAgain; // I wish I had a multi-level break here!
}
// This pass didn't crash without this instruction, try the next
// one.
delete M;
}
if (InstructionsToSkipBeforeDeleting) {
InstructionsToSkipBeforeDeleting = 0;
goto TryAgain;
}
} while (Simplification);
ExitLoops:
// Try to clean up the testcase by running funcresolve and globaldce...
if (!BugpointIsInterrupted) {
std::cout << "\n*** Attempting to perform final cleanups: ";
Module *M = CloneModule(BD.getProgram());
M = BD.performFinalCleanups(M, true);
// Find out if the pass still crashes on the cleaned up program...
if (TestFn(BD, M)) {
BD.setNewProgram(M); // Yup, it does, keep the reduced version...
} else {
delete M;
}
}
BD.EmitProgressBytecode("reduced-simplified");
return false;
}
