bool ReduceCrashingBlocks::TestBlocks(std::vector<const BasicBlock*> &BBs) {
// Clone the program to try hacking it apart...
Module *M = CloneModule(BD.getProgram());
// 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...
const Function *F = BBs[i]->getParent();
Function *CMF = M->getFunction(F->getName());
assert(CMF && "Function not in module?!");
assert(CMF->getFunctionType() == F->getFunctionType() && "wrong type?");
// Get the mapped basic block...
Function::iterator CBI = CMF->begin();
std::advance(CBI, std::distance(F->begin(),
Function::const_iterator(BBs[i])));
Blocks.insert(CBI);
}
std::cout << "Checking for crash with only these blocks:";
unsigned NumPrint = Blocks.size();
if (NumPrint > 10) NumPrint = 10;
for (unsigned i = 0, e = NumPrint; i != e; ++i)
std::cout << " " << BBs[i]->getName();
if (NumPrint < Blocks.size())
std::cout << "... <" << Blocks.size() << " total>";
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) && BB->getTerminator()->getNumSuccessors()) {
// 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);
if (BB->getTerminator()->getType() != Type::VoidTy)
BB->getTerminator()->replaceAllUsesWith(
Constant::getNullValue(BB->getTerminator()->getType()));
// Delete the old terminator instruction...
BB->getInstList().pop_back();
// Add a new return instruction of the appropriate type...
const Type *RetTy = BB->getParent()->getReturnType();
new ReturnInst(RetTy == Type::VoidTy ? 0 :
Constant::getNullValue(RetTy), BB);
}
// 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...
if (TestFn(BD, M)) {
BD.setNewProgram(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) {
ValueSymbolTable &ST = BlockInfo[i].first->getValueSymbolTable();
Value* V = ST.lookup(BlockInfo[i].second);
if (V && V->getType() == Type::LabelTy)
BBs.push_back(cast<BasicBlock>(V));
}
return true;
}
delete M; // It didn't crash, try something else.
return false;
}
