/// AddLandingPadInfo - Extract the exception handling information from the
/// landingpad instruction and add them to the specified machine module info.
void llvm::AddLandingPadInfo(const LandingPadInst &I, MachineModuleInfo &MMI,
MachineBasicBlock *MBB) {
MMI.addPersonality(MBB,
cast<Function>(I.getPersonalityFn()->stripPointerCasts()));
if (I.isCleanup())
MMI.addCleanup(MBB);
// FIXME: New EH - Add the clauses in reverse order. This isn't 100% correct,
// but we need to do it this way because of how the DWARF EH emitter
// processes the clauses.
for (unsigned i = I.getNumClauses(); i != 0; --i) {
Value *Val = I.getClause(i - 1);
if (I.isCatch(i - 1)) {
MMI.addCatchTypeInfo(MBB,
dyn_cast<GlobalValue>(Val->stripPointerCasts()));
} else {
// Add filters in a list.
Constant *CVal = cast<Constant>(Val);
SmallVector<const GlobalValue*, 4> FilterList;
for (User::op_iterator
II = CVal->op_begin(), IE = CVal->op_end(); II != IE; ++II)
FilterList.push_back(cast<GlobalValue>((*II)->stripPointerCasts()));
MMI.addFilterTypeInfo(MBB, FilterList);
}
}
}
bool LowerEmExceptions::runOnModule(Module &M) {
TheModule = &M;
// Add functions
Type *i32 = Type::getInt32Ty(M.getContext());
Type *i8 = Type::getInt8Ty(M.getContext());
Type *i1 = Type::getInt1Ty(M.getContext());
Type *i8P = i8->getPointerTo();
Type *Void = Type::getVoidTy(M.getContext());
if (!(GetHigh = TheModule->getFunction("getHigh32"))) {
FunctionType *GetHighFunc = FunctionType::get(i32, false);
GetHigh = Function::Create(GetHighFunc, GlobalValue::ExternalLinkage,
"getHigh32", TheModule);
}
if (!(PreInvoke = TheModule->getFunction("emscripten_preinvoke"))) {
FunctionType *VoidFunc = FunctionType::get(Void, false);
PreInvoke = Function::Create(VoidFunc, GlobalValue::ExternalLinkage, "emscripten_preinvoke", TheModule);
}
if (!(PostInvoke = TheModule->getFunction("emscripten_postinvoke"))) {
FunctionType *IntFunc = FunctionType::get(i32, false);
PostInvoke = Function::Create(IntFunc, GlobalValue::ExternalLinkage, "emscripten_postinvoke", TheModule);
}
FunctionType *LandingPadFunc = FunctionType::get(i8P, true);
LandingPad = Function::Create(LandingPadFunc, GlobalValue::ExternalLinkage, "emscripten_landingpad", TheModule);
FunctionType *ResumeFunc = FunctionType::get(Void, true);
Resume = Function::Create(ResumeFunc, GlobalValue::ExternalLinkage, "emscripten_resume", TheModule);
// Process
bool HasWhitelist = Whitelist.size() > 0;
std::string WhitelistChecker;
if (HasWhitelist) WhitelistChecker = "," + Whitelist + ",";
bool Changed = false;
for (Module::iterator Iter = M.begin(), E = M.end(); Iter != E; ) {
Function *F = Iter++;
std::vector<Instruction*> ToErase;
std::set<LandingPadInst*> LandingPads;
bool AllowExceptionsInFunc = !HasWhitelist || int(WhitelistChecker.find(F->getName())) > 0;
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
// check terminator for invokes
if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
LandingPads.insert(II->getLandingPadInst());
bool NeedInvoke = AllowExceptionsInFunc && canThrow(II->getCalledValue());
if (NeedInvoke) {
// Insert a normal call instruction folded in between pre- and post-invoke
CallInst::Create(PreInvoke, "", II);
SmallVector<Value*,16> CallArgs(II->op_begin(), II->op_end() - 3);
CallInst *NewCall = CallInst::Create(II->getCalledValue(),
CallArgs, "", II);
NewCall->takeName(II);
NewCall->setCallingConv(II->getCallingConv());
NewCall->setAttributes(II->getAttributes());
NewCall->setDebugLoc(II->getDebugLoc());
II->replaceAllUsesWith(NewCall);
ToErase.push_back(II);
CallInst *Post = CallInst::Create(PostInvoke, "", II);
Instruction *Post1 = new TruncInst(Post, i1, "", II);
// Insert a branch based on the postInvoke
BranchInst::Create(II->getUnwindDest(), II->getNormalDest(), Post1, II);
} else {
// This can't throw, and we don't need this invoke, just replace it with a call+branch
SmallVector<Value*,16> CallArgs(II->op_begin(), II->op_end() - 3);
CallInst *NewCall = CallInst::Create(II->getCalledValue(),
CallArgs, "", II);
NewCall->takeName(II);
NewCall->setCallingConv(II->getCallingConv());
NewCall->setAttributes(II->getAttributes());
NewCall->setDebugLoc(II->getDebugLoc());
II->replaceAllUsesWith(NewCall);
ToErase.push_back(II);
BranchInst::Create(II->getNormalDest(), II);
// Remove any PHI node entries from the exception destination.
II->getUnwindDest()->removePredecessor(BB);
}
Changed = true;
}
// scan the body of the basic block for resumes
for (BasicBlock::iterator Iter = BB->begin(), E = BB->end();
Iter != E; ) {
Instruction *I = Iter++;
if (ResumeInst *R = dyn_cast<ResumeInst>(I)) {
// split the input into legal values
Value *Input = R->getValue();
ExtractValueInst *Low = ExtractValueInst::Create(Input, 0, "", R);
ExtractValueInst *High = ExtractValueInst::Create(Input, 1, "", R);
// create a resume call
SmallVector<Value*,2> CallArgs;
CallArgs.push_back(Low);
CallArgs.push_back(High);
CallInst::Create(Resume, CallArgs, "", R);
new UnreachableInst(TheModule->getContext(), R); // add a terminator to the block
ToErase.push_back(R);
}
}
}
// Look for orphan landingpads, can occur in blocks with no predecesors
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
Instruction *I = BB->getFirstNonPHI();
if (LandingPadInst *LP = dyn_cast<LandingPadInst>(I)) {
LandingPads.insert(LP);
}
}
// Handle all the landingpad for this function together, as multiple invokes may share a single lp
for (std::set<LandingPadInst*>::iterator I = LandingPads.begin(); I != LandingPads.end(); I++) {
// Replace the landingpad with a landingpad call to get the low part, and a getHigh for the high
LandingPadInst *LP = *I;
unsigned Num = LP->getNumClauses();
SmallVector<Value*,16> NewLPArgs;
NewLPArgs.push_back(LP->getPersonalityFn());
for (unsigned i = 0; i < Num; i++) {
Value *Arg = LP->getClause(i);
// As a temporary workaround for the lack of aggregate varargs support
// in the varargs lowering code, break out filter operands into their
// component elements.
if (LP->isFilter(i)) {
ArrayType *ATy = cast<ArrayType>(Arg->getType());
for (unsigned elem = 0, elemEnd = ATy->getNumElements(); elem != elemEnd; ++elem) {
Instruction *EE = ExtractValueInst::Create(Arg, makeArrayRef(elem), "", LP);
NewLPArgs.push_back(EE);
}
} else {
NewLPArgs.push_back(Arg);
}
}
NewLPArgs.push_back(LP->isCleanup() ? ConstantInt::getTrue(i1) : ConstantInt::getFalse(i1));
CallInst *NewLP = CallInst::Create(LandingPad, NewLPArgs, "", LP);
Instruction *High = CallInst::Create(GetHigh, "", LP);
// New recreate an aggregate for them, which will be all simplified later (simplification cannot handle landingpad, hence all this)
InsertValueInst *IVA = InsertValueInst::Create(UndefValue::get(LP->getType()), NewLP, 0, "", LP);
InsertValueInst *IVB = InsertValueInst::Create(IVA, High, 1, "", LP);
LP->replaceAllUsesWith(IVB);
ToErase.push_back(LP);
}
// erase everything we no longer need in this function
for (unsigned i = 0; i < ToErase.size(); i++) ToErase[i]->eraseFromParent();
}
return Changed;
}
