void IRLandingPad::constructLandingPad(llvm::BasicBlock* inBB)
{
// save and rewrite scope
IRScope savedscope = gIR->scope();
gIR->scope() = IRScope(inBB,savedscope.end);
// eh_ptr = llvm.eh.exception();
llvm::Function* eh_exception_fn = GET_INTRINSIC_DECL(eh_exception);
LLValue* eh_ptr = gIR->ir->CreateCall(eh_exception_fn);
// build selector arguments
LLSmallVector<LLValue*, 6> selectorargs;
// put in classinfos in the right order
bool hasFinally = false;
bool hasCatch = false;
std::deque<IRLandingPadInfo>::iterator it = infos.begin(), end = infos.end();
for(; it != end; ++it)
{
if(it->finallyBody)
hasFinally = true;
else
{
hasCatch = true;
assert(it->catchType);
assert(it->catchType->ir.irStruct);
selectorargs.insert(selectorargs.begin(), it->catchType->ir.irStruct->getClassInfoSymbol());
}
}
// if there's a finally, the eh table has to have a 0 action
if(hasFinally)
selectorargs.push_back(DtoConstUint(0));
// personality fn
llvm::Function* personality_fn = LLVM_D_GetRuntimeFunction(gIR->module, "_d_eh_personality");
LLValue* personality_fn_arg = gIR->ir->CreateBitCast(personality_fn, getPtrToType(LLType::getInt8Ty(gIR->context())));
selectorargs.insert(selectorargs.begin(), personality_fn_arg);
// eh storage target
selectorargs.insert(selectorargs.begin(), eh_ptr);
// if there is a catch and some catch allocated storage, store exception object
if(hasCatch && catch_var)
{
const LLType* objectTy = DtoType(ClassDeclaration::object->type);
gIR->ir->CreateStore(gIR->ir->CreateBitCast(eh_ptr, objectTy), catch_var);
}
// eh_sel = llvm.eh.selector(eh_ptr, cast(byte*)&_d_eh_personality, <selectorargs>);
llvm::Function* eh_selector_fn = GET_INTRINSIC_DECL(eh_selector);
LLValue* eh_sel = gIR->ir->CreateCall(eh_selector_fn, selectorargs.begin(), selectorargs.end());
// emit finallys and 'if' chain to catch the exception
llvm::Function* eh_typeid_for_fn = GET_INTRINSIC_DECL(eh_typeid_for);
std::deque<IRLandingPadInfo> infos = this->infos;
std::stack<size_t> nInfos = this->nInfos;
std::deque<IRLandingPadInfo>::reverse_iterator rit, rend = infos.rend();
for(rit = infos.rbegin(); rit != rend; ++rit)
{
// if it's a finally, emit its code
if(rit->finallyBody)
{
size_t n = this->nInfos.top();
this->infos.resize(n);
this->nInfos.pop();
rit->finallyBody->toIR(gIR);
}
// otherwise it's a catch and we'll add a if-statement
else
{
llvm::BasicBlock *next = llvm::BasicBlock::Create(gIR->context(), "eh.next", gIR->topfunc(), gIR->scopeend());
LLValue *classInfo = DtoBitCast(rit->catchType->ir.irStruct->getClassInfoSymbol(),
getPtrToType(DtoType(Type::tint8)));
LLValue *eh_id = gIR->ir->CreateCall(eh_typeid_for_fn, classInfo);
gIR->ir->CreateCondBr(gIR->ir->CreateICmpEQ(eh_sel, eh_id), rit->target, next);
gIR->scope() = IRScope(next, gIR->scopeend());
}
}
// restore landing pad infos
this->infos = infos;
this->nInfos = nInfos;
// no catch matched and all finallys executed - resume unwind
llvm::Function* unwind_resume_fn = LLVM_D_GetRuntimeFunction(gIR->module, "_d_eh_resume_unwind");
gIR->ir->CreateCall(unwind_resume_fn, eh_ptr);
gIR->ir->CreateUnreachable();
gIR->scope() = savedscope;
}
