/// GetExceptionObject - Return the exception object from the value passed into
/// the 'resume' instruction (typically an aggregate). Clean up any dead
/// instructions, including the 'resume' instruction.
Value *DwarfEHPrepare::GetExceptionObject(ResumeInst *RI) {
Value *V = RI->getOperand(0);
Value *ExnObj = 0;
InsertValueInst *SelIVI = dyn_cast<InsertValueInst>(V);
LoadInst *SelLoad = 0;
InsertValueInst *ExcIVI = 0;
bool EraseIVIs = false;
if (SelIVI) {
if (SelIVI->getNumIndices() == 1 && *SelIVI->idx_begin() == 1) {
ExcIVI = dyn_cast<InsertValueInst>(SelIVI->getOperand(0));
if (ExcIVI && isa<UndefValue>(ExcIVI->getOperand(0)) &&
ExcIVI->getNumIndices() == 1 && *ExcIVI->idx_begin() == 0) {
ExnObj = ExcIVI->getOperand(1);
SelLoad = dyn_cast<LoadInst>(SelIVI->getOperand(1));
EraseIVIs = true;
}
}
}
if (!ExnObj)
ExnObj = ExtractValueInst::Create(RI->getOperand(0), 0, "exn.obj", RI);
RI->eraseFromParent();
if (EraseIVIs) {
if (SelIVI->getNumUses() == 0)
SelIVI->eraseFromParent();
if (ExcIVI->getNumUses() == 0)
ExcIVI->eraseFromParent();
if (SelLoad && SelLoad->getNumUses() == 0)
SelLoad->eraseFromParent();
}
return ExnObj;
}
