[LLVMdev] Steps to addDestination

Tim Northover t.p.northover at gmail.com
Thu Jul 25 00:08:20 PDT 2013

Hi Rasha,

> for(rit=Result.begin();rit!=Result.end();++rit)
>   {
>           Value* Address= BlockAddress::get (*rit);
>            IndirectBrInst *IBI = IndirectBrInst::Create(Address, Result.size(),i->getTerminator() );
>            IBI->addDestination((*rit));
>   }

This would be creating a block looking something like:
    [ Do stuff ]
    indirectbr i8* blockaddress(@foo, %result1), [label %result1]
    indirectbr i8* blockaddress(@foo, %result2), [label %result2]
    indirectbr i8* blockaddress(@foo, %resultN), [label %resultN]

which isn't valid LLVM IR. Each basic block has to have a single
branch at the end so you need to create the IndirectBrInst outside the

How do you decide which of the results you want to jump to at
run-time? I think that's the key question you have to answer. You want
to emit LLVM IR to make this decision and produce a single Value
representing it, then use the value just once to create a single

Your code might look like:
    Value *Address = emitCodeToChooseResult(Results, Loc);

    IndirectBrInst *IBI = IndirectBrInst::Create(Address, Result.size(), i);
    for (rit = Result.begin(); rit != Result.end(); ++rit)



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