How to check if instruction is a PHI instruction in LLVM IR

Question

I am writing an LLVM pass. For an instruction (llvm::Instruction Class), how can I check if an instruction is a PHI instruction?

Mystical - yup, something similar, that is, isa(x), worked for me! — MetallicPriest, Feb 27 '12 at 19:28

MetallicPriest · Answer 1 · 2012-02-28T11:34:01.970

15

I found the solution. You can check for a PHI node like this, isa<PHINode>(inst).

edited Feb 28 '12 at 11:34

answered Feb 27 '12 at 19:02

MetallicPriest

Well, I didn't know that `isa` existed. To that's a +1 from me. – Mysticial Feb 27 '12 at 19:30
6

@Mystical, http://llvm.org/docs/ProgrammersManual.html is a good source of information :) – Anton Korobeynikov Feb 27 '12 at 20:43

score 1 · Answer 2 · answered Dec 03 '13 at 02:07

1

    Instruction* I;

    if(I->getOpcode()==Instruction::PHI){
    //code
    }

answered Dec 03 '13 at 02:07

blankboy2011

4

the isa<> solution is how these checks should be carried out. If I had enough reputation I would downvoat this so you should maybe delete it. – baibo Jan 10 '15 at 10:50
@baibo Do you mean that for a higher level instruction like `PHINode`, `isa` is more idiomatic? Is there any room for error or any maintainability issue with using the opcode? – Hari Jun 26 '23 at 10:03
@Hari No idea, I wrote this 8 years ago and I have since long moved away from working on LLVM. Maybe it is :D – baibo Aug 05 '23 at 07:49

2 Answers2