[PATCH] D108903: [llvm-reduce] Add reduce operands pass

Thu Sep 9 10:11:29 PDT 2021

aeubanks added a comment.

In D108903#2992079 <https://reviews.llvm.org/D108903#2992079>, @nikic wrote:

> @aeubanks I believe @lebedev.ri is asking you to use `undef` for the initial patch and then switch `undef` to `0` consistently for all reductions in llvm-reduce. Right now everything else uses undef, and this place is going to use 0.

When I said

In D108903#2988082 <https://reviews.llvm.org/D108903#2988082>, @aeubanks wrote:

> Sure I suppose we can split up this patch
> @swamulism can you do that?

I was expecting a separate patch to add a helper method to choose what value to replace things with given a type.
Since replacing most operands with undef seems not ideal when it comes to reducing, I'd rather that patch come first, but I wouldn't object to making this patch use undef first then having the patch to choose what value to reduce to coming after.

Separately, after rereading @lebedev.ri 's comments, I was getting the impression that maybe I misunderstood the comments about not wanting to replace every operand of every instruction with null (or undef). Perhaps you meant that we should skip replacing the pointer operand of a GEP or the second operand of a div with null/undef?

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D108903/new/

https://reviews.llvm.org/D108903