[PATCH] D70079: [SelectionDAG] Combine U{ADD,SUB}O diamonds into {ADD,SUB}CARRY

David Zarzycki via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Wed Nov 20 02:06:34 PST 2019


davezarzycki added a comment.

In D70079#1752991 <https://reviews.llvm.org/D70079#1752991>, @craig.topper wrote:

> In D70079#1752986 <https://reviews.llvm.org/D70079#1752986>, @davezarzycki wrote:
>
> > Unless I'm misunderstanding you, I think the many rounds of review feedback are clouding the code review. Lines 2874 and 2875 replace Carry1's result 0 in all cases (OR, XOR, and AND).
>
>
> Doesn't line 2873 return if the opcode is not ISD::AND?


Ah. Oops. I paused on uploading new patches while @chfast and @lebedev.ri were debating whether `DAG.ReplaceAllUsesOfValueWith(…)` or `Combiner.CombineTo(…)` was better. (Do you have a preference?) I'll update the patch now with the former.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D70079/new/

https://reviews.llvm.org/D70079





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