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

Wed Nov 20 05:59:48 PST 2019

davezarzycki updated this revision to Diff 230247.
davezarzycki added a comment.

This patch fixes a bug introduced during the last round of feedback. By making the patch robust against the optimizer swapping operands to UADDO, the patch started tolerating the carry in bit being on the lefthand side of USUBO. That is wrong, and it's now fixed.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D70079/new/

https://reviews.llvm.org/D70079

Files:
  lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  test/CodeGen/X86/addcarry.ll
  test/CodeGen/X86/subcarry.ll

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