[all-commits] [llvm/llvm-project] b4f61c: [InstCombine] add tests for compare of sub-with-ov...

[Sanjay Patel via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: b4f61c5ecdad54cb145f8ec339cf3924514ac3c3
      https://github.com/llvm/llvm-project/commit/b4f61c5ecdad54cb145f8ec339cf3924514ac3c3
  Author: Sanjay Patel <spatel at rotateright.com>
  Date:   2022-08-15 (Mon, 15 Aug 2022)

  Changed paths:
    M llvm/test/Transforms/InstCombine/ssubo.ll
    M llvm/test/Transforms/InstCombine/usubo.ll

  Log Message:
  -----------
  [InstCombine] add tests for compare of sub-with-overflow; NFC


  Commit: e5748c6e73e7a3173046002b1f9a556965552c37
      https://github.com/llvm/llvm-project/commit/e5748c6e73e7a3173046002b1f9a556965552c37
  Author: Sanjay Patel <spatel at rotateright.com>
  Date:   2022-08-15 (Mon, 15 Aug 2022)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
    M llvm/test/Transforms/InstCombine/ssubo.ll
    M llvm/test/Transforms/InstCombine/usubo.ll

  Log Message:
  -----------
  [InstCombine] reduce sub-with-overflow ==/!= 0

The basic patterns look like this:
https://alive2.llvm.org/ce/z/MDj9EC

The tests have a use of the overflow value too.
Otherwise, existing folds should reduce already.

This was noted as a missing IR fold in:
926e7312b2f20f2f7b

Hopefully, this makes it easier to implement a backend
fix because we should get the same IR regardless of
whether the source used builtins or inline code.


Compare: https://github.com/llvm/llvm-project/compare/e471fdad7c32...e5748c6e73e7