[all-commits] [llvm/llvm-project] 5ab489: [NFC][InstCombine] Add tests for '((X - Y) - Z)' p...

[Roman Lebedev via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 5ab489d9ae99c60d6f7e1e01194e0b4aacaf68af
      https://github.com/llvm/llvm-project/commit/5ab489d9ae99c60d6f7e1e01194e0b4aacaf68af
  Author: Roman Lebedev <lebedev.ri at gmail.com>
  Date:   2021-04-06 (Tue, 06 Apr 2021)

  Changed paths:
    A llvm/test/Transforms/InstCombine/sub-from-sub.ll

  Log Message:
  -----------
  [NFC][InstCombine] Add tests for '((X - Y) - Z)' pattern (PR49858)


  Commit: 31d219d2997fed1b7dc97e0adf170d5aaf65883e
      https://github.com/llvm/llvm-project/commit/31d219d2997fed1b7dc97e0adf170d5aaf65883e
  Author: Roman Lebedev <lebedev.ri at gmail.com>
  Date:   2021-04-06 (Tue, 06 Apr 2021)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
    M llvm/test/Transforms/InstCombine/abs-1.ll
    M llvm/test/Transforms/InstCombine/sub-from-sub.ll

  Log Message:
  -----------
  [InstCombine] Fold `((X - Y) - Z)` to `X - (Y + Z)` (PR49858)

https://alive2.llvm.org/ce/z/67w-wQ

We prefer `add`s over `sub`, and this particular xform
allows further folds to happen:

Fixes https://bugs.llvm.org/show_bug.cgi?id=49858


Compare: https://github.com/llvm/llvm-project/compare/5efe9efdadcb...31d219d2997f