[PATCH] D71312: [InstCombine] Fold X / abs(X) to X < 0 ? -1 : 1

[Dávid Bolvanský via Phabricator via llvm-commits]

xbolva00 added a comment.

Isn't abs(INT_MIN) undefined?

expensive div is removed:

  _Z4fooai: # @_Z4fooai
    mov eax, edi
    mov ecx, edi
    neg ecx
    cmovl ecx, edi
    cdq
    idiv ecx
    ret
  _Z5fooari: # @_Z5fooari
    mov eax, edi
    sar eax, 31
    or eax, 1
    ret

GCC knows this trick too.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D71312/new/

https://reviews.llvm.org/D71312