[all-commits] [llvm/llvm-project] f64580: [AArch64][GISel] Optimize 8 and 16 bit variants of...

[Florian Hahn via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: f64580f8d2ce5e1161857f9c89c2eee7a74c5ab8
      https://github.com/llvm/llvm-project/commit/f64580f8d2ce5e1161857f9c89c2eee7a74c5ab8
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2021-11-05 (Fri, 05 Nov 2021)

  Changed paths:
    M llvm/lib/Target/AArch64/GISel/AArch64PreLegalizerCombiner.cpp
    M llvm/test/CodeGen/AArch64/GlobalISel/uaddo-8-16-bits.mir

  Log Message:
  -----------
  [AArch64][GISel] Optimize 8 and 16 bit variants of uaddo.

Try simplify G_UADDO with 8 or 16 bit operands to wide G_ADD and TBNZ if
result is only used in the no-overflow case. It is restricted to cases
where we know that the high-bits of the operands are 0. If there's an
overflow, then the the 9th or 17th bit must be set, which can be checked
using TBNZ.

Reviewed By: paquette

Differential Revision: https://reviews.llvm.org/D111888