[all-commits] [llvm/llvm-project] 685c8b: [AARCH64] Improve accumulator forwarding for Corte...

[David Green via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 685c8b537af3138cff24ec6060a86140b8963a1e
      https://github.com/llvm/llvm-project/commit/685c8b537af3138cff24ec6060a86140b8963a1e
  Author: Usman Nadeem <mnadeem at quicinc.com>
  Date:   2021-01-04 (Mon, 04 Jan 2021)

  Changed paths:
    M llvm/lib/Target/AArch64/AArch64SchedA57.td
    M llvm/lib/Target/AArch64/AArch64SchedA57WriteRes.td
    A llvm/test/tools/llvm-mca/AArch64/Cortex/forwarding-A57.s

  Log Message:
  -----------
  [AARCH64] Improve accumulator forwarding for Cortex-A57 model

The old CPU model only had MLA->MLA forwarding. I added some missing
MUL->MLA read advances and a missing absolute diff accumulator read
advance according to the Cortex A57 Software Optimization Guide.

The patch improves performance in EEMBC rgbyiqv2 by about 6%-7% and
spec2006/milc by 8% (repeated runs on multiple devices), causes no
significant regressions (none in SPEC).

Differential Revision: https://reviews.llvm.org/D92296