[all-commits] [llvm/llvm-project] b723d5: [llvm-exegesis][x86] Add option to prevent use of ...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: b723d5a625c0135a8c6a72572ba91ddf566e8723
      https://github.com/llvm/llvm-project/commit/b723d5a625c0135a8c6a72572ba91ddf566e8723
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2022-12-07 (Wed, 07 Dec 2022)

  Changed paths:
    M llvm/docs/CommandGuide/llvm-exegesis.rst
    A llvm/test/tools/llvm-exegesis/X86/inverse_throughput/inverse_throughput-disable-upper-sse-registers.s
    M llvm/tools/llvm-exegesis/lib/X86/Target.cpp

  Log Message:
  -----------
  [llvm-exegesis][x86] Add option to prevent use of xmm8-xmm15 upper SSE registers

Noticed while trying to use llvm-exegesis to get some accurate capture numbers on some old Atom/Silverment hardware as part of the work with D103695.

These targets' frontends are particularly poor and the use of the xmm8-xmm15 SSE registers results in longer instruction encodings which were affecting the latency/throughput estimates.

Thanks to @lebedev.ri for the --skip-measurements command line argument which made testing much easier!

Differential Revision: https://reviews.llvm.org/D138832