[all-commits] [llvm/llvm-project] 033bf6: [X86] Remove brand_id check from cpu_indicator_init.

[topperc via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 033bf61cc514dfa271e0bc9dd2c7e11240328c8c
      https://github.com/llvm/llvm-project/commit/033bf61cc514dfa271e0bc9dd2c7e11240328c8c
  Author: Craig Topper <craig.topper at intel.com>
  Date:   2020-06-12 (Fri, 12 Jun 2020)

  Changed paths:
    M compiler-rt/lib/builtins/cpu_model.c

  Log Message:
  -----------
  [X86] Remove brand_id check from cpu_indicator_init.

Brand index was a feature some Pentium III and Pentium 4 CPUs.
It provided an index into a software lookup table to provide a
brand name for the CPU. This is separate from the family/model.

It's unclear to me why this index being non-zero was used to
block checking family/model. None of the CPUs that had a non-zero
brand index are supported by __builtin_cpu_is or target
multi-versioning so this should have no real effect.


  Commit: 2831f7852f724b2638fb686142f7c04b9e00b7b4
      https://github.com/llvm/llvm-project/commit/2831f7852f724b2638fb686142f7c04b9e00b7b4
  Author: Craig Topper <craig.topper at intel.com>
  Date:   2020-06-12 (Fri, 12 Jun 2020)

  Changed paths:
    M llvm/lib/Support/Host.cpp

  Log Message:
  -----------
  [X86] Remove brand_id check from getHostCPUName.

Brand index was a feature some Pentium III and Pentium 4 CPUs.
It provided an index into a software lookup table to provide a
brand name for the CPU. This is separate from the family/model.

It's unclear to me why this index being non-zero was used to
block checking family/model. I think the effect of this is that
-march=native was not working correctly on the CPUs that have a
non-zero brand index. They are all about 20 years old so this
probably hasn't affected many users.


Compare: https://github.com/llvm/llvm-project/compare/339e49e2ca4b...2831f7852f72