[all-commits] [llvm/llvm-project] 2c9dc7: Revert "[llvm-exegesis] Add option to check the ha...

[darkbuck via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 2c9dc7bbbf514b1ed7bdefacb3213beae5916b3d
      https://github.com/llvm/llvm-project/commit/2c9dc7bbbf514b1ed7bdefacb3213beae5916b3d
  Author: Michael Liao <michael.hliao at gmail.com>
  Date:   2020-09-30 (Wed, 30 Sep 2020)

  Changed paths:
    M llvm/test/tools/llvm-exegesis/X86/lbr/lit.local.cfg
    M llvm/tools/llvm-exegesis/lib/Target.h
    M llvm/tools/llvm-exegesis/lib/X86/Target.cpp
    M llvm/tools/llvm-exegesis/lib/X86/X86Counter.cpp
    M llvm/tools/llvm-exegesis/lib/X86/X86Counter.h
    M llvm/tools/llvm-exegesis/llvm-exegesis.cpp

  Log Message:
  -----------
  Revert "[llvm-exegesis] Add option to check the hardware support for a given feature before benchmarking."

This reverts commit 4fcd1a8e6528ca42fe656f2745e15d2b7f5de495 as
`llvm/test/tools/llvm-exegesis/X86/lbr/mov-add.s` failed on hosts
without LBR supported if the build has LIBPFM enabled. On that host,
`perf_event_open` fails with `EOPNOTSUPP` on LBR config. That change's
basic assumption

> If this is run on a non-supported hardware, it will produce all zeroes for latency.

could not stand as `perf_event_open` system call will fail if the
underlying hardware really don't have LBR supported.