[all-commits] [llvm/llvm-project] 3fd190: [FuncSpec] Enable it only with -O3

[sjoerdmeijer via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 3fd1902ad8ebfaecc57e68aaa6620332dda8d5f9
      https://github.com/llvm/llvm-project/commit/3fd1902ad8ebfaecc57e68aaa6620332dda8d5f9
  Author: Sjoerd Meijer <sjoerd.meijer at arm.com>
  Date:   2021-11-04 (Thu, 04 Nov 2021)

  Changed paths:
    M llvm/lib/Passes/PassBuilderPipelines.cpp
    M llvm/lib/Transforms/IPO/PassManagerBuilder.cpp

  Log Message:
  -----------
  [FuncSpec] Enable it only with -O3

Function specialisation was running at all optimisation levels (if enabled on
the command line, it is not on by default). That was an oversight and not
something we want to do. Function specialisation duplicates functions when it
triggers, so the backend is processing more functions/instructions resulting in
compile-time increases, which seems more appropriate with -O3 and inline with
GCC. Please note that since function specialisation is not enabled by default,
this didn't require updating any pass manager tests.

Differential Revision: https://reviews.llvm.org/D112129