Ben Dunbobbin 325e7e8b87 [LLVM][LTO][LLD] Enable Profile Guided Layout (--call-graph-profile-sort) for FullLTO ...

The CGProfilePass needs to be run during FullLTO compilation at link
time to emit the .llvm.call-graph-profile section to the compiled LTO
object file. Currently, it is being run only during the initial
LTO-prelink compilation stage (to produce the bitcode files to be
consumed by the linker) and so the section is not produced.

ThinLTO is not affected because:
- For ThinLTO-prelink compilation the CGProfilePass pass is not run
  because ThinLTO-prelink passes are added via
  buildThinLTOPreLinkDefaultPipeline. Normal and FullLTO-prelink
  passes are both added via buildPerModuleDefaultPipeline which uses
  the LTOPreLink parameter to customize its behavior for the
  FullLTO-prelink pass differences.
- ThinLTO backend compilation phase adds the CGProfilePass (see:
  buildModuleOptimizationPipeline).

Adjust when the pass is run so that the .llvm.call-graph-profile
section is produced correctly for FullLTO.

Fixes #56185 (https://github.com/llvm/llvm-project/issues/56185)

2022-07-01 13:57:36 +01:00

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