[all-commits] [llvm/llvm-project] 62d861: [Pseudo Probe] Make .pseudo_probe GC-able

[Fangrui Song via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 62d861422317b3e94a97706f07e8f1abce9a8135
      https://github.com/llvm/llvm-project/commit/62d861422317b3e94a97706f07e8f1abce9a8135
  Author: Fangrui Song <i at maskray.me>
  Date:   2023-06-16 (Fri, 16 Jun 2023)

  Changed paths:
    M llvm/lib/MC/MCObjectFileInfo.cpp
    M llvm/test/Transforms/SampleProfile/pseudo-probe-emit.ll

  Log Message:
  -----------
  [Pseudo Probe] Make .pseudo_probe GC-able

* Add the SHF_LINK_ORDER flag so that the .pseudo_probe section is discarded when the associated text section is discarded.
* Add unique ID so that with `clang -ffunction-sections -fno-unique-section-names`, there is one separate .pseudo_probe for each text section (disambiguated by `.section ....,unique,id` in assembly)

The changes allow .pseudo_probe GC even if we don't place instrumented functions
in an IR comdat (see `getOrCreateFunctionComdat` in SampleProfileProbe.cpp).

Reviewed By: hoy

Differential Revision: https://reviews.llvm.org/D153189