[all-commits] [llvm/llvm-project] fd609e: [lld] Glob-based BP compression sort groups (#185661)

[Zhaoxuan Jiang via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: fd609e5d33eae0df48d37a215f13a78bab3f8ebb
      https://github.com/llvm/llvm-project/commit/fd609e5d33eae0df48d37a215f13a78bab3f8ebb
  Author: Zhaoxuan Jiang <jiangzhaoxuan94 at gmail.com>
  Date:   2026-04-01 (Wed, 01 Apr 2026)

  Changed paths:
    M lld/ELF/BPSectionOrderer.cpp
    M lld/ELF/BPSectionOrderer.h
    M lld/ELF/Config.h
    M lld/ELF/Driver.cpp
    M lld/ELF/Options.td
    M lld/ELF/Writer.cpp
    M lld/MachO/BPSectionOrderer.cpp
    M lld/MachO/BPSectionOrderer.h
    M lld/MachO/Config.h
    M lld/MachO/Driver.cpp
    M lld/MachO/Options.td
    M lld/MachO/SectionPriorities.cpp
    M lld/docs/ReleaseNotes.rst
    A lld/include/lld/Common/BPSectionOrdererBase.h
    M lld/include/lld/Common/BPSectionOrdererBase.inc
    A lld/test/ELF/bp-section-orderer-cold.s
    M lld/test/ELF/bp-section-orderer.s
    M lld/test/MachO/bp-section-orderer-errs.s
    A lld/test/MachO/compression-order-sections.s

  Log Message:
  -----------
  [lld] Glob-based BP compression sort groups (#185661)

Add
--bp-compression-sort-section=<glob>[=<layout_priority>[=<match_priority>]]
to let users split input sections into multiple compression groups, run
balanced partitioning independently per group, and leave out sections
that are poor candidates for BP. This replaces the old coarse
--bp-compression-sort with a more explicit, user-controlled one.

In ELF, the glob matches input section names (.text.unlikely.cold1). In
Mach-O, it matches the concatenated segment+section name (__TEXT__text).

layout_priority controls group placement in the final layout.
match_priority resolves conflicts when multiple globs match the same
section: explicit priority beats positional matching, and among
positional specs the last match wins.

A CRTP hook getCompressionSubgroupKey() allows backends to further
subdivide glob groups into independent BP instances. This allows Mach-O
backend to separate cold functions via N_COLD_FUNC in the future.

The deprecated --bp-compression-sort option keeps its existing
function/data behavior by assigning sections to fixed legacy groups.



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