[all-commits] [llvm/llvm-project] 1b704e: [MC, llvm-readobj, yaml2obj] Support CREL relocation...

[Fangrui Song via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 1b704e889f09b5dfc0549786542bc6d2cd54e85b
      https://github.com/llvm/llvm-project/commit/1b704e889f09b5dfc0549786542bc6d2cd54e85b
  Author: Fangrui Song <i at maskray.me>
  Date:   2024-07-01 (Mon, 01 Jul 2024)

  Changed paths:
    M llvm/include/llvm/BinaryFormat/DynamicTags.def
    M llvm/include/llvm/BinaryFormat/ELF.h
    M llvm/include/llvm/MC/MCTargetOptions.h
    M llvm/include/llvm/MC/MCTargetOptionsCommandFlags.h
    M llvm/include/llvm/Object/ELF.h
    M llvm/include/llvm/Object/ELFTypes.h
    M llvm/lib/MC/ELFObjectWriter.cpp
    M llvm/lib/MC/MCTargetOptionsCommandFlags.cpp
    M llvm/lib/Object/ELF.cpp
    M llvm/lib/ObjectYAML/ELFEmitter.cpp
    M llvm/lib/ObjectYAML/ELFYAML.cpp
    A llvm/test/MC/ELF/crel-32.s
    A llvm/test/MC/ELF/crel.s
    A llvm/test/tools/llvm-readobj/ELF/crel.test
    M llvm/test/tools/llvm-readobj/ELF/dynamic-reloc.test
    M llvm/test/tools/llvm-readobj/ELF/dynamic-tags.test
    M llvm/test/tools/llvm-readobj/ELF/relocation-errors.test
    M llvm/test/tools/llvm-readobj/ELF/section-types.test
    M llvm/test/tools/yaml2obj/ELF/dynamic-relocations.yaml
    M llvm/test/tools/yaml2obj/ELF/reloc-sec-entry-size.yaml
    A llvm/test/tools/yaml2obj/ELF/relocation-crel.yaml
    M llvm/test/tools/yaml2obj/ELF/relocation-missing-symbol.yaml
    M llvm/test/tools/yaml2obj/ELF/relocation-type.yaml
    M llvm/tools/llvm-readobj/ELFDumper.cpp

  Log Message:
  -----------
  [MC,llvm-readobj,yaml2obj] Support CREL relocation format

CREL is a compact relocation format for the ELF object file format.

This patch adds integrated assembler support (using the RELA form)
available with `llvm-mc -filetype=obj -crel a.s -o a.o`.
A dependent patch will add `clang -c -Wa,--crel,--allow-experimental-crel`.

Also add llvm-readobj support (for both REL and RELA forms) to
facilitate testing the assembler. Additionally, yaml2obj gains support
for the RELA form to aid testing with llvm-readobj.

We temporarily assign the section type code 0x40000020 from the generic
range to `SHT_CREL`. We avoided using `SHT_LLVM_` or `SHT_GNU_` to
avoid code churn and maintain broader applicability for interested psABIs.
Similarly, `DT_CREL` is temporarily 0x40000026.

LLVM will change the code and break compatibility. This is not an issue
if all relocatable files using CREL are regenerated (aka no prebuilt
relocatable files).

Link: https://discourse.llvm.org/t/rfc-crel-a-compact-relocation-format-for-elf/77600

Pull Request: https://github.com/llvm/llvm-project/pull/91280



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