[PATCH] D89828: [ELF] Set SHF_INFO_LINK for .rel[a].plt and .rel[a].dyn

[Fangrui Song via Phabricator via llvm-commits]

MaskRay created this revision.
MaskRay added reviewers: grimar, psmith.
Herald added subscribers: llvm-commits, arichardson, emaste.
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MaskRay requested review of this revision.

The ELF spec says

> If the sh_flags field for this section header includes the attribute SHF_INFO_LINK, then this member represents a section header table index.

Set SHF_INFO_LINK so that binary manipulation tools know that sh_info is
an index instead of (the number of local symbols in the case of SHT_SYMTAB/SHT_DYNSYM).
For example, we can teach llvm-objcopy to preserve the section index if
SHF_INFO_LINK is set. (GNU objcopy recognizes .rel[a].plt and updates
sh_info even if SHF_INFO_LINK is not set).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D89828

Files:
  lld/ELF/SyntheticSections.cpp
  lld/test/ELF/aarch64-gnu-ifunc.s
  lld/test/ELF/arm-combined-dynrel-ifunc.s
  lld/test/ELF/arm-gnu-ifunc.s
  lld/test/ELF/dynamic-reloc.s
  lld/test/ELF/gnu-ifunc-i386.s
  lld/test/ELF/gnu-ifunc.s
  lld/test/ELF/x86-64-combined-dynrel.s

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