[PATCH] D83103: [lld-macho] Support binding dysyms to any section

[Jez Ng via Phabricator via llvm-commits]

int3 created this revision.
int3 added a reviewer: lld-macho.
Herald added subscribers: llvm-commits, mgrang.
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int3 updated this revision to Diff 275255.
int3 added a comment.
int3 updated this revision to Diff 275256.

update


int3 added a comment.

more const


Previously, we only supported binding dysyms to the GOT. This
diff adds support for binding them to any arbitrary section. C++
programs appear to use this, I believe for vtables and type_info.

This diff also makes our bind opcode encoding a bit smarter -- we now
encode just the differences between bindings, which will make things
more compact.

I was initially concerned about the performance overhead of iterating
over these relocations, but it turns out that the number of such
relocations is small. A quick analysis of my llvm-project build
directory showed that < 1.3% out of ~7M relocations are RELOC_UNSIGNED
bindings to symbols (including both dynamic and static symbols).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D83103

Files:
  lld/MachO/Arch/X86_64.cpp
  lld/MachO/SyntheticSections.cpp
  lld/MachO/SyntheticSections.h
  lld/MachO/Target.h
  lld/MachO/Writer.cpp
  lld/test/MachO/dylink.s

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