[PATCH] D103303: [ELF] Add --overwrite-script

[Fangrui Song via Phabricator via llvm-commits]

MaskRay created this revision.
MaskRay added reviewers: grimar, jhenderson, peter.smith, phosek.
Herald added subscribers: dang, arichardson, emaste.
MaskRay requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

This implements https://sourceware.org/bugzilla/show_bug.cgi?id=26404#c6

--overwrite-script specifies a script which contains several `SECTIONS`
commands. Each `SECTIONS` specifies exactly one output section description. The
initial syntax is intentionally narrow. Symbol assignments cannot be used.
Not supporting multiple output section descriptions in one `SECTIONS` makes it
clear the sections don't have order guarantee.

The semantics are similar to `INSERT [BEFORE|AFTER]`: LinkerScript::hasSectionsCommand
is not set. --overwrite-script can be more convenient without a main script
because --overwrite-script does not need a random anchor section used by `INSERT`.

This feature is versatile. To list a few usage:

- Use `KEEP(...)` to retain sections under GC
- Define encapsulation symbols (start/end) for an output section
- Use `: ALIGN(...)` to overalign an output section


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D103303

Files:
  lld/ELF/Driver.cpp
  lld/ELF/LinkerScript.cpp
  lld/ELF/LinkerScript.h
  lld/ELF/Options.td
  lld/ELF/ScriptParser.cpp
  lld/ELF/ScriptParser.h
  lld/test/ELF/linkerscript/overwrite-script-discard.test
  lld/test/ELF/linkerscript/overwrite-script.test

-------------- next part --------------
A non-text attachment was scrubbed...
Name: D103303.348461.patch
Type: text/x-patch
Size: 14047 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20210528/6c94ec33/attachment.bin>