tree 339ace2d4b08fded0a8893f6b8282483fc47e427
parent b5f5aa94e8f716a7056f9509018bf7c20fea1104
author Fangrui Song <i@maskray.me> 1710435087 -0700
committer Copybara-Service <copybara-worker@google.com> 1710435447 -0700

[ELF] Eliminate symbols demoted due to /DISCARD/ discarded sections (#85167)

#69295 demoted Defined symbols relative to discarded sections.
If such a symbol is unreferenced, the desired behavior is to
eliminate it from .symtab just like --gc-sections discarded
definitions.
Linux kernel's CONFIG_DEBUG_FORCE_WEAK_PER_CPU=y configuration expects
that the unreferenced `unused` is not emitted to .symtab
(https://github.com/ClangBuiltLinux/linux/issues/2006).

For relocations referencing demoted symbols, the symbol index restores
to 0 like older lld (`R_X86_64_64 0` in `discard-section.s`).

Fix #85048

GitOrigin-RevId: 8fe3e70e810b409dce36f6d415e86f0f9b1cf22d