[PATCH] D85100: [ELF] Allow sections after a non-allocable section to be covered by PT_LOAD

[Fangrui Song via Phabricator via llvm-commits]

MaskRay created this revision.
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GNU ld allows sections after a non-allocable section to be covered by PT_LOAD
(PR37607) and assigns addresses to non-allocable output sections (similar to
allocable NOBITS sections. The location counter is not advanced).

This patch tries to fix PR37607 (remove a special case in
`Writer<ELFT>::createPhdrs`). To make the created PT_LOAD meaningful, we cannot
reset dot to 0 for a middle non-allocable output section. This results in
removal of wwo special cases in LinkerScript::assignOffsets. Non-allocable
non-orphan sections can have non-zero addresses like in GNU ld.

The zero address rule for non-allocable sections is weakened to apply to orphan
only. This results in a special case in `createSection` and findOrphanPos, respectively.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D85100

Files:
  lld/ELF/LinkerScript.cpp
  lld/ELF/Writer.cpp
  lld/test/ELF/linkerscript/compress-debug-sections-custom.s
  lld/test/ELF/linkerscript/sections.s
  lld/test/ELF/linkerscript/symbols-non-alloc.test

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