[PATCH] D59986: [ELF] Respect NonAlloc when copying flags from the previous sections

[Fangrui Song via Phabricator via llvm-commits]

MaskRay marked an inline comment as done.
MaskRay added a comment.

> So the rule you said is that, if a section is empty, its section attribute is copied from the previous (non-empty) section.

Yes. `(SHF_ALLOC | SHF_WRITE | SHF_EXECINSTR)` may be copied.

> Therefore, if the previous section is SHF_ALLOC, the empty section would have SHF_ALLOC, and vice versa.

The empty OutputSection may have its `NonAlloc` bit set. In that case, The `SHF_ALLOC` bit shouldn't be copied.

> But you are doing more than copying section attributes -- nullifying only SHF_ALLOC using other bits. Why?

If `Sec->NonAlloc`, `Sec->Flags` can't have the `SHF_ALLOC` bit set. The bit (if set originally) has been cleared by:

  void LinkerScript::processSectionCommands() {
  ...
        if (Sec->NonAlloc)
          Sec->Flags &= ~(uint64_t)SHF_ALLOC;


Repository:
  rLLD LLVM Linker

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  https://reviews.llvm.org/D59986/new/

https://reviews.llvm.org/D59986