[PATCH] D40364: [ELF] Skip over empty sections when checking for contiguous relro

[Peter Smith via Phabricator via llvm-commits]

peter.smith created this revision.
Herald added subscribers: arichardson, emaste.

This is patch 2 of 3 spun out from https://reviews.llvm.org/D40029 covering : Relax handling of empty sections..

When checking for contiguous relro sections we can skip over empty sections. If there is an empty non-relro section in the middle of a contiguous block of relro sections then it cannot be written to so it is safe to include in PT_GNU_RELRO header. If there is a contiguous block of empty relro sections then no PT_GNU_RELRO header is required for them.

The check for an OutputSection being empty is a little more complex than I'd like. As the size of some synthetic sections isn't known at the point we need to check for zero size we have to use SyntheticSection::empty() to check.

Patch 3 will cover:

- Name change when linker scripts are used.


https://reviews.llvm.org/D40364

Files:
  ELF/Writer.cpp
  test/ELF/relro-non-contiguous-zerosize.s

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