[PATCH] D74755: [llvm-objcopy] Attribute an empty section to a segment ending at its address

[Fangrui Song via Phabricator via llvm-commits]

MaskRay created this revision.
MaskRay added reviewers: grimar, jhenderson, rupprecht, kongyi.
Herald added subscribers: llvm-commits, abrachet, emaste.
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Herald added a reviewer: alexshap.
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sectionWithinSegment treats an empty section as having a size of 1.
Due to the rule, an empty .tdata will not be attributed to an empty PT_TLS.
--only-keep-debug will not layout a segment with no section
(layoutSegmentsForOnlyKeepDebug), thus p_offset of PT_TLS can go past
the end of the file. The strange p_offset can trigger validation errors, e.g.
llvm-objcopy errors when reading back the separate debug file
(readProgramHeaders).

This special rule is actually unneeded. So just delete it.
(A section can be added to multiple nested segments, e.g. PT_TLS \subset
PT_GNU_RELRO \subset PT_LOAD.)

A side effect is that an empty non-SHF_ALLOC section following SHF_ALLOC
sections will be considered included by a segment.  The added test in
strip-non-alloc.test documents this behavior change, which should be
benign.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D74755

Files:
  llvm/test/tools/llvm-objcopy/ELF/only-keep-debug.test
  llvm/test/tools/llvm-objcopy/ELF/strip-all.test
  llvm/test/tools/llvm-objcopy/ELF/strip-non-alloc.test
  llvm/tools/llvm-objcopy/ELF/Object.cpp

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