[PATCH] D114172: [ARM] implement support for ALU PC-relative group relocations

[Ard Biesheuvel via Phabricator via llvm-commits]

ardb created this revision.
ardb added reviewers: nickdesaulniers, nathanchance, peter.smith.
Herald added subscribers: kristof.beyls, arichardson, emaste.
Herald added a reviewer: MaskRay.
ardb requested review of this revision.
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Herald added a subscriber: llvm-commits.

Currently, LLD does not support the complete set of ARM group relocations.
Given that I intend to start using these in the Linux kernel [0], let's add support for these.

This implements the group processing as documented in the ELF psABI. Notably, this means support is dropped for very far symbol references that also carry a small component, where the immediate is rotated in such a way that only part of it wraps to the other end of the 32-bit word. To me, it seems unlikely that this is something anyone could be relying on, but of course I could be wrong.

[0] https://git.kernel.org/pub/scm/linux/kernel/git/ardb/linux.git/commit/?id=5d43c8cff9ed3edb37456fddc0ec2db77d219e7d


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D114172

Files:
  lld/ELF/Arch/ARM.cpp
  lld/test/ELF/arm-adr-long.s
  lld/test/ELF/arm-adr.s

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