[PATCH] D77694: [WIP][RISCV][ELF] Linker relaxation support

[Jessica Clarke via Phabricator via llvm-commits]

jrtc27 created this revision.
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This is a proof-of-concept implementation for R_RISCV_ALIGN that I've had lying
around for a while. I just rebased it, but it has not been build tested, let
alone run. It was previously able to link a working FreeBSD kernel, though, and
compared bit-for-bit identical to an -mno-relax build. I'm posting this here as
it came up on IRC and I figured it would be best to share it and avoid
duplicating work (and perhaps also promoting a bit more discussion about how to
implement this correctly in LLD; the mutableData/makeMutableDataCopy is a bit
of a gross hack that could potentially go wrong if consumers of data hang on to
now-stale pointers, and it would be nice if we could instead just
mprotect/mremap/etc the mapping and let the OS CoW as needed whilst retaining
the same address, although given I work on CHERI and CHERI has minor issues
with the mprotect/mremap interface _increasing_ permissions, perhaps I should
not be pushing for that).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D77694

Files:
  lld/ELF/Arch/RISCV.cpp
  lld/ELF/InputSection.cpp
  lld/ELF/InputSection.h
  lld/ELF/Relocations.cpp
  lld/ELF/Relocations.h
  lld/ELF/Target.cpp
  lld/ELF/Target.h
  lld/ELF/Writer.cpp

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