[PATCH] D75347: [MC][ELF][ARM] Add relocations for some ARM pc-relative fixups.

[Peter Smith via Phabricator via llvm-commits]

psmith created this revision.
psmith added reviewers: MaskRay, ostannard, eli.friedman.
Herald added subscribers: hiraditya, kristof.beyls.
Herald added a project: LLVM.

Add ELF relocations for the following fixups:

- fixup_arm_ldst_pcrel_12 -> R_ARM_LDR_PC_G0
- fixup_arm_adr_pcrel_12 -> R_ARM_ALU_PC_G0

These relocations map to the pseudo instructions:

- ldr rd, label
- adr rd, label

They are short ranged and normally resolved by the fixup, however MC will no longer resolve the fixups to global symbols due to interpositioning concerns. We can handle these at link time by implementing the relocations.

This is the ARM equivalent of D75039 <https://reviews.llvm.org/D75039>, LLD patch implementing the relocations will be submitted later today.


https://reviews.llvm.org/D75347

Files:
  llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
  llvm/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp
  llvm/test/MC/ARM/arm-relax-adr.s
  llvm/test/MC/ARM/arm-relax-ldrlit.s
  llvm/test/MC/ARM/pcrel-global-rel.s
  llvm/test/MC/ARM/pcrel-global.s

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