[all-commits] [llvm/llvm-project] 290279: [ARM] Use .reloc for weak symbols in PIC mode inst...

[dong jianqiang via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 290279b6b69138f4162cace4865713efa12ec262
      https://github.com/llvm/llvm-project/commit/290279b6b69138f4162cace4865713efa12ec262
  Author: dong jianqiang <dongjianqiang2 at huawei.com>
  Date:   2026-07-11 (Sat, 11 Jul 2026)

  Changed paths:
    M llvm/lib/Target/ARM/ARMAsmPrinter.cpp
    M llvm/lib/Target/ARM/ARMFastISel.cpp
    M llvm/lib/Target/ARM/ARMISelLowering.cpp
    M llvm/lib/Target/ARM/ARMSubtarget.cpp
    M llvm/lib/Target/ARM/ARMTargetMachine.h
    M llvm/test/CodeGen/ARM/elf-preemption.ll
    M llvm/test/CodeGen/ARM/weak-hidden-pic.ll

  Log Message:
  -----------
  [ARM] Use .reloc for weak symbols in PIC mode instead of GOT indirection (#208372)

In ARM ELF PIC mode, weak symbols referenced via the constant pool use a
PC-relative expression like `.long sym-(.LPC+8)`. The assembler eagerly
resolves this when both the symbol and reference are in the same
section, which prevents the linker from overriding a weak definition
with a strong one from another object file.

The previous approach (#198577) forced weak symbols to go through GOT
indirection to avoid this, but that adds an extra load. This patch
instead emits a `.reloc` directive alongside the local PC-relative
expression, forcing the assembler to emit a proper `R_ARM_REL32`
relocation. This lets the linker perform the override without the
runtime cost of a GOT load.



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