[PATCH] D72197: [MC][ELF] Emit a relocation if target is defined in the same section and is non-local

[Fangrui Song via Phabricator via llvm-commits]

MaskRay added a comment.

In D72197#1825012 <https://reviews.llvm.org/D72197#1825012>, @pcc wrote:

> It looks like this change caused us to start rejecting:
>
>   .thumb
>   .thumb_func
>   .globl foo
>   .hidden foo
>   foo:
>   adr lr, foo + 1
>
>
> with:
>
>   test.s:6:1: error: unsupported relocation on symbol
>   adr lr, foo + 1
>   ^
>  
>
>
> This is exposed by this Android ART code: https://cs.android.com/android/platform/superproject/+/master:art/runtime/arch/arm/quick_entrypoints_arm.S;l=1826
>
> I see a couple of possible fixes for this:
>
> 1. We could go back to the previous behaviour for global hidden symbols.
> 2. We could teach MC and LLD about the `R_ARM_THM_ALU_PREL_11_0` relocation required to relocate this instruction. Arguably the ART code shouldn't be adding the 1 for Thumb here (because `R_ARM_THM_ALU_PREL_11_0` adds the 1 itself), so ART would then need to be fixed.




  % arm-linux-gnueabi-as /tmp/c/a.s -o /tmp/c/a.o
  /tmp/c/a.s: Assembler messages:
  /tmp/c/a.s:6: Error: invalid Hi register with immediate
  /tmp/c/a.s:6: Error: invalid immediate for address calculation (value = 0xFFFFFFFFFFFFFFFE)

How can I make GNU as recognize it?


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https://reviews.llvm.org/D72197