[PATCH] D144617: [AVR][MC] Add ELF flag 'EF_AVR_LINKRELAX_PREPARED' to OBJ files

Thu Feb 23 19:18:04 PST 2023

benshi001 added a comment.

In D144617#4149200 <https://reviews.llvm.org/D144617#4149200>, @MaskRay wrote:

> In D144617#4149029 <https://reviews.llvm.org/D144617#4149029>, @benshi001 wrote:
>
>> In D144617#4148171 <https://reviews.llvm.org/D144617#4148171>, @MaskRay wrote:
>>
>>> I think we should understand what this flag does and how it affects assemblers/linkers.
>>> If it does not cause behavior difference, I am unsure we should add it.
>>
>> This is how gnu ld perform linker relaxation for AVR
>> https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=bfd/elf32-avr.c;h=702719136d09acbc8c98ec49ab8129d0f33fffa8;hb=6777dece58127236db900215857f9070ad63e0bf#l2423
>>
>> We can see this flag `EF_AVR_LINKRELAX_PREPARED` does affect
>> https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=bfd/elf32-avr.c;h=702719136d09acbc8c98ec49ab8129d0f33fffa8;hb=6777dece58127236db900215857f9070ad63e0bf#l2533
>>
>> The gnu ld will optimize long call (absolute address) to short call (PC relative address) only if this flag is set. (Of course `--relax` must also be specified.)
>
> s/gnu ld/GNU ld/. Change the summary to say that it affects GNU ld.

Thanks for your comment. I will update my commit message when committing.

Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D144617/new/

https://reviews.llvm.org/D144617