Re: [PATCH v3] elf: Rewrite long RESOLVE_MAP macro to a debug friendly function

[Siddhesh Poyarekar <siddhesh@gotplt.org>]

On 23/05/2022 03:54, Fangrui Song wrote:
> Hope that the -O2 requirement can be lifted:)
> 
> The original decision might be related to guaranteed inlining and 
> relocations in -O0
> but it should be revisited nowadays... (Both FreeBSD rtld and musl rtld 
> allow -O0).

I don't know TBH, maybe it's something Andreas, Carlos or someone else 
who's been around longer may know.

>>> Looks good to me, I think the always_inline here does not affect
>>> performance, as shown in my testing with a large PIE with many
>>> R_*_RELATIVE (function call overhead is larger with a non-R_*_RELATIVE).
>>
>> If you want to make a decision based on this then please quantify it 
>> more precisely with a microbenchmark added to benchtests.  Otherwise 
>> just add __always_inline because it is a more minimal change.  TBH I'd 
>> prefer the former because it then adds a new microbenchmark that we 
>> can measure dynamic linker changes in future but I can live with the 
>> latter.
> 
> Thanks. I can add __always_inline.
> (I don't think it matters but I guess I just want to avoid a debate :))
> 

Bummer, I was hoping you'd write the benchmark; we don't nearly have 
enough microbenchmarks for the linker :)

Siddhesh