Re: [PATCH] linux/compiler-clang.h: define HAVE_BUILTIN_BSWAP*

[Miguel Ojeda]

On Thu, Feb 25, 2021 at 9:18 PM Nathan Chancellor <nathan@xxxxxxxxxx> wrote:
>
> Indeed. Any wins that we can get with compile time, we should take.
> Clang is being widely used in production systems now so I feel like with
> a trivial change plus user visible impact, it should be backported.
>
> Not to mention that the generated code in theory should be better
> because it is the compiler's builtin, rather than a hand rolled one, AND
> this is technically a regression, given that it worked before compiler.h
> was split.

Compilation speed shouldn't be an argument for a stable change unless
it is something egregious like a 50% that may affect users or tightly
timed CIs.

Fixing an important runtime regression is a stronger argument, but the
patch doesn't show what the effects are, so it isn't justified (yet).

Please note that this kind of change touches a lot of code all over
the place, which could always trigger other runtime regressions or
even bad codegen (yes, very unlikely, but it happens).

Cheers,
Miguel