Re: [RFC PATCH 0/2] RISC-V: __builtin_riscv_pause for all environment

[Palmer Dabbelt <palmer@dabbelt.com>]

On Fri, 11 Aug 2023 16:30:29 PDT (-0700), gcc-patches@gcc.gnu.org wrote:
>
>
> On 8/9/23 16:39, Tsukasa OI wrote:
>> On 2023/08/10 5:05, Jeff Law wrote:
>
>>> I'd tend to think we do not want to expose the intrinsic unless the
>>> right extensions are enabled -- even though the encoding is a no-op and
>>> we could emit it as a .insn.
>>
>> I think that makes sense.  The only reason I implemented the
>> no-'Zihintpause' version is because GCC 13 implemented the built-in
>> unconditionally.  If the compatibility breakage is considered minimum (I
>> don't know, though), I'm ready to submit 'Zihintpause'-only version of
>> this patch set.
> While it's a compatibility break I don't think we have a need to
> preserve this kind of compatibility.  I suspect anyone using
> __builtin_riscv_pause was probably already turning on Zihintpause and if
> they weren't they should have been :-0

I agree it's fine to just call this a bug: the builtin wasn't doing 
anything on non-Zihintpause systems anyway, so it's not like it could 
have been all that useful.

> I'm sure we'll kick this around in the Tuesday meeting and hopefully
> make a decision about the desired direction.  You're obviously welcome
> to join if you're inclined.  Let me know if you need an invite.
>
> jeff