Re: [PATCH] RISC-V: Note that __builtin_riscv_pause() implies Xgnuzihintpausestate

[Palmer Dabbelt <palmer@rivosinc.com>]

On Thu, 17 Nov 2022 22:59:08 PST (-0800), Kito Cheng wrote:
> Wait, what's Xgnuzihintpausestate???

I just made it up, it's defined right next to the name like those 
profile extensions are.  I figured that's the most RISC-V way to define 
something like this, but we could just drop it and run with the 
definition -- IIRC we just stuck a comment in for Linux and QEMU, I 
doubt anyone is actually going to implement the "doesn't touch PC" 
version of pause.

> On Fri, Nov 18, 2022 at 12:30 PM Palmer Dabbelt <palmer@rivosinc.com> wrote:
>>
>> gcc/ChangeLog:
>>
>>         * doc/extend.texi (__builtin_riscv_pause): Imply
>>         Xgnuzihintpausestate.
>> ---
>>  gcc/doc/extend.texi | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
>> index b1dd39e64b8..26f14e61bc8 100644
>> --- a/gcc/doc/extend.texi
>> +++ b/gcc/doc/extend.texi
>> @@ -21103,7 +21103,9 @@ Returns the value that is currently set in the @samp{tp} register.
>>  @end deftypefn
>>
>>  @deftypefn {Built-in Function}  void __builtin_riscv_pause (void)
>> -Generates the @code{pause} (hint) machine instruction.
>> +Generates the @code{pause} (hint) machine instruction.  This implies the
>> +Xgnuzihintpausestate extension, which redefines the @code{pause} instruction to
>> +change architectural state.
>>  @end deftypefn
>>
>>  @node RX Built-in Functions
>> --
>> 2.38.1
>>