[Mesa-dev] [PATCH] radeonsi: use minnum and maxnum LLVM intrinsics for MIN and MAX opcodes

[Matt Arsenault]

> On Nov 22, 2014, at 7:35 AM, Marek Olšák <maraeo at gmail.com> wrote:
> 
> AFAICS, the R600 backend doesn't implement the intrinsics for R600.
> 
> Marek


Should it? It’s trivial to switch to these for it, but I wasn’t sure what the actual semantics of its instructions were. There’s MAX and MAX_DX10, where I think MAX_DX10 corresponds to maxnum and MAX is the legacy version, but I’m not sure.


> 
> On Sat, Nov 22, 2014 at 3:53 AM, Michel Dänzer <michel at daenzer.net> wrote:
>> On 21.11.2014 06:21, Marek Olšák wrote:
>>> 
>>> From: Marek Olšák <marek.olsak at amd.com>
>>> 
>>> So far it has been compiled into pretty ugly code (8 instructions or so
>>> for either opcode).
>>> ---
>>>  src/gallium/drivers/radeonsi/si_shader.c | 7 +++++++
>>>  1 file changed, 7 insertions(+)
>>> 
>>> diff --git a/src/gallium/drivers/radeonsi/si_shader.c
>>> b/src/gallium/drivers/radeonsi/si_shader.c
>>> index ee08d1a..973bac2 100644
>>> --- a/src/gallium/drivers/radeonsi/si_shader.c
>>> +++ b/src/gallium/drivers/radeonsi/si_shader.c
>>> @@ -2792,6 +2792,13 @@ int si_shader_create(struct si_screen *sscreen,
>>> struct si_shader *shader)
>>>        bld_base->op_actions[TGSI_OPCODE_EMIT].emit = si_llvm_emit_vertex;
>>>        bld_base->op_actions[TGSI_OPCODE_ENDPRIM].emit =
>>> si_llvm_emit_primitive;
>>> 
>>> +       if (HAVE_LLVM >= 0x0306) {
>>> +               bld_base->op_actions[TGSI_OPCODE_MAX].emit =
>>> build_tgsi_intrinsic_nomem;
>>> +               bld_base->op_actions[TGSI_OPCODE_MAX].intr_name =
>>> "llvm.maxnum.f32";
>>> +               bld_base->op_actions[TGSI_OPCODE_MIN].emit =
>>> build_tgsi_intrinsic_nomem;
>>> +               bld_base->op_actions[TGSI_OPCODE_MIN].intr_name =
>>> "llvm.minnum.f32";
>>> +       }
>>> +
>>>        si_shader_ctx.radeon_bld.load_system_value = declare_system_value;
>>>        si_shader_ctx.tokens = sel->tokens;
>>>        tgsi_parse_init(&si_shader_ctx.parse, si_shader_ctx.tokens);
>>> 
>> 
>> Shouldn't this be done in
>> src/gallium/drivers/radeon/radeon_setup_tgsi_llvm.c, so it benefits r600g as
>> well?
>> 
>> 
>> --
>> Earthling Michel Dänzer               |               http://www.amd.com
>> Libre software enthusiast             |             Mesa and X developer
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