[Mesa-dev] [PATCH 2/6] glsl: Implement any(v) as any_nequal(v, false).

[Ilia Mirkin]

On Mon, Nov 30, 2015 at 7:15 PM, Matt Turner <mattst88 at gmail.com> wrote:
> On Mon, Nov 30, 2015 at 3:51 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>> On Mon, Nov 30, 2015 at 6:38 PM, Matt Turner <mattst88 at gmail.com> wrote:
>>> On Mon, Nov 30, 2015 at 3:34 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>>>> On Mon, Nov 30, 2015 at 6:32 PM, Matt Turner <mattst88 at gmail.com> wrote:
>>>>> ---
>>>>>  src/glsl/builtin_functions.cpp | 15 ++++++++++++++-
>>>>>  1 file changed, 14 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/src/glsl/builtin_functions.cpp b/src/glsl/builtin_functions.cpp
>>>>> index 88f9a71..2f21ffc 100644
>>>>> --- a/src/glsl/builtin_functions.cpp
>>>>> +++ b/src/glsl/builtin_functions.cpp
>>>>> @@ -538,6 +538,7 @@ private:
>>>>>     ir_variable *in_var(const glsl_type *type, const char *name);
>>>>>     ir_variable *out_var(const glsl_type *type, const char *name);
>>>>>     ir_constant *imm(float f, unsigned vector_elements=1);
>>>>> +   ir_constant *imm(bool b, unsigned vector_elements=1);
>>>>>     ir_constant *imm(int i, unsigned vector_elements=1);
>>>>>     ir_constant *imm(unsigned u, unsigned vector_elements=1);
>>>>>     ir_constant *imm(double d, unsigned vector_elements=1);
>>>>> @@ -3000,6 +3001,12 @@ builtin_builder::out_var(const glsl_type *type, const char *name)
>>>>>  }
>>>>>
>>>>>  ir_constant *
>>>>> +builtin_builder::imm(bool b, unsigned vector_elements)
>>>>> +{
>>>>> +   return new(mem_ctx) ir_constant(b, vector_elements);
>>>>> +}
>>>>> +
>>>>> +ir_constant *
>>>>>  builtin_builder::imm(float f, unsigned vector_elements)
>>>>>  {
>>>>>     return new(mem_ctx) ir_constant(f, vector_elements);
>>>>> @@ -4358,7 +4365,13 @@ builtin_builder::_notEqual(builtin_available_predicate avail,
>>>>>  ir_function_signature *
>>>>>  builtin_builder::_any(const glsl_type *type)
>>>>>  {
>>>>> -   return unop(always_available, ir_unop_any, glsl_type::bool_type, type);
>>>>> +   ir_variable *v = in_var(type, "v");
>>>>> +   MAKE_SIG(glsl_type::bool_type, always_available, 1, v);
>>>>> +
>>>>> +   const unsigned vec_elem = v->type->vector_elements;
>>>>> +   body.emit(ret(expr(ir_binop_any_nequal, v, imm(false, vec_elem))));
>>>>
>>>> This results in an extra comparison generated by the st_glsl_to_tgsi
>>>> code, which can be annoying to get rid of... Why do you need to do
>>>> this?
>>>
>>> Couldn't we fix the st_glsl_to_tgsi to handle that better? I wouldn't
>>> be surprised to find such a thing in the wild.
>>
>> I guess it could special-case the exact IR generated there? The thing
>> is that it just OR's everything together (when you have native integer
>> support... which everything does outside of r300/nv30), which you can
>> only do in a few select cases. If you'd like to implement that, I
>> wouldn't object. As-is, it's a pessimization though.
>
> I'm not familiar with any of this code and I don't know how to test or
> debug it -- sorry.
>
> It should be trivial to optimize if someone cares. I believe all you
> need to do is skip emitting the SNE and instead copy src[0] to temp
> under these circumstances:
>
>    if (ir->operands[0]->type == glsl_type::bool_type &&
>        ir->operands[1]->as_constant() &&
>        ir->operands[1]->as_constant()->is_zero())

As long as you can build the gallium swrast (and enable debug), you
can add ST_DEBUG=tgsi to get the generated TGSI printed out.

  -ilia