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

[Ilia Mirkin]

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.

  -ilia