[Mesa-dev] [PATCH 03/50] glsl: Add "built-in" function to do sign(fp64) (v2)

[Dave Airlie]

On 14 March 2018 at 10:46, Roland Scheidegger <sroland at vmware.com> wrote:
> Am 13.03.2018 um 05:24 schrieb Dave Airlie:
>> From: Elie Tournier <tournier.elie at gmail.com>
>>
>> v2: use mix.
>>
>> Signed-off-by: Elie Tournier <elie.tournier at collabora.com>
>> ---
>>  src/compiler/glsl/builtin_float64.h     | 28 ++++++++++++++++++++++++++++
>>  src/compiler/glsl/builtin_functions.cpp |  4 ++++
>>  src/compiler/glsl/builtin_functions.h   |  3 +++
>>  src/compiler/glsl/float64.glsl          |  9 +++++++++
>>  src/compiler/glsl/glcpp/glcpp-parse.y   |  1 +
>>  5 files changed, 45 insertions(+)
>>
>> diff --git a/src/compiler/glsl/builtin_float64.h b/src/compiler/glsl/builtin_float64.h
>> index 2898fc9..8546048 100644
>> --- a/src/compiler/glsl/builtin_float64.h
>> +++ b/src/compiler/glsl/builtin_float64.h
>> @@ -68,3 +68,31 @@ fneg64(void *mem_ctx, builtin_available_predicate avail)
>>     sig->replace_parameters(&sig_parameters);
>>     return sig;
>>  }
>> +ir_function_signature *
>> +fsign64(void *mem_ctx, builtin_available_predicate avail)
>> +{
>> +   ir_function_signature *const sig =
>> +      new(mem_ctx) ir_function_signature(glsl_type::uvec2_type, avail);
>> +   ir_factory body(&sig->body, mem_ctx);
>> +   sig->is_defined = true;
>> +
>> +   exec_list sig_parameters;
>> +
>> +   ir_variable *const r001D = new(mem_ctx) ir_variable(glsl_type::uvec2_type, "a", ir_var_function_in);
>> +   sig_parameters.push_tail(r001D);
>> +   ir_variable *const r001E = new(mem_ctx) ir_variable(glsl_type::uvec2_type, "retval", ir_var_auto);
>> +   body.emit(r001E);
>> +   body.emit(assign(r001E, body.constant(0u), 0x01));
>> +
>> +   ir_expression *const r001F = lshift(swizzle_y(r001D), body.constant(int(1)));
>> +   ir_expression *const r0020 = bit_or(r001F, swizzle_x(r001D));
>> +   ir_expression *const r0021 = equal(r0020, body.constant(0u));
>> +   ir_expression *const r0022 = bit_and(swizzle_y(r001D), body.constant(2147483648u));
>> +   ir_expression *const r0023 = bit_or(r0022, body.constant(1072693248u));
>> +   body.emit(assign(r001E, expr(ir_triop_csel, r0021, body.constant(0u), r0023), 0x02));
>> +
>> +   body.emit(ret(r001E));
>> +
>> +   sig->replace_parameters(&sig_parameters);
>> +   return sig;
>> +}
>> diff --git a/src/compiler/glsl/builtin_functions.cpp b/src/compiler/glsl/builtin_functions.cpp
>> index 9d88a31..17aa868 100644
>> --- a/src/compiler/glsl/builtin_functions.cpp
>> +++ b/src/compiler/glsl/builtin_functions.cpp
>> @@ -3350,6 +3350,10 @@ builtin_builder::create_builtins()
>>                  generate_ir::fneg64(mem_ctx, integer_functions_supported),
>>                  NULL);
>>
>> +   add_function("__builtin_fsign64",
>> +                generate_ir::fsign64(mem_ctx, integer_functions_supported),
>> +                NULL);
>> +
>>  #undef F
>>  #undef FI
>>  #undef FIUD_VEC
>> diff --git a/src/compiler/glsl/builtin_functions.h b/src/compiler/glsl/builtin_functions.h
>> index adec424..7954373 100644
>> --- a/src/compiler/glsl/builtin_functions.h
>> +++ b/src/compiler/glsl/builtin_functions.h
>> @@ -73,6 +73,9 @@ fabs64(void *mem_ctx, builtin_available_predicate avail);
>>  ir_function_signature *
>>  fneg64(void *mem_ctx, builtin_available_predicate avail);
>>
>> +ir_function_signature *
>> +fsign64(void *mem_ctx, builtin_available_predicate avail);
>> +
>>  }
>>
>>  #endif /* BULITIN_FUNCTIONS_H */
>> diff --git a/src/compiler/glsl/float64.glsl b/src/compiler/glsl/float64.glsl
>> index fedf8b7..f8eb1f3 100644
>> --- a/src/compiler/glsl/float64.glsl
>> +++ b/src/compiler/glsl/float64.glsl
>> @@ -51,3 +51,12 @@ fneg64(uvec2 a)
>>     a.y = mix(t, a.y, is_nan(a));
>>     return a;
>>  }
>> +
>
> I think a function comment indicating what this returns would be quite
> useful here(I had to look quite a long time at it to realize it returns
> -1.0/1.0/0.0 depending on sign).

https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/sign.xhtml

Dave.