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

[Roland Scheidegger]

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).

Roland

> +uvec2
> +fsign64(uvec2 a)
> +{
> +   uvec2 retval;
> +   retval.x = 0u;
> +   retval.y = mix((a.y & 0x80000000u) | 0x3FF00000u, 0u, (a.y << 1 | a.x) == 0u);
> +   return retval;
> +}
> diff --git a/src/compiler/glsl/glcpp/glcpp-parse.y b/src/compiler/glsl/glcpp/glcpp-parse.y
> index b9506d8..666543b 100644
> --- a/src/compiler/glsl/glcpp/glcpp-parse.y
> +++ b/src/compiler/glsl/glcpp/glcpp-parse.y
> @@ -2370,6 +2370,7 @@ _glcpp_parser_handle_version_declaration(glcpp_parser_t *parser, intmax_t versio
>           add_builtin_define(parser, "__have_builtin_builtin_imod64", 1);
>           add_builtin_define(parser, "__have_builtin_builtin_fabs64", 1);
>           add_builtin_define(parser, "__have_builtin_builtin_fneg64", 1);
> +         add_builtin_define(parser, "__have_builtin_builtin_fsign64", 1);
>        }
>     }
>  
>