[Mesa-dev] [RFC 02/11] glsl: Add "built-in" function to do neg(fp64)

[Ilia Mirkin]

On Fri, Mar 3, 2017 at 11:22 AM, Elie Tournier <tournier.elie at gmail.com> wrote:
> Signed-off-by: Elie Tournier <elie.tournier at collabora.com>
> ---
>  src/compiler/glsl/builtin_float64.h     | 19 +++++++++++++++++++
>  src/compiler/glsl/builtin_functions.cpp |  4 ++++
>  src/compiler/glsl/builtin_functions.h   |  3 +++
>  src/compiler/glsl/float64.glsl          | 10 ++++++++++
>  4 files changed, 36 insertions(+)
>
> diff --git a/src/compiler/glsl/builtin_float64.h b/src/compiler/glsl/builtin_float64.h
> index c1ec89d210..6df91e10f5 100644
> --- a/src/compiler/glsl/builtin_float64.h
> +++ b/src/compiler/glsl/builtin_float64.h
> @@ -17,3 +17,22 @@ fabs64(void *mem_ctx, builtin_available_predicate avail)
>     sig->replace_parameters(&sig_parameters);
>     return sig;
>  }
> +ir_function_signature *
> +fneg64(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 r000C = new(mem_ctx) ir_variable(glsl_type::uvec2_type, "a", ir_var_function_in);
> +   sig_parameters.push_tail(r000C);
> +   body.emit(assign(r000C, bit_xor(swizzle_x(r000C), body.constant(2147483648u)), 0x01));
> +
> +   body.emit(ret(r000C));
> +
> +   sig->replace_parameters(&sig_parameters);
> +   return sig;
> +}
> diff --git a/src/compiler/glsl/builtin_functions.cpp b/src/compiler/glsl/builtin_functions.cpp
> index b0b1781725..a189b84190 100644
> --- a/src/compiler/glsl/builtin_functions.cpp
> +++ b/src/compiler/glsl/builtin_functions.cpp
> @@ -3133,6 +3133,10 @@ builtin_builder::create_builtins()
>                  generate_ir::fabs64(mem_ctx, integer_functions_supported),
>                  NULL);
>
> +   add_function("__builtin_fneg64",
> +                generate_ir::fneg64(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 abe02d97b6..37c6cc33c2 100644
> --- a/src/compiler/glsl/builtin_functions.h
> +++ b/src/compiler/glsl/builtin_functions.h
> @@ -66,6 +66,9 @@ sign64(void *mem_ctx, builtin_available_predicate avail);
>  ir_function_signature *
>  fabs64(void *mem_ctx, builtin_available_predicate avail);
>
> +ir_function_signature *
> +fneg64(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 b8f0c2e444..82875e9407 100644
> --- a/src/compiler/glsl/float64.glsl
> +++ b/src/compiler/glsl/float64.glsl
> @@ -26,3 +26,13 @@ fabs64( uvec2 a )
>      a.x &= 0x7FFFFFFFu;
>      return a;
>  }
> +
> +/* Negate value of a Float64 :
> + * Toggle the sign bit
> + */
> +uvec2
> +fneg64( uvec2 a )
> +{
> +    a.x ^= (1u<<31);

Is this right for NaN? Presumably neg(NaN) should == NaN.

> +    return a;
> +}
> --
> 2.11.0
>
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