On Sun, May 4, 2014 at 1:24 AM, Chris Forbes <chr...@ijw.co.nz> wrote:
> The ARB_gpu_shader5 spec says:
>
> "To determine whether the conversion for a single argument in one match is
> better than that for another match, the following rules are applied, in
> order:
>
> 1. An exact match is better than a match involving any implicit
> conversion.
>
> 2. A match involving an implicit conversion from float to double is
> better than a match involving any other implicit conversion.
>
> 3. A match involving an implicit conversion from either int or uint to
> float is better than a match involving an implicit conversion from
> either int or uint to double.
>
> If none of the rules above apply to a particular pair of conversions,
> neither conversion is considered better than the other."
>
> Signed-off-by: Chris Forbes <chr...@ijw.co.nz>
> ---
> src/glsl/ir_function.cpp | 74
> ++++++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 71 insertions(+), 3 deletions(-)
>
> diff --git a/src/glsl/ir_function.cpp b/src/glsl/ir_function.cpp
> index 2b88535..6d2de47 100644
> --- a/src/glsl/ir_function.cpp
> +++ b/src/glsl/ir_function.cpp
> @@ -117,6 +117,73 @@ parameter_lists_match(_mesa_glsl_parse_state *state,
> }
>
>
> +typedef enum {
> + PARAMETER_EXACT_MATCH,
> + PARAMETER_FLOAT_TO_DOUBLE,
> + PARAMETER_INT_TO_FLOAT,
> + PARAMETER_INT_TO_DOUBLE,
> + PARAMETER_OTHER_CONVERSION,
> +} parameter_match_t;
How about a comment noting these are sorted with 'best' match listed first?
> +
> +
> +static parameter_match_t
> +get_parameter_match_type(const ir_variable *param,
> + const ir_rvalue *actual)
> +{
> + const glsl_type *from_type;
> + const glsl_type *to_type;
> +
> + if (param->data.mode == ir_var_function_out) {
> + from_type = param->type;
> + to_type = actual->type;
> + } else {
> + from_type = actual->type;
> + to_type = param->type;
> + }
> +
> + if (from_type == to_type)
> + return PARAMETER_EXACT_MATCH;
> +
> + /* XXX: When ARB_gpu_shader_fp64 support is added, check for
> float->double,
> + * and int/uint->double conversions
> + */
> +
> + if (to_type->base_type == GLSL_TYPE_FLOAT)
> + return PARAMETER_INT_TO_FLOAT;
> +
> + /* int -> uint and any other oddball conversions */
> + return PARAMETER_OTHER_CONVERSION;
> +}
> +
> +
> +static bool
> +is_better_parameter_match(parameter_match_t a_match,
> + parameter_match_t b_match)
> +{
> + /* 1. An exact match is better than a match involving any implicit
> + * conversion.
> + *
> + * 2. A match involving an implicit conversion from float to double
> + * is better than match involving any other implicit conversion.
> + *
> + * 3. A match involving an implicit conversion from either int or uint
> + * to float is better than a match involving an implicit conversion
> + * from either int or uint to double.
> + *
> + * If none of the rules above apply to a particular pair of conversions,
> + * neither conversion is considered better than the other.
Maybe reference the GLSL 4.00 spec location for this text?
-Jordan
> + *
> + * Notably, the int->uint conversion is *not* considered to be better
> + * or worse than int/uint->float or int/uint->double.
> + */
> +
> + if (a_match >= PARAMETER_INT_TO_FLOAT && b_match ==
> PARAMETER_OTHER_CONVERSION)
> + return false;
> +
> + return a_match < b_match;
> +}
> +
> +
> static ir_function_signature *
> choose_best_inexact_overload(_mesa_glsl_parse_state *state,
> const exec_list *actual_parameters,
> @@ -173,9 +240,10 @@ ir_function::matching_signature(_mesa_glsl_parse_state
> *state,
> free(inexact_matches);
> return sig;
> case PARAMETER_LIST_INEXACT_MATCH:
> - inexact_matches = realloc(inexact_matches,
> - sizeof(*inexact_matches) *
> - (num_inexact_matches + 1));
> + inexact_matches = (ir_function_signature **)
> + realloc(inexact_matches,
> + sizeof(*inexact_matches) *
> + (num_inexact_matches + 1));
> assert(inexact_matches);
> inexact_matches[num_inexact_matches++] = sig;
> continue;
> --
> 1.9.2
>
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