+
+static bool
+is_better_parameter_match(parameter_match_t a_match,
+ parameter_match_t b_match)
+{
+ /* From section 6.1 of the GLSL 4.00 spec (and the ARB_gpu_shader5 spec):
+ *
+ * 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.
+ *
+ * [XXX: Not in GLSL 4.0: Only in ARB_gpu_shader5:
+ * 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.
+ *
+ * --
+ *
+ * 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 bool
+is_best_inexact_overload(const exec_list *actual_parameters,
+ ir_function_signature **matches,
+ int num_matches,
+ ir_function_signature *sig)
+{
+ /* From section 6.1 of the GLSL 4.00 spec (and the ARB_gpu_shader5 spec):
+ *
+ * "A function definition A is considered a better
+ * match than function definition B if:
+ *
+ * * for at least one function argument, the conversion for that argument
+ * in A is better than the corresponding conversion in B; and
+ *
+ * * there is no function argument for which the conversion in B is better
+ * than the corresponding conversion in A.
+ *
+ * If a single function definition is considered a better match than every
+ * other matching function definition, it will be used. Otherwise, a
+ * semantic error occurs and the shader will fail to compile."
+ */
+ for (ir_function_signature **other = matches;
+ other < matches + num_matches; other++) {
+ if (*other == sig)
+ continue;
+
+ const exec_node *node_a = sig->parameters.head;
+ const exec_node *node_b = (*other)->parameters.head;
+ const exec_node *node_p = actual_parameters->head;
+
+ bool better_for_some_parameter = false;
+
+ for (/* empty */
+ ; !node_a->is_tail_sentinel()
+ ; node_a = node_a->next,
+ node_b = node_b->next,
+ node_p = node_p->next) {
+ parameter_match_t a_match = get_parameter_match_type(
+ (const ir_variable *)node_a,
+ (const ir_rvalue *)node_p);
+ parameter_match_t b_match = get_parameter_match_type(
+ (const ir_variable *)node_b,
+ (const ir_rvalue *)node_p);
+
+ if (is_better_parameter_match(a_match, b_match))
+ better_for_some_parameter = true;
+
+ if (is_better_parameter_match(b_match, a_match))
+ return false; /* B is better for this parameter */
+ }
+
+ if (!better_for_some_parameter)
+ return false; /* A must be better than B for some parameter */
+
+ }
+
+ return true;
+}
+
+
+static ir_function_signature *
+choose_best_inexact_overload(_mesa_glsl_parse_state *state,
+ const exec_list *actual_parameters,
+ ir_function_signature **matches,
+ int num_matches)
+{
+ if (num_matches == 0)
+ return NULL;
+
+ if (num_matches == 1)
+ return *matches;
+
+ /* Without GLSL 4.0 / ARB_gpu_shader5, there is no overload resolution
+ * among multiple inexact matches. Note that state may be NULL here if
+ * called from the linker; in that case we assume everything supported in
+ * any GLSL version is available. */
+ if (!state || state->is_version(400, 0) || state->ARB_gpu_shader5_enable) {
+ for (ir_function_signature **sig = matches; sig < matches + num_matches; sig++) {
+ if (is_best_inexact_overload(actual_parameters, matches, num_matches, *sig))
+ return *sig;
+ }
+ }
+
+ return NULL; /* no best candidate */
+}
+
+
+ir_function_signature *
+ir_function::matching_signature(_mesa_glsl_parse_state *state,
+ const exec_list *actual_parameters,
+ bool allow_builtins)
+{
+ bool is_exact;
+ return matching_signature(state, actual_parameters, allow_builtins,
+ &is_exact);
+}
+
+ir_function_signature *
+ir_function::matching_signature(_mesa_glsl_parse_state *state,
+ const exec_list *actual_parameters,
+ bool allow_builtins,
+ bool *is_exact)
+{
+ ir_function_signature **inexact_matches = NULL;
+ ir_function_signature *match = NULL;
+ int num_inexact_matches = 0;
+
+ /* From page 42 (page 49 of the PDF) of the GLSL 1.20 spec:
+ *
+ * "If an exact match is found, the other signatures are ignored, and
+ * the exact match is used. Otherwise, if no exact match is found, then
+ * the implicit conversions in Section 4.1.10 "Implicit Conversions" will
+ * be applied to the calling arguments if this can make their types match
+ * a signature. In this case, it is a semantic error if there are
+ * multiple ways to apply these conversions to the actual arguments of a
+ * call such that the call can be made to match multiple signatures."
+ */
+ foreach_in_list(ir_function_signature, sig, &this->signatures) {
+ /* Skip over any built-ins that aren't available in this shader. */
+ if (sig->is_builtin() && (!allow_builtins ||
+ !sig->is_builtin_available(state)))
+ continue;
+
+ switch (parameter_lists_match(state, & sig->parameters, actual_parameters)) {
+ case PARAMETER_LIST_EXACT_MATCH:
+ *is_exact = true;
+ free(inexact_matches);
+ return sig;
+ case PARAMETER_LIST_INEXACT_MATCH:
+ 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;
+ case PARAMETER_LIST_NO_MATCH:
+ continue;
+ default:
+ assert(false);
+ return NULL;