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/*

 * Copyright © 2010 Intel Corporation

 *

 * Permission is hereby granted, free of charge, to any person obtaining a

 * copy of this software and associated documentation files (the "Software"),

 * to deal in the Software without restriction, including without limitation

 * the rights to use, copy, modify, merge, publish, distribute, sublicense,

 * and/or sell copies of the Software, and to permit persons to whom the

 * Software is furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice (including the next

 * paragraph) shall be included in all copies or substantial portions of the

 * Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL

 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

 * DEALINGS IN THE SOFTWARE.

 */

#include "glsl_types.h"

#include "ir.h"

typedef enum {

   PARAMETER_LIST_NO_MATCH,

   PARAMETER_LIST_EXACT_MATCH,

   PARAMETER_LIST_INEXACT_MATCH /*< Match requires implicit conversion. */

} parameter_list_match_t;

/**

 * \brief Check if two parameter lists match.

 *

 * \param list_a Parameters of the function definition.

 * \param list_b Actual parameters passed to the function.

 * \see matching_signature()

 */

static parameter_list_match_t

parameter_lists_match(const exec_list *list_a, const exec_list *list_b)

{

   const exec_node *node_a = list_a->head;

   const exec_node *node_b = list_b->head;

   /* This is set to true if there is an inexact match requiring an implicit

    * conversion. */

   bool inexact_match = false;

   for (/* empty */

	; !node_a->is_tail_sentinel()

	; node_a = node_a->next, node_b = node_b->next) {

      /* If all of the parameters from the other parameter list have been

       * exhausted, the lists have different length and, by definition,

       * do not match.

       */

      if (node_b->is_tail_sentinel())

	 return PARAMETER_LIST_NO_MATCH;

      const ir_variable *const param = (ir_variable *) node_a;

      const ir_rvalue *const actual = (ir_rvalue *) node_b;

      if (param->type == actual->type)

	 continue;

      /* Try to find an implicit conversion from actual to param. */

      inexact_match = true;

      switch ((enum ir_variable_mode)(param->mode)) {

      case ir_var_auto:

      case ir_var_uniform:

      case ir_var_temporary:

	 /* These are all error conditions.  It is invalid for a parameter to

	  * a function to be declared as auto (not in, out, or inout) or

	  * as uniform.

	  */

	 assert(0);

	 return PARAMETER_LIST_NO_MATCH;

      case ir_var_const_in:

      case ir_var_function_in:

	 if (!actual->type->can_implicitly_convert_to(param->type))

	    return PARAMETER_LIST_NO_MATCH;

	 break;

      case ir_var_function_out:

	 if (!param->type->can_implicitly_convert_to(actual->type))

	    return PARAMETER_LIST_NO_MATCH;

	 break;

      case ir_var_function_inout:

	 /* Since there are no bi-directional automatic conversions (e.g.,

	  * there is int -> float but no float -> int), inout parameters must

	  * be exact matches.

	  */

	 return PARAMETER_LIST_NO_MATCH;

      default:

	 assert(false);

	 return PARAMETER_LIST_NO_MATCH;

      }

   }

   /* If all of the parameters from the other parameter list have been

    * exhausted, the lists have different length and, by definition, do not

    * match.

    */

   if (!node_b->is_tail_sentinel())

      return PARAMETER_LIST_NO_MATCH;

   if (inexact_match)

      return PARAMETER_LIST_INEXACT_MATCH;

   else

      return PARAMETER_LIST_EXACT_MATCH;

}

ir_function_signature *

ir_function::matching_signature(const exec_list *actual_parameters)

{

   bool is_exact;

   return matching_signature(actual_parameters, &is_exact);

}

ir_function_signature *

ir_function::matching_signature(const exec_list *actual_parameters,

			        bool *is_exact)

{

   ir_function_signature *match = NULL;

   bool multiple_inexact_matches = false;

   /* 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_iter(exec_list_iterator, iter, signatures) {

      ir_function_signature *const sig =

	 (ir_function_signature *) iter.get();

      switch (parameter_lists_match(& sig->parameters, actual_parameters)) {

      case PARAMETER_LIST_EXACT_MATCH:

	 *is_exact = true;

	 return sig;

      case PARAMETER_LIST_INEXACT_MATCH:

	 if (match == NULL)

	    match = sig;

	 else

	    multiple_inexact_matches = true;

	 continue;

      case PARAMETER_LIST_NO_MATCH:

	 continue;

      default:

	 assert(false);

	 return NULL;

      }

   }

   /* There is no exact match (we would have returned it by now).  If there

    * are multiple inexact matches, the call is ambiguous, which is an error.

    *

    * FINISHME: Report a decent error.  Returning NULL will likely result in

    * FINISHME: a "no matching signature" error; it should report that the

    * FINISHME: call is ambiguous.  But reporting errors from here is hard.

    */

   *is_exact = false;

   if (multiple_inexact_matches)

      return NULL;

   return match;

}

static bool

parameter_lists_match_exact(const exec_list *list_a, const exec_list *list_b)

{

   const exec_node *node_a = list_a->head;

   const exec_node *node_b = list_b->head;

   for (/* empty */

	; !node_a->is_tail_sentinel() && !node_b->is_tail_sentinel()

	; node_a = node_a->next, node_b = node_b->next) {

      ir_variable *a = (ir_variable *) node_a;

      ir_variable *b = (ir_variable *) node_b;

      /* If the types of the parameters do not match, the parameters lists

       * are different.

       */

      if (a->type != b->type)

         return false;

   }

   /* Unless both lists are exhausted, they differ in length and, by

    * definition, do not match.

    */

   return (node_a->is_tail_sentinel() == node_b->is_tail_sentinel());

}

ir_function_signature *

ir_function::exact_matching_signature(const exec_list *actual_parameters)

{

   foreach_iter(exec_list_iterator, iter, signatures) {

      ir_function_signature *const sig =

	 (ir_function_signature *) iter.get();

      if (parameter_lists_match_exact(&sig->parameters, actual_parameters))

	 return sig;

   }

   return NULL;

}