1/*
2 * Copyright © 2010 Intel Corporation
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
21 * DEALINGS IN THE SOFTWARE.
22 */
23
24#include "glsl_types.h"
25#include "ir.h"
26
27typedef enum {
28   PARAMETER_LIST_NO_MATCH,
29   PARAMETER_LIST_EXACT_MATCH,
30   PARAMETER_LIST_INEXACT_MATCH /*< Match requires implicit conversion. */
31} parameter_list_match_t;
32
33/**
34 * \brief Check if two parameter lists match.
35 *
36 * \param list_a Parameters of the function definition.
37 * \param list_b Actual parameters passed to the function.
38 * \see matching_signature()
39 */
40static parameter_list_match_t
41parameter_lists_match(const exec_list *list_a, const exec_list *list_b)
42{
43   const exec_node *node_a = list_a->head;
44   const exec_node *node_b = list_b->head;
45
46   /* This is set to true if there is an inexact match requiring an implicit
47    * conversion. */
48   bool inexact_match = false;
49
50   for (/* empty */
51	; !node_a->is_tail_sentinel()
52	; node_a = node_a->next, node_b = node_b->next) {
53      /* If all of the parameters from the other parameter list have been
54       * exhausted, the lists have different length and, by definition,
55       * do not match.
56       */
57      if (node_b->is_tail_sentinel())
58	 return PARAMETER_LIST_NO_MATCH;
59
60
61      const ir_variable *const param = (ir_variable *) node_a;
62      const ir_rvalue *const actual = (ir_rvalue *) node_b;
63
64      if (param->type == actual->type)
65	 continue;
66
67      /* Try to find an implicit conversion from actual to param. */
68      inexact_match = true;
69      switch ((enum ir_variable_mode)(param->mode)) {
70      case ir_var_auto:
71      case ir_var_uniform:
72      case ir_var_temporary:
73	 /* These are all error conditions.  It is invalid for a parameter to
74	  * a function to be declared as auto (not in, out, or inout) or
75	  * as uniform.
76	  */
77	 assert(0);
78	 return PARAMETER_LIST_NO_MATCH;
79
80      case ir_var_const_in:
81      case ir_var_in:
82	 if (!actual->type->can_implicitly_convert_to(param->type))
83	    return PARAMETER_LIST_NO_MATCH;
84	 break;
85
86      case ir_var_out:
87	 if (!param->type->can_implicitly_convert_to(actual->type))
88	    return PARAMETER_LIST_NO_MATCH;
89	 break;
90
91      case ir_var_inout:
92	 /* Since there are no bi-directional automatic conversions (e.g.,
93	  * there is int -> float but no float -> int), inout parameters must
94	  * be exact matches.
95	  */
96	 return PARAMETER_LIST_NO_MATCH;
97
98      default:
99	 assert(false);
100	 return PARAMETER_LIST_NO_MATCH;
101      }
102   }
103
104   /* If all of the parameters from the other parameter list have been
105    * exhausted, the lists have different length and, by definition, do not
106    * match.
107    */
108   if (!node_b->is_tail_sentinel())
109      return PARAMETER_LIST_NO_MATCH;
110
111   if (inexact_match)
112      return PARAMETER_LIST_INEXACT_MATCH;
113   else
114      return PARAMETER_LIST_EXACT_MATCH;
115}
116
117
118ir_function_signature *
119ir_function::matching_signature(const exec_list *actual_parameters)
120{
121   bool is_exact;
122   return matching_signature(actual_parameters, &is_exact);
123}
124
125ir_function_signature *
126ir_function::matching_signature(const exec_list *actual_parameters,
127			        bool *is_exact)
128{
129   ir_function_signature *match = NULL;
130   bool multiple_inexact_matches = false;
131
132   /* From page 42 (page 49 of the PDF) of the GLSL 1.20 spec:
133    *
134    * "If an exact match is found, the other signatures are ignored, and
135    *  the exact match is used.  Otherwise, if no exact match is found, then
136    *  the implicit conversions in Section 4.1.10 "Implicit Conversions" will
137    *  be applied to the calling arguments if this can make their types match
138    *  a signature.  In this case, it is a semantic error if there are
139    *  multiple ways to apply these conversions to the actual arguments of a
140    *  call such that the call can be made to match multiple signatures."
141    */
142   foreach_iter(exec_list_iterator, iter, signatures) {
143      ir_function_signature *const sig =
144	 (ir_function_signature *) iter.get();
145
146      switch (parameter_lists_match(& sig->parameters, actual_parameters)) {
147      case PARAMETER_LIST_EXACT_MATCH:
148	 *is_exact = true;
149	 return sig;
150      case PARAMETER_LIST_INEXACT_MATCH:
151	 if (match == NULL)
152	    match = sig;
153	 else
154	    multiple_inexact_matches = true;
155	 continue;
156      case PARAMETER_LIST_NO_MATCH:
157	 continue;
158      default:
159	 assert(false);
160	 return NULL;
161      }
162   }
163
164   /* There is no exact match (we would have returned it by now).  If there
165    * are multiple inexact matches, the call is ambiguous, which is an error.
166    *
167    * FINISHME: Report a decent error.  Returning NULL will likely result in
168    * FINISHME: a "no matching signature" error; it should report that the
169    * FINISHME: call is ambiguous.  But reporting errors from here is hard.
170    */
171   *is_exact = false;
172
173   if (multiple_inexact_matches)
174      return NULL;
175
176   return match;
177}
178
179
180static bool
181parameter_lists_match_exact(const exec_list *list_a, const exec_list *list_b)
182{
183   const exec_node *node_a = list_a->head;
184   const exec_node *node_b = list_b->head;
185
186   for (/* empty */
187	; !node_a->is_tail_sentinel() && !node_b->is_tail_sentinel()
188	; node_a = node_a->next, node_b = node_b->next) {
189      ir_variable *a = (ir_variable *) node_a;
190      ir_variable *b = (ir_variable *) node_b;
191
192      /* If the types of the parameters do not match, the parameters lists
193       * are different.
194       */
195      if (a->type != b->type)
196         return false;
197   }
198
199   /* Unless both lists are exhausted, they differ in length and, by
200    * definition, do not match.
201    */
202   return (node_a->is_tail_sentinel() == node_b->is_tail_sentinel());
203}
204
205ir_function_signature *
206ir_function::exact_matching_signature(const exec_list *actual_parameters)
207{
208   foreach_iter(exec_list_iterator, iter, signatures) {
209      ir_function_signature *const sig =
210	 (ir_function_signature *) iter.get();
211
212      if (parameter_lists_match_exact(&sig->parameters, actual_parameters))
213	 return sig;
214   }
215   return NULL;
216}
217