workbench/libs/mesa/src/glsl/ir_function.cpp

   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
  27 int
  28 type_compare(const glsl_type *a, const glsl_type *b)
  29 {
  30    /* If the types are the same, they trivially match.
  31     */
  32    if (a == b)
  33       return 0;
  34
  35    switch (a->base_type) {
  36    case GLSL_TYPE_UINT:
  37    case GLSL_TYPE_INT:
  38    case GLSL_TYPE_BOOL:
  39       /* There is no implicit conversion to or from integer types or bool.
  40        */
  41       if ((a->is_integer() != b->is_integer())
  42           || (a->is_boolean() != b->is_boolean()))
  43          return -1;
  44
  45       /* FALLTHROUGH */
  46
  47    case GLSL_TYPE_FLOAT:
  48       if ((a->vector_elements != b->vector_elements)
  49           || (a->matrix_columns != b->matrix_columns))
  50          return -1;
  51
  52       return 1;
  53
  54    case GLSL_TYPE_SAMPLER:
  55    case GLSL_TYPE_STRUCT:
  56       /* Samplers and structures must match exactly.
  57        */
  58       return -1;
  59
  60    case GLSL_TYPE_ARRAY:
  61       if ((b->base_type != GLSL_TYPE_ARRAY)
  62           || (a->length != b->length))
  63          return -1;
  64
  65       /* From GLSL 1.50 spec, page 27 (page 33 of the PDF):
  66        *    "There are no implicit array or structure conversions."
  67        *
  68        * If the comparison of the array element types detects that a conversion
  69        * would be required, the array types do not match.
  70        */
  71       return (type_compare(a->fields.array, b->fields.array) == 0) ? 0 : -1;
  72
  73    case GLSL_TYPE_VOID:
  74    case GLSL_TYPE_ERROR:
  75    default:
  76       /* These are all error conditions.  It is invalid for a parameter to
  77        * a function to be declared as error, void, or a function.
  78        */
  79       return -1;
  80    }
  81
  82    /* This point should be unreachable.
  83     */
  84    assert(0);
  85 }
  86
  87
  88 static int
  89 parameter_lists_match(const exec_list *list_a, const exec_list *list_b)
  90 {
  91    const exec_node *node_a = list_a->head;
  92    const exec_node *node_b = list_b->head;
  93    int total_score = 0;
  94
  95    for (/* empty */
  96         ; !node_a->is_tail_sentinel()
  97         ; node_a = node_a->next, node_b = node_b->next) {
  98       /* If all of the parameters from the other parameter list have been
  99        * exhausted, the lists have different length and, by definition,
 100        * do not match.
 101        */
 102       if (node_b->is_tail_sentinel())
 103          return -1;
 104
 105
 106       const ir_variable *const param = (ir_variable *) node_a;
 107       const ir_instruction *const actual = (ir_instruction *) node_b;
 108
 109       /* Determine whether or not the types match.  If the types are an
 110        * exact match, the match score is zero.  If the types don't match
 111        * but the actual parameter can be coerced to the type of the declared
 112        * parameter, the match score is one.
 113        */
 114       int score = -1;
 115       switch ((enum ir_variable_mode)(param->mode)) {
 116       case ir_var_auto:
 117       case ir_var_uniform:
 118       case ir_var_temporary:
 119          /* These are all error conditions.  It is invalid for a parameter to
 120           * a function to be declared as auto (not in, out, or inout) or
 121           * as uniform.
 122           */
 123          assert(0);
 124          return -1;
 125
 126       case ir_var_const_in:
 127       case ir_var_in:
 128          score = type_compare(param->type, actual->type);
 129          break;
 130
 131       case ir_var_out:
 132          score = type_compare(actual->type, param->type);
 133          break;
 134
 135       case ir_var_inout:
 136          /* Since there are no bi-directional automatic conversions (e.g.,
 137           * there is int -> float but no float -> int), inout parameters must
 138           * be exact matches.
 139           */
 140          score = (type_compare(actual->type, param->type) == 0) ? 0 : -1;
 141          break;
 142
 143       default:
 144          assert(false);
 145       }
 146
 147       if (score < 0)
 148          return -1;
 149
 150       total_score += score;
 151    }
 152
 153    /* If all of the parameters from the other parameter list have been
 154     * exhausted, the lists have different length and, by definition, do not
 155     * match.
 156     */
 157    if (!node_b->is_tail_sentinel())
 158       return -1;
 159
 160    return total_score;
 161 }
 162
 163
 164 ir_function_signature *
 165 ir_function::matching_signature(const exec_list *actual_parameters)
 166 {
 167    ir_function_signature *match = NULL;
 168    bool multiple_inexact_matches = false;
 169
 170    /* From page 42 (page 49 of the PDF) of the GLSL 1.20 spec:
 171     *
 172     * "If an exact match is found, the other signatures are ignored, and
 173     *  the exact match is used.  Otherwise, if no exact match is found, then
 174     *  the implicit conversions in Section 4.1.10 "Implicit Conversions" will
 175     *  be applied to the calling arguments if this can make their types match
 176     *  a signature.  In this case, it is a semantic error if there are
 177     *  multiple ways to apply these conversions to the actual arguments of a
 178     *  call such that the call can be made to match multiple signatures."
 179     */
 180    foreach_iter(exec_list_iterator, iter, signatures) {
 181       ir_function_signature *const sig =
 182          (ir_function_signature *) iter.get();
 183
 184       const int score = parameter_lists_match(& sig->parameters,
 185                                               actual_parameters);
 186
 187       /* If we found an exact match, simply return it */
 188       if (score == 0)
 189          return sig;
 190
 191       if (score > 0) {
 192          if (match == NULL)
 193             match = sig;
 194          else
 195             multiple_inexact_matches = true;
 196       }
 197    }
 198
 199    /* There is no exact match (we would have returned it by now).  If there
 200     * are multiple inexact matches, the call is ambiguous, which is an error.
 201     *
 202     * FINISHME: Report a decent error.  Returning NULL will likely result in
 203     * FINISHME: a "no matching signature" error; it should report that the
 204     * FINISHME: call is ambiguous.  But reporting errors from here is hard.
 205     */
 206    if (multiple_inexact_matches)
 207       return NULL;
 208
 209    return match;
 210 }
 211
 212
 213 static bool
 214 parameter_lists_match_exact(const exec_list *list_a, const exec_list *list_b)
 215 {
 216    const exec_node *node_a = list_a->head;
 217    const exec_node *node_b = list_b->head;
 218
 219    for (/* empty */
 220         ; !node_a->is_tail_sentinel() && !node_b->is_tail_sentinel()
 221         ; node_a = node_a->next, node_b = node_b->next) {
 222       ir_variable *a = (ir_variable *) node_a;
 223       ir_variable *b = (ir_variable *) node_b;
 224
 225       /* If the types of the parameters do not match, the parameters lists
 226        * are different.
 227        */
 228       if (a->type != b->type)
 229          return false;
 230    }
 231
 232    /* Unless both lists are exhausted, they differ in length and, by
 233     * definition, do not match.
 234     */
 235    return (node_a->is_tail_sentinel() == node_b->is_tail_sentinel());
 236 }
 237
 238 ir_function_signature *
 239 ir_function::exact_matching_signature(const exec_list *actual_parameters)
 240 {
 241    foreach_iter(exec_list_iterator, iter, signatures) {
 242       ir_function_signature *const sig =
 243          (ir_function_signature *) iter.get();
 244
 245       if (parameter_lists_match_exact(&sig->parameters, actual_parameters))
 246          return sig;
 247    }
 248    return NULL;
 249 }