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 /**
  89  * \brief Check if two parameter lists match.
  90  *
  91  * \param list_a Parameters of the function definition.
  92  * \param list_b Actual parameters passed to the function.
  93  * \return If an exact match, return 0.
  94  *         If an inexact match requiring implicit conversion, return 1.
  95  *         If not a match, return -1.
  96  * \see matching_signature()
  97  */
  98 static int
  99 parameter_lists_match(const exec_list *list_a, const exec_list *list_b)
 100 {
 101    const exec_node *node_a = list_a->head;
 102    const exec_node *node_b = list_b->head;
 103
 104    /* This is set to true if there is an inexact match requiring an implicit
 105     * conversion. */
 106    bool inexact_match = false;
 107
 108    for (/* empty */
 109         ; !node_a->is_tail_sentinel()
 110         ; node_a = node_a->next, node_b = node_b->next) {
 111       /* If all of the parameters from the other parameter list have been
 112        * exhausted, the lists have different length and, by definition,
 113        * do not match.
 114        */
 115       if (node_b->is_tail_sentinel())
 116          return -1;
 117
 118
 119       const ir_variable *const param = (ir_variable *) node_a;
 120       const ir_instruction *const actual = (ir_instruction *) node_b;
 121
 122       if (param->type == actual->type)
 123          continue;
 124
 125       /* Try to find an implicit conversion from actual to param. */
 126       inexact_match = true;
 127       switch ((enum ir_variable_mode)(param->mode)) {
 128       case ir_var_auto:
 129       case ir_var_uniform:
 130       case ir_var_temporary:
 131          /* These are all error conditions.  It is invalid for a parameter to
 132           * a function to be declared as auto (not in, out, or inout) or
 133           * as uniform.
 134           */
 135          assert(0);
 136          return -1;
 137
 138       case ir_var_const_in:
 139       case ir_var_in:
 140          if (!actual->type->can_implicitly_convert_to(param->type))
 141             return -1;
 142          break;
 143
 144       case ir_var_out:
 145          if (!param->type->can_implicitly_convert_to(actual->type))
 146             return -1;
 147          break;
 148
 149       case ir_var_inout:
 150          /* Since there are no bi-directional automatic conversions (e.g.,
 151           * there is int -> float but no float -> int), inout parameters must
 152           * be exact matches.
 153           */
 154          return -1;
 155
 156       default:
 157          assert(false);
 158          return -1;
 159       }
 160    }
 161
 162    /* If all of the parameters from the other parameter list have been
 163     * exhausted, the lists have different length and, by definition, do not
 164     * match.
 165     */
 166    if (!node_b->is_tail_sentinel())
 167       return -1;
 168
 169    if (inexact_match)
 170       return 1;
 171    else
 172       return 0;
 173 }
 174
 175
 176 ir_function_signature *
 177 ir_function::matching_signature(const exec_list *actual_parameters)
 178 {
 179    ir_function_signature *match = NULL;
 180    bool multiple_inexact_matches = false;
 181
 182    /* From page 42 (page 49 of the PDF) of the GLSL 1.20 spec:
 183     *
 184     * "If an exact match is found, the other signatures are ignored, and
 185     *  the exact match is used.  Otherwise, if no exact match is found, then
 186     *  the implicit conversions in Section 4.1.10 "Implicit Conversions" will
 187     *  be applied to the calling arguments if this can make their types match
 188     *  a signature.  In this case, it is a semantic error if there are
 189     *  multiple ways to apply these conversions to the actual arguments of a
 190     *  call such that the call can be made to match multiple signatures."
 191     */
 192    foreach_iter(exec_list_iterator, iter, signatures) {
 193       ir_function_signature *const sig =
 194          (ir_function_signature *) iter.get();
 195
 196       const int score = parameter_lists_match(& sig->parameters,
 197                                               actual_parameters);
 198
 199       /* If we found an exact match, simply return it */
 200       if (score == 0)
 201          return sig;
 202
 203       if (score > 0) {
 204          if (match == NULL)
 205             match = sig;
 206          else
 207             multiple_inexact_matches = true;
 208       }
 209    }
 210
 211    /* There is no exact match (we would have returned it by now).  If there
 212     * are multiple inexact matches, the call is ambiguous, which is an error.
 213     *
 214     * FINISHME: Report a decent error.  Returning NULL will likely result in
 215     * FINISHME: a "no matching signature" error; it should report that the
 216     * FINISHME: call is ambiguous.  But reporting errors from here is hard.
 217     */
 218    if (multiple_inexact_matches)
 219       return NULL;
 220
 221    return match;
 222 }
 223
 224
 225 static bool
 226 parameter_lists_match_exact(const exec_list *list_a, const exec_list *list_b)
 227 {
 228    const exec_node *node_a = list_a->head;
 229    const exec_node *node_b = list_b->head;
 230
 231    for (/* empty */
 232         ; !node_a->is_tail_sentinel() && !node_b->is_tail_sentinel()
 233         ; node_a = node_a->next, node_b = node_b->next) {
 234       ir_variable *a = (ir_variable *) node_a;
 235       ir_variable *b = (ir_variable *) node_b;
 236
 237       /* If the types of the parameters do not match, the parameters lists
 238        * are different.
 239        */
 240       if (a->type != b->type)
 241          return false;
 242    }
 243
 244    /* Unless both lists are exhausted, they differ in length and, by
 245     * definition, do not match.
 246     */
 247    return (node_a->is_tail_sentinel() == node_b->is_tail_sentinel());
 248 }
 249
 250 ir_function_signature *
 251 ir_function::exact_matching_signature(const exec_list *actual_parameters)
 252 {
 253    foreach_iter(exec_list_iterator, iter, signatures) {
 254       ir_function_signature *const sig =
 255          (ir_function_signature *) iter.get();
 256
 257       if (parameter_lists_match_exact(&sig->parameters, actual_parameters))
 258          return sig;
 259    }
 260    return NULL;
 261 }