src/glsl/ast_array_index.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 "ast.h"
  25 #include "glsl_types.h"
  26 #include "ir.h"
  27
  28 void
  29 ast_array_specifier::print(void) const
  30 {
  31    if (this->is_unsized_array) {
  32       printf("[ ] ");
  33    }
  34
  35    foreach_list_typed (ast_node, array_dimension, link, &this->array_dimensions) {
  36       printf("[ ");
  37       array_dimension->print();
  38       printf("] ");
  39    }
  40 }
  41
  42 /**
  43  * If \c ir is a reference to an array for which we are tracking the max array
  44  * element accessed, track that the given element has been accessed.
  45  * Otherwise do nothing.
  46  *
  47  * This function also checks whether the array is a built-in array whose
  48  * maximum size is too small to accommodate the given index, and if so uses
  49  * loc and state to report the error.
  50  */
  51 static void
  52 update_max_array_access(ir_rvalue *ir, unsigned idx, YYLTYPE *loc,
  53                         struct _mesa_glsl_parse_state *state)
  54 {
  55    if (ir_dereference_variable *deref_var = ir->as_dereference_variable()) {
  56       ir_variable *var = deref_var->var;
  57       if (idx > var->data.max_array_access) {
  58          var->data.max_array_access = idx;
  59
  60          /* Check whether this access will, as a side effect, implicitly cause
  61           * the size of a built-in array to be too large.
  62           */
  63          check_builtin_array_max_size(var->name, idx+1, *loc, state);
  64       }
  65    } else if (ir_dereference_record *deref_record =
  66               ir->as_dereference_record()) {
  67       /* There are two possibilities we need to consider:
  68        *
  69        * - Accessing an element of an array that is a member of a named
  70        *   interface block (e.g. ifc.foo[i])
  71        *
  72        * - Accessing an element of an array that is a member of a named
  73        *   interface block array (e.g. ifc[j].foo[i]).
  74        */
  75       ir_dereference_variable *deref_var =
  76          deref_record->record->as_dereference_variable();
  77       if (deref_var == NULL) {
  78          if (ir_dereference_array *deref_array =
  79              deref_record->record->as_dereference_array()) {
  80             deref_var = deref_array->array->as_dereference_variable();
  81          }
  82       }
  83
  84       if (deref_var != NULL) {
  85          if (deref_var->var->is_interface_instance()) {
  86             const glsl_type *interface_type =
  87                deref_var->var->get_interface_type();
  88             unsigned field_index =
  89                deref_record->record->type->field_index(deref_record->field);
  90             assert(field_index < interface_type->length);
  91             if (idx > deref_var->var->max_ifc_array_access[field_index]) {
  92                deref_var->var->max_ifc_array_access[field_index] = idx;
  93
  94                /* Check whether this access will, as a side effect, implicitly
  95                 * cause the size of a built-in array to be too large.
  96                 */
  97                check_builtin_array_max_size(deref_record->field, idx+1, *loc,
  98                                             state);
  99             }
 100          }
 101       }
 102    }
 103 }
 104
 105
 106 ir_rvalue *
 107 _mesa_ast_array_index_to_hir(void *mem_ctx,
 108                              struct _mesa_glsl_parse_state *state,
 109                              ir_rvalue *array, ir_rvalue *idx,
 110                              YYLTYPE &loc, YYLTYPE &idx_loc)
 111 {
 112    if (!array->type->is_error()
 113        && !array->type->is_array()
 114        && !array->type->is_matrix()
 115        && !array->type->is_vector()) {
 116       _mesa_glsl_error(& idx_loc, state,
 117                        "cannot dereference non-array / non-matrix / "
 118                        "non-vector");
 119    }
 120
 121    if (!idx->type->is_error()) {
 122       if (!idx->type->is_integer()) {
 123          _mesa_glsl_error(& idx_loc, state, "array index must be integer type");
 124       } else if (!idx->type->is_scalar()) {
 125          _mesa_glsl_error(& idx_loc, state, "array index must be scalar");
 126       }
 127    }
 128
 129    /* If the array index is a constant expression and the array has a
 130     * declared size, ensure that the access is in-bounds.  If the array
 131     * index is not a constant expression, ensure that the array has a
 132     * declared size.
 133     */
 134    ir_constant *const const_index = idx->constant_expression_value();
 135    if (const_index != NULL && idx->type->is_integer()) {
 136       const int idx = const_index->value.i[0];
 137       const char *type_name = "error";
 138       unsigned bound = 0;
 139
 140       /* From page 24 (page 30 of the PDF) of the GLSL 1.50 spec:
 141        *
 142        *    "It is illegal to declare an array with a size, and then
 143        *    later (in the same shader) index the same array with an
 144        *    integral constant expression greater than or equal to the
 145        *    declared size. It is also illegal to index an array with a
 146        *    negative constant expression."
 147        */
 148       if (array->type->is_matrix()) {
 149          if (array->type->row_type()->vector_elements <= idx) {
 150             type_name = "matrix";
 151             bound = array->type->row_type()->vector_elements;
 152          }
 153       } else if (array->type->is_vector()) {
 154          if (array->type->vector_elements <= idx) {
 155             type_name = "vector";
 156             bound = array->type->vector_elements;
 157          }
 158       } else {
 159          /* glsl_type::array_size() returns -1 for non-array types.  This means
 160           * that we don't need to verify that the type is an array before
 161           * doing the bounds checking.
 162           */
 163          if ((array->type->array_size() > 0)
 164              && (array->type->array_size() <= idx)) {
 165             type_name = "array";
 166             bound = array->type->array_size();
 167          }
 168       }
 169
 170       if (bound > 0) {
 171          _mesa_glsl_error(& loc, state, "%s index must be < %u",
 172                           type_name, bound);
 173       } else if (idx < 0) {
 174          _mesa_glsl_error(& loc, state, "%s index must be >= 0",
 175                           type_name);
 176       }
 177
 178       if (array->type->is_array())
 179          update_max_array_access(array, idx, &loc, state);
 180    } else if (const_index == NULL && array->type->is_array()) {
 181       if (array->type->is_unsized_array()) {
 182          _mesa_glsl_error(&loc, state, "unsized array index must be constant");
 183       } else if (array->type->fields.array->is_interface()
 184                  && array->variable_referenced()->data.mode == ir_var_uniform) {
 185          /* Page 46 in section 4.3.7 of the OpenGL ES 3.00 spec says:
 186           *
 187           *     "All indexes used to index a uniform block array must be
 188           *     constant integral expressions."
 189           */
 190          _mesa_glsl_error(&loc, state,
 191                           "uniform block array index must be constant");
 192       } else {
 193          /* whole_variable_referenced can return NULL if the array is a
 194           * member of a structure.  In this case it is safe to not update
 195           * the max_array_access field because it is never used for fields
 196           * of structures.
 197           */
 198          ir_variable *v = array->whole_variable_referenced();
 199          if (v != NULL)
 200             v->data.max_array_access = array->type->array_size() - 1;
 201       }
 202
 203       /* From page 23 (29 of the PDF) of the GLSL 1.30 spec:
 204        *
 205        *    "Samplers aggregated into arrays within a shader (using square
 206        *    brackets [ ]) can only be indexed with integral constant
 207        *    expressions [...]."
 208        *
 209        * This restriction was added in GLSL 1.30.  Shaders using earlier
 210        * version of the language should not be rejected by the compiler
 211        * front-end for using this construct.  This allows useful things such
 212        * as using a loop counter as the index to an array of samplers.  If the
 213        * loop in unrolled, the code should compile correctly.  Instead, emit a
 214        * warning.
 215        */
 216       if (array->type->element_type()->is_sampler()) {
 217          if (!state->is_version(130, 100)) {
 218             if (state->es_shader) {
 219                _mesa_glsl_warning(&loc, state,
 220                                   "sampler arrays indexed with non-constant "
 221                                   "expressions is optional in %s",
 222                                   state->get_version_string());
 223             } else {
 224                _mesa_glsl_warning(&loc, state,
 225                                   "sampler arrays indexed with non-constant "
 226                                   "expressions will be forbidden in GLSL 1.30 "
 227                                   "and later");
 228             }
 229          } else {
 230             _mesa_glsl_error(&loc, state,
 231                              "sampler arrays indexed with non-constant "
 232                              "expressions is forbidden in GLSL 1.30 and "
 233                              "later");
 234          }
 235       }
 236    }
 237
 238    /* After performing all of the error checking, generate the IR for the
 239     * expression.
 240     */
 241    if (array->type->is_array()
 242        || array->type->is_matrix()) {
 243       return new(mem_ctx) ir_dereference_array(array, idx);
 244    } else if (array->type->is_vector()) {
 245       return new(mem_ctx) ir_expression(ir_binop_vector_extract, array, idx);
 246    } else if (array->type->is_error()) {
 247       return array;
 248    } else {
 249       ir_rvalue *result = new(mem_ctx) ir_dereference_array(array, idx);
 250       result->type = glsl_type::error_type;
 251
 252       return result;
 253    }
 254 }