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, int 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 > (int)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
  92             unsigned *const max_ifc_array_access =
  93                deref_var->var->get_max_ifc_array_access();
  94
  95             assert(max_ifc_array_access != NULL);
  96
  97             if (idx > (int)max_ifc_array_access[field_index]) {
  98                max_ifc_array_access[field_index] = idx;
  99
 100                /* Check whether this access will, as a side effect, implicitly
 101                 * cause the size of a built-in array to be too large.
 102                 */
 103                check_builtin_array_max_size(deref_record->field, idx+1, *loc,
 104                                             state);
 105             }
 106          }
 107       }
 108    }
 109 }
 110
 111
 112 ir_rvalue *
 113 _mesa_ast_array_index_to_hir(void *mem_ctx,
 114                              struct _mesa_glsl_parse_state *state,
 115                              ir_rvalue *array, ir_rvalue *idx,
 116                              YYLTYPE &loc, YYLTYPE &idx_loc)
 117 {
 118    if (!array->type->is_error()
 119        && !array->type->is_array()
 120        && !array->type->is_matrix()
 121        && !array->type->is_vector()) {
 122       _mesa_glsl_error(& idx_loc, state,
 123                        "cannot dereference non-array / non-matrix / "
 124                        "non-vector");
 125    }
 126
 127    if (!idx->type->is_error()) {
 128       if (!idx->type->is_integer()) {
 129          _mesa_glsl_error(& idx_loc, state, "array index must be integer type");
 130       } else if (!idx->type->is_scalar()) {
 131          _mesa_glsl_error(& idx_loc, state, "array index must be scalar");
 132       }
 133    }
 134
 135    /* If the array index is a constant expression and the array has a
 136     * declared size, ensure that the access is in-bounds.  If the array
 137     * index is not a constant expression, ensure that the array has a
 138     * declared size.
 139     */
 140    ir_constant *const const_index = idx->constant_expression_value();
 141    if (const_index != NULL && idx->type->is_integer()) {
 142       const int idx = const_index->value.i[0];
 143       const char *type_name = "error";
 144       unsigned bound = 0;
 145
 146       /* From page 24 (page 30 of the PDF) of the GLSL 1.50 spec:
 147        *
 148        *    "It is illegal to declare an array with a size, and then
 149        *    later (in the same shader) index the same array with an
 150        *    integral constant expression greater than or equal to the
 151        *    declared size. It is also illegal to index an array with a
 152        *    negative constant expression."
 153        */
 154       if (array->type->is_matrix()) {
 155          if (array->type->row_type()->vector_elements <= idx) {
 156             type_name = "matrix";
 157             bound = array->type->row_type()->vector_elements;
 158          }
 159       } else if (array->type->is_vector()) {
 160          if (array->type->vector_elements <= idx) {
 161             type_name = "vector";
 162             bound = array->type->vector_elements;
 163          }
 164       } else {
 165          /* glsl_type::array_size() returns -1 for non-array types.  This means
 166           * that we don't need to verify that the type is an array before
 167           * doing the bounds checking.
 168           */
 169          if ((array->type->array_size() > 0)
 170              && (array->type->array_size() <= idx)) {
 171             type_name = "array";
 172             bound = array->type->array_size();
 173          }
 174       }
 175
 176       if (bound > 0) {
 177          _mesa_glsl_error(& loc, state, "%s index must be < %u",
 178                           type_name, bound);
 179       } else if (idx < 0) {
 180          _mesa_glsl_error(& loc, state, "%s index must be >= 0",
 181                           type_name);
 182       }
 183
 184       if (array->type->is_array())
 185          update_max_array_access(array, idx, &loc, state);
 186    } else if (const_index == NULL && array->type->is_array()) {
 187       if (array->type->is_unsized_array()) {
 188          _mesa_glsl_error(&loc, state, "unsized array index must be constant");
 189       } else if (array->type->fields.array->is_interface()
 190                  && array->variable_referenced()->data.mode == ir_var_uniform
 191                  && !state->is_version(400, 0) && !state->ARB_gpu_shader5_enable) {
 192          /* Page 46 in section 4.3.7 of the OpenGL ES 3.00 spec says:
 193           *
 194           *     "All indexes used to index a uniform block array must be
 195           *     constant integral expressions."
 196           */
 197          _mesa_glsl_error(&loc, state,
 198                           "uniform block array index must be constant");
 199       } else {
 200          /* whole_variable_referenced can return NULL if the array is a
 201           * member of a structure.  In this case it is safe to not update
 202           * the max_array_access field because it is never used for fields
 203           * of structures.
 204           */
 205          ir_variable *v = array->whole_variable_referenced();
 206          if (v != NULL)
 207             v->data.max_array_access = array->type->array_size() - 1;
 208       }
 209
 210       /* From page 23 (29 of the PDF) of the GLSL 1.30 spec:
 211        *
 212        *    "Samplers aggregated into arrays within a shader (using square
 213        *    brackets [ ]) can only be indexed with integral constant
 214        *    expressions [...]."
 215        *
 216        * This restriction was added in GLSL 1.30.  Shaders using earlier
 217        * version of the language should not be rejected by the compiler
 218        * front-end for using this construct.  This allows useful things such
 219        * as using a loop counter as the index to an array of samplers.  If the
 220        * loop in unrolled, the code should compile correctly.  Instead, emit a
 221        * warning.
 222        *
 223        * In GLSL 4.00 / ARB_gpu_shader5, this requirement is relaxed again to allow
 224        * indexing with dynamically uniform expressions. Note that these are not
 225        * required to be uniforms or expressions based on them, but merely that the
 226        * values must not diverge between shader invocations run together. If the
 227        * values *do* diverge, then the behavior of the operation requiring a
 228        * dynamically uniform expression is undefined.
 229        */
 230       if (array->type->element_type()->is_sampler()) {
 231          if (!state->is_version(130, 100)) {
 232             if (state->es_shader) {
 233                _mesa_glsl_warning(&loc, state,
 234                                   "sampler arrays indexed with non-constant "
 235                                   "expressions is optional in %s",
 236                                   state->get_version_string());
 237             } else {
 238                _mesa_glsl_warning(&loc, state,
 239                                   "sampler arrays indexed with non-constant "
 240                                   "expressions will be forbidden in GLSL 1.30 "
 241                                   "and later");
 242             }
 243          } else if (!state->is_version(400, 0) && !state->ARB_gpu_shader5_enable) {
 244             _mesa_glsl_error(&loc, state,
 245                              "sampler arrays indexed with non-constant "
 246                              "expressions is forbidden in GLSL 1.30 and "
 247                              "later");
 248          }
 249       }
 250    }
 251
 252    /* After performing all of the error checking, generate the IR for the
 253     * expression.
 254     */
 255    if (array->type->is_array()
 256        || array->type->is_matrix()) {
 257       return new(mem_ctx) ir_dereference_array(array, idx);
 258    } else if (array->type->is_vector()) {
 259       return new(mem_ctx) ir_expression(ir_binop_vector_extract, array, idx);
 260    } else if (array->type->is_error()) {
 261       return array;
 262    } else {
 263       ir_rvalue *result = new(mem_ctx) ir_dereference_array(array, idx);
 264       result->type = glsl_type::error_type;
 265
 266       return result;
 267    }
 268 }