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             unsigned field_index =
  87                deref_record->record->type->field_index(deref_record->field);
  88             assert(field_index < deref_var->var->get_interface_type()->length);
  89
  90             unsigned *const max_ifc_array_access =
  91                deref_var->var->get_max_ifc_array_access();
  92
  93             assert(max_ifc_array_access != NULL);
  94
  95             if (idx > (int)max_ifc_array_access[field_index]) {
  96                max_ifc_array_access[field_index] = idx;
  97
  98                /* Check whether this access will, as a side effect, implicitly
  99                 * cause the size of a built-in array to be too large.
 100                 */
 101                check_builtin_array_max_size(deref_record->field, idx+1, *loc,
 102                                             state);
 103             }
 104          }
 105       }
 106    }
 107 }
 108
 109
 110 static int
 111 get_implicit_array_size(struct _mesa_glsl_parse_state *state,
 112                         ir_rvalue *array)
 113 {
 114    ir_variable *var = array->variable_referenced();
 115
 116    /* Inputs in control shader are implicitly sized
 117     * to the maximum patch size.
 118     */
 119    if (state->stage == MESA_SHADER_TESS_CTRL &&
 120        var->data.mode == ir_var_shader_in) {
 121       return state->Const.MaxPatchVertices;
 122    }
 123
 124    /* Non-patch inputs in evaluation shader are implicitly sized
 125     * to the maximum patch size.
 126     */
 127    if (state->stage == MESA_SHADER_TESS_EVAL &&
 128        var->data.mode == ir_var_shader_in &&
 129        !var->data.patch) {
 130       return state->Const.MaxPatchVertices;
 131    }
 132
 133    return 0;
 134 }
 135
 136
 137 ir_rvalue *
 138 _mesa_ast_array_index_to_hir(void *mem_ctx,
 139                              struct _mesa_glsl_parse_state *state,
 140                              ir_rvalue *array, ir_rvalue *idx,
 141                              YYLTYPE &loc, YYLTYPE &idx_loc)
 142 {
 143    if (!array->type->is_error()
 144        && !array->type->is_array()
 145        && !array->type->is_matrix()
 146        && !array->type->is_vector()) {
 147       _mesa_glsl_error(& idx_loc, state,
 148                        "cannot dereference non-array / non-matrix / "
 149                        "non-vector");
 150    }
 151
 152    if (!idx->type->is_error()) {
 153       if (!idx->type->is_integer()) {
 154          _mesa_glsl_error(& idx_loc, state, "array index must be integer type");
 155       } else if (!idx->type->is_scalar()) {
 156          _mesa_glsl_error(& idx_loc, state, "array index must be scalar");
 157       }
 158    }
 159
 160    /* If the array index is a constant expression and the array has a
 161     * declared size, ensure that the access is in-bounds.  If the array
 162     * index is not a constant expression, ensure that the array has a
 163     * declared size.
 164     */
 165    ir_constant *const const_index = idx->constant_expression_value();
 166    if (const_index != NULL && idx->type->is_integer()) {
 167       const int idx = const_index->value.i[0];
 168       const char *type_name = "error";
 169       unsigned bound = 0;
 170
 171       /* From page 24 (page 30 of the PDF) of the GLSL 1.50 spec:
 172        *
 173        *    "It is illegal to declare an array with a size, and then
 174        *    later (in the same shader) index the same array with an
 175        *    integral constant expression greater than or equal to the
 176        *    declared size. It is also illegal to index an array with a
 177        *    negative constant expression."
 178        */
 179       if (array->type->is_matrix()) {
 180          if (array->type->row_type()->vector_elements <= idx) {
 181             type_name = "matrix";
 182             bound = array->type->row_type()->vector_elements;
 183          }
 184       } else if (array->type->is_vector()) {
 185          if (array->type->vector_elements <= idx) {
 186             type_name = "vector";
 187             bound = array->type->vector_elements;
 188          }
 189       } else {
 190          /* glsl_type::array_size() returns -1 for non-array types.  This means
 191           * that we don't need to verify that the type is an array before
 192           * doing the bounds checking.
 193           */
 194          if ((array->type->array_size() > 0)
 195              && (array->type->array_size() <= idx)) {
 196             type_name = "array";
 197             bound = array->type->array_size();
 198          }
 199       }
 200
 201       if (bound > 0) {
 202          _mesa_glsl_error(& loc, state, "%s index must be < %u",
 203                           type_name, bound);
 204       } else if (idx < 0) {
 205          _mesa_glsl_error(& loc, state, "%s index must be >= 0",
 206                           type_name);
 207       }
 208
 209       if (array->type->is_array())
 210          update_max_array_access(array, idx, &loc, state);
 211    } else if (const_index == NULL && array->type->is_array()) {
 212       if (array->type->is_unsized_array()) {
 213          int implicit_size = get_implicit_array_size(state, array);
 214          if (implicit_size) {
 215             ir_variable *v = array->whole_variable_referenced();
 216             if (v != NULL)
 217                v->data.max_array_access = implicit_size - 1;
 218          }
 219          else if (state->stage == MESA_SHADER_TESS_CTRL &&
 220                   array->variable_referenced()->data.mode == ir_var_shader_out &&
 221                   !array->variable_referenced()->data.patch) {
 222             /* Tessellation control shader output non-patch arrays are
 223              * initially unsized. Despite that, they are allowed to be
 224              * indexed with a non-constant expression (typically
 225              * "gl_InvocationID"). The array size will be determined
 226              * by the linker.
 227              */
 228          }
 229          else {
 230             _mesa_glsl_error(&loc, state, "unsized array index must be constant");
 231          }
 232       } else if (array->type->fields.array->is_interface()
 233                  && array->variable_referenced()->data.mode == ir_var_uniform
 234                  && !state->is_version(400, 0) && !state->ARB_gpu_shader5_enable) {
 235          /* Page 46 in section 4.3.7 of the OpenGL ES 3.00 spec says:
 236           *
 237           *     "All indexes used to index a uniform block array must be
 238           *     constant integral expressions."
 239           */
 240          _mesa_glsl_error(&loc, state,
 241                           "uniform block array index must be constant");
 242       } else {
 243          /* whole_variable_referenced can return NULL if the array is a
 244           * member of a structure.  In this case it is safe to not update
 245           * the max_array_access field because it is never used for fields
 246           * of structures.
 247           */
 248          ir_variable *v = array->whole_variable_referenced();
 249          if (v != NULL)
 250             v->data.max_array_access = array->type->array_size() - 1;
 251       }
 252
 253       /* From page 23 (29 of the PDF) of the GLSL 1.30 spec:
 254        *
 255        *    "Samplers aggregated into arrays within a shader (using square
 256        *    brackets [ ]) can only be indexed with integral constant
 257        *    expressions [...]."
 258        *
 259        * This restriction was added in GLSL 1.30.  Shaders using earlier
 260        * version of the language should not be rejected by the compiler
 261        * front-end for using this construct.  This allows useful things such
 262        * as using a loop counter as the index to an array of samplers.  If the
 263        * loop in unrolled, the code should compile correctly.  Instead, emit a
 264        * warning.
 265        *
 266        * In GLSL 4.00 / ARB_gpu_shader5, this requirement is relaxed again to allow
 267        * indexing with dynamically uniform expressions. Note that these are not
 268        * required to be uniforms or expressions based on them, but merely that the
 269        * values must not diverge between shader invocations run together. If the
 270        * values *do* diverge, then the behavior of the operation requiring a
 271        * dynamically uniform expression is undefined.
 272        */
 273       if (array->type->without_array()->is_sampler()) {
 274          if (!state->is_version(400, 0) && !state->ARB_gpu_shader5_enable) {
 275             if (state->is_version(130, 300))
 276                _mesa_glsl_error(&loc, state,
 277                                 "sampler arrays indexed with non-constant "
 278                                 "expressions are forbidden in GLSL %s "
 279                                 "and later",
 280                                 state->es_shader ? "ES 3.00" : "1.30");
 281             else if (state->es_shader)
 282                _mesa_glsl_warning(&loc, state,
 283                                   "sampler arrays indexed with non-constant "
 284                                   "expressions will be forbidden in GLSL "
 285                                   "3.00 and later");
 286             else
 287                _mesa_glsl_warning(&loc, state,
 288                                   "sampler arrays indexed with non-constant "
 289                                   "expressions will be forbidden in GLSL "
 290                                   "1.30 and later");
 291          }
 292       }
 293
 294       /* From page 27 of the GLSL ES 3.1 specification:
 295        *
 296        * "When aggregated into arrays within a shader, images can only be
 297        *  indexed with a constant integral expression."
 298        *
 299        * On the other hand the desktop GL specification extension allows
 300        * non-constant indexing of image arrays, but behavior is left undefined
 301        * in cases where the indexing expression is not dynamically uniform.
 302        */
 303       if (state->es_shader && array->type->without_array()->is_image()) {
 304          _mesa_glsl_error(&loc, state,
 305                           "image arrays indexed with non-constant "
 306                           "expressions are forbidden in GLSL ES.");
 307       }
 308    }
 309
 310    /* After performing all of the error checking, generate the IR for the
 311     * expression.
 312     */
 313    if (array->type->is_array()
 314        || array->type->is_matrix()) {
 315       return new(mem_ctx) ir_dereference_array(array, idx);
 316    } else if (array->type->is_vector()) {
 317       return new(mem_ctx) ir_expression(ir_binop_vector_extract, array, idx);
 318    } else if (array->type->is_error()) {
 319       return array;
 320    } else {
 321       ir_rvalue *result = new(mem_ctx) ir_dereference_array(array, idx);
 322       result->type = glsl_type::error_type;
 323
 324       return result;
 325    }
 326 }