src/compiler/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 "compiler/glsl_types.h"
  26 #include "ir.h"
  27
  28 void
  29 ast_array_specifier::print(void) const
  30 {
  31    foreach_list_typed (ast_node, array_dimension, link, &this->array_dimensions) {
  32       printf("[ ");
  33       if (((ast_expression*)array_dimension)->oper != ast_unsized_array_dim)
  34          array_dimension->print();
  35       printf("] ");
  36    }
  37 }
  38
  39 /**
  40  * If \c ir is a reference to an array for which we are tracking the max array
  41  * element accessed, track that the given element has been accessed.
  42  * Otherwise do nothing.
  43  *
  44  * This function also checks whether the array is a built-in array whose
  45  * maximum size is too small to accommodate the given index, and if so uses
  46  * loc and state to report the error.
  47  */
  48 static void
  49 update_max_array_access(ir_rvalue *ir, int idx, YYLTYPE *loc,
  50                         struct _mesa_glsl_parse_state *state)
  51 {
  52    if (ir_dereference_variable *deref_var = ir->as_dereference_variable()) {
  53       ir_variable *var = deref_var->var;
  54       if (idx > (int)var->data.max_array_access) {
  55          var->data.max_array_access = idx;
  56
  57          /* Check whether this access will, as a side effect, implicitly cause
  58           * the size of a built-in array to be too large.
  59           */
  60          check_builtin_array_max_size(var->name, idx+1, *loc, state);
  61       }
  62    } else if (ir_dereference_record *deref_record =
  63               ir->as_dereference_record()) {
  64       /* There are three possibilities we need to consider:
  65        *
  66        * - Accessing an element of an array that is a member of a named
  67        *   interface block (e.g. ifc.foo[i])
  68        *
  69        * - Accessing an element of an array that is a member of a named
  70        *   interface block array (e.g. ifc[j].foo[i]).
  71        *
  72        * - Accessing an element of an array that is a member of a named
  73        *   interface block array of arrays (e.g. ifc[j][k].foo[i]).
  74        */
  75       ir_dereference_variable *deref_var =
  76          deref_record->record->as_dereference_variable();
  77       if (deref_var == NULL) {
  78          ir_dereference_array *deref_array =
  79             deref_record->record->as_dereference_array();
  80          ir_dereference_array *deref_array_prev = NULL;
  81          while (deref_array != NULL) {
  82             deref_array_prev = deref_array;
  83             deref_array = deref_array->array->as_dereference_array();
  84          }
  85          if (deref_array_prev != NULL)
  86             deref_var = deref_array_prev->array->as_dereference_variable();
  87       }
  88
  89       if (deref_var != NULL) {
  90          if (deref_var->var->is_interface_instance()) {
  91             unsigned field_idx = deref_record->field_idx;
  92             assert(field_idx < deref_var->var->get_interface_type()->length);
  93
  94             int *const max_ifc_array_access =
  95                deref_var->var->get_max_ifc_array_access();
  96
  97             assert(max_ifc_array_access != NULL);
  98
  99             if (idx > max_ifc_array_access[field_idx]) {
 100                max_ifc_array_access[field_idx] = idx;
 101
 102                /* Check whether this access will, as a side effect, implicitly
 103                 * cause the size of a built-in array to be too large.
 104                 */
 105                const char *field_name =
 106                   deref_record->record->type->fields.structure[field_idx].name;
 107                check_builtin_array_max_size(field_name, idx+1, *loc, state);
 108             }
 109          }
 110       }
 111    }
 112 }
 113
 114
 115 static int
 116 get_implicit_array_size(struct _mesa_glsl_parse_state *state,
 117                         ir_rvalue *array)
 118 {
 119    ir_variable *var = array->variable_referenced();
 120
 121    /* Inputs in control shader are implicitly sized
 122     * to the maximum patch size.
 123     */
 124    if (state->stage == MESA_SHADER_TESS_CTRL &&
 125        var->data.mode == ir_var_shader_in) {
 126       return state->Const.MaxPatchVertices;
 127    }
 128
 129    /* Non-patch inputs in evaluation shader are implicitly sized
 130     * to the maximum patch size.
 131     */
 132    if (state->stage == MESA_SHADER_TESS_EVAL &&
 133        var->data.mode == ir_var_shader_in &&
 134        !var->data.patch) {
 135       return state->Const.MaxPatchVertices;
 136    }
 137
 138    return 0;
 139 }
 140
 141
 142 ir_rvalue *
 143 _mesa_ast_array_index_to_hir(void *mem_ctx,
 144                              struct _mesa_glsl_parse_state *state,
 145                              ir_rvalue *array, ir_rvalue *idx,
 146                              YYLTYPE &loc, YYLTYPE &idx_loc)
 147 {
 148    if (!array->type->is_error()
 149        && !array->type->is_array()
 150        && !array->type->is_matrix()
 151        && !array->type->is_vector()) {
 152       _mesa_glsl_error(& idx_loc, state,
 153                        "cannot dereference non-array / non-matrix / "
 154                        "non-vector");
 155    }
 156
 157    if (!idx->type->is_error()) {
 158       if (!idx->type->is_integer_32()) {
 159          _mesa_glsl_error(& idx_loc, state, "array index must be integer type");
 160       } else if (!idx->type->is_scalar()) {
 161          _mesa_glsl_error(& idx_loc, state, "array index must be scalar");
 162       }
 163    }
 164
 165    /* If the array index is a constant expression and the array has a
 166     * declared size, ensure that the access is in-bounds.  If the array
 167     * index is not a constant expression, ensure that the array has a
 168     * declared size.
 169     */
 170    ir_constant *const const_index = idx->constant_expression_value(mem_ctx);
 171    if (const_index != NULL && idx->type->is_integer_32()) {
 172       const int idx = const_index->value.i[0];
 173       const char *type_name = "error";
 174       unsigned bound = 0;
 175
 176       /* From page 24 (page 30 of the PDF) of the GLSL 1.50 spec:
 177        *
 178        *    "It is illegal to declare an array with a size, and then
 179        *    later (in the same shader) index the same array with an
 180        *    integral constant expression greater than or equal to the
 181        *    declared size. It is also illegal to index an array with a
 182        *    negative constant expression."
 183        */
 184       if (array->type->is_matrix()) {
 185          if (array->type->row_type()->vector_elements <= idx) {
 186             type_name = "matrix";
 187             bound = array->type->row_type()->vector_elements;
 188          }
 189       } else if (array->type->is_vector()) {
 190          if (array->type->vector_elements <= idx) {
 191             type_name = "vector";
 192             bound = array->type->vector_elements;
 193          }
 194       } else {
 195          /* glsl_type::array_size() returns -1 for non-array types.  This means
 196           * that we don't need to verify that the type is an array before
 197           * doing the bounds checking.
 198           */
 199          if ((array->type->array_size() > 0)
 200              && (array->type->array_size() <= idx)) {
 201             type_name = "array";
 202             bound = array->type->array_size();
 203          }
 204       }
 205
 206       if (bound > 0) {
 207          _mesa_glsl_error(& loc, state, "%s index must be < %u",
 208                           type_name, bound);
 209       } else if (idx < 0) {
 210          _mesa_glsl_error(& loc, state, "%s index must be >= 0", type_name);
 211       }
 212
 213       if (array->type->is_array())
 214          update_max_array_access(array, idx, &loc, state);
 215    } else if (const_index == NULL && array->type->is_array()) {
 216       if (array->type->is_unsized_array()) {
 217          int implicit_size = get_implicit_array_size(state, array);
 218          if (implicit_size) {
 219             ir_variable *v = array->whole_variable_referenced();
 220             if (v != NULL)
 221                v->data.max_array_access = implicit_size - 1;
 222          }
 223          else if (state->stage == MESA_SHADER_TESS_CTRL &&
 224                   array->variable_referenced()->data.mode == ir_var_shader_out &&
 225                   !array->variable_referenced()->data.patch) {
 226             /* Tessellation control shader output non-patch arrays are
 227              * initially unsized. Despite that, they are allowed to be
 228              * indexed with a non-constant expression (typically
 229              * "gl_InvocationID"). The array size will be determined
 230              * by the linker.
 231              */
 232          }
 233          else if (array->variable_referenced()->data.mode !=
 234                   ir_var_shader_storage) {
 235             _mesa_glsl_error(&loc, state, "unsized array index must be constant");
 236          } else {
 237             /* Unsized array non-constant indexing on SSBO is allowed only for
 238              * the last member of the SSBO definition.
 239              */
 240             ir_variable *var = array->variable_referenced();
 241             const glsl_type *iface_type = var->get_interface_type();
 242             int field_index = iface_type->field_index(var->name);
 243             /* Field index can be < 0 for instance arrays */
 244             if (field_index >= 0 &&
 245                 field_index != (int) iface_type->length - 1) {
 246                _mesa_glsl_error(&loc, state, "Indirect access on unsized "
 247                                 "array is limited to the last member of "
 248                                 "SSBO.");
 249             }
 250          }
 251       } else if (array->type->without_array()->is_interface()
 252                  && ((array->variable_referenced()->data.mode == ir_var_uniform
 253                       && !state->is_version(400, 320)
 254                       && !state->ARB_gpu_shader5_enable
 255                       && !state->EXT_gpu_shader5_enable
 256                       && !state->OES_gpu_shader5_enable) ||
 257                      (array->variable_referenced()->data.mode == ir_var_shader_storage
 258                       && !state->is_version(400, 0)
 259                       && !state->ARB_gpu_shader5_enable))) {
 260          /* Page 50 in section 4.3.9 of the OpenGL ES 3.10 spec says:
 261           *
 262           *     "All indices used to index a uniform or shader storage block
 263           *     array must be constant integral expressions."
 264           *
 265           * But OES_gpu_shader5 (and ESSL 3.20) relax this to allow indexing
 266           * on uniform blocks but not shader storage blocks.
 267           *
 268           */
 269          _mesa_glsl_error(&loc, state, "%s block array index must be constant",
 270                           array->variable_referenced()->data.mode
 271                           == ir_var_uniform ? "uniform" : "shader storage");
 272       } else {
 273          /* whole_variable_referenced can return NULL if the array is a
 274           * member of a structure.  In this case it is safe to not update
 275           * the max_array_access field because it is never used for fields
 276           * of structures.
 277           */
 278          ir_variable *v = array->whole_variable_referenced();
 279          if (v != NULL)
 280             v->data.max_array_access = array->type->array_size() - 1;
 281       }
 282
 283       /* From page 23 (29 of the PDF) of the GLSL 1.30 spec:
 284        *
 285        *    "Samplers aggregated into arrays within a shader (using square
 286        *    brackets [ ]) can only be indexed with integral constant
 287        *    expressions [...]."
 288        *
 289        * This restriction was added in GLSL 1.30.  Shaders using earlier
 290        * version of the language should not be rejected by the compiler
 291        * front-end for using this construct.  This allows useful things such
 292        * as using a loop counter as the index to an array of samplers.  If the
 293        * loop in unrolled, the code should compile correctly.  Instead, emit a
 294        * warning.
 295        *
 296        * In GLSL 4.00 / ARB_gpu_shader5, this requirement is relaxed again to allow
 297        * indexing with dynamically uniform expressions. Note that these are not
 298        * required to be uniforms or expressions based on them, but merely that the
 299        * values must not diverge between shader invocations run together. If the
 300        * values *do* diverge, then the behavior of the operation requiring a
 301        * dynamically uniform expression is undefined.
 302        *
 303        * From section 4.1.7 of the ARB_bindless_texture spec:
 304        *
 305        *    "Samplers aggregated into arrays within a shader (using square
 306        *    brackets []) can be indexed with arbitrary integer expressions."
 307        */
 308       if (array->type->without_array()->is_sampler()) {
 309          if (!state->is_version(400, 320) &&
 310              !state->ARB_gpu_shader5_enable &&
 311              !state->EXT_gpu_shader5_enable &&
 312              !state->OES_gpu_shader5_enable &&
 313              !state->has_bindless()) {
 314             if (state->is_version(130, 300))
 315                _mesa_glsl_error(&loc, state,
 316                                 "sampler arrays indexed with non-constant "
 317                                 "expressions are forbidden in GLSL %s "
 318                                 "and later",
 319                                 state->es_shader ? "ES 3.00" : "1.30");
 320             else if (state->es_shader)
 321                _mesa_glsl_warning(&loc, state,
 322                                   "sampler arrays indexed with non-constant "
 323                                   "expressions will be forbidden in GLSL "
 324                                   "3.00 and later");
 325             else
 326                _mesa_glsl_warning(&loc, state,
 327                                   "sampler arrays indexed with non-constant "
 328                                   "expressions will be forbidden in GLSL "
 329                                   "1.30 and later");
 330          }
 331       }
 332
 333       /* From page 27 of the GLSL ES 3.1 specification:
 334        *
 335        * "When aggregated into arrays within a shader, images can only be
 336        *  indexed with a constant integral expression."
 337        *
 338        * On the other hand the desktop GL specification extension allows
 339        * non-constant indexing of image arrays, but behavior is left undefined
 340        * in cases where the indexing expression is not dynamically uniform.
 341        */
 342       if (state->es_shader && array->type->without_array()->is_image()) {
 343          _mesa_glsl_error(&loc, state,
 344                           "image arrays indexed with non-constant "
 345                           "expressions are forbidden in GLSL ES.");
 346       }
 347    }
 348
 349    /* After performing all of the error checking, generate the IR for the
 350     * expression.
 351     */
 352    if (array->type->is_array()
 353        || array->type->is_matrix()
 354        || array->type->is_vector()) {
 355       return new(mem_ctx) ir_dereference_array(array, idx);
 356    } else if (array->type->is_error()) {
 357       return array;
 358    } else {
 359       ir_rvalue *result = new(mem_ctx) ir_dereference_array(array, idx);
 360       result->type = glsl_type::error_type;
 361
 362       return result;
 363    }
 364 }