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_index =
  92                deref_record->record->type->field_index(deref_record->field);
  93             assert(field_index < deref_var->var->get_interface_type()->length);
  94
  95             unsigned *const max_ifc_array_access =
  96                deref_var->var->get_max_ifc_array_access();
  97
  98             assert(max_ifc_array_access != NULL);
  99
 100             if (idx > (int)max_ifc_array_access[field_index]) {
 101                max_ifc_array_access[field_index] = idx;
 102
 103                /* Check whether this access will, as a side effect, implicitly
 104                 * cause the size of a built-in array to be too large.
 105                 */
 106                check_builtin_array_max_size(deref_record->field, idx+1, *loc,
 107                                             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()) {
 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();
 171    if (const_index != NULL && idx->type->is_integer()) {
 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",
 211                           type_name);
 212       }
 213
 214       if (array->type->is_array())
 215          update_max_array_access(array, idx, &loc, state);
 216    } else if (const_index == NULL && array->type->is_array()) {
 217       if (array->type->is_unsized_array()) {
 218          int implicit_size = get_implicit_array_size(state, array);
 219          if (implicit_size) {
 220             ir_variable *v = array->whole_variable_referenced();
 221             if (v != NULL)
 222                v->data.max_array_access = implicit_size - 1;
 223          }
 224          else if (state->stage == MESA_SHADER_TESS_CTRL &&
 225                   array->variable_referenced()->data.mode == ir_var_shader_out &&
 226                   !array->variable_referenced()->data.patch) {
 227             /* Tessellation control shader output non-patch arrays are
 228              * initially unsized. Despite that, they are allowed to be
 229              * indexed with a non-constant expression (typically
 230              * "gl_InvocationID"). The array size will be determined
 231              * by the linker.
 232              */
 233          }
 234          else if (array->variable_referenced()->data.mode !=
 235                   ir_var_shader_storage) {
 236             _mesa_glsl_error(&loc, state, "unsized array index must be constant");
 237          }
 238       } else if (array->type->without_array()->is_interface()
 239                  && (array->variable_referenced()->data.mode == ir_var_uniform ||
 240                      array->variable_referenced()->data.mode == ir_var_shader_storage)
 241                  && !state->is_version(400, 0) && !state->ARB_gpu_shader5_enable) {
 242          /* Page 50 in section 4.3.9 of the OpenGL ES 3.10 spec says:
 243           *
 244           *     "All indices used to index a uniform or shader storage block
 245           *     array must be constant integral expressions."
 246           */
 247          _mesa_glsl_error(&loc, state, "%s block array index must be constant",
 248                           array->variable_referenced()->data.mode
 249                           == ir_var_uniform ? "uniform" : "shader storage");
 250       } else {
 251          /* whole_variable_referenced can return NULL if the array is a
 252           * member of a structure.  In this case it is safe to not update
 253           * the max_array_access field because it is never used for fields
 254           * of structures.
 255           */
 256          ir_variable *v = array->whole_variable_referenced();
 257          if (v != NULL)
 258             v->data.max_array_access = array->type->array_size() - 1;
 259       }
 260
 261       /* From page 23 (29 of the PDF) of the GLSL 1.30 spec:
 262        *
 263        *    "Samplers aggregated into arrays within a shader (using square
 264        *    brackets [ ]) can only be indexed with integral constant
 265        *    expressions [...]."
 266        *
 267        * This restriction was added in GLSL 1.30.  Shaders using earlier
 268        * version of the language should not be rejected by the compiler
 269        * front-end for using this construct.  This allows useful things such
 270        * as using a loop counter as the index to an array of samplers.  If the
 271        * loop in unrolled, the code should compile correctly.  Instead, emit a
 272        * warning.
 273        *
 274        * In GLSL 4.00 / ARB_gpu_shader5, this requirement is relaxed again to allow
 275        * indexing with dynamically uniform expressions. Note that these are not
 276        * required to be uniforms or expressions based on them, but merely that the
 277        * values must not diverge between shader invocations run together. If the
 278        * values *do* diverge, then the behavior of the operation requiring a
 279        * dynamically uniform expression is undefined.
 280        */
 281       if (array->type->without_array()->is_sampler()) {
 282          if (!state->is_version(400, 0) && !state->ARB_gpu_shader5_enable) {
 283             if (state->is_version(130, 300))
 284                _mesa_glsl_error(&loc, state,
 285                                 "sampler arrays indexed with non-constant "
 286                                 "expressions are forbidden in GLSL %s "
 287                                 "and later",
 288                                 state->es_shader ? "ES 3.00" : "1.30");
 289             else if (state->es_shader)
 290                _mesa_glsl_warning(&loc, state,
 291                                   "sampler arrays indexed with non-constant "
 292                                   "expressions will be forbidden in GLSL "
 293                                   "3.00 and later");
 294             else
 295                _mesa_glsl_warning(&loc, state,
 296                                   "sampler arrays indexed with non-constant "
 297                                   "expressions will be forbidden in GLSL "
 298                                   "1.30 and later");
 299          }
 300       }
 301
 302       /* From page 27 of the GLSL ES 3.1 specification:
 303        *
 304        * "When aggregated into arrays within a shader, images can only be
 305        *  indexed with a constant integral expression."
 306        *
 307        * On the other hand the desktop GL specification extension allows
 308        * non-constant indexing of image arrays, but behavior is left undefined
 309        * in cases where the indexing expression is not dynamically uniform.
 310        */
 311       if (state->es_shader && array->type->without_array()->is_image()) {
 312          _mesa_glsl_error(&loc, state,
 313                           "image arrays indexed with non-constant "
 314                           "expressions are forbidden in GLSL ES.");
 315       }
 316    }
 317
 318    /* After performing all of the error checking, generate the IR for the
 319     * expression.
 320     */
 321    if (array->type->is_array()
 322        || array->type->is_matrix()
 323        || array->type->is_vector()) {
 324       return new(mem_ctx) ir_dereference_array(array, idx);
 325    } else if (array->type->is_error()) {
 326       return array;
 327    } else {
 328       ir_rvalue *result = new(mem_ctx) ir_dereference_array(array, idx);
 329       result->type = glsl_type::error_type;
 330
 331       return result;
 332    }
 333 }