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 ir_rvalue *
  29 _mesa_ast_array_index_to_hir(void *mem_ctx,
  30                              struct _mesa_glsl_parse_state *state,
  31                              ir_rvalue *array, ir_rvalue *idx,
  32                              YYLTYPE &loc, YYLTYPE &idx_loc)
  33 {
  34    if (!array->type->is_error()
  35        && !array->type->is_array()
  36        && !array->type->is_matrix()
  37        && !array->type->is_vector()) {
  38       _mesa_glsl_error(& idx_loc, state,
  39                        "cannot dereference non-array / non-matrix / "
  40                        "non-vector");
  41    }
  42
  43    if (!idx->type->is_error()) {
  44       if (!idx->type->is_integer()) {
  45          _mesa_glsl_error(& idx_loc, state, "array index must be integer type");
  46       } else if (!idx->type->is_scalar()) {
  47          _mesa_glsl_error(& idx_loc, state, "array index must be scalar");
  48       }
  49    }
  50
  51    /* If the array index is a constant expression and the array has a
  52     * declared size, ensure that the access is in-bounds.  If the array
  53     * index is not a constant expression, ensure that the array has a
  54     * declared size.
  55     */
  56    ir_constant *const const_index = idx->constant_expression_value();
  57    if (const_index != NULL && idx->type->is_integer()) {
  58       const int idx = const_index->value.i[0];
  59       const char *type_name = "error";
  60       unsigned bound = 0;
  61
  62       /* From page 24 (page 30 of the PDF) of the GLSL 1.50 spec:
  63        *
  64        *    "It is illegal to declare an array with a size, and then
  65        *    later (in the same shader) index the same array with an
  66        *    integral constant expression greater than or equal to the
  67        *    declared size. It is also illegal to index an array with a
  68        *    negative constant expression."
  69        */
  70       if (array->type->is_matrix()) {
  71          if (array->type->row_type()->vector_elements <= idx) {
  72             type_name = "matrix";
  73             bound = array->type->row_type()->vector_elements;
  74          }
  75       } else if (array->type->is_vector()) {
  76          if (array->type->vector_elements <= idx) {
  77             type_name = "vector";
  78             bound = array->type->vector_elements;
  79          }
  80       } else {
  81          /* glsl_type::array_size() returns 0 for non-array types.  This means
  82           * that we don't need to verify that the type is an array before
  83           * doing the bounds checking.
  84           */
  85          if ((array->type->array_size() > 0)
  86              && (array->type->array_size() <= idx)) {
  87             type_name = "array";
  88             bound = array->type->array_size();
  89          }
  90       }
  91
  92       if (bound > 0) {
  93          _mesa_glsl_error(& loc, state, "%s index must be < %u",
  94                           type_name, bound);
  95       } else if (idx < 0) {
  96          _mesa_glsl_error(& loc, state, "%s index must be >= 0",
  97                           type_name);
  98       }
  99
 100       if (array->type->is_array()) {
 101          /* If the array is a variable dereference, it dereferences the
 102           * whole array, by definition.  Use this to get the variable.
 103           *
 104           * FINISHME: Should some methods for getting / setting / testing
 105           * FINISHME: array access limits be added to ir_dereference?
 106           */
 107          ir_variable *const v = array->whole_variable_referenced();
 108          if ((v != NULL) && (unsigned(idx) > v->max_array_access)) {
 109             v->max_array_access = idx;
 110
 111             /* Check whether this access will, as a side effect, implicitly
 112              * cause the size of a built-in array to be too large.
 113              */
 114             check_builtin_array_max_size(v->name, idx+1, loc, state);
 115          }
 116       }
 117    } else if (const_index == NULL && array->type->is_array()) {
 118       if (array->type->array_size() == 0) {
 119          _mesa_glsl_error(&loc, state, "unsized array index must be constant");
 120       } else if (array->type->fields.array->is_interface()) {
 121          /* Page 46 in section 4.3.7 of the OpenGL ES 3.00 spec says:
 122           *
 123           *     "All indexes used to index a uniform block array must be
 124           *     constant integral expressions."
 125           */
 126          _mesa_glsl_error(&loc, state,
 127                           "uniform block array index must be constant");
 128       } else {
 129          /* whole_variable_referenced can return NULL if the array is a
 130           * member of a structure.  In this case it is safe to not update
 131           * the max_array_access field because it is never used for fields
 132           * of structures.
 133           */
 134          ir_variable *v = array->whole_variable_referenced();
 135          if (v != NULL)
 136             v->max_array_access = array->type->array_size() - 1;
 137       }
 138
 139       /* From page 23 (29 of the PDF) of the GLSL 1.30 spec:
 140        *
 141        *    "Samplers aggregated into arrays within a shader (using square
 142        *    brackets [ ]) can only be indexed with integral constant
 143        *    expressions [...]."
 144        *
 145        * This restriction was added in GLSL 1.30.  Shaders using earlier
 146        * version of the language should not be rejected by the compiler
 147        * front-end for using this construct.  This allows useful things such
 148        * as using a loop counter as the index to an array of samplers.  If the
 149        * loop in unrolled, the code should compile correctly.  Instead, emit a
 150        * warning.
 151        */
 152       if (array->type->element_type()->is_sampler()) {
 153          if (!state->is_version(130, 100)) {
 154             if (state->es_shader) {
 155                _mesa_glsl_warning(&loc, state,
 156                                   "sampler arrays indexed with non-constant "
 157                                   "expressions is optional in %s",
 158                                   state->get_version_string());
 159             } else {
 160                _mesa_glsl_warning(&loc, state,
 161                                   "sampler arrays indexed with non-constant "
 162                                   "expressions will be forbidden in GLSL 1.30 "
 163                                   "and later");
 164             }
 165          } else {
 166             _mesa_glsl_error(&loc, state,
 167                              "sampler arrays indexed with non-constant "
 168                              "expressions is forbidden in GLSL 1.30 and "
 169                              "later");
 170          }
 171       }
 172    }
 173
 174    /* After performing all of the error checking, generate the IR for the
 175     * expression.
 176     */
 177    if (array->type->is_array()
 178        || array->type->is_matrix()) {
 179       return new(mem_ctx) ir_dereference_array(array, idx);
 180    } else if (array->type->is_vector()) {
 181       return new(mem_ctx) ir_expression(ir_binop_vector_extract, array, idx);
 182    } else if (array->type->is_error()) {
 183       return array;
 184    } else {
 185       ir_rvalue *result = new(mem_ctx) ir_dereference_array(array, idx);
 186       result->type = glsl_type::error_type;
 187
 188       return result;
 189    }
 190 }