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
  29 /**
  30  * If \c ir is a reference to an array for which we are tracking the max array
  31  * element accessed, track that the given element has been accessed.
  32  * Otherwise do nothing.
  33  *
  34  * This function also checks whether the array is a built-in array whose
  35  * maximum size is too small to accommodate the given index, and if so uses
  36  * loc and state to report the error.
  37  */
  38 static void
  39 update_max_array_access(ir_rvalue *ir, unsigned idx, YYLTYPE *loc,
  40                         struct _mesa_glsl_parse_state *state)
  41 {
  42    if (ir_dereference_variable *deref_var = ir->as_dereference_variable()) {
  43       ir_variable *var = deref_var->var;
  44       if (idx > var->max_array_access) {
  45          var->max_array_access = idx;
  46
  47          /* Check whether this access will, as a side effect, implicitly cause
  48           * the size of a built-in array to be too large.
  49           */
  50          check_builtin_array_max_size(var->name, idx+1, *loc, state);
  51       }
  52    }
  53 }
  54
  55
  56 ir_rvalue *
  57 _mesa_ast_array_index_to_hir(void *mem_ctx,
  58                              struct _mesa_glsl_parse_state *state,
  59                              ir_rvalue *array, ir_rvalue *idx,
  60                              YYLTYPE &loc, YYLTYPE &idx_loc)
  61 {
  62    if (!array->type->is_error()
  63        && !array->type->is_array()
  64        && !array->type->is_matrix()
  65        && !array->type->is_vector()) {
  66       _mesa_glsl_error(& idx_loc, state,
  67                        "cannot dereference non-array / non-matrix / "
  68                        "non-vector");
  69    }
  70
  71    if (!idx->type->is_error()) {
  72       if (!idx->type->is_integer()) {
  73          _mesa_glsl_error(& idx_loc, state, "array index must be integer type");
  74       } else if (!idx->type->is_scalar()) {
  75          _mesa_glsl_error(& idx_loc, state, "array index must be scalar");
  76       }
  77    }
  78
  79    /* If the array index is a constant expression and the array has a
  80     * declared size, ensure that the access is in-bounds.  If the array
  81     * index is not a constant expression, ensure that the array has a
  82     * declared size.
  83     */
  84    ir_constant *const const_index = idx->constant_expression_value();
  85    if (const_index != NULL && idx->type->is_integer()) {
  86       const int idx = const_index->value.i[0];
  87       const char *type_name = "error";
  88       unsigned bound = 0;
  89
  90       /* From page 24 (page 30 of the PDF) of the GLSL 1.50 spec:
  91        *
  92        *    "It is illegal to declare an array with a size, and then
  93        *    later (in the same shader) index the same array with an
  94        *    integral constant expression greater than or equal to the
  95        *    declared size. It is also illegal to index an array with a
  96        *    negative constant expression."
  97        */
  98       if (array->type->is_matrix()) {
  99          if (array->type->row_type()->vector_elements <= idx) {
 100             type_name = "matrix";
 101             bound = array->type->row_type()->vector_elements;
 102          }
 103       } else if (array->type->is_vector()) {
 104          if (array->type->vector_elements <= idx) {
 105             type_name = "vector";
 106             bound = array->type->vector_elements;
 107          }
 108       } else {
 109          /* glsl_type::array_size() returns 0 for non-array types.  This means
 110           * that we don't need to verify that the type is an array before
 111           * doing the bounds checking.
 112           */
 113          if ((array->type->array_size() > 0)
 114              && (array->type->array_size() <= idx)) {
 115             type_name = "array";
 116             bound = array->type->array_size();
 117          }
 118       }
 119
 120       if (bound > 0) {
 121          _mesa_glsl_error(& loc, state, "%s index must be < %u",
 122                           type_name, bound);
 123       } else if (idx < 0) {
 124          _mesa_glsl_error(& loc, state, "%s index must be >= 0",
 125                           type_name);
 126       }
 127
 128       if (array->type->is_array())
 129          update_max_array_access(array, idx, &loc, state);
 130    } else if (const_index == NULL && array->type->is_array()) {
 131       if (array->type->array_size() == 0) {
 132          _mesa_glsl_error(&loc, state, "unsized array index must be constant");
 133       } else if (array->type->fields.array->is_interface()
 134                  && array->variable_referenced()->mode == ir_var_uniform) {
 135          /* Page 46 in section 4.3.7 of the OpenGL ES 3.00 spec says:
 136           *
 137           *     "All indexes used to index a uniform block array must be
 138           *     constant integral expressions."
 139           */
 140          _mesa_glsl_error(&loc, state,
 141                           "uniform block array index must be constant");
 142       } else {
 143          /* whole_variable_referenced can return NULL if the array is a
 144           * member of a structure.  In this case it is safe to not update
 145           * the max_array_access field because it is never used for fields
 146           * of structures.
 147           */
 148          ir_variable *v = array->whole_variable_referenced();
 149          if (v != NULL)
 150             v->max_array_access = array->type->array_size() - 1;
 151       }
 152
 153       /* From page 23 (29 of the PDF) of the GLSL 1.30 spec:
 154        *
 155        *    "Samplers aggregated into arrays within a shader (using square
 156        *    brackets [ ]) can only be indexed with integral constant
 157        *    expressions [...]."
 158        *
 159        * This restriction was added in GLSL 1.30.  Shaders using earlier
 160        * version of the language should not be rejected by the compiler
 161        * front-end for using this construct.  This allows useful things such
 162        * as using a loop counter as the index to an array of samplers.  If the
 163        * loop in unrolled, the code should compile correctly.  Instead, emit a
 164        * warning.
 165        */
 166       if (array->type->element_type()->is_sampler()) {
 167          if (!state->is_version(130, 100)) {
 168             if (state->es_shader) {
 169                _mesa_glsl_warning(&loc, state,
 170                                   "sampler arrays indexed with non-constant "
 171                                   "expressions is optional in %s",
 172                                   state->get_version_string());
 173             } else {
 174                _mesa_glsl_warning(&loc, state,
 175                                   "sampler arrays indexed with non-constant "
 176                                   "expressions will be forbidden in GLSL 1.30 "
 177                                   "and later");
 178             }
 179          } else {
 180             _mesa_glsl_error(&loc, state,
 181                              "sampler arrays indexed with non-constant "
 182                              "expressions is forbidden in GLSL 1.30 and "
 183                              "later");
 184          }
 185       }
 186    }
 187
 188    /* After performing all of the error checking, generate the IR for the
 189     * expression.
 190     */
 191    if (array->type->is_array()
 192        || array->type->is_matrix()) {
 193       return new(mem_ctx) ir_dereference_array(array, idx);
 194    } else if (array->type->is_vector()) {
 195       return new(mem_ctx) ir_expression(ir_binop_vector_extract, array, idx);
 196    } else if (array->type->is_error()) {
 197       return array;
 198    } else {
 199       ir_rvalue *result = new(mem_ctx) ir_dereference_array(array, idx);
 200       result->type = glsl_type::error_type;
 201
 202       return result;
 203    }
 204 }