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