Move count_attribute_slots() out of the linker and into glsl_type.

[mesa.git] / src / glsl / glsl_types.cpp

/*
 * Copyright © 2009 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

#include <stdio.h>
#include <stdlib.h>
#include "main/core.h" /* for Elements */
#include "glsl_symbol_table.h"
#include "glsl_parser_extras.h"
#include "glsl_types.h"
extern "C" {
#include "program/hash_table.h"
}

hash_table *glsl_type::array_types = NULL;
hash_table *glsl_type::record_types = NULL;
hash_table *glsl_type::interface_types = NULL;
void *glsl_type::mem_ctx = NULL;

void
glsl_type::init_ralloc_type_ctx(void)
{
   if (glsl_type::mem_ctx == NULL) {
      glsl_type::mem_ctx = ralloc_autofree_context();
      assert(glsl_type::mem_ctx != NULL);
   }
}

glsl_type::glsl_type(GLenum gl_type,
                     glsl_base_type base_type, unsigned vector_elements,
                     unsigned matrix_columns, const char *name) :
   gl_type(gl_type),
   base_type(base_type),
   sampler_dimensionality(0), sampler_shadow(0), sampler_array(0),
   sampler_type(0), interface_packing(0),
   vector_elements(vector_elements), matrix_columns(matrix_columns),
   length(0)
{
   init_ralloc_type_ctx();
   assert(name != NULL);
   this->name = ralloc_strdup(this->mem_ctx, name);
   /* Neither dimension is zero or both dimensions are zero.
    */
   assert((vector_elements == 0) == (matrix_columns == 0));
   memset(& fields, 0, sizeof(fields));
}

glsl_type::glsl_type(GLenum gl_type,
                     enum glsl_sampler_dim dim, bool shadow, bool array,
                     unsigned type, const char *name) :
   gl_type(gl_type),
   base_type(GLSL_TYPE_SAMPLER),
   sampler_dimensionality(dim), sampler_shadow(shadow),
   sampler_array(array), sampler_type(type), interface_packing(0),
   vector_elements(0), matrix_columns(0),
   length(0)
{
   init_ralloc_type_ctx();
   assert(name != NULL);
   this->name = ralloc_strdup(this->mem_ctx, name);
   memset(& fields, 0, sizeof(fields));
}

glsl_type::glsl_type(const glsl_struct_field *fields, unsigned num_fields,
                     const char *name) :
   gl_type(0),
   base_type(GLSL_TYPE_STRUCT),
   sampler_dimensionality(0), sampler_shadow(0), sampler_array(0),
   sampler_type(0), interface_packing(0),
   vector_elements(0), matrix_columns(0),
   length(num_fields)
{
   unsigned int i;

   init_ralloc_type_ctx();
   assert(name != NULL);
   this->name = ralloc_strdup(this->mem_ctx, name);
   this->fields.structure = ralloc_array(this->mem_ctx,
                                         glsl_struct_field, length);
   for (i = 0; i < length; i++) {
      this->fields.structure[i].type = fields[i].type;
      this->fields.structure[i].name = ralloc_strdup(this->fields.structure,
                                                     fields[i].name);
      this->fields.structure[i].row_major = fields[i].row_major;
   }
}

glsl_type::glsl_type(const glsl_struct_field *fields, unsigned num_fields,
                     enum glsl_interface_packing packing, const char *name) :
   gl_type(0),
   base_type(GLSL_TYPE_INTERFACE),
   sampler_dimensionality(0), sampler_shadow(0), sampler_array(0),
   sampler_type(0), interface_packing((unsigned) packing),
   vector_elements(0), matrix_columns(0),
   length(num_fields)
{
   unsigned int i;

   init_ralloc_type_ctx();
   assert(name != NULL);
   this->name = ralloc_strdup(this->mem_ctx, name);
   this->fields.structure = ralloc_array(this->mem_ctx,
                                         glsl_struct_field, length);
   for (i = 0; i < length; i++) {
      this->fields.structure[i].type = fields[i].type;
      this->fields.structure[i].name = ralloc_strdup(this->fields.structure,
                                                     fields[i].name);
      this->fields.structure[i].row_major = fields[i].row_major;
   }
}


bool
glsl_type::contains_sampler() const
{
   if (this->is_array()) {
      return this->fields.array->contains_sampler();
   } else if (this->is_record()) {
      for (unsigned int i = 0; i < this->length; i++) {
         if (this->fields.structure[i].type->contains_sampler())
            return true;
      }
      return false;
   } else {
      return this->is_sampler();
   }
}


bool
glsl_type::contains_integer() const
{
   if (this->is_array()) {
      return this->fields.array->contains_integer();
   } else if (this->is_record()) {
      for (unsigned int i = 0; i < this->length; i++) {
         if (this->fields.structure[i].type->contains_integer())
            return true;
      }
      return false;
   } else {
      return this->is_integer();
   }
}


gl_texture_index
glsl_type::sampler_index() const
{
   const glsl_type *const t = (this->is_array()) ? this->fields.array : this;

   assert(t->is_sampler());

   switch (t->sampler_dimensionality) {
   case GLSL_SAMPLER_DIM_1D:
      return (t->sampler_array) ? TEXTURE_1D_ARRAY_INDEX : TEXTURE_1D_INDEX;
   case GLSL_SAMPLER_DIM_2D:
      return (t->sampler_array) ? TEXTURE_2D_ARRAY_INDEX : TEXTURE_2D_INDEX;
   case GLSL_SAMPLER_DIM_3D:
      return TEXTURE_3D_INDEX;
   case GLSL_SAMPLER_DIM_CUBE:
      return (t->sampler_array) ? TEXTURE_CUBE_ARRAY_INDEX : TEXTURE_CUBE_INDEX;
   case GLSL_SAMPLER_DIM_RECT:
      return TEXTURE_RECT_INDEX;
   case GLSL_SAMPLER_DIM_BUF:
      return TEXTURE_BUFFER_INDEX;
   case GLSL_SAMPLER_DIM_EXTERNAL:
      return TEXTURE_EXTERNAL_INDEX;
   case GLSL_SAMPLER_DIM_MS:
      return (t->sampler_array) ? TEXTURE_2D_MULTISAMPLE_ARRAY_INDEX : TEXTURE_2D_MULTISAMPLE_INDEX;
   default:
      assert(!"Should not get here.");
      return TEXTURE_BUFFER_INDEX;
   }
}


const glsl_type *glsl_type::get_base_type() const
{
   switch (base_type) {
   case GLSL_TYPE_UINT:
      return uint_type;
   case GLSL_TYPE_INT:
      return int_type;
   case GLSL_TYPE_FLOAT:
      return float_type;
   case GLSL_TYPE_BOOL:
      return bool_type;
   default:
      return error_type;
   }
}


const glsl_type *glsl_type::get_scalar_type() const
{
   const glsl_type *type = this;

   /* Handle arrays */
   while (type->base_type == GLSL_TYPE_ARRAY)
      type = type->fields.array;

   /* Handle vectors and matrices */
   switch (type->base_type) {
   case GLSL_TYPE_UINT:
      return uint_type;
   case GLSL_TYPE_INT:
      return int_type;
   case GLSL_TYPE_FLOAT:
      return float_type;
   case GLSL_TYPE_BOOL:
      return bool_type;
   default:
      /* Handle everything else */
      return type;
   }
}


void
_mesa_glsl_release_types(void)
{
   if (glsl_type::array_types != NULL) {
      hash_table_dtor(glsl_type::array_types);
      glsl_type::array_types = NULL;
   }

   if (glsl_type::record_types != NULL) {
      hash_table_dtor(glsl_type::record_types);
      glsl_type::record_types = NULL;
   }
}


glsl_type::glsl_type(const glsl_type *array, unsigned length) :
   base_type(GLSL_TYPE_ARRAY),
   sampler_dimensionality(0), sampler_shadow(0), sampler_array(0),
   sampler_type(0), interface_packing(0),
   vector_elements(0), matrix_columns(0),
   name(NULL), length(length)
{
   this->fields.array = array;
   /* Inherit the gl type of the base. The GL type is used for
    * uniform/statevar handling in Mesa and the arrayness of the type
    * is represented by the size rather than the type.
    */
   this->gl_type = array->gl_type;

   /* Allow a maximum of 10 characters for the array size.  This is enough
    * for 32-bits of ~0.  The extra 3 are for the '[', ']', and terminating
    * NUL.
    */
   const unsigned name_length = strlen(array->name) + 10 + 3;
   char *const n = (char *) ralloc_size(this->mem_ctx, name_length);

   if (length == 0)
      snprintf(n, name_length, "%s[]", array->name);
   else
      snprintf(n, name_length, "%s[%u]", array->name, length);

   this->name = n;
}


const glsl_type *
glsl_type::vec(unsigned components)
{
   if (components == 0 || components > 4)
      return error_type;

   static const glsl_type *const ts[] = {
      float_type, vec2_type, vec3_type, vec4_type
   };
   return ts[components - 1];
}


const glsl_type *
glsl_type::ivec(unsigned components)
{
   if (components == 0 || components > 4)
      return error_type;

   static const glsl_type *const ts[] = {
      int_type, ivec2_type, ivec3_type, ivec4_type
   };
   return ts[components - 1];
}


const glsl_type *
glsl_type::uvec(unsigned components)
{
   if (components == 0 || components > 4)
      return error_type;

   static const glsl_type *const ts[] = {
      uint_type, uvec2_type, uvec3_type, uvec4_type
   };
   return ts[components - 1];
}


const glsl_type *
glsl_type::bvec(unsigned components)
{
   if (components == 0 || components > 4)
      return error_type;

   static const glsl_type *const ts[] = {
      bool_type, bvec2_type, bvec3_type, bvec4_type
   };
   return ts[components - 1];
}


const glsl_type *
glsl_type::get_instance(unsigned base_type, unsigned rows, unsigned columns)
{
   if (base_type == GLSL_TYPE_VOID)
      return void_type;

   if ((rows < 1) || (rows > 4) || (columns < 1) || (columns > 4))
      return error_type;

   /* Treat GLSL vectors as Nx1 matrices.
    */
   if (columns == 1) {
      switch (base_type) {
      case GLSL_TYPE_UINT:
         return uvec(rows);
      case GLSL_TYPE_INT:
         return ivec(rows);
      case GLSL_TYPE_FLOAT:
         return vec(rows);
      case GLSL_TYPE_BOOL:
         return bvec(rows);
      default:
         return error_type;
      }
   } else {
      if ((base_type != GLSL_TYPE_FLOAT) || (rows == 1))
         return error_type;

      /* GLSL matrix types are named mat{COLUMNS}x{ROWS}.  Only the following
       * combinations are valid:
       *
       *   1 2 3 4
       * 1
       * 2   x x x
       * 3   x x x
       * 4   x x x
       */
#define IDX(c,r) (((c-1)*3) + (r-1))

      switch (IDX(columns, rows)) {
      case IDX(2,2): return mat2_type;
      case IDX(2,3): return mat2x3_type;
      case IDX(2,4): return mat2x4_type;
      case IDX(3,2): return mat3x2_type;
      case IDX(3,3): return mat3_type;
      case IDX(3,4): return mat3x4_type;
      case IDX(4,2): return mat4x2_type;
      case IDX(4,3): return mat4x3_type;
      case IDX(4,4): return mat4_type;
      default: return error_type;
      }
   }

   assert(!"Should not get here.");
   return error_type;
}


const glsl_type *
glsl_type::get_array_instance(const glsl_type *base, unsigned array_size)
{

   if (array_types == NULL) {
      array_types = hash_table_ctor(64, hash_table_string_hash,
                                    hash_table_string_compare);
   }

   /* Generate a name using the base type pointer in the key.  This is
    * done because the name of the base type may not be unique across
    * shaders.  For example, two shaders may have different record types
    * named 'foo'.
    */
   char key[128];
   snprintf(key, sizeof(key), "%p[%u]", (void *) base, array_size);

   const glsl_type *t = (glsl_type *) hash_table_find(array_types, key);
   if (t == NULL) {
      t = new glsl_type(base, array_size);

      hash_table_insert(array_types, (void *) t, ralloc_strdup(mem_ctx, key));
   }

   assert(t->base_type == GLSL_TYPE_ARRAY);
   assert(t->length == array_size);
   assert(t->fields.array == base);

   return t;
}


int
glsl_type::record_key_compare(const void *a, const void *b)
{
   const glsl_type *const key1 = (glsl_type *) a;
   const glsl_type *const key2 = (glsl_type *) b;

   /* Return zero is the types match (there is zero difference) or non-zero
    * otherwise.
    */
   if (strcmp(key1->name, key2->name) != 0)
      return 1;

   if (key1->length != key2->length)
      return 1;

   if (key1->interface_packing != key2->interface_packing)
      return 1;

   for (unsigned i = 0; i < key1->length; i++) {
      if (key1->fields.structure[i].type != key2->fields.structure[i].type)
         return 1;
      if (strcmp(key1->fields.structure[i].name,
                 key2->fields.structure[i].name) != 0)
         return 1;
      if (key1->fields.structure[i].row_major
         != key2->fields.structure[i].row_major)
        return 1;
   }

   return 0;
}


unsigned
glsl_type::record_key_hash(const void *a)
{
   const glsl_type *const key = (glsl_type *) a;
   char hash_key[128];
   unsigned size = 0;

   size = snprintf(hash_key, sizeof(hash_key), "%08x", key->length);

   for (unsigned i = 0; i < key->length; i++) {
      if (size >= sizeof(hash_key))
         break;

      size += snprintf(& hash_key[size], sizeof(hash_key) - size,
                       "%p", (void *) key->fields.structure[i].type);
   }

   return hash_table_string_hash(& hash_key);
}


const glsl_type *
glsl_type::get_record_instance(const glsl_struct_field *fields,
                               unsigned num_fields,
                               const char *name)
{
   const glsl_type key(fields, num_fields, name);

   if (record_types == NULL) {
      record_types = hash_table_ctor(64, record_key_hash, record_key_compare);
   }

   const glsl_type *t = (glsl_type *) hash_table_find(record_types, & key);
   if (t == NULL) {
      t = new glsl_type(fields, num_fields, name);

      hash_table_insert(record_types, (void *) t, t);
   }

   assert(t->base_type == GLSL_TYPE_STRUCT);
   assert(t->length == num_fields);
   assert(strcmp(t->name, name) == 0);

   return t;
}


const glsl_type *
glsl_type::get_interface_instance(const glsl_struct_field *fields,
                                  unsigned num_fields,
                                  enum glsl_interface_packing packing,
                                  const char *name)
{
   const glsl_type key(fields, num_fields, packing, name);

   if (interface_types == NULL) {
      interface_types = hash_table_ctor(64, record_key_hash, record_key_compare);
   }

   const glsl_type *t = (glsl_type *) hash_table_find(interface_types, & key);
   if (t == NULL) {
      t = new glsl_type(fields, num_fields, packing, name);

      hash_table_insert(interface_types, (void *) t, t);
   }

   assert(t->base_type == GLSL_TYPE_INTERFACE);
   assert(t->length == num_fields);
   assert(strcmp(t->name, name) == 0);

   return t;
}


const glsl_type *
glsl_type::field_type(const char *name) const
{
   if (this->base_type != GLSL_TYPE_STRUCT
       && this->base_type != GLSL_TYPE_INTERFACE)
      return error_type;

   for (unsigned i = 0; i < this->length; i++) {
      if (strcmp(name, this->fields.structure[i].name) == 0)
         return this->fields.structure[i].type;
   }

   return error_type;
}


int
glsl_type::field_index(const char *name) const
{
   if (this->base_type != GLSL_TYPE_STRUCT
       && this->base_type != GLSL_TYPE_INTERFACE)
      return -1;

   for (unsigned i = 0; i < this->length; i++) {
      if (strcmp(name, this->fields.structure[i].name) == 0)
         return i;
   }

   return -1;
}


unsigned
glsl_type::component_slots() const
{
   switch (this->base_type) {
   case GLSL_TYPE_UINT:
   case GLSL_TYPE_INT:
   case GLSL_TYPE_FLOAT:
   case GLSL_TYPE_BOOL:
      return this->components();

   case GLSL_TYPE_STRUCT:
   case GLSL_TYPE_INTERFACE: {
      unsigned size = 0;

      for (unsigned i = 0; i < this->length; i++)
         size += this->fields.structure[i].type->component_slots();

      return size;
   }

   case GLSL_TYPE_ARRAY:
      return this->length * this->fields.array->component_slots();

   case GLSL_TYPE_SAMPLER:
   case GLSL_TYPE_VOID:
   case GLSL_TYPE_ERROR:
      break;
   }

   return 0;
}

bool
glsl_type::can_implicitly_convert_to(const glsl_type *desired) const
{
   if (this == desired)
      return true;

   /* There is no conversion among matrix types. */
   if (this->matrix_columns > 1 || desired->matrix_columns > 1)
      return false;

   /* int and uint can be converted to float. */
   return desired->is_float()
          && this->is_integer()
          && this->vector_elements == desired->vector_elements;
}

unsigned
glsl_type::std140_base_alignment(bool row_major) const
{
   /* (1) If the member is a scalar consuming <N> basic machine units, the
    *     base alignment is <N>.
    *
    * (2) If the member is a two- or four-component vector with components
    *     consuming <N> basic machine units, the base alignment is 2<N> or
    *     4<N>, respectively.
    *
    * (3) If the member is a three-component vector with components consuming
    *     <N> basic machine units, the base alignment is 4<N>.
    */
   if (this->is_scalar() || this->is_vector()) {
      switch (this->vector_elements) {
      case 1:
         return 4;
      case 2:
         return 8;
      case 3:
      case 4:
         return 16;
      }
   }

   /* (4) If the member is an array of scalars or vectors, the base alignment
    *     and array stride are set to match the base alignment of a single
    *     array element, according to rules (1), (2), and (3), and rounded up
    *     to the base alignment of a vec4. The array may have padding at the
    *     end; the base offset of the member following the array is rounded up
    *     to the next multiple of the base alignment.
    *
    * (6) If the member is an array of <S> column-major matrices with <C>
    *     columns and <R> rows, the matrix is stored identically to a row of
    *     <S>*<C> column vectors with <R> components each, according to rule
    *     (4).
    *
    * (8) If the member is an array of <S> row-major matrices with <C> columns
    *     and <R> rows, the matrix is stored identically to a row of <S>*<R>
    *     row vectors with <C> components each, according to rule (4).
    *
    * (10) If the member is an array of <S> structures, the <S> elements of
    *      the array are laid out in order, according to rule (9).
    */
   if (this->is_array()) {
      if (this->fields.array->is_scalar() ||
          this->fields.array->is_vector() ||
          this->fields.array->is_matrix()) {
         return MAX2(this->fields.array->std140_base_alignment(row_major), 16);
      } else {
         assert(this->fields.array->is_record());
         return this->fields.array->std140_base_alignment(row_major);
      }
   }

   /* (5) If the member is a column-major matrix with <C> columns and
    *     <R> rows, the matrix is stored identically to an array of
    *     <C> column vectors with <R> components each, according to
    *     rule (4).
    *
    * (7) If the member is a row-major matrix with <C> columns and <R>
    *     rows, the matrix is stored identically to an array of <R>
    *     row vectors with <C> components each, according to rule (4).
    */
   if (this->is_matrix()) {
      const struct glsl_type *vec_type, *array_type;
      int c = this->matrix_columns;
      int r = this->vector_elements;

      if (row_major) {
         vec_type = get_instance(GLSL_TYPE_FLOAT, c, 1);
         array_type = glsl_type::get_array_instance(vec_type, r);
      } else {
         vec_type = get_instance(GLSL_TYPE_FLOAT, r, 1);
         array_type = glsl_type::get_array_instance(vec_type, c);
      }

      return array_type->std140_base_alignment(false);
   }

   /* (9) If the member is a structure, the base alignment of the
    *     structure is <N>, where <N> is the largest base alignment
    *     value of any of its members, and rounded up to the base
    *     alignment of a vec4. The individual members of this
    *     sub-structure are then assigned offsets by applying this set
    *     of rules recursively, where the base offset of the first
    *     member of the sub-structure is equal to the aligned offset
    *     of the structure. The structure may have padding at the end;
    *     the base offset of the member following the sub-structure is
    *     rounded up to the next multiple of the base alignment of the
    *     structure.
    */
   if (this->is_record()) {
      unsigned base_alignment = 16;
      for (unsigned i = 0; i < this->length; i++) {
         const struct glsl_type *field_type = this->fields.structure[i].type;
         base_alignment = MAX2(base_alignment,
                               field_type->std140_base_alignment(row_major));
      }
      return base_alignment;
   }

   assert(!"not reached");
   return -1;
}

unsigned
glsl_type::std140_size(bool row_major) const
{
   /* (1) If the member is a scalar consuming <N> basic machine units, the
    *     base alignment is <N>.
    *
    * (2) If the member is a two- or four-component vector with components
    *     consuming <N> basic machine units, the base alignment is 2<N> or
    *     4<N>, respectively.
    *
    * (3) If the member is a three-component vector with components consuming
    *     <N> basic machine units, the base alignment is 4<N>.
    */
   if (this->is_scalar() || this->is_vector()) {
      return this->vector_elements * 4;
   }

   /* (5) If the member is a column-major matrix with <C> columns and
    *     <R> rows, the matrix is stored identically to an array of
    *     <C> column vectors with <R> components each, according to
    *     rule (4).
    *
    * (6) If the member is an array of <S> column-major matrices with <C>
    *     columns and <R> rows, the matrix is stored identically to a row of
    *     <S>*<C> column vectors with <R> components each, according to rule
    *     (4).
    *
    * (7) If the member is a row-major matrix with <C> columns and <R>
    *     rows, the matrix is stored identically to an array of <R>
    *     row vectors with <C> components each, according to rule (4).
    *
    * (8) If the member is an array of <S> row-major matrices with <C> columns
    *     and <R> rows, the matrix is stored identically to a row of <S>*<R>
    *     row vectors with <C> components each, according to rule (4).
    */
   if (this->is_matrix() || (this->is_array() &&
                             this->fields.array->is_matrix())) {
      const struct glsl_type *element_type;
      const struct glsl_type *vec_type;
      unsigned int array_len;

      if (this->is_array()) {
         element_type = this->fields.array;
         array_len = this->length;
      } else {
         element_type = this;
         array_len = 1;
      }

      if (row_major) {
         vec_type = get_instance(GLSL_TYPE_FLOAT,
                                 element_type->matrix_columns, 1);
         array_len *= element_type->vector_elements;
      } else {
         vec_type = get_instance(GLSL_TYPE_FLOAT,
                                 element_type->vector_elements, 1);
         array_len *= element_type->matrix_columns;
      }
      const glsl_type *array_type = glsl_type::get_array_instance(vec_type,
                                                                  array_len);

      return array_type->std140_size(false);
   }

   /* (4) If the member is an array of scalars or vectors, the base alignment
    *     and array stride are set to match the base alignment of a single
    *     array element, according to rules (1), (2), and (3), and rounded up
    *     to the base alignment of a vec4. The array may have padding at the
    *     end; the base offset of the member following the array is rounded up
    *     to the next multiple of the base alignment.
    *
    * (10) If the member is an array of <S> structures, the <S> elements of
    *      the array are laid out in order, according to rule (9).
    */
   if (this->is_array()) {
      if (this->fields.array->is_record()) {
         return this->length * this->fields.array->std140_size(row_major);
      } else {
         unsigned element_base_align =
            this->fields.array->std140_base_alignment(row_major);
         return this->length * MAX2(element_base_align, 16);
      }
   }

   /* (9) If the member is a structure, the base alignment of the
    *     structure is <N>, where <N> is the largest base alignment
    *     value of any of its members, and rounded up to the base
    *     alignment of a vec4. The individual members of this
    *     sub-structure are then assigned offsets by applying this set
    *     of rules recursively, where the base offset of the first
    *     member of the sub-structure is equal to the aligned offset
    *     of the structure. The structure may have padding at the end;
    *     the base offset of the member following the sub-structure is
    *     rounded up to the next multiple of the base alignment of the
    *     structure.
    */
   if (this->is_record()) {
      unsigned size = 0;
      for (unsigned i = 0; i < this->length; i++) {
         const struct glsl_type *field_type = this->fields.structure[i].type;
         unsigned align = field_type->std140_base_alignment(row_major);
         size = glsl_align(size, align);
         size += field_type->std140_size(row_major);
      }
      size = glsl_align(size,
                        this->fields.structure[0].type->std140_base_alignment(row_major));
      return size;
   }

   assert(!"not reached");
   return -1;
}


unsigned
glsl_type::count_attribute_slots() const
{
   /* From page 31 (page 37 of the PDF) of the GLSL 1.50 spec:
    *
    *     "A scalar input counts the same amount against this limit as a vec4,
    *     so applications may want to consider packing groups of four
    *     unrelated float inputs together into a vector to better utilize the
    *     capabilities of the underlying hardware. A matrix input will use up
    *     multiple locations.  The number of locations used will equal the
    *     number of columns in the matrix."
    *
    * The spec does not explicitly say how arrays are counted.  However, it
    * should be safe to assume the total number of slots consumed by an array
    * is the number of entries in the array multiplied by the number of slots
    * consumed by a single element of the array.
    */

   if (this->is_array())
      return this->array_size() * this->element_type()->count_attribute_slots();

   if (this->is_matrix())
      return this->matrix_columns;

   return 1;
}