[Mesa-dev] [PATCH] mesa: shrink size of gl_array_attributes (v2)

[Brian Paul]

Inspired by Marek's earlier patch, but even smaller.  Sort fields from
largest to smallest.  Use bitfields for more fields (sometimes with an
extra bit for MSVC).  Reduce Stride field to GLshort.

Note that some fields cannot be bitfields because they're accessed via
pointers (such as for glEnableClientState(GL_VERTEX_ARRAY) to set the
Enabled field).

Reduces size from 48 to 24 bytes.
Also reduces size of gl_vertex_array_object from 3632 to 2864 bytes.

And add some assertions in init_array().

v2: use s/GLuint/unsigned/, improve commit comments.
---
 src/mesa/main/arrayobj.c |  4 ++++
 src/mesa/main/mtypes.h   | 20 +++++++++++---------
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/src/mesa/main/arrayobj.c b/src/mesa/main/arrayobj.c
index 1951638..7208f4c 100644
--- a/src/mesa/main/arrayobj.c
+++ b/src/mesa/main/arrayobj.c
@@ -233,7 +233,9 @@ init_array(struct gl_context *ctx,
            struct gl_vertex_array_object *vao,
            gl_vert_attrib index, GLint size, GLint type)
 {
+   assert(index < ARRAY_SIZE(vao->VertexAttrib));
    struct gl_array_attributes *array = &vao->VertexAttrib[index];
+   assert(index < ARRAY_SIZE(vao->BufferBinding));
    struct gl_vertex_buffer_binding *binding = &vao->BufferBinding[index];
 
    array->Size = size;
@@ -247,6 +249,8 @@ init_array(struct gl_context *ctx,
    array->Integer = GL_FALSE;
    array->Doubles = GL_FALSE;
    array->_ElementSize = size * _mesa_sizeof_type(type);
+   ASSERT_BITFIELD_SIZE(struct gl_array_attributes, BufferBindingIndex,
+                        VERT_ATTRIB_MAX - 1);
    array->BufferBindingIndex = index;
 
    binding->Offset = 0;
diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
index 329402a..dccc152 100644
--- a/src/mesa/main/mtypes.h
+++ b/src/mesa/main/mtypes.h
@@ -1528,19 +1528,21 @@ struct gl_vertex_array
  */
 struct gl_array_attributes
 {
-   GLint Size;              /**< Components per element (1,2,3,4) */
+   /** Points to client array data. Not used when a VBO is bound */
+   const GLubyte *Ptr;
+   /** Offset of the first element relative to the binding offset */
+   GLuint RelativeOffset;
+   GLshort Stride;          /**< Stride as specified with gl*Pointer() */
    GLenum16 Type;           /**< Datatype: GL_FLOAT, GL_INT, etc */
    GLenum16 Format;         /**< Default: GL_RGBA, but may be GL_BGRA */
-   GLsizei Stride;          /**< Stride as specified with gl*Pointer() */
-   const GLubyte *Ptr;      /**< Points to client array data. Not used when a VBO is bound */
-   GLintptr RelativeOffset; /**< Offset of the first element relative to the binding offset */
    GLboolean Enabled;       /**< Whether the array is enabled */
-   GLboolean Normalized;    /**< Fixed-point values are normalized when converted to floats */
-   GLboolean Integer;       /**< Fixed-point values are not converted to floats */
-   GLboolean Doubles;       /**< double precision values are not converted to floats */
-   GLuint _ElementSize;     /**< Size of each element in bytes */
+   GLubyte Size;            /**< Components per element (1,2,3,4) */
+   unsigned Normalized:1;   /**< Fixed-point values are normalized when converted to floats */
+   unsigned Integer:1;      /**< Fixed-point values are not converted to floats */
+   unsigned Doubles:1;      /**< double precision values are not converted to floats */
+   unsigned _ElementSize:8; /**< Size of each element in bytes */
    /** Index into gl_vertex_array_object::BufferBinding[] array */
-   GLuint BufferBindingIndex;
+   unsigned BufferBindingIndex:6;
 };
 
 
-- 
2.7.4