mesa: Add shader storage buffer support to struct gl_context

This includes the array of bindings, the current buffer bound to the
GL_SHADER_STORAGE_BUFFER target and a set of general limits and default
values for shader storage buffers.

v2:
- Use spec values for the new defined constants (Jordan)

Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

src/mesa/main/bufferobj.c

@@ -112,6 +112,11 @@ get_buffer_target(struct gl_context *ctx, GLenum target)
          return &ctx->UniformBuffer;
       }
       break;
+   case GL_SHADER_STORAGE_BUFFER:
+      if (ctx->Extensions.ARB_shader_storage_buffer_object) {
+         return &ctx->ShaderStorageBuffer;
+      }
+      break;
    case GL_ATOMIC_COUNTER_BUFFER:
       if (ctx->Extensions.ARB_shader_atomic_counters) {
          return &ctx->AtomicBuffer;

src/mesa/main/config.h

@@ -171,8 +171,10 @@
 #define MAX_PROGRAM_LOCAL_PARAMS       4096
 #define MAX_UNIFORMS                   4096
 #define MAX_UNIFORM_BUFFERS            15 /* + 1 default uniform buffer */
+#define MAX_SHADER_STORAGE_BUFFERS     7  /* + 1 default shader storage buffer */
 /* 6 is for vertex, hull, domain, geometry, fragment, and compute shader. */
 #define MAX_COMBINED_UNIFORM_BUFFERS   (MAX_UNIFORM_BUFFERS * 6)
+#define MAX_COMBINED_SHADER_STORAGE_BUFFERS   (MAX_SHADER_STORAGE_BUFFERS * 6)
 #define MAX_ATOMIC_COUNTERS            4096
 /* 6 is for vertex, hull, domain, geometry, fragment, and compute shader. */
 #define MAX_COMBINED_ATOMIC_BUFFERS    (MAX_UNIFORM_BUFFERS * 6)

src/mesa/main/context.c

@@ -597,6 +597,12 @@ _mesa_init_constants(struct gl_constants *consts, gl_api api)
    consts->MaxUniformBlockSize = 16384;
    consts->UniformBufferOffsetAlignment = 1;
 
+   /** GL_ARB_shader_storage_buffer_object */
+   consts->MaxCombinedShaderStorageBlocks = 8;
+   consts->MaxShaderStorageBufferBindings = 8;
+   consts->MaxShaderStorageBlockSize = 16 * 1024 * 1024;
+   consts->ShaderStorageBufferOffsetAlignment = 256;
+
    /* GL_ARB_explicit_uniform_location, GL_MAX_UNIFORM_LOCATIONS */
    consts->MaxUserAssignableUniformLocations =
       4 * MESA_SHADER_STAGES * MAX_UNIFORMS;

src/mesa/main/mtypes.h

@@ -3403,6 +3403,15 @@ struct gl_constants
    GLuint UniformBufferOffsetAlignment;
    /** @} */
 
+   /** @{
+    * GL_ARB_shader_storage_buffer_object
+    */
+   GLuint MaxCombinedShaderStorageBlocks;
+   GLuint MaxShaderStorageBufferBindings;
+   GLuint MaxShaderStorageBlockSize;
+   GLuint ShaderStorageBufferOffsetAlignment;
+   /** @} */
+
    /**
     * GL_ARB_explicit_uniform_location
     */
@@ -4049,6 +4058,20 @@ struct gl_uniform_buffer_binding
    GLboolean AutomaticSize;
 };
 
+struct gl_shader_storage_buffer_binding
+{
+   struct gl_buffer_object *BufferObject;
+   /** Start of shader storage block data in the buffer */
+   GLintptr Offset;
+   /** Size of data allowed to be referenced from the buffer (in bytes) */
+   GLsizeiptr Size;
+   /**
+    * glBindBufferBase() indicates that the Size should be ignored and only
+    * limited by the current size of the BufferObject.
+    */
+   GLboolean AutomaticSize;
+};
+
 /**
  * ARB_shader_image_load_store image unit.
  */
@@ -4295,6 +4318,12 @@ struct gl_context
     */
    struct gl_buffer_object *UniformBuffer;
 
+   /**
+    * Current GL_ARB_shader_storage_buffer_object binding referenced by
+    * GL_SHADER_STORAGE_BUFFER target for glBufferData, glMapBuffer, etc.
+    */
+   struct gl_buffer_object *ShaderStorageBuffer;
+
    /**
     * Array of uniform buffers for GL_ARB_uniform_buffer_object and GL 3.1.
     * This is set up using glBindBufferRange() or glBindBufferBase().  They are
@@ -4304,6 +4333,15 @@ struct gl_context
    struct gl_uniform_buffer_binding
       UniformBufferBindings[MAX_COMBINED_UNIFORM_BUFFERS];
 
+   /**
+    * Array of shader storage buffers for ARB_shader_storage_buffer_object
+    * and GL 4.3. This is set up using glBindBufferRange() or
+    * glBindBufferBase().  They are associated with shader storage blocks by
+    * glShaderStorageBlockBinding()'s state in the shader program.
+    */
+   struct gl_shader_storage_buffer_binding
+      ShaderStorageBufferBindings[MAX_COMBINED_SHADER_STORAGE_BUFFERS];
+
    /**
     * Object currently associated with the GL_ATOMIC_COUNTER_BUFFER
     * target.