gallium: add PIPE_CAP_CONSTANT_BUFFER_OFFSET_ALIGNMENT

This is required for any serious constant buffer support.
Constant buffer offsets on ATI and NVIDIA DX10 and DX11 GPUs must be
a multiple of 256.

In OpenGL, this can be queried via GL_UNIFORM_BUFFER_OFFSET_ALIGNMENT.

src/gallium/docs/source/screen.rst

@@ -116,6 +116,8 @@ The integer capabilities:
 * ``PIPE_CAP_USER_CONSTANT_BUFFERS``: Whether user constant buffers are
   supported. If not, the state tracker must upload constants which are not in hw
   resources.
+* ``PIPE_CAP_CONSTANT_BUFFER_OFFSET_ALIGNMENT``: Describes the required
+  alignment of pipe_constant_buffer::buffer_offset.
 
 
 

src/gallium/drivers/i915/i915_screen.c

@@ -208,6 +208,9 @@ i915_get_param(struct pipe_screen *screen, enum pipe_cap cap)
    case PIPE_CAP_QUADS_FOLLOW_PROVOKING_VERTEX_CONVENTION:
       return 0;
 
+   case PIPE_CAP_CONSTANT_BUFFER_OFFSET_ALIGNMENT:
+      return 16;
+
    /* Features we can lie about (boolean caps). */
    case PIPE_CAP_OCCLUSION_QUERY:
       return is->debug.lie ? 1 : 0;

src/gallium/drivers/llvmpipe/lp_screen.c

@@ -163,6 +163,8 @@ llvmpipe_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_USER_INDEX_BUFFERS:
    case PIPE_CAP_USER_CONSTANT_BUFFERS:
       return 1;
+   case PIPE_CAP_CONSTANT_BUFFER_OFFSET_ALIGNMENT:
+      return 16;
    default:
       return 0;
    }

src/gallium/drivers/nv30/nv30_screen.c

@@ -82,6 +82,8 @@ nv30_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_USER_INDEX_BUFFERS:
    case PIPE_CAP_USER_CONSTANT_BUFFERS:
       return 1;
+   case PIPE_CAP_CONSTANT_BUFFER_OFFSET_ALIGNMENT:
+      return 16;
    /* nv4x capabilities */
    case PIPE_CAP_BLEND_EQUATION_SEPARATE:
    case PIPE_CAP_NPOT_TEXTURES:

src/gallium/drivers/nv50/nv50_screen.c

@@ -154,6 +154,8 @@ nv50_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_USER_INDEX_BUFFERS:
    case PIPE_CAP_USER_CONSTANT_BUFFERS:
       return 1;
+   case PIPE_CAP_CONSTANT_BUFFER_OFFSET_ALIGNMENT:
+      return 256;
    case PIPE_CAP_VERTEX_BUFFER_OFFSET_4BYTE_ALIGNED_ONLY:
    case PIPE_CAP_VERTEX_BUFFER_STRIDE_4BYTE_ALIGNED_ONLY:
    case PIPE_CAP_VERTEX_ELEMENT_SRC_OFFSET_4BYTE_ALIGNED_ONLY:

src/gallium/drivers/nvc0/nvc0_screen.c

@@ -144,6 +144,8 @@ nvc0_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_USER_INDEX_BUFFERS:
    case PIPE_CAP_USER_CONSTANT_BUFFERS:
       return 1;
+   case PIPE_CAP_CONSTANT_BUFFER_OFFSET_ALIGNMENT:
+      return 256;
    case PIPE_CAP_VERTEX_BUFFER_OFFSET_4BYTE_ALIGNED_ONLY:
    case PIPE_CAP_VERTEX_BUFFER_STRIDE_4BYTE_ALIGNED_ONLY:
    case PIPE_CAP_VERTEX_ELEMENT_SRC_OFFSET_4BYTE_ALIGNED_ONLY:

src/gallium/drivers/r300/r300_screen.c

@@ -110,6 +110,9 @@ static int r300_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
         case PIPE_CAP_USER_CONSTANT_BUFFERS:
             return 1;
 
+        case PIPE_CAP_CONSTANT_BUFFER_OFFSET_ALIGNMENT:
+            return 16;
+
         case PIPE_CAP_GLSL_FEATURE_LEVEL:
             return 120;
 

src/gallium/drivers/r600/r600_pipe.c

@@ -407,6 +407,9 @@ static int r600_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
 	case PIPE_CAP_USER_CONSTANT_BUFFERS:
 		return 1;
 
+	case PIPE_CAP_CONSTANT_BUFFER_OFFSET_ALIGNMENT:
+		return 256;
+
 	case PIPE_CAP_GLSL_FEATURE_LEVEL:
 		return rscreen->glsl_feature_level;
 

src/gallium/drivers/radeonsi/radeonsi_pipe.c

@@ -349,6 +349,9 @@ static int r600_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
 	case PIPE_CAP_USER_CONSTANT_BUFFERS:
 		return 1;
 
+	case PIPE_CAP_CONSTANT_BUFFER_OFFSET_ALIGNMENT:
+		return 256;
+
 	case PIPE_CAP_GLSL_FEATURE_LEVEL:
 		return debug_get_bool_option("R600_GLSL130", FALSE) ? 130 : 120;
 

src/gallium/drivers/softpipe/sp_screen.c

@@ -142,6 +142,8 @@ softpipe_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_USER_INDEX_BUFFERS:
    case PIPE_CAP_USER_CONSTANT_BUFFERS:
       return 1;
+   case PIPE_CAP_CONSTANT_BUFFER_OFFSET_ALIGNMENT:
+      return 16;
    default:
       return 0;
    }

src/gallium/drivers/svga/svga_screen.c

@@ -164,6 +164,8 @@ svga_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_USER_INDEX_BUFFERS:
    case PIPE_CAP_USER_CONSTANT_BUFFERS:
       return 1;
+   case PIPE_CAP_CONSTANT_BUFFER_OFFSET_ALIGNMENT:
+      return 16;
 
    case PIPE_CAP_MAX_TEXTURE_2D_LEVELS:
       {

src/gallium/include/pipe/p_defines.h

@@ -478,7 +478,8 @@ enum pipe_cap {
    PIPE_CAP_VERTEX_BUFFER_STRIDE_4BYTE_ALIGNED_ONLY = 66,
    PIPE_CAP_VERTEX_ELEMENT_SRC_OFFSET_4BYTE_ALIGNED_ONLY = 67,
    PIPE_CAP_USER_INDEX_BUFFERS = 68,
-   PIPE_CAP_USER_CONSTANT_BUFFERS = 69
+   PIPE_CAP_USER_CONSTANT_BUFFERS = 69,
+   PIPE_CAP_CONSTANT_BUFFER_OFFSET_ALIGNMENT = 70
 };
 
 /**