[Mesa-dev] [PATCH 2/6] i965/fs: Enumerate logical fb writes arguments

[Matt Turner]

On Tue, Oct 20, 2015 at 2:29 PM, Ben Widawsky
<benjamin.widawsky at intel.com> wrote:
> Gen9 adds the ability to write out a stencil value, so we need to expand the
> virtual payload by one. Abstracting this now makes that change easier to read.
>
> I was admittedly confused early on about some of the hardcoding. If people
> believe the resulting code is inferior, I am not super attached to the patch.
>
> Cc: Francisco Jerez <currojerez at riseup.net>
> Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
> ---
>  src/mesa/drivers/dri/i965/brw_defines.h | 18 ++++++++++--------
>  src/mesa/drivers/dri/i965/brw_fs.cpp    | 21 +++++++++++----------
>  2 files changed, 21 insertions(+), 18 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_defines.h b/src/mesa/drivers/dri/i965/brw_defines.h
> index 7a5ee1b..e06c9d6 100644
> --- a/src/mesa/drivers/dri/i965/brw_defines.h
> +++ b/src/mesa/drivers/dri/i965/brw_defines.h
> @@ -912,14 +912,6 @@ enum opcode {
>     /**
>      * Same as FS_OPCODE_FB_WRITE but expects its arguments separately as
>      * individual sources instead of as a single payload blob:
> -    *
> -    * Source 0: [required] Color 0.
> -    * Source 1: [optional] Color 1 (for dual source blend messages).
> -    * Source 2: [optional] Src0 Alpha.
> -    * Source 3: [optional] Source Depth (gl_FragDepth)
> -    * Source 4: [optional (gen4-5)] Destination Depth passthrough from thread
> -    * Source 5: [optional] Sample Mask (gl_SampleMask).
> -    * Source 6: [required] Number of color components (as a UD immediate).
>      */
>     FS_OPCODE_FB_WRITE_LOGICAL,
>
> @@ -1318,6 +1310,16 @@ enum brw_urb_write_flags {
>        BRW_URB_WRITE_ALLOCATE | BRW_URB_WRITE_COMPLETE,
>  };
>
> +enum fb_write_logical_args {
> +   FB_WRITE_COLOR0 = 0,      /* REQUIRED */
> +   FB_WRITE_COLOR1 = 1,      /* for dual source blend messages */
> +   FB_WRITE_SRC0_ALPHA = 2,
> +   FB_WRITE_SRC_DEPTH = 3,   /* gl_FragDepth */
> +   FB_WRITE_DST_DEPTH = 4,   /* GEN4-5: passthrough from thread */
> +   FB_WRITE_OMASK = 5,       /* Sample Mask (gl_SampleMask) */
> +   FB_WRITE_COMPONENTS = 6,  /* REQUIRED */

Do we gain anything by assigning values explicitly?