i965/fs: Enumerate logical fb writes arguments

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.

v2:
Remove explicit numbering from the enumeration (Matt).
Use a real naming scheme, and reference it in the opcode definition (Curro)
Add a missed hardcoded logical position in get_lowered_simd_width (Ben)
Add an assertion to make sure the component numbering is correct (Ben)

Cc: Matt Turner <[email protected]>
Cc: Francisco Jerez <[email protected]>
Signed-off-by: Ben Widawsky <[email protected]>
Reviewed-by: Kenneth Graunke <[email protected]>

1 files changed, 13 insertions, 9 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_defines.h b/src/mesa/drivers/dri/i965/brw_defines.h
index bd7d0b1c9a7..457f49c9709 100644
--- a/src/mesa/drivers/dri/i965/brw_defines.h
+++ b/src/mesa/drivers/dri/i965/brw_defines.h
@@ -911,15 +911,9 @@ 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).
+    * individual sources instead of as a single payload blob. The
+    * position/ordering of the arguments are defined by the enum
+    * fb_write_logical_srcs.
     */
    FS_OPCODE_FB_WRITE_LOGICAL,
 
@@ -1330,6 +1324,16 @@ enum brw_urb_write_flags {
       BRW_URB_WRITE_ALLOCATE | BRW_URB_WRITE_COMPLETE,
 };
 
+enum fb_write_logical_srcs {
+   FB_WRITE_LOGICAL_SRC_COLOR0,      /* REQUIRED */
+   FB_WRITE_LOGICAL_SRC_COLOR1,      /* for dual source blend messages */
+   FB_WRITE_LOGICAL_SRC_SRC0_ALPHA,
+   FB_WRITE_LOGICAL_SRC_SRC_DEPTH,   /* gl_FragDepth */
+   FB_WRITE_LOGICAL_SRC_DST_DEPTH,   /* GEN4-5: passthrough from thread */
+   FB_WRITE_LOGICAL_SRC_OMASK,       /* Sample Mask (gl_SampleMask) */
+   FB_WRITE_LOGICAL_SRC_COMPONENTS,  /* REQUIRED */
+};
+
 #ifdef __cplusplus
 /**
  * Allow brw_urb_write_flags enums to be ORed together.