[Mesa-dev] [PATCH] i965/sbe: fix number of inputs for active components

[Iago Toral Quiroga]

In 16631ca30ea6 we fixed gen9 active components to account for padded
inputs in the URB, which we can have with SSO programs. To do that,
instead of going through the bitfield of inputs (which doesn't include
padding information), we compute the number of inputs from the size
of the URB entry.

Unfortunately, there are some special inputs that are not stored in
the URB and that we also need to account for. These special inputs
are identified and handled during calculate_attr_overrides(), so this
patch modifies this function to return a value with the total number
of inputs, including the ones that are not stored in the URB, so we
can use that number to program the correct number of active components.

This fixes a regression in a WebGL program that uses Point Sprite
functionality (specifically, VARYING_SLOT_PNTC).

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105224
---
 src/mesa/drivers/dri/i965/genX_state_upload.c | 31 ++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 8 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/genX_state_upload.c b/src/mesa/drivers/dri/i965/genX_state_upload.c
index 8668abd591..617f0ab2c4 100644
--- a/src/mesa/drivers/dri/i965/genX_state_upload.c
+++ b/src/mesa/drivers/dri/i965/genX_state_upload.c
@@ -1015,7 +1015,7 @@ genX(get_attr_override)(struct GENX(SF_OUTPUT_ATTRIBUTE_DETAIL) *attr,
 }
 
 
-static void
+static int
 genX(calculate_attr_overrides)(const struct brw_context *brw,
                                struct GENX(SF_OUTPUT_ATTRIBUTE_DETAIL) *attr_overrides,
                                uint32_t *point_sprite_enables,
@@ -1064,6 +1064,7 @@ genX(calculate_attr_overrides)(const struct brw_context *brw,
     */
    bool drawing_points = brw_is_drawing_points(brw);
 
+   uint32_t no_vue_inputs = 0;
    for (int attr = 0; attr < VARYING_SLOT_MAX; attr++) {
       int input_index = wm_prog_data->urb_setup[attr];
 
@@ -1097,6 +1098,12 @@ genX(calculate_attr_overrides)(const struct brw_context *brw,
                                  &max_source_attr);
       }
 
+      if (point_sprite ||
+          (attr == VARYING_SLOT_PRIMITIVE_ID &&
+           brw->vue_map_geom_out.varying_to_slot[attr] == -1)) {
+         no_vue_inputs++;
+      }
+
       /* The hardware can only do the overrides on 16 overrides at a
        * time, and the other up to 16 have to be lined up so that the
        * input index = the output index.  We'll need to do some
@@ -1124,6 +1131,8 @@ genX(calculate_attr_overrides)(const struct brw_context *brw,
     * Similar text exists for Ivy Bridge.
     */
    *urb_entry_read_length = DIV_ROUND_UP(max_source_attr + 1, 2);
+
+   return *urb_entry_read_length * 2 + no_vue_inputs;
 }
 #endif
 
@@ -3434,11 +3443,12 @@ genX(upload_sbe)(struct brw_context *brw)
        * BRW_NEW_GS_PROG_DATA | BRW_NEW_PRIMITIVE | BRW_NEW_TES_PROG_DATA |
        * BRW_NEW_VUE_MAP_GEOM_OUT
        */
-      genX(calculate_attr_overrides)(brw,
-                                     attr_overrides,
-                                     &point_sprite_enables,
-                                     &urb_entry_read_length,
-                                     &urb_entry_read_offset);
+      int num_inputs =
+         genX(calculate_attr_overrides)(brw,
+                                        attr_overrides,
+                                        &point_sprite_enables,
+                                        &urb_entry_read_length,
+                                        &urb_entry_read_offset);
 
       /* Typically, the URB entry read length and offset should be programmed
        * in 3DSTATE_VS and 3DSTATE_GS; SBE inherits it from the last active
@@ -3459,8 +3469,13 @@ genX(upload_sbe)(struct brw_context *brw)
 #endif
 
 #if GEN_GEN >= 9
-      /* prepare the active component dwords */
-      const int num_inputs = urb_entry_read_length * 2;
+      /* prepare the active component dwords
+       *
+       * For this, we need to account for padded inputs (that we can have with
+       * SSO programs), so we take the number of inputs from the size of the
+       * URB entry. To that, we need to add the number of special inputs, if
+       * any, that are not in the URB (such as point sprite inputs).
+       */
       for (int input_index = 0; input_index < num_inputs; input_index++) {
          sbe.AttributeActiveComponentFormat[input_index] = ACTIVE_COMPONENT_XYZW;
       }
-- 
2.14.1