llvmpipe: Use struct lp_shader_input in the interpolator.

Eliminates all this identical yet slightly different code to decide how
shader inputs should be interpolated.

As bonus, don't interpolate the position twice when it is listed in the
TGSI shader inputs.

1 files changed, 52 insertions, 25 deletions

diff --git a/src/gallium/drivers/llvmpipe/lp_setup_tri.c b/src/gallium/drivers/llvmpipe/lp_setup_tri.c
index b560061542..0557d35f8b 100644
--- a/src/gallium/drivers/llvmpipe/lp_setup_tri.c
+++ b/src/gallium/drivers/llvmpipe/lp_setup_tri.c
@@ -147,20 +147,32 @@ setup_fragcoord_coef(struct lp_setup_context *setup,
                      unsigned slot,
                      const float (*v1)[4],
                      const float (*v2)[4],
-                     const float (*v3)[4])
+                     const float (*v3)[4],
+                     unsigned usage_mask)
 {
    /*X*/
-   tri->inputs.a0[slot][0] = 0.0;
-   tri->inputs.dadx[slot][0] = 1.0;
-   tri->inputs.dady[slot][0] = 0.0;
+   if (usage_mask & TGSI_WRITEMASK_X) {
+      tri->inputs.a0[slot][0] = 0.0;
+      tri->inputs.dadx[slot][0] = 1.0;
+      tri->inputs.dady[slot][0] = 0.0;
+   }
+
    /*Y*/
-   tri->inputs.a0[slot][1] = 0.0;
-   tri->inputs.dadx[slot][1] = 0.0;
-   tri->inputs.dady[slot][1] = 1.0;
+   if (usage_mask & TGSI_WRITEMASK_Y) {
+      tri->inputs.a0[slot][1] = 0.0;
+      tri->inputs.dadx[slot][1] = 0.0;
+      tri->inputs.dady[slot][1] = 1.0;
+   }
+
    /*Z*/
-   linear_coef(setup, tri, oneoverarea, slot, v1, v2, v3, 0, 2);
+   if (usage_mask & TGSI_WRITEMASK_Z) {
+      linear_coef(setup, tri, oneoverarea, slot, v1, v2, v3, 0, 2);
+   }
+
    /*W*/
-   linear_coef(setup, tri, oneoverarea, slot, v1, v2, v3, 0, 3);
+   if (usage_mask & TGSI_WRITEMASK_W) {
+      linear_coef(setup, tri, oneoverarea, slot, v1, v2, v3, 0, 3);
+   }
 }
 
 
@@ -171,13 +183,21 @@ setup_fragcoord_coef(struct lp_setup_context *setup,
 static void setup_facing_coef( struct lp_setup_context *setup,
                                struct lp_rast_triangle *tri,
                                unsigned slot,
-                               boolean frontface )
+                               boolean frontface,
+                               unsigned usage_mask)
 {
    /* convert TRUE to 1.0 and FALSE to -1.0 */
-   constant_coef( setup, tri, slot, 2.0f * frontface - 1.0f, 0 );
-   constant_coef( setup, tri, slot, 0.0f, 1 ); /* wasted */
-   constant_coef( setup, tri, slot, 0.0f, 2 ); /* wasted */
-   constant_coef( setup, tri, slot, 0.0f, 3 ); /* wasted */
+   if (usage_mask & TGSI_WRITEMASK_X)
+      constant_coef( setup, tri, slot, 2.0f * frontface - 1.0f, 0 );
+
+   if (usage_mask & TGSI_WRITEMASK_Y)
+      constant_coef( setup, tri, slot, 0.0f, 1 ); /* wasted */
+
+   if (usage_mask & TGSI_WRITEMASK_Z)
+      constant_coef( setup, tri, slot, 0.0f, 2 ); /* wasted */
+
+   if (usage_mask & TGSI_WRITEMASK_W)
+      constant_coef( setup, tri, slot, 0.0f, 3 ); /* wasted */
 }
 
 
@@ -192,58 +212,65 @@ static void setup_tri_coefficients( struct lp_setup_context *setup,
 				    const float (*v3)[4],
 				    boolean frontface)
 {
+   unsigned fragcoord_usage_mask = TGSI_WRITEMASK_XYZ;
    unsigned slot;
 
-   /* The internal position input is in slot zero:
-    */
-   setup_fragcoord_coef(setup, tri, oneoverarea, 0, v1, v2, v3);
-
    /* setup interpolation for all the remaining attributes:
     */
    for (slot = 0; slot < setup->fs.nr_inputs; slot++) {
       unsigned vert_attr = setup->fs.input[slot].src_index;
+      unsigned usage_mask = setup->fs.input[slot].usage_mask;
       unsigned i;
 
       switch (setup->fs.input[slot].interp) {
       case LP_INTERP_CONSTANT:
          if (setup->flatshade_first) {
             for (i = 0; i < NUM_CHANNELS; i++)
-               if (setup->fs.input[slot].usage_mask & (1 << i))
+               if (usage_mask & (1 << i))
                   constant_coef(setup, tri, slot+1, v1[vert_attr][i], i);
          }
          else {
             for (i = 0; i < NUM_CHANNELS; i++)
-               if (setup->fs.input[slot].usage_mask & (1 << i))
+               if (usage_mask & (1 << i))
                   constant_coef(setup, tri, slot+1, v3[vert_attr][i], i);
          }
          break;
 
       case LP_INTERP_LINEAR:
          for (i = 0; i < NUM_CHANNELS; i++)
-            if (setup->fs.input[slot].usage_mask & (1 << i))
+            if (usage_mask & (1 << i))
                linear_coef(setup, tri, oneoverarea, slot+1, v1, v2, v3, vert_attr, i);
          break;
 
       case LP_INTERP_PERSPECTIVE:
          for (i = 0; i < NUM_CHANNELS; i++)
-            if (setup->fs.input[slot].usage_mask & (1 << i))
+            if (usage_mask & (1 << i))
                perspective_coef(setup, tri, oneoverarea, slot+1, v1, v2, v3, vert_attr, i);
+         fragcoord_usage_mask |= TGSI_WRITEMASK_W;
          break;
 
       case LP_INTERP_POSITION:
-         /* XXX: fix me - duplicates the values in slot zero.
+         /*
+          * The generated pixel interpolators will pick up the coeffs from
+          * slot 0, so all need to ensure that the usage mask is covers all
+          * usages.
           */
-         setup_fragcoord_coef(setup, tri, oneoverarea, slot+1, v1, v2, v3);
+         fragcoord_usage_mask |= usage_mask;
          break;
 
       case LP_INTERP_FACING:
-         setup_facing_coef(setup, tri, slot+1, frontface);
+         setup_facing_coef(setup, tri, slot+1, frontface, usage_mask);
          break;
 
       default:
          assert(0);
       }
    }
+
+   /* The internal position input is in slot zero:
+    */
+   setup_fragcoord_coef(setup, tri, oneoverarea, 0, v1, v2, v3,
+                        fragcoord_usage_mask);
 }