CELL: fix use of stencil value mask

The Cell stencil tests were completely ignoring the stencil value mask.
Now the original code paths are still used if the stencil value mask
is all 1s; but code to use the mask for the stencil value and reference
value comparisons is now emitted if the mask is not all 1s.

src/gallium/drivers/cell/ppu/cell_gen_fragment.c

@@ -1141,13 +1141,17 @@ gen_colormask(struct spe_function *f,
  * access to the Compare Immediate instructions where we don't in 
  * gen_depth_test(), which is what makes us very different.
  *
+ * There's some added complexity if there's a non-trivial state->mask
+ * value; then stencil and reference both must be masked
+ *
  * The return value in the stencil_pass_reg is a bitmask of valid
  * fragments that also passed the stencil test.  The bitmask of valid
- * fragments that failed would be found in (mask_reg & ~stencil_pass_reg).
+ * fragments that failed would be found in (fragment_mask_reg & ~stencil_pass_reg).
  */
 static void
 gen_stencil_test(struct spe_function *f, const struct pipe_stencil_state *state, 
-                 unsigned int mask_reg, unsigned int fbS_reg, 
+                 unsigned int stencil_max_value,
+                 unsigned int fragment_mask_reg, unsigned int fbS_reg, 
                  unsigned int stencil_pass_reg)
 {
    /* Generate code that puts the set of passing fragments into the stencil_pass_reg
@@ -1155,68 +1159,134 @@ gen_stencil_test(struct spe_function *f, const struct pipe_stencil_state *state,
     */
    switch (state->func) {
    case PIPE_FUNC_EQUAL:
-      /* stencil_pass = mask & (s == reference) */
-      spe_compare_equal_uint(f, stencil_pass_reg, fbS_reg, state->ref_value);
-      spe_and(f, stencil_pass_reg, mask_reg, stencil_pass_reg);
+      if (state->value_mask == stencil_max_value) {
+         /* stencil_pass = fragment_mask & (s == reference) */
+         spe_compare_equal_uint(f, stencil_pass_reg, fbS_reg, state->ref_value);
+         spe_and(f, stencil_pass_reg, fragment_mask_reg, stencil_pass_reg);
+      }
+      else {
+         /* stencil_pass = fragment_mask & ((s&mask) == (reference&mask)) */
+         unsigned int tmp_masked_stencil = spe_allocate_available_register(f);
+         spe_and_uint(f, tmp_masked_stencil, fbS_reg, state->value_mask);
+         spe_compare_equal_uint(f, stencil_pass_reg, tmp_masked_stencil, state->value_mask & state->ref_value);
+         spe_and(f, stencil_pass_reg, fragment_mask_reg, stencil_pass_reg);
+         spe_release_register(f, tmp_masked_stencil);
+      }
       break;
 
    case PIPE_FUNC_NOTEQUAL:
-      /* stencil_pass = mask & ~(s == reference) */
-      spe_compare_equal_uint(f, stencil_pass_reg, fbS_reg, state->ref_value);
-      spe_andc(f, stencil_pass_reg, mask_reg, stencil_pass_reg);
+      if (state->value_mask == stencil_max_value) {
+         /* stencil_pass = fragment_mask & ~(s == reference) */
+         spe_compare_equal_uint(f, stencil_pass_reg, fbS_reg, state->ref_value);
+         spe_andc(f, stencil_pass_reg, fragment_mask_reg, stencil_pass_reg);
+      }
+      else {
+         /* stencil_pass = fragment_mask & ~((s&mask) == (reference&mask)) */
+         unsigned int tmp_masked_stencil = spe_allocate_available_register(f);
+         spe_and_uint(f, tmp_masked_stencil, fbS_reg, state->value_mask);
+         spe_compare_equal_uint(f, stencil_pass_reg, tmp_masked_stencil, state->value_mask & state->ref_value);
+         spe_andc(f, stencil_pass_reg, fragment_mask_reg, stencil_pass_reg);
+         spe_release_register(f, tmp_masked_stencil);
+      }
       break;
 
    case PIPE_FUNC_GREATER:
-      /* stencil_pass = mask & (s > reference) */
-      spe_compare_greater_uint(f, stencil_pass_reg, fbS_reg, state->ref_value);
-      spe_and(f, stencil_pass_reg, mask_reg, stencil_pass_reg);
+      if (state->value_mask == stencil_max_value) {
+         /* stencil_pass = fragment_mask & (s > reference) */
+         spe_compare_greater_uint(f, stencil_pass_reg, fbS_reg, state->ref_value);
+         spe_and(f, stencil_pass_reg, fragment_mask_reg, stencil_pass_reg);
+      }
+      else {
+         /* stencil_pass = fragment_mask & ((s&mask) > (reference&mask)) */
+         unsigned int tmp_masked_stencil = spe_allocate_available_register(f);
+         spe_and_uint(f, tmp_masked_stencil, fbS_reg, state->value_mask);
+         spe_compare_greater_uint(f, stencil_pass_reg, tmp_masked_stencil, state->value_mask & state->ref_value);
+         spe_and(f, stencil_pass_reg, fragment_mask_reg, stencil_pass_reg);
+         spe_release_register(f, tmp_masked_stencil);
+      }
       break;
 
-   case PIPE_FUNC_LESS: {
-      /* stencil_pass = mask & (reference > s) */
-      /* There's no convenient Compare Less Than Immediate instruction, so
-       * we'll have to do this one the harder way, by loading a register and 
-       * comparing directly.  Compare Logical Greater Than Word (clgt) 
-       * treats its operands as unsigned - no sign extension.
-       */
-      unsigned int tmp_reg = spe_allocate_available_register(f);
-      spe_load_uint(f, tmp_reg, state->ref_value);
-      spe_clgt(f, stencil_pass_reg, tmp_reg, fbS_reg);
-      spe_and(f, stencil_pass_reg, mask_reg, stencil_pass_reg);
-      spe_release_register(f, tmp_reg);
+   case PIPE_FUNC_LESS:
+      if (state->value_mask == stencil_max_value) {
+         /* stencil_pass = fragment_mask & (reference > s) */
+         /* There's no convenient Compare Less Than Immediate instruction, so
+          * we'll have to do this one the harder way, by loading a register and 
+          * comparing directly.  Compare Logical Greater Than Word (clgt) 
+          * treats its operands as unsigned - no sign extension.
+          */
+         unsigned int tmp_reg = spe_allocate_available_register(f);
+         spe_load_uint(f, tmp_reg, state->ref_value);
+         spe_clgt(f, stencil_pass_reg, tmp_reg, fbS_reg);
+         spe_and(f, stencil_pass_reg, fragment_mask_reg, stencil_pass_reg);
+         spe_release_register(f, tmp_reg);
+      }
+      else {
+         /* stencil_pass = fragment_mask & ((reference&mask) > (s&mask)) */
+         unsigned int tmp_reg = spe_allocate_available_register(f);
+         unsigned int tmp_masked_stencil = spe_allocate_available_register(f);
+         spe_load_uint(f, tmp_reg, state->value_mask & state->ref_value);
+         spe_and_uint(f, tmp_masked_stencil, fbS_reg, state->value_mask);
+         spe_clgt(f, stencil_pass_reg, tmp_reg, tmp_masked_stencil);
+         spe_and(f, stencil_pass_reg, fragment_mask_reg, stencil_pass_reg);
+         spe_release_register(f, tmp_reg);
+         spe_release_register(f, tmp_masked_stencil);
+      }
       break;
-   }
 
    case PIPE_FUNC_LEQUAL:
-      /* stencil_pass = mask & (s <= reference) = mask & ~(s > reference) */
-      spe_compare_greater_uint(f, stencil_pass_reg, fbS_reg, state->ref_value);
-      spe_andc(f, stencil_pass_reg, mask_reg, stencil_pass_reg);
+      if (state->value_mask == stencil_max_value) {
+         /* stencil_pass = fragment_mask & (s <= reference) 
+          *              = fragment_mask & ~(s > reference) */
+         spe_compare_greater_uint(f, stencil_pass_reg, fbS_reg, state->ref_value);
+         spe_andc(f, stencil_pass_reg, fragment_mask_reg, stencil_pass_reg);
+      }
+      else {
+         /* stencil_pass = fragment_mask & ~((s&mask) > (reference&mask)) */
+         unsigned int tmp_masked_stencil = spe_allocate_available_register(f);
+         spe_and_uint(f, tmp_masked_stencil, fbS_reg, state->value_mask);
+         spe_compare_greater_uint(f, stencil_pass_reg, tmp_masked_stencil, state->value_mask & state->ref_value);
+         spe_andc(f, stencil_pass_reg, fragment_mask_reg, stencil_pass_reg);
+         spe_release_register(f, tmp_masked_stencil);
+      }
       break;
 
-   case PIPE_FUNC_GEQUAL: {
-      /* stencil_pass = mask & (s >= reference) = mask & ~(reference > s) */
-      /* As above, we have to do this by loading a register */
-      unsigned int tmp_reg = spe_allocate_available_register(f);
-      spe_load_uint(f, tmp_reg, state->ref_value);
-      spe_clgt(f, stencil_pass_reg, tmp_reg, fbS_reg);
-      spe_andc(f, stencil_pass_reg, mask_reg, stencil_pass_reg);
-      spe_release_register(f, tmp_reg);
+   case PIPE_FUNC_GEQUAL:
+      if (state->value_mask == stencil_max_value) {
+         /* stencil_pass = fragment_mask & (s >= reference) ]
+          *               = fragment_mask & ~(reference > s) */
+         /* As above, we have to do this by loading a register */
+         unsigned int tmp_reg = spe_allocate_available_register(f);
+         spe_load_uint(f, tmp_reg, state->ref_value);
+         spe_clgt(f, stencil_pass_reg, tmp_reg, fbS_reg);
+         spe_andc(f, stencil_pass_reg, fragment_mask_reg, stencil_pass_reg);
+         spe_release_register(f, tmp_reg);
+      }
+      else {
+         /* stencil_pass = fragment_mask & ~((reference&mask) > (s&mask)) */
+         unsigned int tmp_reg = spe_allocate_available_register(f);
+         unsigned int tmp_masked_stencil = spe_allocate_available_register(f);
+         spe_load_uint(f, tmp_reg, state->ref_value & state->value_mask);
+         spe_and_uint(f, tmp_masked_stencil, fbS_reg, state->value_mask);
+         spe_clgt(f, stencil_pass_reg, tmp_reg, tmp_masked_stencil);
+         spe_andc(f, stencil_pass_reg, fragment_mask_reg, stencil_pass_reg);
+         spe_release_register(f, tmp_reg);
+         spe_release_register(f, tmp_masked_stencil);
+      }
       break;
-   }
 
    case PIPE_FUNC_NEVER:
-      /* stencil_pass = mask & 0 = 0 */
+      /* stencil_pass = fragment_mask & 0 = 0 */
       spe_load_uint(f, stencil_pass_reg, 0);
       break;
 
    case PIPE_FUNC_ALWAYS:
-      /* stencil_pass = mask & 1 = mask */
-      spe_move(f, stencil_pass_reg, mask_reg);
+      /* stencil_pass = fragment_mask & 1 = fragment_mask */
+      spe_move(f, stencil_pass_reg, fragment_mask_reg);
       break;
    }
 
    /* The fragments that passed the stencil test are now in stencil_pass_reg.
-    * The fragments that failed would be (mask_reg & ~stencil_pass_reg).
+    * The fragments that failed would be (fragment_mask_reg & ~stencil_pass_reg).
     */
 }
 
@@ -1596,7 +1666,7 @@ gen_stencil_depth_test(struct spe_function *f,
     */
    spe_comment(f, 0, "Running basic stencil test");
    stencil_pass_reg = spe_allocate_available_register(f);
-   gen_stencil_test(f, &dsa->stencil[0], mask_reg, fbS_reg, stencil_pass_reg);
+   gen_stencil_test(f, &dsa->stencil[0], 0xff, mask_reg, fbS_reg, stencil_pass_reg);
 
    /* If two-sided stenciling is on, generate code to run the stencil
     * test on the backfacing stencil as well, and combine the two results
@@ -1605,7 +1675,7 @@ gen_stencil_depth_test(struct spe_function *f,
    if (dsa->stencil[1].enabled) {
       unsigned int temp_reg = spe_allocate_available_register(f);
       spe_comment(f, 0, "Running backface stencil test");
-      gen_stencil_test(f, &dsa->stencil[1], mask_reg, fbS_reg, temp_reg);
+      gen_stencil_test(f, &dsa->stencil[1], 0xff, mask_reg, fbS_reg, temp_reg);
       spe_selb(f, stencil_pass_reg, stencil_pass_reg, temp_reg, facing_reg);
       spe_release_register(f, temp_reg);
    }