CELL: stencil bug fixes

Two definitive bugs in stenciling were fixed.

The first, reversed registers in the generated Select Bytes (selb)
instruction, caused the stenciling INCR and DECR operations to
fail dramatically, putting new values in where old values were
supposed to be and vice versa.

The second caused stencil tiles to not be read and written from
main memory by the SPUs.  A per-spu flag, spu.read_depth, was used
to indicate whether the SPU should be reading depth tiles, and was set
only when depth was enabled.  A second flag, spu.read_stencil, was
set when stenciling was enabled, but never referenced.

As stenciling and depth are in the same tiles on the Cell, and there
is no corresponding TAG_WRITE_TILE_STENCIL to complement
TAG_WRITE_TILE_COLOR and TAG_WRITE_TILE_Z, I fixed this by
eliminating the unused "spu.read_stencil", renaming "spu.read_depth"
to "spu.read_depth_stencil", and setting it if either stenciling or
depth is enabled.

I also added an optimization to the fragment ops generation code,
that avoids calculating stencil values and/or stencil writemask
when the stencil operations are all KEEP.

4 files changed, 5 insertions, 7 deletions

diff --git a/src/gallium/drivers/cell/spu/spu_command.c b/src/gallium/drivers/cell/spu/spu_command.c
index 63818d4c46..d726622d94 100644
--- a/src/gallium/drivers/cell/spu/spu_command.c
+++ b/src/gallium/drivers/cell/spu/spu_command.c
@@ -244,8 +244,7 @@ cmd_state_fragment_ops(const struct cell_command_fragment_ops *fops)
       }
    }
 
-   spu.read_depth = spu.depth_stencil_alpha.depth.enabled;
-   spu.read_stencil = spu.depth_stencil_alpha.stencil[0].enabled;
+   spu.read_depth_stencil = (spu.depth_stencil_alpha.depth.enabled || spu.depth_stencil_alpha.stencil[0].enabled);
 }
 
 
diff --git a/src/gallium/drivers/cell/spu/spu_main.h b/src/gallium/drivers/cell/spu/spu_main.h
index 668af10be2..692790c9f3 100644
--- a/src/gallium/drivers/cell/spu/spu_main.h
+++ b/src/gallium/drivers/cell/spu/spu_main.h
@@ -160,8 +160,7 @@ struct spu_global
    tile_t ztile ALIGN16_ATTRIB;
 
    /** Read depth/stencil tiles? */
-   boolean read_depth;
-   boolean read_stencil;
+   boolean read_depth_stencil;
 
    /** Current tiles' status */
    ubyte cur_ctile_status, cur_ztile_status;
diff --git a/src/gallium/drivers/cell/spu/spu_render.c b/src/gallium/drivers/cell/spu/spu_render.c
index 5515bb55c9..7c225e2f27 100644
--- a/src/gallium/drivers/cell/spu/spu_render.c
+++ b/src/gallium/drivers/cell/spu/spu_render.c
@@ -98,7 +98,7 @@ my_tile(uint tx, uint ty)
 static INLINE void
 get_cz_tiles(uint tx, uint ty)
 {
-   if (spu.read_depth) {
+   if (spu.read_depth_stencil) {
       if (spu.cur_ztile_status != TILE_STATUS_CLEAR) {
          //printf("SPU %u: getting Z tile %u, %u\n", spu.init.id, tx, ty);
          get_tile(tx, ty, &spu.ztile, TAG_READ_TILE_Z, 1);
@@ -153,7 +153,7 @@ static INLINE void
 wait_put_cz_tiles(void)
 {
    wait_on_mask(1 << TAG_WRITE_TILE_COLOR);
-   if (spu.read_depth) {
+   if (spu.read_depth_stencil) {
       wait_on_mask(1 << TAG_WRITE_TILE_Z);
    }
 }
diff --git a/src/gallium/drivers/cell/spu/spu_tri.c b/src/gallium/drivers/cell/spu/spu_tri.c
index 4caf7d6b61..5f908159bb 100644
--- a/src/gallium/drivers/cell/spu/spu_tri.c
+++ b/src/gallium/drivers/cell/spu/spu_tri.c
@@ -369,7 +369,7 @@ flush_spans(void)
    }
    ASSERT(spu.cur_ctile_status != TILE_STATUS_DEFINED);
 
-   if (spu.read_depth) {
+   if (spu.read_depth_stencil) {
       if (spu.cur_ztile_status == TILE_STATUS_GETTING) {
          /* wait for mfc_get() to complete */
          //printf("SPU: %u: waiting for ztile\n", spu.init.id);