Mesa (master): llvmpipe: fix bogus layer clamping in setup

[Roland Scheidegger]

Module: Mesa
Branch: master
Commit: e4195acab57a6ab7a604073c46e72b7a49da9e21
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=e4195acab57a6ab7a604073c46e72b7a49da9e21

Author: Roland Scheidegger <sroland at vmware.com>
Date:   Sat Oct 26 04:22:55 2013 +0200

llvmpipe: fix bogus layer clamping in setup

The layer coming from GS needs to be clamped (not sure if that's actually
the correct error behavior but we need something) as the number can be higher
than the amount of layers in the fb. However, this code was using the layer
calculation from the scene, and this was actually calculated in
lp_scene_begin_rasterization() hence too late (so setup was using the value
from the _previous_ scene or just zero if it was the first scene).
Since the value is used in both rasterization and setup, move calculation up
to lp_scene_begin_binning() though it's a bit more inconvenient to calculate
there. (Theoretically could move _all_ code which was in
lp_scene_begin_rasterization() to there, because ever since we got rid of
swizzled render/depth buffers our "map" functions preparing the fb data for
render don't actually change the data in there at all, but it feels like
it would be a hack.)

v2: improve comments

Reviewed-by: Brian Paul <brianp at vmware.com>
Reviewed-by: Jose Fonseca <jfonseca at vmware.com>

---

 src/gallium/drivers/llvmpipe/lp_scene.c |   31 ++++++++++++++++++++++++-------
 src/gallium/drivers/llvmpipe/lp_scene.h |    2 +-
 2 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/src/gallium/drivers/llvmpipe/lp_scene.c b/src/gallium/drivers/llvmpipe/lp_scene.c
index 2abbd25..0296b79 100644
--- a/src/gallium/drivers/llvmpipe/lp_scene.c
+++ b/src/gallium/drivers/llvmpipe/lp_scene.c
@@ -151,7 +151,6 @@ lp_scene_begin_rasterization(struct lp_scene *scene)
 {
    const struct pipe_framebuffer_state *fb = &scene->fb;
    int i;
-   unsigned max_layer = ~0;
 
    //LP_DBG(DEBUG_RAST, "%s\n", __FUNCTION__);
 
@@ -162,7 +161,6 @@ lp_scene_begin_rasterization(struct lp_scene *scene)
                                                            cbuf->u.tex.level);
          scene->cbufs[i].layer_stride = llvmpipe_layer_stride(cbuf->texture,
                                                               cbuf->u.tex.level);
-         max_layer = MIN2(max_layer, cbuf->u.tex.last_layer - cbuf->u.tex.first_layer);
 
          scene->cbufs[i].map = llvmpipe_resource_map(cbuf->texture,
                                                      cbuf->u.tex.level,
@@ -173,7 +171,6 @@ lp_scene_begin_rasterization(struct lp_scene *scene)
          struct llvmpipe_resource *lpr = llvmpipe_resource(cbuf->texture);
          unsigned pixstride = util_format_get_blocksize(cbuf->format);
          scene->cbufs[i].stride = cbuf->texture->width0;
-         max_layer = 0;
 
          scene->cbufs[i].map = lpr->data;
          scene->cbufs[i].map += cbuf->u.buf.first_element * pixstride;
@@ -184,15 +181,12 @@ lp_scene_begin_rasterization(struct lp_scene *scene)
       struct pipe_surface *zsbuf = scene->fb.zsbuf;
       scene->zsbuf.stride = llvmpipe_resource_stride(zsbuf->texture, zsbuf->u.tex.level);
       scene->zsbuf.layer_stride = llvmpipe_layer_stride(zsbuf->texture, zsbuf->u.tex.level);
-      max_layer = MIN2(max_layer, zsbuf->u.tex.last_layer - zsbuf->u.tex.first_layer);
 
       scene->zsbuf.map = llvmpipe_resource_map(zsbuf->texture,
                                                zsbuf->u.tex.level,
                                                zsbuf->u.tex.first_layer,
                                                LP_TEX_USAGE_READ_WRITE);
    }
-
-   scene->fb_max_layer = max_layer;
 }
 
 
@@ -506,6 +500,9 @@ end:
 void lp_scene_begin_binning( struct lp_scene *scene,
                              struct pipe_framebuffer_state *fb, boolean discard )
 {
+   int i;
+   unsigned max_layer = ~0;
+
    assert(lp_scene_is_empty(scene));
 
    scene->discard = discard;
@@ -513,9 +510,29 @@ void lp_scene_begin_binning( struct lp_scene *scene,
 
    scene->tiles_x = align(fb->width, TILE_SIZE) / TILE_SIZE;
    scene->tiles_y = align(fb->height, TILE_SIZE) / TILE_SIZE;
-
    assert(scene->tiles_x <= TILES_X);
    assert(scene->tiles_y <= TILES_Y);
+
+   /*
+    * Determine how many layers the fb has (used for clamping layer value).
+    * OpenGL (but not d3d10) permits different amount of layers per rt, however
+    * results are undefined if layer exceeds the amount of layers of ANY
+    * attachment hence don't need separate per cbuf and zsbuf max.
+    */
+   for (i = 0; i < scene->fb.nr_cbufs; i++) {
+      struct pipe_surface *cbuf = scene->fb.cbufs[i];
+      if (llvmpipe_resource_is_texture(cbuf->texture)) {
+         max_layer = MIN2(max_layer, cbuf->u.tex.last_layer - cbuf->u.tex.first_layer);
+      }
+      else {
+         max_layer = 0;
+      }
+   }
+   if (fb->zsbuf) {
+      struct pipe_surface *zsbuf = scene->fb.zsbuf;
+      max_layer = MIN2(max_layer, zsbuf->u.tex.last_layer - zsbuf->u.tex.first_layer);
+   }
+   scene->fb_max_layer = max_layer;
 }
 
 
diff --git a/src/gallium/drivers/llvmpipe/lp_scene.h b/src/gallium/drivers/llvmpipe/lp_scene.h
index 5501d40..94b1779 100644
--- a/src/gallium/drivers/llvmpipe/lp_scene.h
+++ b/src/gallium/drivers/llvmpipe/lp_scene.h
@@ -144,7 +144,7 @@ struct lp_scene {
       unsigned layer_stride;
    } zsbuf, cbufs[PIPE_MAX_COLOR_BUFS];
 
-   /* OpenGL permits different amount of layers per rt, but rendering limited to minimum */
+   /* The amount of layers in the fb (minimum of all attachments) */
    unsigned fb_max_layer;
 
    /** the framebuffer to render the scene into */