llvmpipe: avoid flushing depth buffer cache on swapbuffers

There's no need to push out depth buffer contents on swapbuffers.

Note that this change doesn't throw away depth buffer changes, it simply
holds them in the cache over calls to swapbuffers.  The hope is
that swapbuffers will be followed by a clear() which means in that case
we won't have to write the changes out.

1 files changed, 15 insertions, 5 deletions

diff --git a/src/gallium/drivers/llvmpipe/lp_flush.c b/src/gallium/drivers/llvmpipe/lp_flush.c
index f815e79003..866d4fb099 100644
--- a/src/gallium/drivers/llvmpipe/lp_flush.c
+++ b/src/gallium/drivers/llvmpipe/lp_flush.c
@@ -56,14 +56,16 @@ llvmpipe_flush( struct pipe_context *pipe,
       }
    }
 
-   if (flags & PIPE_FLUSH_RENDER_CACHE) {
+   if (flags & PIPE_FLUSH_SWAPBUFFERS) {
+      /* If this is a swapbuffers, just flush color buffers.
+       *
+       * The zbuffer changes are not discarded, but held in the cache
+       * in the hope that a later clear will wipe them out.
+       */
       for (i = 0; i < llvmpipe->framebuffer.nr_cbufs; i++)
          if (llvmpipe->cbuf_cache[i])
             lp_flush_tile_cache(llvmpipe->cbuf_cache[i]);
 
-      if (llvmpipe->zsbuf_cache)
-         lp_flush_tile_cache(llvmpipe->zsbuf_cache);
-
       /* Need this call for hardware buffers before swapbuffers.
        *
        * there should probably be another/different flush-type function
@@ -71,7 +73,15 @@ llvmpipe_flush( struct pipe_context *pipe,
        * to unmap surfaces when flushing.
        */
       llvmpipe_unmap_transfers(llvmpipe);
-      
+   }
+   else if (flags & PIPE_FLUSH_RENDER_CACHE) {
+      for (i = 0; i < llvmpipe->framebuffer.nr_cbufs; i++)
+         if (llvmpipe->cbuf_cache[i])
+            lp_flush_tile_cache(llvmpipe->cbuf_cache[i]);
+
+      if (llvmpipe->zsbuf_cache)
+         lp_flush_tile_cache(llvmpipe->zsbuf_cache);
+     
       llvmpipe->dirty_render_cache = FALSE;
    }