[Mesa-dev] [PATCH] i965/miptree_map_blit: Don't do the initial copy if INVALIDATE_RANGE is set

[Jason Ekstrand]

Before we were always coping from the buffer being mapped into the
temporary buffer.  However, if INVALIDATE_RANGE is set, then we know that
the data is going to be junk after we unmap so there's no point in doing
the blit.  This is important because doing the blit will cause a stall 3
lines later when we map the buffer.

Signed-off-by: Jason Ekstrand <jason.ekstrand at intel.com>
---
 src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
index f815fbe..d44df18 100644
--- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
+++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
@@ -1807,14 +1807,21 @@ intel_miptree_map_blit(struct brw_context *brw,
    }
    map->stride = map->mt->pitch;
 
-   if (!intel_miptree_blit(brw,
-                           mt, level, slice,
-                           map->x, map->y, false,
-                           map->mt, 0, 0,
-                           0, 0, false,
-                           map->w, map->h, GL_COPY)) {
-      fprintf(stderr, "Failed to blit\n");
-      goto fail;
+   /* One of either READ_BIT or WRITE_BIT or both is set.  READ_BIT implies no
+    * INVALIDATE_RANGE_BIT.  WRITE_BIT needs the original values read in unless
+    * invalidate is set, since we'll be writing the whole rectangle from our
+    * temporary buffer back out.
+    */
+   if (!(map->mode & GL_MAP_INVALIDATE_RANGE_BIT)) {
+      if (!intel_miptree_blit(brw,
+                              mt, level, slice,
+                              map->x, map->y, false,
+                              map->mt, 0, 0,
+                              0, 0, false,
+                              map->w, map->h, GL_COPY)) {
+         fprintf(stderr, "Failed to blit\n");
+         goto fail;
+      }
    }
 
    map->ptr = intel_miptree_map_raw(brw, map->mt);
-- 
2.2.0