glamor: Semi-accelerate GetImage with non-trivial planemaskglamor-getimage-planemask

Just always do the download, and if the planemask isn't trivial mask the
returned data by the planemask on the CPU side.

This assumes that the image scanlines are padded to 32 bits, and that
bpp for the format is an even divisor of 32. This is true of fb if you
haven't forced 24bpp, which glamor doesn't support, and honestly neither
should fb.

This is a pretty decent speedup! With Xephyr, before and after this
change, with x11perf -pm 0x123456:

      before          after           Operation
------------   --------------------   -------------------------
     10100.0        89900.0 (8.901)   ShmGetImage 10x10 square
      6940.0        48500.0 (6.988)   ShmGetImage 100x100 square
      1190.0         4300.0 (3.613)   ShmGetImage 500x500 square
      9020.0        79600.0 (8.825)   GetImage 10x10 square
      6700.0        30600.0 (4.567)   GetImage 100x100 square
       395.0         2080.0 (5.266)   GetImage 500x500 square

For comparison, after this change, with planemask, glamor is if anything
a little faster than fb for large images:

      glamor             fb           Operation
------------   --------------------   -------------------------
     89900.0       101000.0 (1.123)   ShmGetImage 10x10 square
     48500.0        42800.0 (0.882)   ShmGetImage 100x100 square
      4300.0         3090.0 (0.719)   ShmGetImage 500x500 square
     79600.0        97900.0 (1.230)   GetImage 10x10 square
     30600.0        29400.0 (0.961)   GetImage 100x100 square
      2080.0         2060.0 (0.990)   GetImage 500x500 square

With no planemask, fb is still appreciably faster:

      glamor             fb           Operation
------------   --------------------   -------------------------
     88400.0       104000.0 (1.176)   ShmGetImage 10x10 square
     58300.0        80400.0 (1.379)   ShmGetImage 100x100 square
      8270.0        14800.0 (1.790)   ShmGetImage 500x500 square
     77900.0        96900.0 (1.244)   GetImage 10x10 square
     35400.0        44500.0 (1.257)   GetImage 100x100 square
      2600.0         4150.0 (1.596)   GetImage 500x500 square

Which is fair enough. fb is very nearly memcpy in this path, and there's
still some overhead in glamor itself.

Signed-off-by: Adam Jackson <ajax@redhat.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/glamor/glamor_image.c b/glamor/glamor_image.c
index 315874995..62ac7dc9a 100644
--- a/glamor/glamor_image.c
+++ b/glamor/glamor_image.c
@@ -116,7 +116,7 @@ glamor_get_image_gl(DrawablePtr drawable, int x, int y, int w, int h,
     if (!GLAMOR_PIXMAP_PRIV_HAS_FBO(pixmap_priv))
         goto bail;
 
-    if (format != ZPixmap || !glamor_pm_is_solid(drawable->depth, plane_mask))
+    if (format != ZPixmap)
         goto bail;
 
     glamor_get_drawable_deltas(drawable, pixmap, &off_x, &off_y);
@@ -128,6 +128,17 @@ glamor_get_image_gl(DrawablePtr drawable, int x, int y, int w, int h,
                           drawable->x + off_x, drawable->y + off_y,
                           -x, -y,
                           (uint8_t *) d, byte_stride);
+
+    if (!glamor_pm_is_solid(drawable->depth, plane_mask)) {
+        int i;
+        uint32_t *dest = (void *)d;
+        plane_mask = fbReplicatePixel(plane_mask,
+                                      BitsPerPixel(drawable->depth));
+
+        for (i = 0; i < w * h; i++)
+            dest[i] &= plane_mask;
+    }
+
     return TRUE;
 bail:
     return FALSE;