analyze_extents: Fast path for non-transformed BITS images

Profiling various cairo traces showed that we were spending a lot of
time in analyze_extents and compute_sample_extents(). This was
especially bad for glyphs where all this computation was completely
unnecessary.

This patch adds a fast path for the case of non-transformed BITS
images. The result is approximately a 6% improvement on the
firefox-talos-gfx benchmark:

Before:

[ # ]  backend                         test   min(s) median(s) stddev. count
[  0]    image            firefox-talos-gfx   13.797   13.848   0.20%    6/6

After:

[ # ]  backend                         test   min(s) median(s) stddev. count
[  0]    image            firefox-talos-gfx   12.946   13.018   0.39%    6/6

diff --git a/pixman/pixman.c b/pixman/pixman.c
index 72779c8..2296325 100644 (file)
--- a/pixman/pixman.c
+++ b/pixman/pixman.c
@@ -724,6 +724,7 @@ analyze_extent (pixman_image_t *image, int x, int y,
        return FALSE;
     }
 
+    transform = image->common.transform;
     if (image->common.type == BITS)
     {
        /* During repeat mode calculations we might convert the
@@ -733,6 +734,18 @@ analyze_extent (pixman_image_t *image, int x, int y,
        if (image->bits.width >= 0x7fff || image->bits.height >= 0x7fff)
            return FALSE;
 
+#define ID_AND_NEAREST (FAST_PATH_ID_TRANSFORM | FAST_PATH_NEAREST_FILTER)
+       
+       if ((image->common.flags & ID_AND_NEAREST) == ID_AND_NEAREST &&
+           extents->x1 - x >= 0 &&
+           extents->y1 - y >= 0 &&
+           extents->x2 - x <= image->bits.width &&
+           extents->y2 - y <= image->bits.height)
+       {
+           *flags |= (FAST_PATH_SAMPLES_COVER_CLIP | FAST_PATH_COVERS_CLIP);
+           return TRUE;
+       }
+    
        switch (image->common.filter)
        {
        case PIXMAN_FILTER_CONVOLUTION:
@@ -763,6 +776,17 @@ analyze_extent (pixman_image_t *image, int x, int y,
        default:
            return FALSE;
        }
+
+       /* Check whether the non-expanded, transformed extent is entirely within
+        * the source image, and set the FAST_PATH_SAMPLES_COVER_CLIP if it is.
+        */
+       ex = *extents;
+       if (compute_sample_extents (transform, &ex, x, y, x_off, y_off, width, height) &&
+           ex.x1 >= 0 && ex.y1 >= 0 &&
+           ex.x2 <= image->bits.width && ex.y2 <= image->bits.height)
+       {
+           *flags |= (FAST_PATH_SAMPLES_COVER_CLIP | FAST_PATH_COVERS_CLIP);
+       }
     }
     else
     {
@@ -781,24 +805,9 @@ analyze_extent (pixman_image_t *image, int x, int y,
     ex.x2 = extents->x2 + 1;
     ex.y2 = extents->y2 + 1;
 
-    transform = image->common.transform;
-
     if (!compute_sample_extents (transform, &ex, x, y, x_off, y_off, width, height))
        return FALSE;
 
-    if (image->type == BITS)
-    {
-       /* Check whether the non-expanded, transformed extent is entirely within
-        * the source image, and set the FAST_PATH_SAMPLES_COVER_CLIP if it is.
-        */
-       ex = *extents;
-       if (compute_sample_extents (transform, &ex, x, y, x_off, y_off, width, height))
-       {
-           if (ex.x1 >= 0 && ex.y1 >= 0 && ex.x2 <= image->bits.width && ex.y2 <= image->bits.height)
-               *flags |= (FAST_PATH_SAMPLES_COVER_CLIP | FAST_PATH_COVERS_CLIP);
-       }
-    }
-
     return TRUE;
 }