[Pixman] [PATCH v2 8/8] Speed up _pixman_image_get_solid() in common cases

[Søren Sandmann]

From: Søren Sandmann Pedersen <ssp at redhat.com>

Make _pixman_image_get_solid() faster by special-casing the common
cases where the image is SOLID or a repeating a8r8g8b8 image.

This optimization together with the previous one results in a small
but reproducable performance improvement on the xfce4-terminal-a1
cairo trace:

[ # ]  backend                         test   min(s) median(s) stddev. count
Before:
[  0]    image            xfce4-terminal-a1    1.221    1.239   1.21%  100/100
After:
[  0]    image            xfce4-terminal-a1    1.170    1.199   1.26%  100/100

Either optimization by itself is difficult to separate from noise.
---
 pixman/pixman-image.c |   33 +++++++++++++++++++++++++++------
 1 file changed, 27 insertions(+), 6 deletions(-)

diff --git a/pixman/pixman-image.c b/pixman/pixman-image.c
index 6a965e4..8b634a7 100644
--- a/pixman/pixman-image.c
+++ b/pixman/pixman-image.c
@@ -879,13 +879,34 @@ _pixman_image_get_solid (pixman_implementation_t *imp,
                          pixman_format_code_t     format)
 {
     uint32_t result;
-    pixman_iter_t iter;
 
-    _pixman_implementation_src_iter_init (
-	imp, &iter, image, 0, 0, 1, 1,
-	(uint8_t *)&result, ITER_NARROW, image->common.flags);
-
-    result = *iter.get_scanline (&iter, NULL);
+    if (image->type == SOLID)
+    {
+	result = image->solid.color_32;
+    }
+    else if (image->type == BITS)
+    {
+	if (image->bits.format == PIXMAN_a8r8g8b8)
+	    result = image->bits.bits[0];
+	else if (image->bits.format == PIXMAN_x8r8g8b8)
+	    result = image->bits.bits[0] | 0xff000000;
+	else if (image->bits.format == PIXMAN_a8)
+	    result = (*(uint8_t *)image->bits.bits) << 24;
+	else
+	    goto otherwise;
+    }
+    else
+    {
+	pixman_iter_t iter;
+
+    otherwise:
+	_pixman_implementation_src_iter_init (
+	    imp, &iter, image, 0, 0, 1, 1,
+	    (uint8_t *)&result,
+	    ITER_NARROW, image->common.flags);
+	
+	result = *iter.get_scanline (&iter, NULL);
+    }
 
     /* If necessary, convert RGB <--> BGR. */
     if (PIXMAN_FORMAT_TYPE (format) != PIXMAN_TYPE_ARGB)
-- 
1.7.10.2