xf86-video-intel: src/sna/sna_accel.c src/sna/sna.h

[Chris Wilson]

 src/sna/sna.h       |    8 ++++++--
 src/sna/sna_accel.c |   29 ++++++++++-------------------
 2 files changed, 16 insertions(+), 21 deletions(-)

New commits:
commit f6ba71ac194a19c80aa64f4769f76a47ebb7bd16
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date:   Sun Mar 1 15:47:50 2015 +0000

    sna: Unrecurse clip box search
    
    Unwind the trivial tail recursion from the clip box bisection and add a
    couple of assertions on the inlined fast-paths.
    
    References: https://bugs.freedesktop.org/show_bug.cgi?id=89295
    Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

diff --git a/src/sna/sna.h b/src/sna/sna.h
index 04875b8..ff1c9c1 100644
--- a/src/sna/sna.h
+++ b/src/sna/sna.h
@@ -1207,10 +1207,14 @@ find_clip_box_for_y(const BoxRec *begin, const BoxRec *end, int16_t y)
 		return end;
 
 	/* Quick test if scanline is within range of clip boxes */
-	if (begin->y2 > y)
+	if (begin->y2 > y) {
+		assert(__find_clip_box_for_y(begin, end, y) == begin);
 		return begin;
-	if (y > end[-1].y2)
+	}
+	if (y >= end[-1].y2) {
+		assert(__find_clip_box_for_y(begin, end, y) == end);
 		return end;
+	}
 
 	/* Otherwise bisect to find the first box crossing y */
 	return __find_clip_box_for_y(begin, end, y);
diff --git a/src/sna/sna_accel.c b/src/sna/sna_accel.c
index 7c7c734..29bf6c4 100644
--- a/src/sna/sna_accel.c
+++ b/src/sna/sna_accel.c
@@ -7165,27 +7165,18 @@ sna_copy_area(DrawablePtr src, DrawablePtr dst, GCPtr gc,
 const BoxRec *
 __find_clip_box_for_y(const BoxRec *begin, const BoxRec *end, int16_t y)
 {
-    const BoxRec *mid;
-
-    if (end == begin)
-	return end;
-
-    if (end - begin == 1) {
+	assert(begin != end);
+	while (end > begin + 1) {
+		const BoxRec *mid = begin + (end - begin) / 2;
+		if (mid->y2 > y)
+			end = mid;
+		else
+			begin = mid;
+	}
 	if (begin->y2 > y)
-	    return begin;
+		return begin;
 	else
-	    return end;
-    }
-
-    mid = begin + (end - begin) / 2;
-    if (mid->y2 > y)
-	/* If no box is found in [begin, mid], the function
-	 * will return @mid, which is then known to be the
-	 * correct answer.
-	 */
-	return __find_clip_box_for_y(begin, mid, y);
-    else
-	return __find_clip_box_for_y(mid, end, y);
+		return end;
 }
 
 struct sna_fill_spans {