sna/trapezoids: Use incremental region clipping for spans

Within a span, we have the advantage of knowing that we only need to
intersect one box with the clip region, and that box has monotonically
increasing y. This avoid having to compute RegionIntersect for every
span element which was very slow (e.g. libreoffice).

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 56 insertions, 17 deletions

diff --git a/src/sna/sna_trapezoids_mono.c b/src/sna/sna_trapezoids_mono.c
index 808703a9..29cb58ff 100644
--- a/src/sna/sna_trapezoids_mono.c
+++ b/src/sna/sna_trapezoids_mono.c
@@ -72,6 +72,7 @@ struct mono {
 	struct sna *sna;
 	struct sna_composite_op op;
 	pixman_region16_t clip;
+	const BoxRec *clip_start, *clip_end;
 
 	fastcall void (*span)(struct mono *, int, int, BoxPtr);
 
@@ -474,6 +475,34 @@ mono_span__fast(struct mono *c, int x1, int x2, BoxPtr box)
 	c->op.box(c->sna, &c->op, box);
 }
 
+fastcall static void
+mono_span__clipped(struct mono *c, int x1, int x2, BoxPtr box)
+{
+	const BoxRec *b;
+
+	__DBG(("%s [%d, %d]\n", __FUNCTION__, x1, x2));
+
+	c->clip_start =
+		find_clip_box_for_y(c->clip_start, c->clip_end, box->y1);
+
+	b = c->clip_start;
+	while (b != c->clip_end) {
+		BoxRec clipped;
+
+		if (box->y2 <= b->y1)
+			break;
+
+		clipped.x1 = x1;
+		clipped.x2 = x2;
+		clipped.y1 = box->y1;
+		clipped.y2 = box->y2;
+		if (!box_intersect(&clipped, b++))
+			continue;
+
+		c->op.box(c->sna, &c->op, &clipped);
+	}
+}
+
 struct mono_span_thread_boxes {
 	const struct sna_composite_op *op;
 #define MONO_SPAN_MAX_BOXES (8192/sizeof(BoxRec))
@@ -482,40 +511,45 @@ struct mono_span_thread_boxes {
 };
 
 inline static void
-thread_mono_span_add_boxes(struct mono *c, const BoxRec *box, int count)
+thread_mono_span_add_box(struct mono *c, const BoxRec *box)
 {
 	struct mono_span_thread_boxes *b = c->op.priv;
 
-	assert(count > 0 && count <= MONO_SPAN_MAX_BOXES);
-	if (unlikely(b->num_boxes + count > MONO_SPAN_MAX_BOXES)) {
+	if (unlikely(b->num_boxes == MONO_SPAN_MAX_BOXES)) {
 		b->op->thread_boxes(c->sna, b->op, b->boxes, b->num_boxes);
 		b->num_boxes = 0;
 	}
 
-	memcpy(b->boxes + b->num_boxes, box, count*sizeof(BoxRec));
-	b->num_boxes += count;
+	b->boxes[b->num_boxes++] = *box;
 	assert(b->num_boxes <= MONO_SPAN_MAX_BOXES);
 }
 
 fastcall static void
 thread_mono_span_clipped(struct mono *c, int x1, int x2, BoxPtr box)
 {
-	pixman_region16_t region;
+	const BoxRec *b;
 
 	__DBG(("%s [%d, %d]\n", __FUNCTION__, x1, x2));
 
-	box->x1 = x1;
-	box->x2 = x2;
+	c->clip_start =
+		find_clip_box_for_y(c->clip_start, c->clip_end, box->y1);
 
-	assert(c->clip.data);
+	b = c->clip_start;
+	while (b != c->clip_end) {
+		BoxRec clipped;
 
-	pixman_region_init_rects(&region, box, 1);
-	RegionIntersect(&region, &region, &c->clip);
-	if (region_num_rects(&region))
-		thread_mono_span_add_boxes(c,
-					   region_rects(&region),
-					   region_num_rects(&region));
-	pixman_region_fini(&region);
+		if (box->y2 <= b->y1)
+			break;
+
+		clipped.x1 = x1;
+		clipped.x2 = x2;
+		clipped.y1 = box->y1;
+		clipped.y2 = box->y2;
+		if (!box_intersect(&clipped, b++))
+			continue;
+
+		thread_mono_span_add_box(c, &clipped);
+	}
 }
 
 fastcall static void
@@ -525,7 +559,7 @@ thread_mono_span(struct mono *c, int x1, int x2, BoxPtr box)
 
 	box->x1 = x1;
 	box->x2 = x2;
-	thread_mono_span_add_boxes(c, box, 1);
+	thread_mono_span_add_box(c, box);
 }
 
 inline static void
@@ -717,6 +751,7 @@ mono_span_thread(void *arg)
 		if (RegionNil(&mono.clip))
 			return;
 	}
+	region_get_boxes(&mono.clip, &mono.clip_start, &mono.clip_end);
 
 	boxes.op = thread->op;
 	boxes.num_boxes = 0;
@@ -891,9 +926,12 @@ mono_trapezoids_span_converter(struct sna *sna,
 
 	if (mono.clip.data == NULL && mono.op.damage == NULL)
 		mono.span = mono_span__fast;
+	else if (mono.clip.data != NULL && mono.op.damage == NULL)
+		mono.span = mono_span__clipped;
 	else
 		mono.span = mono_span;
 
+	region_get_boxes(&mono.clip, &mono.clip_start, &mono.clip_end);
 	mono_render(&mono);
 	mono.op.done(mono.sna, &mono.op);
 	mono_fini(&mono);
@@ -939,6 +977,7 @@ mono_trapezoids_span_converter(struct sna *sna,
 					       mono.clip.extents.x2 - mono.clip.extents.x1,
 					       mono.clip.extents.y2 - mono.clip.extents.y1,
 					       COMPOSITE_PARTIAL, memset(&mono.op, 0, sizeof(mono.op)))) {
+			region_get_boxes(&mono.clip, &mono.clip_start, &mono.clip_end);
 			mono_render(&mono);
 			mono.op.done(mono.sna, &mono.op);
 		}