From: Sven Verdoolaege <skimo@kotnet.org>
Date: Tue, 7 Feb 2012 11:19:20 +0000 (+0100)
Subject: isl_pw_*_union_add: don't subtract non-overlapping cells
X-Git-Tag: isl-0.10~127
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=be75156f10fd796a985b117892787af180347470;p=platform%2Fupstream%2Fisl.git

isl_pw_*_union_add: don't subtract non-overlapping cells

There is no point in subtracting a cell from another if their intersection
is empty.  It can only lead to a further subdivision of the other cell.

Signed-off-by: Sven Verdoolaege <skimo@kotnet.org>
---

diff --git a/isl_pw_templ.c b/isl_pw_templ.c
index 10bc4b8..448b082 100644
--- a/isl_pw_templ.c
+++ b/isl_pw_templ.c
@@ -371,14 +371,14 @@ static __isl_give PW *FN(PW,union_add_aligned)(__isl_take PW *pw1,
 		for (j = 0; j < pw2->n; ++j) {
 			struct isl_set *common;
 			EL *sum;
-			set = isl_set_subtract(set,
-					isl_set_copy(pw2->p[j].set));
 			common = isl_set_intersect(isl_set_copy(pw1->p[i].set),
 						isl_set_copy(pw2->p[j].set));
 			if (isl_set_plain_is_empty(common)) {
 				isl_set_free(common);
 				continue;
 			}
+			set = isl_set_subtract(set,
+					isl_set_copy(pw2->p[j].set));
 
 			sum = FN(EL,add_on_domain)(common,
 						   FN(EL,copy)(pw1->p[i].FIELD),