From 5710646abdff9e5ed43c6b6124f77398c76dd642 Mon Sep 17 00:00:00 2001
From: Sven Verdoolaege <skimo@kotnet.org>
Date: Fri, 24 Jun 2011 14:55:22 +0200
Subject: [PATCH] add isl_pw_aff_max

Signed-off-by: Sven Verdoolaege <skimo@kotnet.org>
---
 doc/user.pod      | 12 +++++++++
 include/isl/aff.h |  3 +++
 isl_aff.c         | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 95 insertions(+)

diff --git a/doc/user.pod b/doc/user.pod
index 144b7125..4063f477 100644
--- a/doc/user.pod
+++ b/doc/user.pod
@@ -2291,6 +2291,18 @@ The function C<isl_aff_ge_basic_set> returns a basic set
 containing those elements in the shared space
 of C<aff1> and C<aff2> where C<aff1> is greater than or equal to C<aff2>.
 
+	#include <isl/aff.h>
+	__isl_give isl_pw_aff *isl_pw_aff_max(
+		__isl_take isl_pw_aff *pwaff1,
+		__isl_take isl_pw_aff *pwaff2);
+
+The function C<isl_pw_aff_max> computes a piecewise quasi-affine
+expression with a domain that is the union of those of C<pwaff1> and
+C<pwaff2> and such that on each cell, the quasi-affine expression is
+the maximum of those of C<pwaff1> and C<pwaff2>.  If only one of
+C<pwaff1> or C<pwaff2> is defined on a given cell, then the
+associated expression is the defined one.
+
 An expression can be printed using
 
 	#include <isl/aff.h>
diff --git a/include/isl/aff.h b/include/isl/aff.h
index 90e5a905..65abb1ad 100644
--- a/include/isl/aff.h
+++ b/include/isl/aff.h
@@ -85,6 +85,9 @@ __isl_give isl_pw_aff *isl_pw_aff_alloc(__isl_take isl_set *set,
 
 int isl_pw_aff_is_empty(__isl_keep isl_pw_aff *pwaff);
 
+__isl_give isl_pw_aff *isl_pw_aff_max(__isl_take isl_pw_aff *pwaff1,
+	__isl_take isl_pw_aff *pwaff2);
+
 __isl_give isl_pw_aff *isl_pw_aff_copy(__isl_keep isl_pw_aff *pwaff);
 void *isl_pw_aff_free(__isl_take isl_pw_aff *pwaff);
 
diff --git a/isl_aff.c b/isl_aff.c
index 33dffa03..055c46c9 100644
--- a/isl_aff.c
+++ b/isl_aff.c
@@ -778,3 +778,83 @@ int isl_aff_is_empty(__isl_keep isl_aff *aff)
 #define NO_RESET_DIM
 
 #include <isl_pw_templ.c>
+
+/* Compute a piecewise quasi-affine expression with a domain that
+ * is the union of those of pwaff1 and pwaff2 and such that on each
+ * cell, the quasi-affine expression is the maximum of those of pwaff1
+ * and pwaff2.  If only one of pwaff1 or pwaff2 is defined on a given
+ * cell, then the associated expression is the defined one.
+ */
+__isl_give isl_pw_aff *isl_pw_aff_max(__isl_take isl_pw_aff *pwaff1,
+	__isl_take isl_pw_aff *pwaff2)
+{
+	int i, j, n;
+	isl_pw_aff *res;
+	isl_ctx *ctx;
+	isl_set *set;
+
+	if (!pwaff1 || !pwaff2)
+		goto error;
+
+	ctx = isl_dim_get_ctx(pwaff1->dim);
+	if (!isl_dim_equal(pwaff1->dim, pwaff2->dim))
+		isl_die(ctx, isl_error_invalid,
+			"arguments should live in same space", goto error);
+
+	if (isl_pw_aff_is_empty(pwaff1)) {
+		isl_pw_aff_free(pwaff1);
+		return pwaff2;
+	}
+
+	if (isl_pw_aff_is_empty(pwaff2)) {
+		isl_pw_aff_free(pwaff2);
+		return pwaff1;
+	}
+
+	n = 2 * (pwaff1->n + 1) * (pwaff2->n + 1);
+	res = isl_pw_aff_alloc_(isl_dim_copy(pwaff1->dim), n);
+
+	for (i = 0; i < pwaff1->n; ++i) {
+		set = isl_set_copy(pwaff1->p[i].set);
+		for (j = 0; j < pwaff2->n; ++j) {
+			struct isl_set *common;
+			isl_set *ge;
+
+			common = isl_set_intersect(
+					isl_set_copy(pwaff1->p[i].set),
+					isl_set_copy(pwaff2->p[j].set));
+			ge = isl_set_from_basic_set(isl_aff_ge_basic_set(
+					isl_aff_copy(pwaff2->p[j].aff),
+					isl_aff_copy(pwaff1->p[i].aff)));
+			ge = isl_set_intersect(common, ge);
+			if (isl_set_plain_is_empty(ge)) {
+				isl_set_free(ge);
+				continue;
+			}
+			set = isl_set_subtract(set, isl_set_copy(ge));
+
+			res = isl_pw_aff_add_piece(res, ge,
+						isl_aff_copy(pwaff2->p[j].aff));
+		}
+		res = isl_pw_aff_add_piece(res, set,
+						isl_aff_copy(pwaff1->p[i].aff));
+	}
+
+	for (j = 0; j < pwaff2->n; ++j) {
+		set = isl_set_copy(pwaff2->p[j].set);
+		for (i = 0; i < pwaff1->n; ++i)
+			set = isl_set_subtract(set,
+					isl_set_copy(pwaff1->p[i].set));
+		res = isl_pw_aff_add_piece(res, set,
+						isl_aff_copy(pwaff2->p[j].aff));
+	}
+
+	isl_pw_aff_free(pwaff1);
+	isl_pw_aff_free(pwaff2);
+
+	return res;
+error:
+	isl_pw_aff_free(pwaff1);
+	isl_pw_aff_free(pwaff2);
+	return NULL;
+}
-- 
2.11.4.GIT