From 5f2df0734a48dd09b890fcb6884b8b5a35e5b763 Mon Sep 17 00:00:00 2001
From: Sven Verdoolaege <skimo@kotnet.org>
Date: Thu, 14 Feb 2013 18:53:43 +0100
Subject: [PATCH] isl_pw_multi_aff_drop_dims: fix dropping of output dimensions

Most isl_pw_*_drop_dims functions don't support dropping of output dimensions
because their pieces have a fixed single output dimension.
However, the pieces of isl_pw_multi_* objects do support dropping of output
dimensions and therefore so should the isl_pw_multi_*_drop_dims functions.

We simply need to skip dropping dimensions from the domains.
The original code would leave the result in an inconsistent state.

Signed-off-by: Sven Verdoolaege <skimo@kotnet.org>
---
 isl_pw_templ.c |  8 +++++---
 isl_test.c     | 30 ++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/isl_pw_templ.c b/isl_pw_templ.c
index f112fc02..39939740 100644
--- a/isl_pw_templ.c
+++ b/isl_pw_templ.c
@@ -983,12 +983,14 @@ __isl_give PW *FN(PW,drop_dims)(__isl_take PW *pw,
 	if (!pw->dim)
 		goto error;
 	for (i = 0; i < pw->n; ++i) {
-		pw->p[i].set = isl_set_drop(pw->p[i].set, set_type, first, n);
-		if (!pw->p[i].set)
-			goto error;
 		pw->p[i].FIELD = FN(EL,drop_dims)(pw->p[i].FIELD, type, first, n);
 		if (!pw->p[i].FIELD)
 			goto error;
+		if (type == isl_dim_out)
+			continue;
+		pw->p[i].set = isl_set_drop(pw->p[i].set, set_type, first, n);
+		if (!pw->p[i].set)
+			goto error;
 	}
 
 	return pw;
diff --git a/isl_test.c b/isl_test.c
index f0aee84e..82fa8d26 100644
--- a/isl_test.c
+++ b/isl_test.c
@@ -3750,10 +3750,40 @@ static int test_ast_gen(isl_ctx *ctx)
 	return 0;
 }
 
+/* Check if dropping output dimensions from an isl_pw_multi_aff
+ * works properly.
+ */
+static int test_pw_multi_aff(isl_ctx *ctx)
+{
+	const char *str;
+	isl_pw_multi_aff *pma1, *pma2;
+	int equal;
+
+	str = "{ [i,j] -> [i+j, 4i-j] }";
+	pma1 = isl_pw_multi_aff_read_from_str(ctx, str);
+	str = "{ [i,j] -> [4i-j] }";
+	pma2 = isl_pw_multi_aff_read_from_str(ctx, str);
+
+	pma1 = isl_pw_multi_aff_drop_dims(pma1, isl_dim_out, 0, 1);
+
+	equal = isl_pw_multi_aff_plain_is_equal(pma1, pma2);
+
+	isl_pw_multi_aff_free(pma1);
+	isl_pw_multi_aff_free(pma2);
+	if (equal < 0)
+		return -1;
+	if (!equal)
+		isl_die(ctx, isl_error_unknown,
+			"expressions not equal", return -1);
+
+	return 0;
+}
+
 struct {
 	const char *name;
 	int (*fn)(isl_ctx *ctx);
 } tests [] = {
+	{ "piecewise multi affine expressions", &test_pw_multi_aff },
 	{ "conversion", &test_conversion },
 	{ "list", &test_list },
 	{ "align parameters", &test_align_parameters },
-- 
2.11.4.GIT