From patchwork Mon Dec 13 13:40:26 2010
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Subject: [PR46761] graphite: fix testing of boundary wrapping
From: Alexander Monakov <amonakov@ispras.ru>
X-Patchwork-Id: 75353
Message-Id: <alpine.LNX.2.00.1012131624320.5687@monoid.intra.ispras.ru>
To: gcc-patches@gcc.gnu.org
Cc: Sebastian Pop <sebpop@gmail.com>
Date: Mon, 13 Dec 2010 16:40:26 +0300 (MSK)

Hi,

As indicated by the testcase, sometimes Graphite would generate wrong region
guards if UB_ONE overflows, but does not become zero (i.e. it is signed).
The patch changes the corresponding test to use TREE_OVERFLOW flag.

Bootstrapped and regtested on x86_64-linux, OK for trunk?

2010-12-13  Alexander Monakov  <amonakov@ispras.ru>

	PR middle-end/46761
	* graphite-clast-to-gimple.c (graphite_create_new_loop_guard): Use
	TREE_OVERFLOW_P to test overflow.

testsuite:
	* gcc.dg/graphite/pr46761.c: New.


diff --git a/gcc/graphite-clast-to-gimple.c b/gcc/graphite-clast-to-gimple.c
index 4894b52..183dde7 100644
--- a/gcc/graphite-clast-to-gimple.c
+++ b/gcc/graphite-clast-to-gimple.c
@@ -985,7 +985,7 @@ graphite_create_new_loop_guard (sese region, edge entry_edge,
 			     : PLUS_EXPR, type, ub, one);
 
   /* When ub + 1 wraps around, use lb <= ub.  */
-  if (integer_zerop (ub_one))
+  if (TREE_OVERFLOW_P (ub_one))
     cond_expr = fold_build2 (LE_EXPR, boolean_type_node, lb, ub);
   else
     cond_expr = fold_build2 (LT_EXPR, boolean_type_node, lb, ub_one);
diff --git a/gcc/testsuite/gcc.dg/graphite/pr46761.c b/gcc/testsuite/gcc.dg/graphite/pr46761.c
new file mode 100644
index 0000000..f45398a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/graphite/pr46761.c
@@ -0,0 +1,22 @@
+/* { dg-do run } */
+/* { dg-options "-O -fgraphite-identity" } */
+
+#define N 128
+
+int
+main ()
+{
+  int arr[N], i, s = 0;
+  for (i = 0; i < N; i++)
+    arr[i] = i;
+
+  for (i = 0; i < N; i++)
+    if (arr[i] != i)
+      __builtin_abort ();
+
+  for (i = 0; i < N; i++)
+    s += arr[i];
+  if (s != (N * (N - 1)) / 2)
+    __builtin_abort ();
+  return 0;
+}