[PATCH, PR70045] Unshare create_empty_if_region_on_edge argument

[Tom de Vries]

Hi,

this patch fixes PR70045, a graphite 6 regression.
The problem is as follows: in graphite_create_new_loop_guard, a 
condition cond_expr is constructed using an upper bound expression *ub.

During the call:
...
    exit_edge = create_empty_if_region_on_edge (entry_edge, cond_expr);
...
the cond_expr is modified in place, which has as side-effect that *ub is 
modified.

The patch fixes this by unsharing the cond_expr before passing it as 
argument to create_empty_if_region_on_edge.

Bootstrapped and reg-tested on x86_64.

OK for stage4 trunk?

Thanks,
- Tom
Unshare create_empty_if_region_on_edge argument

2016-03-11  Tom de Vries  <t...@codesourcery.com>

	PR tree-optimization/70045
	* graphite-isl-ast-to-gimple.c (graphite_create_new_loop_guard): Unshare
	create_empty_if_region_on_edge argument.

	* gcc.dg/graphite/pr70045.c: New test.

---
 gcc/graphite-isl-ast-to-gimple.c        |  3 ++-
 gcc/testsuite/gcc.dg/graphite/pr70045.c | 28 ++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/gcc/graphite-isl-ast-to-gimple.c b/gcc/graphite-isl-ast-to-gimple.c
index 89a4118..8dd5dc8 100644
--- a/gcc/graphite-isl-ast-to-gimple.c
+++ b/gcc/graphite-isl-ast-to-gimple.c
@@ -821,7 +821,8 @@ graphite_create_new_loop_guard (edge entry_edge,
   if (integer_onep (cond_expr))
     exit_edge = entry_edge;
   else
-    exit_edge = create_empty_if_region_on_edge (entry_edge, cond_expr);
+    exit_edge = create_empty_if_region_on_edge (entry_edge,
+						unshare_expr (cond_expr));
 
   return exit_edge;
 }
diff --git a/gcc/testsuite/gcc.dg/graphite/pr70045.c b/gcc/testsuite/gcc.dg/graphite/pr70045.c
new file mode 100644
index 0000000..9f98b1f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/graphite/pr70045.c
@@ -0,0 +1,28 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -floop-interchange" } */
+
+int a, b, d, e, f;
+int c[9];
+void
+fn1 ()
+{
+  e = 1;
+  for (; e >= 0; e--)
+    {
+      d = 1;
+      for (; d >= 0; d--)
+	{
+	  f = 0;
+	  for (; f <= 1; f++)
+	    {
+	      a = 0;
+	      for (; a < 9; a++)
+		{
+		  b = 0;
+		  for (; b < 2; b++)
+		    c[a + b] = 3;
+		}
+	    }
+	}
+    }
+}