1 files changed, 34 insertions, 0 deletions
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr21985.c b/gcc/testsuite/gcc.dg/tree-ssa/pr21985.c
new file mode 100644
index 000000000..19ad0f113
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr21985.c
@@ -0,0 +1,34 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-optimized" } */
+
+struct
+{
+  struct
+    {
+      int a;
+      int b;
+    } a[100];
+} a;
+
+typedef __SIZE_TYPE__ size_t;
+void foo(size_t);
+size_t *bar (void);
+
+int
+main (void)
+{
+  size_t *b = bar ();
+
+  /* This should be folded.  */
+  foo (&a.a[50].a - &a.a[33].b);
+  foo ((size_t) &a.a[50].b - (size_t) &a);
+
+  /* And this should not.  */
+  foo ((size_t) &b - (size_t) b);
+  return 0;
+}
+
+/* Two of the calls to foo should be folded to just foo(constant).  */
+
+/* { dg-final { scan-tree-dump-times "foo \\(\[0-9\]*\\)" 2 "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */