--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gcc.dg/pr83047.c	Thu Oct 25 07:37:49 2018 +0900
@@ -0,0 +1,58 @@
+/* PR tree-optimization/83047 */
+/* { dg-do run { target mmap } } */
+/* { dg-options "-O2" } */
+
+#include <stddef.h>
+#include <stdio.h>
+#include <sys/mman.h>
+#ifndef MAP_ANONYMOUS
+#define MAP_ANONYMOUS MAP_ANON
+#endif
+#ifndef MAP_ANON
+#define MAP_ANON 0
+#endif
+#ifndef MAP_FAILED
+#define MAP_FAILED ((void *)-1)
+#endif
+#include <stdlib.h>
+
+__attribute__((noipa)) void
+foo (char *p, char *q, int r)
+{
+  char a = q[0];
+  if (r || a == '\0')
+    return;
+  char b = q[1];
+  p[0] = a;
+  p[1] = b;
+}
+
+int
+main ()
+{
+  char *p = mmap (NULL, 131072, PROT_READ | PROT_WRITE,
+		  MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  if (p == MAP_FAILED)
+    return 0;
+  if (munmap (p + 65536, 65536) < 0)
+    return 0;
+  p[0] = 'c';
+  p[1] = 'd';
+  p[65536 - 2] = 'a';
+  p[65536 - 1] = 'b';
+  volatile int r = 1;
+  foo (p, p + 65536 - 2, r);
+  if (p[0] != 'c' || p[1] != 'd')
+    abort ();
+  r = 0;
+  foo (p, p + 65536 - 2, r);
+  if (p[0] != 'a' || p[1] != 'b')
+    abort ();
+  p[0] = 'e';
+  p[1] = 'f';
+  r = 1;
+  foo (p, p + 65536 - 1, r);
+  if (p[0] != 'e' || p[1] != 'f')
+    abort ();
+  return 0;
+}