diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6b832ed26d0..26dc3f95368 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2016-09-29  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/77768
+	* tree-ssa-pre.c (eliminate_dom_walker::before_dom_children):
+	Handle stores to readonly memory when removing redundant stores.
+
 2016-09-29  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/77407
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 9269d58bb18..2fd9e97eede 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2016-09-29  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/77768
+	* gcc.dg/torture/pr77768.c: New testcase.
+
 2016-09-28  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/77407
diff --git a/gcc/testsuite/gcc.dg/torture/pr77768.c b/gcc/testsuite/gcc.dg/torture/pr77768.c
new file mode 100644
index 00000000000..47e1484b77a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr77768.c
@@ -0,0 +1,13 @@
+/* { dg-do run } */
+
+static const int a;
+int b;
+int *c, *d;
+int main()
+{
+  c = (int *)&a;
+  c == d ?: __builtin_exit(0); 
+  for (; b; b++ >= (*d = a))
+    ;
+  return 0;
+}
diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c
index 3675fb95fec..39bc2548c10 100644
--- a/gcc/tree-ssa-pre.c
+++ b/gcc/tree-ssa-pre.c
@@ -4443,9 +4443,11 @@ eliminate_dom_walker::before_dom_children (basic_block b)
 	      && operand_equal_p (val, rhs, 0))
 	    {
 	      /* We can only remove the later store if the former aliases
-		 at least all accesses the later one does.  */
+		 at least all accesses the later one does or if the store
+		 was to readonly memory storing the same value.  */
 	      alias_set_type set = get_alias_set (lhs);
-	      if (vnresult->set == set
+	      if (! vnresult
+		  || vnresult->set == set
 		  || alias_set_subset_of (set, vnresult->set))
 		{
 		  if (dump_file && (dump_flags & TDF_DETAILS))