Add new test for PR tree-optimization/92982.

gcc/testsuite/ChangeLog:
	PR tree-optimization/92982
	* gcc.dg/strlenopt-94.c: New test.

gcc/testsuite/ChangeLog

+2020-03-02  Martin Sebor  <msebor@redhat.com>
+
+	PR tree-optimization/92982
+	* gcc.dg/strlenopt-94.c: New test.
+
 2020-03-02  Iain Sandoe  <iain@sandoe.co.uk>
 
 	* g++.dg/coroutines/torture/func-params-09-awaitable-parms.C: New test.

gcc/testsuite/gcc.dg/strlenopt-94.c

+/* PR tree-optimization/93982 - Assignment incorrectly omitted by
+   -foptimize-strlen
+   { dg-do run }
+   { dg-options "-O2 -Wall" } */
+
+struct A { const char **a; };
+const char *buf[5];
+
+__attribute__((noipa)) struct A
+foo (char *p)
+{
+  struct A r = { (const char **) p };
+  r.a[0] = "12345678";
+  r.a[1] = "";
+  r.a[2] = "";
+  r.a[3] = "";
+  r.a[4] = "";
+  return r;
+}
+
+int
+main ()
+{
+  struct A r = foo ((char *) &buf[0]);
+  if (!r.a[1] || r.a[1][0] != '\0')
+    __builtin_abort ();
+  return 0;
+}