New test.

From-SVN: r47370

gcc/testsuite/gcc.c-torture/execute/20011126-2.c

@@ -0,0 +1,43 @@
+/* Problem originally visible on ia64.
+
+   There is a partial redundancy of "in + 1" that makes GCSE want to
+   transform the final while loop to 
+
+     p = in + 1;
+     tmp = p;
+     ...
+     goto start;
+   top:
+     tmp = tmp + 1;
+   start:
+     in = tmp;
+     if (in < p) goto top;
+
+   We miscalculate the number of loop iterations as (p - tmp) = 0
+   instead of (p - in) = 1, which results in overflow in the doloop
+   optimization.  */
+
+static const char *
+test (const char *in, char *out)
+{
+  while (1)
+    {
+      if (*in == 'a')
+	{
+	  const char *p = in + 1;
+	  while (*p == 'x')
+	    ++p;
+	  if (*p == 'b')
+	    return p;
+	  while (in < p)
+	    *out++ = *in++;
+	}
+    }
+}
+
+int main ()
+{
+  char out[4];
+  test ("aab", out);
+  return 0;
+}