BUG: -funroll-all-loops generates unresolved externals

[Manfred Hollstein <manfredh at redhat dot com>]

Hi there,

When  bootstrapping a  recent  checkout from the   mainline sources on
i586-redhat6-linux-gnu   using  BOOT_CFLAGS="-O9 -funroll-all-loops" I
ended up with an unresolved external while creating cc1chill.

Further analysis has shown, that compiling loops of the following form
using -funroll-all-loops generates  jumps to labels, which won't exist
in the final output any more:

  for (;;)
    {
      ch = input ();
      if (ISALNUM (ch))
        obstack_1grow (&temporary_obstack, ch);
      else if (ch != '_')
        break;
    }

Rewriting this loop to  use a do { ...  } while (...) construct can be
used as a work-around:

  do
    {
      ch = input ();
      if (ISALNUM (ch))
        obstack_1grow (&temporary_obstack, ch);
    } while (ch == '_');

BTW, this is an excerpt from gcc/ch/lex.c.

OK to install the attached testcase?

Cheers, manfred.

2000-08-03  Manfred Hollstein  <manfredh@redhat.com>

	* gcc.dg/20000803-1.c: New test.

--- /dev/null	Tue May  5 22:32:27 1998
+++ gcc/testsuite/gcc.dg/20000803-1.c	Thu Aug  3 12:44:19 2000
@@ -0,0 +1,57 @@
+/* Copyright (C) 2000  Free Software Foundation.
+
+   by Manfred Hollstein <manfredh@redhat.com>  */
+
+/* { dg-do link } */
+/* { dg-options "-O2 -funroll-all-loops" } */
+
+void *temporary_obstack;
+
+static int input (void)
+{
+  return 0;
+}
+
+static int ISALNUM (int ch)
+{
+  return ((ch >= 'A' && ch <= 'Z')
+	  || (ch >= 'a' && ch <= 'z')
+	  || (ch >= '0' && ch <= '0'));
+}
+
+static void obstack_1grow (void **ptr, int ch)
+{
+}
+
+
+int yylex (void)
+{
+  int ch;
+
+#ifndef WORK_AROUND
+  for (;;)
+    {
+      ch = input ();
+      if (ISALNUM (ch))
+        obstack_1grow (&temporary_obstack, ch);
+      else if (ch != '_')
+        break;
+    }
+#else
+  do
+    {
+      ch = input ();
+      if (ISALNUM (ch))
+        obstack_1grow (&temporary_obstack, ch);
+    } while (ch == '_');
+#endif
+
+  return ch;
+}
+
+int main (void)
+{
+  int ch = yylex ();
+
+  return ch;
+}