re PR target/21721 (fails to assemble, Use of p0 is not valid in this context)

        PR target/21721
        * config/ia64/ia64.c (emit_predicate_relation_info): Skip p0.

From-SVN: r100745

gcc/ChangeLog

+2005-06-08  Richard Henderson  <rth@redhat.com>
+
+	PR target/21721
+        * config/ia64/ia64.c (emit_predicate_relation_info): Skip p0.
+
 2005-06-08  Eric Botcazou  <ebotcazou@libertysurf.fr>
 
 	PR target/21889

gcc/config/ia64/ia64.c

@@ -7420,7 +7420,9 @@ emit_predicate_relation_info (void)
 	  && NOTE_LINE_NUMBER (NEXT_INSN (head)) == NOTE_INSN_BASIC_BLOCK)
 	head = NEXT_INSN (head);
 
-      for (r = PR_REG (0); r < PR_REG (64); r += 2)
+      /* Skip p0, which may be thought to be live due to (reg:DI p0)
+	 grabbing the entire block of predicate registers.  */
+      for (r = PR_REG (2); r < PR_REG (64); r += 2)
 	if (REGNO_REG_SET_P (bb->global_live_at_start, r))
 	  {
 	    rtx p = gen_rtx_REG (BImode, r);