re PR rtl-optimization/10692 ([m68k] miscompilation of perl with -O2 -fPIC)

        PR rtl-opt/10692
        * reload1.c (do_input_reload): Restrict the optimization deleteing
        a previous output reload to RELOAD_FOR_INPUT.

From-SVN: r92984

gcc/ChangeLog

+2005-01-05  Richard Henderson  <rth@redhat.com>
+
+	PR rtl-opt/10692
+	* reload1.c (do_input_reload): Restrict the optimization deleteing
+	a previous output reload to RELOAD_FOR_INPUT.
+
 2005-01-05  Steven Bosscher  <stevenb@suse.de>
 
 	* combine.c (expand_compound_operation)  <ZERO_EXTRACT>: Add

gcc/reload1.c

@@ -6822,6 +6822,10 @@ do_input_reload (struct insn_chain *chain, struct reload *rl, int j)
      actually no need to store the old value in it.  */
 
   if (optimize
+      /* Only attempt this for input reloads; for RELOAD_OTHER we miss
+	 that there may be multiple uses of the previous output reload.
+	 Restricting to RELOAD_FOR_INPUT is mostly paranoia.  */
+      && rl->when_needed == RELOAD_FOR_INPUT
       && (reload_inherited[j] || reload_override_in[j])
       && rl->reg_rtx
       && REG_P (rl->reg_rtx)