combine.c (can_combine_p): Allow combining insns with REG_RETVAL notes.

	* combine.c (can_combine_p): Allow combining insns with REG_RETVAL
	notes.
	(try_combine): Allow combining insns with REG_LIBCALL notes.

From-SVN: r21833

gcc/ChangeLog

@@ -5,6 +5,10 @@ Tue Aug 18 12:40:27 1998  Richard Henderson  <rth@cygnus.com>
 
 Tue Aug 18 10:33:30 1998  Jeffrey A Law  (law@cygnus.com)
 
+	* combine.c (can_combine_p): Allow combining insns with REG_RETVAL
+	notes.
+	(try_combine): Allow combining insns with REG_LIBCALL notes.
+
 	* expr.c (emit_block_move): Do not call memcpy as a libcall
 	instead build up a CALL_EXPR and call it like any other
 	function.

gcc/combine.c

@@ -958,8 +958,14 @@ can_combine_p (insn, i3, pred, succ, pdest, psrc)
       /* Don't substitute into an incremented register.  */
       || FIND_REG_INC_NOTE (i3, dest)
       || (succ && FIND_REG_INC_NOTE (succ, dest))
+#if 0
       /* Don't combine the end of a libcall into anything.  */
+      /* ??? This gives worse code, and appears to be unnecessary, since no
+	 pass after flow uses REG_LIBCALL/REG_RETVAL notes.  Local-alloc does
+	 use REG_RETVAL notes for noconflict blocks, but other code here
+	 makes sure that those insns don't disappear.  */
       || find_reg_note (insn, REG_RETVAL, NULL_RTX)
+#endif
       /* Make sure that DEST is not used after SUCC but before I3.  */
       || (succ && ! all_adjacent
 	  && reg_used_between_p (dest, succ, i3))
@@ -1371,7 +1377,12 @@ try_combine (i3, i2, i1)
   if (GET_RTX_CLASS (GET_CODE (i3)) != 'i'
       || GET_RTX_CLASS (GET_CODE (i2)) != 'i'
       || (i1 && GET_RTX_CLASS (GET_CODE (i1)) != 'i')
-      || find_reg_note (i3, REG_LIBCALL, NULL_RTX))
+#if 0
+      /* ??? This gives worse code, and appears to be unnecessary, since no
+	 pass after flow uses REG_LIBCALL/REG_RETVAL notes.  */
+      || find_reg_note (i3, REG_LIBCALL, NULL_RTX)
+#endif
+)
     return 0;
 
   combine_attempts++;