rtlanal.c (noop_move_p): Insns with a REG_RETVAL note should not be considered as a no-op.

	* rtlanal.c (noop_move_p): Insns with a REG_RETVAL note
	should not be considered as a no-op.
	* flow.c (delete_noop_moves): Handle REG_LIBCALL notes.

From-SVN: r46174

gcc/ChangeLog

+Wed Oct 10 23:49:06 EDT 2001  John Wehle  (john@feith.com)
+
+	* rtlanal.c (noop_move_p): Insns with a REG_RETVAL note
+	should not be considered as a no-op.
+	* flow.c (delete_noop_moves): Handle REG_LIBCALL notes.
+
 2001-10-10  Stan Shebs  <shebs@apple.com>
 
 	* alias.c: Remove uses of "register" specifier in declarations

gcc/flow.c

@@ -771,8 +771,25 @@ delete_noop_moves (f)
 	  next = NEXT_INSN (insn);
 	  if (INSN_P (insn) && noop_move_p (insn))
 	    {
-	      /* Do not call delete_insn here to not confuse backward
-	         pointers of LIBCALL block.  */
+	      rtx note;
+
+	      /* If we're about to remove the first insn of a libcall
+		 then move the libcall note to the next real insn and
+		 update the retval note.  */
+	      if ((note = find_reg_note (insn, REG_LIBCALL, NULL_RTX))
+		       && XEXP (note, 0) != insn)
+		{
+		  rtx new_libcall_insn = next_real_insn (insn);
+		  rtx retval_note = find_reg_note (XEXP (note, 0),
+						   REG_RETVAL, NULL_RTX);
+		  REG_NOTES (new_libcall_insn)
+		    = gen_rtx_INSN_LIST (REG_LIBCALL, XEXP (note, 0),
+					 REG_NOTES (new_libcall_insn));
+		  XEXP (retval_note, 0) = new_libcall_insn;
+		}
+
+	      /* Do not call delete_insn here since that may change
+	         the basic block boundaries which upsets some callers.  */
 	      PUT_CODE (insn, NOTE);
 	      NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
 	      NOTE_SOURCE_FILE (insn) = 0;

gcc/rtlanal.c

@@ -1037,6 +1037,11 @@ noop_move_p (insn)
   if (find_reg_note (insn, REG_EQUAL, NULL_RTX))
     return 0;
 
+  /* For now treat an insn with a REG_RETVAL note as a
+     a special insn which should not be considered a no-op.  */
+  if (find_reg_note (insn, REG_RETVAL, NULL_RTX))
+    return 0;
+
   if (GET_CODE (pat) == SET && set_noop_p (pat))
     return 1;