trivial diff: add XXX comments about overflow checking

[Simon Taylor]

Estimated hours taken: 0.1

compiler/const_prop.m:
compiler/vn_util.m:
	Add XXX comments about checking for overflow and sharing code
	between these modules.
	

Index: const_prop.m
===================================================================
RCS file: /home/staff/zs/imp/mercury/compiler/const_prop.m,v
retrieving revision 1.8
diff -u -u -r1.8 const_prop.m
--- const_prop.m	1999/03/30 05:55:58	1.8
+++ const_prop.m	1999/04/01 01:40:14
@@ -10,6 +10,9 @@
 % This module provides the facility to evaluate calls at compile time -
 % transforming them to simpler goals such as construction unifications.
 %
+% XXX We should check for overflow.
+% XXX Some of this code should be shared with vn_util__simplify_vnrval.
+% 
 %------------------------------------------------------------------------------%
 
 :- module const_prop.
Index: vn_util.m
===================================================================
RCS file: /home/staff/zs/imp/mercury/compiler/vn_util.m,v
retrieving revision 1.63
diff -u -u -r1.63 vn_util.m
--- vn_util.m	1999/03/30 05:21:51	1.63
+++ vn_util.m	1999/04/01 01:43:36
@@ -244,6 +244,10 @@
 
 	% XXX more simplification opportunities exist
 
+	% XXX we should check for overflow
+
+	% XXX some of this code should be shared with const_prop.m
+
 :- pred vn_util__simplify_vnrval(vnrval, vnrval, vn_tables, vn_tables).
 % :- mode vn_util__simplify_vnrval(in, out, di, uo) is det.
 :- mode vn_util__simplify_vnrval(in, out, in, out) is det.