From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeffrey A Law To: Greg McGary Cc: Jim Wilson , Dave Love , burley@gnu.org, egcs@cygnus.com Subject: Re: array bounds checking? Date: Fri, 22 May 1998 00:21:00 -0000 Message-id: <11492.895806192@hurl.cygnus.com> References: X-SW-Source: 1998-05/msg00826.html I looked over the bounds checking and bounded pointer stuff for a little while today. Based on specs alone it sounds like bounded pointers are the better direction. My biggest concern is the change in pointer size; yes BP has mechanisms to handle this, but it just makes me uneasy. It sounds like you use a CONCAT like rtx to represent a bounded pointer. Is that correct? If so, then we're going to need to actually fix the CONCAT support. It's got some problems right now. The fact that support for the C++ front-end is already done is a major win. I also believe that checking just memory accesses is probably better than checking all pointer arithmetic. It is possible in some languages (Ada) to have a pointer outside the object being pointed to. Some backends do similar things when optimizing. It might be interesting to hear from the Fortran folks if they have any opinions. It would also be good to get some sense of the changes involved; particularly for front-ends. We'd want to be able to hook into the Fortran front end initially. The gpc guys would probably also benefit from this code, so we'll want them to be able to hook in as well. I'd also be a little concerned about legal issues -- do we have any known patent exposure with either implementation? I don't really know what patents might be floating around in this arena. I also don't see a copyright on file for you personally or a disclaimer from Ascend. Those issues will also have to be resolved. We'll probably want to start looking at the code before we go any further. jeff