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Date: Sat, 11 Dec 2004 12:58:01 +0200
From: "Eli Zaretskii" <eliz AT gnu DOT org>
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In-reply-to: <41BA307B.B402D23C@yahoo.com> (message from CBFalconer on Fri, 10
	Dec 2004 18:25:47 -0500)
Subject: Re: Bison 1.875 (release 2)
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> Date: Fri, 10 Dec 2004 18:25:47 -0500
> From: CBFalconer <cbfalconer AT yahoo DOT com>
> 
> I can see how that is much more immediate at catching overwrites,
> etc.  You are aware that nmalloc includes a SAVEMEMORY define that
> removes guard words at the ends of allocations, which in turn
> enables most overwrites to be detected early (at the cost of some
> overhead).

The problem with detecting such bugs is that, unless you run the
detection code after every machine instruction, you cannot detect them
except at some later moment, and that makes it hard to find the buggy
code without further debugging.

YAMD in effect puts a hardware-assisted watchpoint near the edges of
every allocated buffer, so code that accesses invalid memory is caught
right on the spot.

That said, since YAMD has its limitations (e.g., large programs such
as Emacs and GDB cannot at all be run under YAMD), I think any
debugging tools such as malldbg and nmalloc are welcome additions to
our toolchest.