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From: "Dave Korn" <dave.korn@artimi.com>
To: "'teawater'" <teawater@gmail.com>, 	"'Daniel Jacobowitz'" <drow@false.org>, 	"'Jakob Engblom'" <jakob@virtutech.com>, 	"'Michael Snyder'" <msnyder@vmware.com>, 	<gdb@sourceware.org>
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Subject: RE: [discuss] semantics, "replay debugging" vs. "reverse debugging"
Date: Wed, 22 Oct 2008 17:09:00 -0000
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teawater wrote on 22 October 2008 17:43:

> Sorry I am wrong.
> In ARM, Just adds set cpsr reg. So:
> add r0,r0,#10
> Can reverse without record too.

  Your examples are too limited to be of practical use; almost every
instruction executed destroys information.

  It's easy to reverse "add r0,r0,#10" by subtracting 10 from r0.  But how do
you reverse "add r0,r1,#10", or anything else where the source and dest
register are different?  The original value of r0 is gone without trace, and
r1 was not changed by the instruction!


    cheers,
      DaveK
-- 
Can't think of a witty .sigline today....