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Re: basic VRP min/max range overflow question
- From: Paul Schlie <schlie at comcast dot net>
- To: Andrew Pinski <pinskia at physics dot uc dot edu>
- Cc: Paolo Bonzini <paolo dot bonzini at lu dot unisi dot ch>,GCC Development <gcc at gcc dot gnu dot org>,Diego Novillo <dnovillo at redhat dot com>
- Date: Fri, 17 Jun 2005 20:59:44 -0400
- Subject: Re: basic VRP min/max range overflow question
> From: Andrew Pinski <pinskia@physics.uc.edu>
> On Jun 17, 2005, at 8:20 PM, Paul Schlie wrote:
>
>> ["undefined" only provides liberties within the constrains of what
>> is specifically specified as being undefined, but none beyond that.]
>
> That is not true. Undefined means it can run "rm /" if you ever invoke
> the undefined code.
- If the semantics of an operation are "undefined", I'd agree; but if
control is returned to the program, the program's remaining specified
semantics must be correspondingly obeyed, including the those which
may utilize the resulting value of the "undefined" operation.
- If the result value is "undefined", just the value is undefined.
(Unless one advocates that any undefined result implies undefined semantics,
which enables anything to occur, including the arbitrary corruption of
the remaining program's otherwise well defined semantics; in which case any
invocation of implementation specific behavior may then validly result in
arbitrary remaining program behavior.)
Which I'd hope isn't advocated.