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Re: Is the GCC optimazer too smart?
- From: Jonathan Wakely <jwakely dot gcc at gmail dot com>
- To: sergio borghese <sergio dot borghese at gmail dot com>
- Cc: gcc at gcc dot gnu dot org
- Date: Thu, 10 Dec 2009 19:53:03 +0000
- Subject: Re: Is the GCC optimazer too smart?
- References: <2280d7230912100403k6bf05d01p4d719e89c1ed2b52@mail.gmail.com>
2009/12/10 sergio borghese:
>
> Now my question is: is it correct that the compiler enforces the
> constantness of the variable, even tought it states in the warning
> that the const qualifier has been discarded?
the calls to printf can be optimised to printf("i: %dn", 0) so it
doesn't use the value of i, because the compiler knows that the value
of i cannot be changed by a valid program. You didn't show what foo
does, but if you change the value of a const variable the program's
behaviour is undefined, so you can't rely on any particular behaviour.