cost of -fnon-call-exceptions

[Kenny Simpson]

forgot to reply the the list...

From: Ian Lance Taylor <iant@google.com>
Subject: Re: cost of -fnon-call-exceptions
To: "Kenny Simpson" <theonetruekenny@yahoo.com>
Date: Friday, September 10, 2010, 3:48 PM
Kenny Simpson <theonetruekenny@yahoo.com>
writes:

> Meaning every memory reference is treated as though it were volatile ?
> Any rough idea how much this would hurt ?

Please reply to the mailing list, not just to me. 
Thanks.

It's not really accurate to say that every memory reference
is treated as volatile.  A memory reference which is not used
will still be removed from the program.  Also the compiler knows that many
memory references can not trap--e.g., references to variables stored on the
stack.  It would be more accurate to say that the compiler will not in
general reorder indirections through pointers.  How much that
hurts depends a lot on your processor.  On modern x86 other than Atom,
it doesn't hurt much, because the processors are not in-order and have
sophisticated memory reordering.  On Atom it will hurt, but how much
it will hurt depends on your application.  I don't think there is
any one answer.

Ian