You're talking about replacing return flags[t]; with a space optimized  
bit vector? I imagine it would help performance some if for no other  
reason that the trace flags would fit is a single cache block rather  
than spanning multiple as they do now.

Ali


On Sep 23, 2008, at 2:42 AM, Gabe Black wrote:

>    I just finished stepping through some code having to do with PCs in
> simple CPU, and I noticed that not printing DPRINTFs is actually a
> fairly involved process, considering that you're not actually doing
> anything. Part of the issue, I think, is that whether or not a  
> traceflag
> is on is stored in a vector of Bools. Since the size of the vector  
> won't
> change often (ever?) would it make sense to just make it a char [] and
> use something like the following?
>
> flags[t >>  3] &  (1 << (t & 3));
>
>
> I realize when you've got tracing on you're not going for blazing  
> speed
> in the first place, but if it's easy to tighten it up a bit that's
> probably a good idea. The other possibility is that it's actually not
> doing a whole lot but calling through a bunch of functions gdb stops  
> at
> one at a time. That would look like a lot of work to someone stepping
> through with gdb but could be just as fast.
>
> Gabe
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>

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