Improve performance of -profile by factor of 10

[Vladimir Panteleev]

On Tuesday, 26 March 2013 at 02:57:07 UTC, Walter Bright wrote:
> While you can get the caller (after all, debuggers do it), it 
> can be arbitrarily costly (in terms of execution speed) to do 
> so, which can negate many of the advantages of a probing 
> profiler.

What? You just read the value EBP is pointing at, or something 
like that. Walking the call stack is basically walking a linked 
list.

> The ones I've seen didn't bother to do it.

Maybe they just weren't very good profilers ;) I've tried a few 
before I found Very Sleepy.

> Fan in/out is very useful because the most effective 
> optimization is to not call the time consuming functions, and 
> this path information enables you to figure out where you don't 
> really need to call it.

Who's arguing that?