On Tuesday, 28 July 2015 at 21:30:11 UTC, Jonathan M Davis wrote:
On Tuesday, 28 July 2015 at 21:24:31 UTC, David Nadlinger wrote:
On Tuesday, 28 July 2015 at 15:56:52 UTC, Jonathan M Davis
wrote:
It[Accepting Booleans]'s far more flexible in generic code.
It's the other way round. pragma(inline) has currently *three*
behaviors:
pragma(inline);
pragma(inline, true);
pragma(inline, false);
There is no way to represent those as a single boolean.
The second two states can be. So, you can turn inlining on and
off by feeding it a template argument or the result of a
function or something. But it is true that you'd be stuck with
a static if in the case that you just wanted to set it to the
default behavior. I don't know what you'd do to be able to take
an argument for all three though - maybe a string or just some
known integral value?
I don't know how much it really matters ultimately though,
since I expect that for the most part, the folks who are going
to be using this pragma won't be using it generically.
Personally, I very much doubt that I'll ever use it, since I've
never worked on code that cared about performance so much that
you _had_ to force inlining somewhere. The compiler usually
does a good enough job (though that's with C++ compilers; who
knows how well dmd does).
- Jonathan M Davis
Even for an application that you would assume does a fine job, if
you know, via profiling or unittests that a certain expression or
method takes a bit of time due to excessive calls, it might just
shave off a noticeable amount of time.
Case in point: live dynamic report generation. Let's say we have
millions of records from a database and we want to process them
and churn out a report. If this is done live, this could easily
take minutes depending on the calculations and manipulations you
need to do. If a call to a method is made every record, you could
easily shave off 10-30 seconds with forcing an inline. And
believe me, 10-30 seconds makes a huge difference when you're
waiting around for 5+ minutes or more.
There's also time sensitive trading systems that don't want to be
half a second slow, due to all that money they want now, now ,
now.
You'd be surprised how many places you could save a few seconds
here or there with a smart inline attribute that the compiler
might have missed.
It's been my experience that DMD doesn't really do a good job
with this. GDC is much much better, but DMD truly lacks luster
with inlining.
