Re: class initialization

[Bryce McKinlay <bryce at albatross dot co dot nz>]

Tom Tromey wrote:

> A while back Anthony changed the compiler to keep track of whether a
> class was already initialized in a given method.  This lets us
> eliminate some initializations statically, at least when optimization
> is enabled.
>
> Today it occurred to me that we currently initialize this local flag
> as `0' while we could actually initialize it with `class.state >= 12'.
> This is a load, a compare, and a branch per generated call to
> _Jv_InitClass.  Is this worth doing?  When would it hurt?

I can't see how this could be anything but good. A class actually needing
to be initialized is the (very) uncommon case, and checking class.state
is the first thing _Jv_InitClass does anyway. Combined with a
__builtin_expect-style trick (to straight-line the common case), I think
we'd see a respectable speedup!

regards

  [ bryce ]