Re: binary compatibility ABI

[Jeff Sturm <jsturm at one-point dot com>]

On Wed, 10 Sep 2003, Bryce McKinlay wrote:
> > Also, we can dispense with the call to initialize the class that
> > contains a static data member:
>
> I think that keeping the initialization check/call at the call (or
> field access) site gives us more opportunity to optimize it out at
> compile time. eg: hoisting it out of loops, eliminating it if class is
> already known to be initialized in the current method, keeping a local
> cache, etc.

Very good point.  Libgcj hides a lot of class inits now, in 'new' or
'instanceof' calls for example.  The more these can be exposed the easier
they are to eliminate.  The possible downside is increased code size.

(As an aside, I know there's been discussions before about static vs.
local boolean flags to track class initializations.  What about using TLS on
platforms that support it (i.e. x86/linux)?  Each thread would check a
thread-local boolean variable before calling _Jv_InitClass, so it would
have to attempt class initialization at most once per class.  I can't
think of a reason that would violate Java's memory model.)

Jeff