Improving the performance of OpenJDK

[Gary Benson]

Andrew Haley wrote:
> Gary Benson wrote:
> > Edward Nevill wrote:
> > > get_native_u2() and get_Java_u2() ... This seems to be a
> > > misguided attempt of the original authors to optimised reading
> > > of halfwords (judging by the comment immediate preceding the
> > > code).
> > 
> > It's not an optimization, it's to do unaligned access on hardware
> > that doesn't support it.  I'm guessing ARM does allow unaligned
> > access by the fact that your code didn't segfault instantly ;)
> 
> ARM doesn't support unaligned loads.  The new ARM code as posted is
> 
> 	ldrsb	r0, [java_pc, #0]
> 	ldrb	r1, [java_pc, #1]
> 	orr	r1, r1, r0, lsl #8
> 
> i.e two byte loads.

Ah, I didn't realise.  Which is good, it means this optimization is
generic :)

Cheers,
Gary

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