review for 7029167: add support for conditional card marks

[John Rose]

Your comment mentions ldsb/ldub, but I think it is about ldsw/lduw.

(I think you'll get lduw from the LoadI, and whether that turns into a brnz depends on the vagaries of can_branch_register in sparc.ad.)

I spot-checked other places where card marks are processed in opto, and saw no problems.

Reviewed.

-- John

On Mar 30, 2011, at 4:46 PM, Tom Rodriguez wrote:

> http://cr.openjdk.java.net/~never/7029167
> 
> 7029167: add support for conditional card marks
> Reviewed-by:
> 
> Repeated updates to the card table can be a source of contention on
> multiprocessor machines that can greatly inhibit scalability.  This
> adds support in C2 for conditional card marks.  Tested with jbb and
> CTW.  At some point this should be turned on automatically when multi
> socket machines are detected but that's covered under another bug as
> is C1 support.
>