webrev for hsail compiler safepoints

[Caspole, Eric]

Hi everybody,
I put up a new webrev for supporting compiler safepoints in HSAIL. This is an incremental change using the HSAIL deoptimization feature, so if a safepoint is detected in the kernel it will deoptimize back to CPU to complete the workitems. This will help avoid long running loops in kernels from halting the CPU threads in the event a safepoint is required during the kernel execution.

http://cr.openjdk.java.net/~ecaspole/hsail_comp_safepoints/webrev/

There were already about 12 tests in the hsail tests that cause compiler safepoints to be emitted. Also we have an internal app with long running workitems which was a good test. I added a -XX:+UseHSAILSafepoints which is true by default, so we can experiment with it.
Let me know your comments.
Thanks,
Eric