[aarch64-port-dev ] RFR: 8075930: AARCH64: Use FP Register in C2

[Edward Nevill]

On 22 April 2015 at 17:58, Andrew Haley <aph at redhat.com> wrote:

> Looking at this thread:
>
>
> http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2014-December/016477.html
> https://bugs.openjdk.java.net/browse/JDK-8068945
>
> I'm wondering if we should keep FP as a frame pointer.  We'd have a
> slightly more complex method entry sequence, but the profiling and
> debugging advantages look to be quite considerable.
>
> Andrew.
>

Hi,

The two are not incompatible. Zoltán Majó has been working on a patch to
use RBP as a proper frame pointer on x86. See

http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2015-April/017715.html

This provides a new flag -XX:+PreserveFramePointer which uses RBP as a
proper frame pointer and -XX:-PreserveFramePointer which uses RBP as a
general purpose register.

I have prepared a mirror patch for this for aarch64. See

http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2015-March/017543.html

Once Zoltán's patch goes in, I can update this for any recent changes and
post a RFR.

All the best,
Ed.