[9] RFR (L): 8015774: Add support for multiple code heaps

Tobias Hartmann tobias.hartmann at oracle.com
Tue Sep 16 07:31:58 UTC 2014

Hi Andrew,

thanks for your feedback, please see comments inline.

On 16.09.2014 09:22, Andrew Haley wrote:
> This has some potential impact on AArch64.
> The issue there is that branch instructions have a range of +- 128Mb.
> Any further than that and you have to use multiple instructions, and
> then you have problems with thread-safe patching.
> So, is it possible to allocate all of the code heaps in a single
> block, so that we won't exceed that range?

The code heaps are already allocated next to each other because we have 
to make sure that the overall memory size does not exceed 2 GB (as this 
is a general requirement for 32 bit immediates). Further, the code cache 
segmentation is only enabled with TieredCompilation and a 
ReservedCodeCacheSize >= 240 MB.

Does that answer your question?


> Andrew.

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