[aarch64-port-dev ] Very large code caches
aph at redhat.com
Wed May 16 07:35:46 UTC 2018
On 05/16/2018 08:27 AM, Leslie Zhai wrote:
> > 在 2018年05月16日 15:23, Andrew Haley 写道:
>> On 05/16/2018 03:53 AM, Leslie Zhai wrote:
>>> Hi HotSpot developers,
>>> I am trying to implement `patch_verified_entry` for other targets, such
>>> as riscv, but I found that:
>>>> but the real problem is that the resulting call
>>>> site is not MT-safe: it can't be patched atomically. To make that
>>>> work we'd have to move the destination address into the constant pool.
>> Where is that comment? I can't find it.
I changed my mind after that, and we implemented trampolines.
>>> So aarch64 hasn't implemented patched *atomically* yet?
>> We atomically patch everything correctly. If you look at the AArch64
>> implementation of patch_verified_entry you'll see that we replace a
>> direct call instruction if it can reach, and if it can't we jump to a
>> trampoline. The trampoline is a load from a single word followed by
>> an indirect call. In both cases it is atomic.
> And could you share your experience to use PRINT_REG alike or something
> else to catch the bugs for logical issue?
I don't really understand that message. There are problems with the lines
being broken, and the output is combined with PrintCompilation messages.
I don't think I've used PRINT_REG. If I've had problems with code
generation I've usually stepped through in the debugger.
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
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