[aarch64-port-dev ] RFR[xs]: 8245137: aarch64 ICache flush depends on enabling gnu extensions

[Kim Barrett]

> On May 17, 2020, at 7:02 AM, Andrew Haley <aph at redhat.com> wrote:
> 
> On 5/16/20 6:39 PM, Kim Barrett wrote:
>> Please review this small change to the aarch64 implementation of
>> ICache::invalidate_word ICache::invalidate_range.  Rather than calling
>> __clear_cache directly, they are changed to use __builtin___clear_cache.
>> The direct call to __clear_cache requires either providing a
>> declaration for that function or enabling gnu extensions.  Using the
>> builtin requires neither.
>> 
>> CR:
>> https://bugs.openjdk.java.net/browse/JDK-8245137
>> 
>> Webrev:
>> https://cr.openjdk.java.net/~kbarrett/8245137/open.00/
> 
> Sure, it all ends up in libgcc's __aarch64_sync_cache_range anyway.
> 
> I've been a little wary of __builtin___clear_cache for a while, given
> that we need to be certain exactly what it does in order to ensure the
> correctness of HotSpot, but the code in libgcc is fine.
> 
> OK, thanks.

Thanks.