RFR: 8073093: AARCH64: C2 generates poor code for ByteBuffer accesses

Andrew Haley aph at redhat.com
Tue Feb 17 10:22:47 UTC 2015

On 02/17/2015 10:15 AM, Florian Weimer wrote:
> On 02/17/2015 11:00 AM, Andrew Haley wrote:
>> On 02/17/2015 09:39 AM, Florian Weimer wrote:
>>> On 02/14/2015 01:09 AM, John Rose wrote:
>>>> These queries need to go into Unsafe.
>>>> We also need Unsafe.getIntMisaligned, etc., which wire through to whatever second-best mechanism the platform offers.
>>> The safe variants should go into the java.lang.Integer etc. classes
>>> IMHO.  Even the JDK has quite a few uses for them (particularly the
>>> big endian variant).  Putting that into Unsafe only encourages
>>> further use of Unsafe from application code.
>> They'll all be visible as ByteBuffer methods, which should be enough
>> for application code, shouldn't it?  I'm not sure how much sense it
>> makes to put them into java.lang.Integer etc.
> You'll still have to allocate a wrapping ByteBuffer object to use them.
>  I expect that makes them unattractive in many cases.

Hmm.  I'm having a hard time trying to understand why.  If you need to
do a lot of accesses the allocation of the ByteBuffer won't be
significant; if you don't need to do a lot of accesses it won't
matter either.


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