[aarch64-port-dev ] RFR: 8217368: AArch64: C2 recursive stack locking optimisation not triggered

Andrew Haley aph at redhat.com
Mon Jan 21 12:27:56 UTC 2019


On 1/21/19 9:27 AM, Nick Gasson (Arm Technology China) wrote:

> On 21/01/2019 17:10, Andrew Haley wrote:
>> On 1/21/19 6:01 AM, Nick Gasson (Arm Technology China) wrote:
>>> OK I'll change all three places in aarch64_enc_fast_lock/unlock that do
>>> a compare-exchange to use MacroAssembler::cmpxchg.
>> If you wish: be aware that if you change anything other than this place there'll
>> be a lot more testing to do, and review will take longer.
> I think it will be confusing for anyone looking at these functions in 
> the future to have one call to cmpxhg and then two copies of essentially 
> the same code inlined a few lines afterwards. IMO we should either 
> change all three for consistency, or stick with the original minimal 
> patch (+ Derek's cleanup suggestions) which should be easier to review.

OK, if that's your position: you're writing the patch. Using cmpxhg
everywhere will make that rather twisted code much easier to read.

Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
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