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

Nick Gasson (Arm Technology China) Nick.Gasson at arm.com
Mon Jan 21 06:01:01 UTC 2019

Hi Andrew,

On 18/01/2019 22:56, Andrew Haley wrote:
>>> The patch looks good. However, I don't understand why we aren't using
>>> MacroAssembler::cmpxchgptr here. It looks like we should be, and you'd
>>> end up with a less complex result.
>> It's not exactly the same though: MacroAssembler::cmpxchgptr adds a "dmb
>> ish" to the failure path which I don't think is required here.
> Oh, sorry. I should have said MacroAssembler::cmpxchg, with a
> br.eq(cont) afterward.

OK I'll change all three places in aarch64_enc_fast_lock/unlock that do 
a compare-exchange to use MacroAssembler::cmpxchg.


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