RFR: 8255065: Zero: accessor_entry misses the IRIW case

[Martin Doerr]

On Tue, 20 Oct 2020 17:09:59 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> While doing a change in related area, I noticed there is no IRIW handling block in `ZeroInterpreter::accessor_entry`
> when reading volatile fields. This probably breaks PPC64 Zero.
> There is a block in `bytecodeInterpreter.cpp` for [common field
> access](https://github.com/openjdk/jdk/blob/master/src/hotspot/share/interpreter/zero/bytecodeInterpreter.cpp#L1899-L1901):
>           if (cache->is_volatile()) {
>             if (support_IRIW_for_not_multiple_copy_atomic_cpu) {
>               OrderAccess::fence();
>             }
> 
> Attention @TheRealMDoerr ;)
> 
> Testing:
>  - [x] Linux x86_64 zero fastdebug build (includes jmod generation with Zero)

Good catch! I don't think anybody uses zero for PPC64, but it's better to get this fixed. Thanks.

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Marked as reviewed by mdoerr (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/766