RFR: 8260502: [s390] NativeMovRegMem::verify() fails because it's too strict [v2]

[Martin Doerr]

On Thu, 28 Jan 2021 10:09:57 GMT, Richard Reingruber <rrich at openjdk.org> wrote:

>> Martin Doerr has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fix comment for NativeMovRegMem
>
> The fix looks good to me.
> 
> The comment before the declaration of NativeMovRegMem seems to be wrong. I'd suggest to change it like this:
> 
> s/optional, load only/optional, store only/
> 
> // The instruction sequence looks like this:
> //   iihf        %r1,$bits1              ; load offset for mem access
> //   iilf        %r1,$bits2
> //   [compress oop]                      ; optional, store only
> //   load/store  %r2,0(%r1,%r2)          ; memory access
> 
> I noticed that on x86 encoding/decoding the T_OBJECT field value in reg2mem/mem2reg is done before/after the code that is to be patched. Changing the s390/PPC versions to do the same may have solved JDK-8233081 as well. This wouldn't have increased the complexity of the already extremely complex C1 patching mechanics. But it is like it is.

Thanks for the reviews! I've fixed the comment as suggested. Thanks.

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PR: https://git.openjdk.java.net/jdk/pull/2258