[8u] RFR 8191227: Unsafe handle resolution in ConstantOopWriteValue::write_on() / print_on() and LIR_Assembler::jobject2reg()

[Andrew Hughes]

On 19/02/2020 11:51, Aleksey Shipilev wrote:
> Original fix:
>   https://bugs.openjdk.java.net/browse/JDK-8191227
>   https://hg.openjdk.java.net/jdk/jdk/rev/bb957f109a1f
> 
> The patch applies after reshuffling and fuzz. We ship parts of this fix in shenandoah/jdk8u:
>   https://mail.openjdk.java.net/pipermail/shenandoah-dev/2020-February/011434.html
> 
> I would appreciate reviews w.r.t. its bug tail. It seems to be followed up by JDK-8193699, which
> introduced numerous failures in itself. I don't think this fix individually causes those troubles.
> 
> 8u webrev:
>   http://cr.openjdk.java.net/~shade/8191227/webrev.8u.01/
> 
> Testing: tier1
> 

Patch looks fine, just some context differences.

I assume the bug tail is more about JDK-8167372: "Add code to check for
getting oops while thread is in native" (JDK-8193699 "AArch64: Fails to
build after 8167372" is a response to that, and for AArch64, which
currently isn't supported in 8u). I can see the merits in backporting
that, but I'd wait until the 8u262 cycle so we maximise the time to
shake out any issues.

This patch seems pretty safe, given the only product build change is to
introduce ThreadInVMfromUnknown tiv in
ConstantOopWriteValue::print_on(outputStream* st). It's effectively an
instance of the bug JDK-8167372 aims to make easier to catch.

Thanks,
-- 
Andrew :)

Senior Free Java Software Engineer
Red Hat, Inc. (http://www.redhat.com)

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