RFR: 8166188: G1 Needs pre barrier on dereference of weak JNI handles

[Kim Barrett]

> On Feb 7, 2017, at 8:59 AM, Doerr, Martin <martin.doerr at sap.com> wrote:
> 
> Hi Kim,
> 
> thanks for adding and adapting my code. There's only one minor bug on PPC64. Please use the correct label name for the conditional branch as shown in the diff below.
> 
> If you like, you can add simonis and mdoerr as contributors, but I don't insist on it.
> 
> I guess SignatureChekker was written with "kk" to distinguish it from something else?
> 
> Besides that, the change looks good to me.
> 
> Thanks and best regards,
> Martin
> 
> 
> --- a/src/cpu/ppc/vm/sharedRuntime_ppc.cpp      Tue Feb 07 12:48:05 2017 +0100
> +++ b/src/cpu/ppc/vm/sharedRuntime_ppc.cpp      Tue Feb 07 14:30:48 2017 +0100
> @@ -2483,7 +2483,7 @@
>   if (ret_type == T_OBJECT || ret_type == T_ARRAY) {
>     Label done, not_weak;
>     __ cmpdi(CCR0, R3_RET, 0);
> -    __ beq(CCR0, null_result);  // Use NULL as-is.
> +    __ beq(CCR0, done);         // Use NULL as-is.
> 
>     __ andi_(r_temp_1, R3_RET, JNIHandles::weak_tag_mask);
>     __ beq(CCR0, not_weak);     // Test for jweak tag.

Oops.  Thanks for the fix.

And thanks for the review.