RFR 8203466: intermittent crash at jdk.internal.misc.Unsafe::getObjectVolatile (native)

dean.long at oracle.com dean.long at oracle.com
Fri Sep 14 20:01:02 UTC 2018

Hi Coleen.  In the bug you asked:

 > Why can't we just push rdi and rsi to the stack and restore them? 
This code appears to be leaf code so shouldn't care about stack format

Did that ever get answered?  If there is concern about the pushes and 
pops canceling out at the end, you could always reserve the stack space 
at the beginning, after

__ enter();

and then setup_arg_regs/restore_arg_regs would not need to adjust the 
stack pointer.


On 9/14/18 11:32 AM, coleen.phillimore at oracle.com wrote:
> Summary: Save windows 64 callee saved registers rsi, rdi to Thread, 
> save r15, also callee saved to r9
> This is done for generated stubs that do arraycopy that need GC 
> barrier code because GC assumes that r10 is scratch, since it's 
> defined as rscratch1.  See bug for more details.  Thanks Erik for your 
> help and the diagnosis.
> Tested with mach5 hs-tier1-7.  We don't have a reproduceable test case.
> open webrev at http://cr.openjdk.java.net/~coleenp/8203466.01/webrev
> bug link https://bugs.openjdk.java.net/browse/JDK-8203466
> Thanks,
> Coleen

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