RFR (XXS): 8079156: 32 bit Java 9-fastdebug hit assertion in client mode with StackShadowPages flag value from 32 to 50

David Holmes david.holmes at oracle.com
Mon Jul 13 05:34:49 UTC 2015

Hi Gerard,

On 11/07/2015 7:09 AM, gerard ziemski wrote:
> (resending - forgot to include the issue number in the title)
> Hi all,
> Please review this very small fix:
>     bug: https://bugs.openjdk.java.net/browse/JDK-8079156
> webrev: http://cr.openjdk.java.net/~gziemski/8079156_rev0

I'd like to hear from the compiler folk about this bug as I'm unclear on 
why StackBanging adds to the code buffer, and why this suddenly seems to 
be a new problem - did something change? Or have we not exercised the 
range of values before?

I'd also like to understand whether the code buffer resizing should be 
rounded up (or whether it will be rounded up internally)? e.g. power of 
two, multiple of nK for some n etc.

The 112 value seems odd for 50 pages - is this 2 bytes (words?) per page 
plus some fixed overhead? Can it be expressed as a function of 
StackShadowPages rather than hardwiring to 112 which only works for 
values < 50?


> cheers

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