[9] RFR (S): 8150186: Folding mismatched accesses with @Stable is incorrect

[John Rose]

Reviewed. 

– John

> On Feb 24, 2016, at 8:06 AM, Vladimir Ivanov <vladimir.x.ivanov at oracle.com> wrote:
> 
> http://cr.openjdk.java.net/~vlivanov/8150186/webrev.00/
> https://bugs.openjdk.java.net/browse/JDK-8150186
> 
> Constant folding from stable arrays doesn't check for mismatched accesses.
> 
> The fix is to disable the optimization for mismatched accesses.
> 
> Also, added missing range checks in ciArray::element_value_by_offset.
> 
> Testing: failing tests, JPRT
> 
> Best regards,
> Vladimir Ivanov
> 
> PS: I considered converting is_mismatched_access check in fold_stable_ary_elem into an assert, but I spotted some quirks in mismatched access detection (filed JDK-8150543 [1]). So, I'd prefer to keep the check and refine the code as part of JDK-8150543 when more test coverage is available.
> 
> [1] https://bugs.openjdk.java.net/browse/JDK-8150543