RFR (M) CR 8050147: StoreLoad barrier interferes with stack usages

[John Rose]

On Aug 8, 2014, at 5:01 AM, Aleksey Shipilev <aleksey.shipilev at oracle.com> wrote:

> On 08/08/2014 02:57 AM, John Rose wrote:
>>> Vladimir pointed where to look for frame structure [1], but I
>>> still haven't parsed it to make an educated guess about how much to
>>> step back. Any ideas?
>> 
>> Callee saves will get spilled in the general spill area, IIRC.  That
>> will be near the callee SP, which is unpredictable.
>> 
>> I don't see any area in the generic frame layout which is reliably
>> better than SP - CLSize.  Maybe SP - MaxTinyImmediateOffset, or the
>> min of the two.
> 
> Okay, let's go with this one then:
> http://cr.openjdk.java.net/~shade/8050147/webrev.03/

Why 8+CLSize (40/72/136) instead of just CLSize (32/64/128)?
Is there usually something hovering at sp(-8), like a frequently pushed temp?
— John