review(XS): 7058689 Tiered: Reprofiling doesn't happen in presence of level 4 OSR methods

[Tom Rodriguez]

Looks good.

tom

On Jun 23, 2011, at 5:14 PM, Igor Veresov wrote:

> When we deopt from a C2-compiled method and request reprofiling (we're at level 0 at this point) natually we would want to start reprofiling in the interpreter and queue up a level 3 compile and continue profiling at level 3 when it arrives. However, when we decide to which level to switch we check the max comp level of the OSR versions of the method. If a the level is 4 and there's been more than one profiled invocation we would choose to compile at level 4. This was initroduced to avoid deopt loops when we deopt and switch to a higher level OSR method.
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> So, with reprofiling we need to handle the situation differently. The solution is to check at which level an OSR would be even possible at the moment (by calling the transition function with a loop predicate), which will take into account the fact the we need to reprofile and return either level 2 or 3; and then checking what OSR methods are currently available and taking the minimum level.
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> Webrev: http://cr.openjdk.java.net/~iveresov/7058689/webrev.00/
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> 
> Thanks,
> igor