RFR: 8204554: JFR TLAB tracing broken after 8202776

[Thomas Schatzl]

Hi,

On Thu, 2018-06-07 at 16:27 +0200, Erik Österlund wrote:
> Hi,
> 
> The recent allocation path modularization (8202776) broke JFR TLAB 
> sampling. This was discovered in tier 5 testing.
> 
> The problem is that there was previously an early exit TLAB path,
> that should not run the tracing code when not returning NULL, and a 
> mem_allocate call that should run the tracing code when not
> returning NULL. However, these paths were joined in a virtual member
> function, making them look the same to the tracing code, which caused
> the non-TLAB tracing code to be run on TLAB allocations as well.
> 
> The solution I propose is to move the TLAB tracing code into the new 
> virtual member function. It seems that whatever GC overrides this
> code, should also decide what to do about the tracing code there
> anyway.
> 

  looks good.

Thomas