RFR: improve profiled predicates

[Aleksey Shipilev]

On 01/12/2018 05:54 PM, Roland Westrelin wrote:
> http://cr.openjdk.java.net/~roland/shenandoah/improved-profiled-predicates/webrev.00/

Help me understand why we are pushing this to sh/jdk10? Is this for pre-stabilization until we
upstream this separately? We don't backport this at all to sh/jdk9 and sh/jdk8?

Nits:

loopPredicate.cpp
 *) indenting is off starting line 331, also see lines 334 and 339
 *) fenv.h/math.h includes in the middle of the file?
 *) indenting at line 1208

deoptimization.hpp:
 *) Comment for the reason here?
  65     Reason_profile_predicate,

DataLayout.java:
 *) Comment is outdated:
  96   // 4 bits of trap history (none/one reason/many reasons),

 *) Indenting, and also the condition looks reversed. Cell size is the size of ptr, right? And we
have the union with u8 inside, which takes 2 slots on 32-bit VM?

 120   static int headerSizeInCells() {
 121       return VM.getVM().isLP64() ? 2 : 1;
 122   }


Thanks,
-Aleksey