RFR: 8151539: Remove duplicate AlwaysTrueClosures

[Kim Barrett]

> On Mar 9, 2016, at 3:01 PM, Stefan Karlsson <stefan.karlsson at oracle.com> wrote:
> 
> Hi Mikael,
> 
> On 2016-03-09 20:39, Mikael Gerdin wrote:
>> Hi Stefan,
>> 
>> On 2016-03-09 17:44, Stefan Karlsson wrote:
>>> Hi all,
>>> 
>>> Please review this patch to remove a bunch of redundant
>>> AlwaysTrueClosure classes.
>>> 
>>> http://cr.openjdk.java.net/~stefank/8151539/webrev.00/
>> 
>> There is still
>> 2128 // This should be moved to the shared markSweep code!
>> 2129 class PSAlwaysTrueClosure: public BoolObjectClosure {
>> 2130 public:
>> 2131   bool do_object_b(oop p) { return true; }
>> 2132 };
>> 2133 static PSAlwaysTrueClosure always_true;
>> in psParallelCompact.cpp
>> 
>> Otherwise the change looks good, I don't need to see an updated webrev.
> 
> Great that you saw this!
> 
> I've uploaded a new webrev, to make it easier for the second reviewer:
> http://cr.openjdk.java.net/~stefank/8151539/webrev.01/

A couple of things below; otherwise looks good.  I don't need a new
webrev for these.

------------------------------------------------------------------------------ 
src/share/vm/runtime/jniHandles.cpp
 136   static AlwaysTrueClosure always_true;

Function-scoped static initialization is not thread-safe in C++03.

I don't think there's any noticable benefit to a static here even with
thread-safe initialization, as the construction is probably pretty
simple. (It might be simple enough that there's no actual
thread-safety issue, but why take that chance.)

------------------------------------------------------------------------------
src/share/vm/gc/shared/referenceProcessor.cpp
 269   class AlwaysAliveClosure: public BoolObjectClosure {

This local class can go away too.

------------------------------------------------------------------------------
src/share/vm/gc/shared/genCollectedHeap.cpp
[removed]
 688 class AlwaysTrueClosure: public BoolObjectClosure {

src/share/vm/gc/parallel/psMarkSweep.cpp
[removed]
 574 class PSAlwaysTrueClosure: public BoolObjectClosure {

src/share/vm/gc/parallel/psParallelCompact.cpp
[removed]
2129 class PSAlwaysTrueClosure: public BoolObjectClosure {

Nice!  Fortunately, these aren't technically ODR violations, since the
same-named definitions are identical.

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