src/share/vm/gc_implementation/shared/gcTrace.cpp

rev 4213 : 8008382: Remove redundant use of Atomic::add(jlong, jlong *) in create_new_gc_id()
Summary: There is no need to use atomics in create_new_gc_id() since it is not called by multiple threads in parallel. Also, Atomic::add(jlong, jlong *) is broken for ARM.
Reviewed-by:

*** 25,43 ****
  #include "precompiled.hpp"
  #include "gc_implementation/shared/gcHeapSummary.hpp"
  #include "gc_implementation/shared/gcTimer.hpp"
  #include "gc_implementation/shared/gcTrace.hpp"
  #include "memory/referenceProcessorStats.hpp"
- #include "runtime/atomic.hpp"
  #include "utilities/globalDefinitions.hpp"
  
  #define assert_unset_gc_id() assert(_shared_gc_info.id() == SharedGCInfo::UNSET_GCID, "GC already started?")
  #define assert_set_gc_id() assert(_shared_gc_info.id() != SharedGCInfo::UNSET_GCID, "GC not started?")
  
! static volatile jlong GCTracer_next_gc_id = 0;
  static GCId create_new_gc_id() {
!   return Atomic::add((jlong)1, &GCTracer_next_gc_id);
  }
  
  void GCTracer::report_gc_start_impl(GCCause::Cause cause, jlong timestamp) {
    assert_unset_gc_id();
  
--- 25,42 ----
  #include "precompiled.hpp"
  #include "gc_implementation/shared/gcHeapSummary.hpp"
  #include "gc_implementation/shared/gcTimer.hpp"
  #include "gc_implementation/shared/gcTrace.hpp"
  #include "memory/referenceProcessorStats.hpp"
  #include "utilities/globalDefinitions.hpp"
  
  #define assert_unset_gc_id() assert(_shared_gc_info.id() == SharedGCInfo::UNSET_GCID, "GC already started?")
  #define assert_set_gc_id() assert(_shared_gc_info.id() != SharedGCInfo::UNSET_GCID, "GC not started?")
  
! static jlong GCTracer_next_gc_id = 0;
  static GCId create_new_gc_id() {
!   return GCTracer_next_gc_id++;
  }
  
  void GCTracer::report_gc_start_impl(GCCause::Cause cause, jlong timestamp) {
    assert_unset_gc_id();