822 
 823 // Return the number of bytes available for resizing down the young
 824 // generation.  This is the minimum of
 825 //      input "bytes"
 826 //      bytes to the minimum young gen size
 827 //      bytes to the size currently being used + some small extra
 828 size_t PSYoungGen::limit_gen_shrink(size_t bytes) {
 829   // Allow shrinkage into the current eden but keep eden large enough
 830   // to maintain the minimum young gen size
 831   bytes = MIN3(bytes, available_to_min_gen(), available_to_live());
 832   return align_down(bytes, virtual_space()->alignment());
 833 }
 834 
 835 void PSYoungGen::reset_after_change() {
 836   ShouldNotReachHere();
 837 }
 838 
 839 void PSYoungGen::reset_survivors_after_shrink() {
 840   _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
 841                         (HeapWord*)virtual_space()->high_boundary());
 842   PSScavenge::reference_processor()->set_span(_reserved);
 843 
 844   MutableSpace* space_shrinking = NULL;
 845   if (from_space()->end() > to_space()->end()) {
 846     space_shrinking = from_space();
 847   } else {
 848     space_shrinking = to_space();
 849   }
 850 
 851   HeapWord* new_end = (HeapWord*)virtual_space()->high();
 852   assert(new_end >= space_shrinking->bottom(), "Shrink was too large");
 853   // Was there a shrink of the survivor space?
 854   if (new_end < space_shrinking->end()) {
 855     MemRegion mr(space_shrinking->bottom(), new_end);
 856     space_shrinking->initialize(mr,
 857                                 SpaceDecorator::DontClear,
 858                                 SpaceDecorator::Mangle);
 859   }
 860 }
 861 
 862 // This method currently does not expect to expand into eden (i.e.,

 822 
 823 // Return the number of bytes available for resizing down the young
 824 // generation.  This is the minimum of
 825 //      input "bytes"
 826 //      bytes to the minimum young gen size
 827 //      bytes to the size currently being used + some small extra
 828 size_t PSYoungGen::limit_gen_shrink(size_t bytes) {
 829   // Allow shrinkage into the current eden but keep eden large enough
 830   // to maintain the minimum young gen size
 831   bytes = MIN3(bytes, available_to_min_gen(), available_to_live());
 832   return align_down(bytes, virtual_space()->alignment());
 833 }
 834 
 835 void PSYoungGen::reset_after_change() {
 836   ShouldNotReachHere();
 837 }
 838 
 839 void PSYoungGen::reset_survivors_after_shrink() {
 840   _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
 841                         (HeapWord*)virtual_space()->high_boundary());
 842   PSScavenge::set_subject_to_discovery_span(_reserved);
 843 
 844   MutableSpace* space_shrinking = NULL;
 845   if (from_space()->end() > to_space()->end()) {
 846     space_shrinking = from_space();
 847   } else {
 848     space_shrinking = to_space();
 849   }
 850 
 851   HeapWord* new_end = (HeapWord*)virtual_space()->high();
 852   assert(new_end >= space_shrinking->bottom(), "Shrink was too large");
 853   // Was there a shrink of the survivor space?
 854   if (new_end < space_shrinking->end()) {
 855     MemRegion mr(space_shrinking->bottom(), new_end);
 856     space_shrinking->initialize(mr,
 857                                 SpaceDecorator::DontClear,
 858                                 SpaceDecorator::Mangle);
 859   }
 860 }
 861 
 862 // This method currently does not expect to expand into eden (i.e.,