6765804: GC "dead ratios" should be unsigned

Reviewed-by: ysr, tonyp

src/share/vm/gc_implementation/parallelScavenge/psMarkSweepDecorator.cpp

@@ -90,10 +90,10 @@ void PSMarkSweepDecorator::precompact() {
    */
   bool skip_dead = ((PSMarkSweep::total_invocations() % MarkSweepAlwaysCompactCount) != 0);
 
-  ssize_t allowed_deadspace = 0;
+  size_t allowed_deadspace = 0;
   if (skip_dead) {
-    int ratio = allowed_dead_ratio();
-    allowed_deadspace = (space()->capacity_in_bytes() * ratio / 100) / HeapWordSize;
+    const size_t ratio = allowed_dead_ratio();
+    allowed_deadspace = space()->capacity_in_words() * ratio / 100;
   }
 
   // Fetch the current destination decorator
@@ -271,10 +271,10 @@ void PSMarkSweepDecorator::precompact() {
   dest->set_compaction_top(compact_top);
 }
 
-bool PSMarkSweepDecorator::insert_deadspace(ssize_t& allowed_deadspace_words,
+bool PSMarkSweepDecorator::insert_deadspace(size_t& allowed_deadspace_words,
                                             HeapWord* q, size_t deadlength) {
+  if (allowed_deadspace_words >= deadlength) {
     allowed_deadspace_words -= deadlength;
-  if (allowed_deadspace_words >= 0) {
     oop(q)->set_mark(markOopDesc::prototype()->set_marked());
     const size_t aligned_min_int_array_size =
       align_object_size(typeArrayOopDesc::header_size(T_INT));

src/share/vm/gc_implementation/parallelScavenge/psMarkSweepDecorator.hpp

@@ -39,14 +39,16 @@ class PSMarkSweepDecorator: public CHeapObj {
   HeapWord* _first_dead;
   HeapWord* _end_of_live;
   HeapWord* _compaction_top;
-  unsigned int _allowed_dead_ratio;
+  size_t _allowed_dead_ratio;
 
-  bool insert_deadspace(ssize_t& allowed_deadspace_words, HeapWord* q, size_t word_len);
+  bool insert_deadspace(size_t& allowed_deadspace_words, HeapWord* q,
+                        size_t word_len);
 
  public:
   PSMarkSweepDecorator(MutableSpace* space, ObjectStartArray* start_array,
-                       unsigned int allowed_dead_ratio) :
-    _space(space), _start_array(start_array), _allowed_dead_ratio(allowed_dead_ratio) { }
+                       size_t allowed_dead_ratio) :
+    _space(space), _start_array(start_array),
+    _allowed_dead_ratio(allowed_dead_ratio) { }
 
   // During a compacting collection, we need to collapse objects into
   // spaces in a given order. We want to fill space A, space B, and so
@@ -63,8 +65,8 @@ class PSMarkSweepDecorator: public CHeapObj {
   HeapWord* compaction_top()                { return _compaction_top; }
   void set_compaction_top(HeapWord* value)  { _compaction_top = value; }
 
-  unsigned int allowed_dead_ratio()               { return _allowed_dead_ratio; }
-  void set_allowed_dead_ratio(unsigned int value) { _allowed_dead_ratio = value; }
+  size_t allowed_dead_ratio()               { return _allowed_dead_ratio; }
+  void set_allowed_dead_ratio(size_t value) { _allowed_dead_ratio = value; }
 
   // Work methods
   void adjust_pointers();

src/share/vm/memory/space.cpp

@@ -997,11 +997,11 @@ void OffsetTableContigSpace::serialize_block_offset_array_offsets(
 }
 
 
-int TenuredSpace::allowed_dead_ratio() const {
+size_t TenuredSpace::allowed_dead_ratio() const {
   return MarkSweepDeadRatio;
 }
 
 
-int ContigPermSpace::allowed_dead_ratio() const {
+size_t ContigPermSpace::allowed_dead_ratio() const {
   return PermMarkSweepDeadRatio;
 }

src/share/vm/memory/space.hpp

@@ -421,7 +421,7 @@ public:
 
   // The maximum percentage of objects that can be dead in the compacted
   // live part of a compacted space ("deadwood" support.)
-  virtual int allowed_dead_ratio() const { return 0; };
+  virtual size_t allowed_dead_ratio() const { return 0; };
 
   // Some contiguous spaces may maintain some data structures that should
   // be updated whenever an allocation crosses a boundary.  This function
@@ -507,7 +507,7 @@ protected:
                                                                              \
   size_t allowed_deadspace = 0;                                              \
   if (skip_dead) {                                                           \
-    int ratio = allowed_dead_ratio();                                        \
+    const size_t ratio = allowed_dead_ratio();                               \
     allowed_deadspace = (capacity() * ratio / 100) / HeapWordSize;           \
   }                                                                          \
                                                                              \
@@ -1079,7 +1079,7 @@ class TenuredSpace: public OffsetTableContigSpace {
   friend class VMStructs;
  protected:
   // Mark sweep support
-  int allowed_dead_ratio() const;
+  size_t allowed_dead_ratio() const;
  public:
   // Constructor
   TenuredSpace(BlockOffsetSharedArray* sharedOffsetArray,
@@ -1094,7 +1094,7 @@ class ContigPermSpace: public OffsetTableContigSpace {
   friend class VMStructs;
  protected:
   // Mark sweep support
-  int allowed_dead_ratio() const;
+  size_t allowed_dead_ratio() const;
  public:
   // Constructor
   ContigPermSpace(BlockOffsetSharedArray* sharedOffsetArray, MemRegion mr) :

src/share/vm/memory/tenuredGeneration.hpp

@@ -73,7 +73,6 @@ class TenuredGeneration: public OneContigSpaceCardGeneration {
 
   // Mark sweep support
   void compute_new_size();
-  int allowed_dead_ratio() const;
 
   virtual void gc_prologue(bool full);
   virtual void gc_epilogue(bool full);

src/share/vm/runtime/globals.hpp

@@ -2792,7 +2792,7 @@ class CommandLineFlags {
   product(intx, TargetSurvivorRatio,    50,                                 \
           "Desired percentage of survivor space used after scavenge")       \
                                                                             \
-  product(intx, MarkSweepDeadRatio,     5,                                  \
+  product(uintx, MarkSweepDeadRatio,     5,                                 \
           "Percentage (0-100) of the old gen allowed as dead wood."         \
           "Serial mark sweep treats this as both the min and max value."    \
           "CMS uses this value only if it falls back to mark sweep."        \
@@ -2801,7 +2801,7 @@ class CommandLineFlags {
           "either completely full or completely empty.  Par compact also"   \
           "has a smaller default value; see arguments.cpp.")                \
                                                                             \
-  product(intx, PermMarkSweepDeadRatio,    20,                              \
+  product(uintx, PermMarkSweepDeadRatio,    20,                             \
           "Percentage (0-100) of the perm gen allowed as dead wood."        \
           "See MarkSweepDeadRatio for collector-specific comments.")        \
                                                                             \