snapshot

src/common.h

@@ -15,4 +15,15 @@
 #define MACRO_MakeNameXY(FX, LINE) MACRO_XY(FX, LINE)
 #define MAKE_NAME(FX) MACRO_MakeNameXY(FX, __LINE__)
 
+namespace vm {
+
+typedef void* object;
+
+const unsigned BytesPerWord = sizeof(uintptr_t);
+const unsigned BitsPerWord = BytesPerWord * 8;
+
+const unsigned LikelyPageSize = 4 * 1024;
+
+}
+
 #endif//COMMON_H

src/heap.cpp

@@ -1,14 +1,652 @@
 #include "heap.h"
 #include "system.h"
+#include "common.h"
 
 using namespace vm;
 
 namespace {
 
+class Segment {
+ public:
+  class Map {
+   public:
+    class Iterator {
+     public:
+      Map* map;
+      unsigned index;
+      unsigned limit;
+      
+      Iterator(Map* map, void** start, void** end):
+        map(map)
+      {
+        assert(map);
+        assert(map->bitsPerRecord == 1);
+        assert(map->segment);
+
+        index = map->indexOf(start);
+        assert(index == 0 or
+               start != reinterpret_cast<void**>(map->segment->data));
+
+        void** p = reinterpret_cast<void**>(map->segment->data)
+          + map->segment->position;
+        if (end > p) end = p;
+
+        limit = map->indexOf(end);
+        if (static_cast<unsigned>(end - start) % map->scale) ++ limit;
+
+//         printf("iterating from %p (index %d) to %p (index %d) "
+//                "(%d of %d bytes) (scale: %d)\n",
+//                start, index, end, limit, (end - start) * sizeof(void*),
+//                map->segment->position * sizeof(void*), map->scale);
+      }
+
+      bool hasMore() {
+        assert(map);
+
+        unsigned word = wordOf(index);
+        unsigned bit = bitOf(index);
+        unsigned wordLimit = wordOf(limit);
+        unsigned bitLimit = bitOf(limit);
+
+        for (; word <= wordLimit and (word < wordLimit or bit < bitLimit);
+             ++word)
+        {
+          uintptr_t* p = map->data + word;
+          if (*p) {
+            for (; bit < BitsPerWord and (word < wordLimit or bit < bitLimit);
+                 ++bit)
+            {
+              if (map->data[word] & (static_cast<uintptr_t>(1) << bit)) {
+                index = ::indexOf(word, bit);
+//                 printf("hit at index %d\n", index);
+                return true;
+              } else {
+//                 printf("miss at index %d\n", indexOf(word, bit));
+              }
+            }
+          }
+          bit = 0;
+        }
+
+        index = limit;
+
+        return false;
+      }
+      
+      void** next() {
+        assert(hasMore());
+        assert(map->segment);
+
+        return reinterpret_cast<void**>(map->segment->data) +
+          ((index++) * map->scale);
+      }
+    };
+
+    Segment* segment;
+    unsigned bitsPerRecord;
+    unsigned scale;
+    uintptr_t* data;
+    Map* next;
+    Map* child;
+    
+    void init() {
+      init(0);
+      data = 0;
+    }
+
+    void init(Segment* segment, unsigned bitsPerRecord = 1, unsigned scale = 1,
+              Map* next = 0, Map* child = 0)
+    {
+      assert(bitsPerRecord);
+      assert(scale);
+      assert(powerOfTwo(scale));
+
+      this->segment = segment;
+      this->bitsPerRecord = bitsPerRecord;
+      this->scale = scale;
+      this->next = next;
+      this->child = child;
+    }
+
+    void replaceWith(Map* m) {
+      assert(m);
+      assert(bitsPerRecord == m->bitsPerRecord);
+      assert(scale == m->scale);
+
+      free(data);
+
+      data = m->data;
+      m->data = 0;
+      
+      if (next) next->replaceWith(m->next);
+      if (child) child->replaceWith(m->child);
+    }
+
+    unsigned size(unsigned capacity) {
+      unsigned result = pad
+        (divide(divide(capacity, scale) * bitsPerRecord, 8));
+      assert(result);
+      return result;
+    }
+
+    unsigned size() {
+      assert(segment);
+      return size(max(segment->capacity, 1));
+    }
+
+    unsigned indexOf(void* p) {
+      assert(segment);
+      assert(segment->position
+             and p >= segment->data
+             and p <= segment->data + segment->position);
+      assert(segment->data);
+      return ((static_cast<void**>(p) - reinterpret_cast<void**>(segment->data))
+              / scale) * bitsPerRecord;
+    }
+
+    void update() {
+      data = static_cast<uintptr_t*>(realloc(data, size()));
+      assert(data);
+
+      if (next) next->update();
+      if (child) child->update();
+    }
+
+    void reset(bool clear = true) {
+      free(data);
+      data = static_cast<uintptr_t*>(malloc(size()));
+      assert(data);
+      if (clear) memset(data, 0, size());
+
+      if (next) next->reset();
+      if (child) child->reset();
+    }
+
+    void clear() {
+      memset(data, 0, size());
+
+      if (next) next->clear();
+      if (child) child->clear();
+    }
+
+    void clear(unsigned i) {
+      data[wordOf(i)] &= ~(static_cast<uintptr_t>(1) << bitOf(i));
+    }
+
+    void set(unsigned i) {
+      data[wordOf(i)] |= static_cast<uintptr_t>(1) << bitOf(i);
+    }
+
+    void clearOnly(void* p) {
+      unsigned index = indexOf(p);
+      for (unsigned i = index, limit = index + bitsPerRecord; i < limit; ++i) {
+        clear(i);
+      }
+    }
+
+    void clear(void* p) {
+      clearOnly(p);
+      if (child) child->clear(p);
+    }
+
+    void setOnly(void* p, unsigned v = 1) {
+      unsigned index = indexOf(p);
+      unsigned i = index + bitsPerRecord - 1;
+      while (true) {
+        if (v & 1) set(i); else clear(i);
+        v >>= 1;
+        if (i == index) break;
+        --i;
+      }
+    }
+
+    void set(void* p, unsigned v = 1) {
+      setOnly(p, v);
+      assert(get(p) == v);
+      if (child) child->set(p, v);
+    }
+
+    unsigned get(void* p) {
+      unsigned index = indexOf(p);
+      unsigned v = 0;
+      for (unsigned i = index, limit = index + bitsPerRecord; i < limit; ++i) {
+        unsigned wi = bitOf(i);
+        v <<= 1;
+        v |= ((data[wordOf(i)]) & (static_cast<uintptr_t>(1) << wi))
+          >> wi;
+      }
+      return v;
+    }
+
+    void dispose() {
+      free(data);
+      data = 0;
+      segment = 0;
+      next = 0;
+
+      if (child) {
+        child->dispose();
+        child = 0;
+      }
+    }
+
+    unsigned footprint(unsigned capacity) {
+      unsigned n = size(capacity);
+      if (next) n += next->footprint(capacity);
+      if (child) n += child->footprint(capacity);
+      return n;
+    }
+
+    void setSegment(Segment* s) {
+      segment = s;
+      if (next) next->setSegment(s);
+      if (child) child->setSegment(s);
+    }
+  };
+
+  uintptr_t* data;
+  unsigned position;
+  unsigned capacity;
+  Map* map;
+
+  unsigned footprint(unsigned capacity) {
+    unsigned n = capacity * BytesPerWord;
+    if (map) n += map->size(capacity);
+    return n;
+  }
+
+  unsigned footprint() {
+    return footprint(capacity);
+  }
+
+  void init(unsigned capacityInBytes, Map* map = 0, bool clearMap = true) {
+    this->capacity = divide(capacityInBytes, BytesPerWord);
+    this->data = 0;
+    this->position = 0;
+    this->map = map;
+
+    if (capacity) {
+      if (map) map->reset(clearMap);
+      this->data = static_cast<uintptr_t*>(malloc(capacity * BytesPerWord));
+      assert(this->data);
+    }
+  }
+
+  void* add(System* sys, void* p, unsigned size) {
+    void* target = allocate(size);
+    memcpy(target, p, size);
+    return target;
+  }
+
+  unsigned remaining() {
+    return (capacity - position) * BytesPerWord;
+  }
+
+  void replaceWith(Segment* s) {
+    free(data);
+
+    data = s->data;
+    s->data = 0;
+
+    position = s->position;
+    s->position = 0;
+
+    capacity = s->capacity;
+    s->capacity = 0;
+
+    if (s->map) {
+      if (map) {
+        map->replaceWith(s->map);
+      } else {
+        map = s->map;
+        map->setSegment(this);
+      }
+      s->map = 0;
+    } else {
+      if (map) map->reset();
+    }    
+  }
+
+  void grow(System* sys, unsigned extra) {
+    if (remainingBytes() < extra) {
+      unsigned minimumNeeded = s->usedBytes() + (extra * bytesPerWord);
+      unsigned count = minimumNeeded * 2;
+
+      void* p = sys->allocate(&count);
+
+      if (count >= minimumNeeded) {
+        memcpy(p, s->data, s->usedBytes());
+        s->data = p;
+        sys->free(s->data);
+      } else {
+        abort(sys);
+      }
+    }
+
+    unsigned newCapacity = divide(newCapacityInBytes, BytesPerWord);
+    assert(newCapacity > capacity);
+    capacity = newCapacity;
+    data = static_cast<uintptr_t*>(realloc(data, capacity * BytesPerWord));
+    assert(data);
+    if (map) map->update();
+  }
+
+  bool contains(void* p) {
+    return position and p >= data and p < data + position;
+  }
+
+  void dispose() {
+    free(data);
+    data = 0;
+    position = 0;
+    capacity = 0;
+
+    if (map) map->dispose();
+    map = 0;
+  }
+};
+
 class Context {
  public:
 };
 
+void
+initGen1(Context* c)
+{
+  c->ageMap.init(&(c->gen1), log(Arena::TenureThreshold));
+  c->gen1.init(c->minimumGen1Size, &(c->ageMap), false);
+}
+
+void
+initGen2(Context* c)
+{
+  c->pointerMap.init(&(c->gen2));
+  c->pageMap.init(&(c->gen2), 1, LikelyPageSize / BytesPerWord, 0,
+                  &(c->pointerMap));
+  c->heapMap.init(&(c->gen2), 1, c->pageMap.scale * 1024, 0, &(c->pageMap));
+  c->gen2.init(c->minimumGen2Size, &(c->heapMap));
+}
+
+void
+initNextGen1(Context* c)
+{
+  unsigned size = max(c->minimumGen1Size,
+                      nextPowerOfTwo(c->gen1.position() * BytesPerWord));
+  c->nextAgeMap.init(&(c->nextGen1), log(Arena::TenureThreshold));
+  c->nextGen1.init(size, &(c->nextAgeMap), false);
+}
+
+void
+initNextGen2(Context* c)
+{
+  unsigned size = max(c->minimumGen2Size,
+                      nextPowerOfTwo(c->gen2.position() * BytesPerWord));
+  c->pointerMap.init(&(c->nextGen2));
+  c->pageMap.init(&(c->nextGen2), 1, LikelyPageSize / BytesPerWord, 0,
+                  &(c->pointerMap));
+  c->heapMap.init(&(c->nextGen2), 1, c->pageMap.scale * 1024, 0,
+                  &(c->pageMap));
+  c->nextGen2.init(size, &(c->heapMap));
+  c->gen2.map = 0;
+}
+
+inline object&
+follow(object o)
+{
+  return cast<object>(o, 0);
+}
+
+inline object&
+parent(object o)
+{
+  return cast<object>(o, BytesPerWord);
+}
+
+inline uintptr_t*
+bitset(object o)
+{
+  return &cast<uintptr_t>(o, BytesPerWord * 2);
+}
+
+object
+copyTo(Context* c, Segment* s, object o, unsigned size)
+{
+  assert(c, size >= BytesPerWord);
+  assert(c, size % BytesPerWord == 0);
+
+  if (s->remainingBytes() < size) {
+    s->grow(c->sys, size * bytesPerWord);
+  }
+
+  return static_cast<object>(s->add(o, size));
+}
+
+object
+copy2(Context* c, object o)
+{
+  unsigned size = c->client->sizeOf(o);
+
+  if (c->gen2.contains(o)) {
+    assert(c, c->mode == MajorCollection
+           or c->mode == Gen2Collection);
+
+    return copyTo(c, &(c->nextGen2), o, size);
+  } else if (c->gen1.contains(o)) {
+    unsigned age = c->ageMap.get(o);
+    if (age == Arena::TenureThreshold) {
+      if (c->mode == MinorCollection) {
+        if (c->gen2.front == 0) initGen2(a);
+
+        if (c->gen2.remainingBytes() >= size) {
+          return copyTo(c, &(c->gen2), o, size);
+        } else {
+          c->mode = OverflowCollection;
+          initNextGen2(a);
+          return copyTo(c, &(c->nextGen2), o, size);          
+        }
+      } else {
+        return copyTo(c, &(c->nextGen2), o, size);
+      }
+    } else {
+      o = copyTo(c, &(c->nextGen1), o, size);
+      c->nextAgeMap.setOnly(o, age + 1);
+      return o;
+    }
+  } else {
+    assert(c, not c->nextGen1.contains(o));
+    assert(c, not c->nextGen2.contains(o));
+
+    o = copyTo(c, &(c->nextGen1), o, size);
+
+    c->nextAgeMap.clear(o);
+
+    return o;
+  }
+}
+
+object
+copy(Context* c, object o)
+{
+  object r = copy2(c, o);
+
+  // leave a pointer to the copy in the original
+  follow(o) = r;
+
+  return r;
+}
+
+inline bool
+wasCollected(Context* c, object o)
+{
+  return o and (c->nextGen1.contains(follow(o)) or
+                c->nextGen2.contains(follow(o)));
+}
+
+object
+update3(Context* c, object *p, bool* needsVisit)
+{
+  if (wasCollected(c, *p)) {
+    *needsVisit = false;
+    return follow(*p);
+  } else {
+    *needsVisit = true;
+    return copy(c, *p);
+  }
+}
+
+object
+update2(Context* c, object* p, bool* needsVisit)
+{
+  switch (c->mode) {
+  case MinorCollection:
+  case OverflowCollection:
+    if (c->gen2.contains(*p)) {
+      *needsVisit = false;
+      return *p;
+    }
+    break;
+    
+  case Gen2Collection:
+    if (c->gen2.contains(*p)) {
+      return update3(c, p, needsVisit);
+    } else {
+      *needsVisit = false;
+      return *p;
+    }
+    break;
+
+  default: break;
+  }
+
+  return update3(c, p, needsVisit);
+}
+
+object
+update(Context* c, object* p, bool* needsVisit)
+{
+  if (*p == 0) {
+    *needsVisit = false;
+    return *p;
+  }
+
+  object r = update2(c, p, needsVisit);
+
+  // update heap map.
+  if (r) {
+    if (c->mode == MinorCollection) {
+      if (c->gen2.contains(p) and not c->gen2.contains(r)) {
+        c->heapMap.set(p);
+      }
+    } else {
+      if (c->nextGen2.contains(p) and not c->nextGen2.contains(r)) {
+        c->heapMap.set(p);
+      }      
+    }
+  }
+
+  return r;
+}
+
+const uintptr_t BitsetExtensionBit
+= (static_cast<uintptr_t>(1) << (BitsPerWord - 1));
+
+void
+bitsetInit(uintptr_t* p)
+{
+  memset(p, 0, BytesPerWord);
+}
+
+void
+bitsetClear(uintptr_t* p, unsigned start, unsigned end)
+{
+  if (end < BitsPerWord - 1) {
+    // do nothing
+  } else if (start < BitsPerWord - 1) {
+    memset(p + 1, 0, (wordOf(end + (BitsPerWord * 2) + 1)) * BytesPerWord);
+  } else {
+    unsigned startWord = wordOf(start + (BitsPerWord * 2) + 1);
+    unsigned endWord = wordOf(end + (BitsPerWord * 2) + 1);
+    if (endWord > startWord) {
+      memset(p + startWord + 1, 0, (endWord - startWord) * BytesPerWord);
+    }
+  }
+}
+
+void
+bitsetSet(uintptr_t* p, unsigned i, bool v)
+{
+  if (i >= BitsPerWord - 1) {
+    i += (BitsPerWord * 2) + 1;
+    if (v) {
+      p[0] |= BitsetExtensionBit;
+      if (p[2] <= wordOf(i) - 3) p[2] = wordOf(i) - 2;
+    }
+  }
+
+  if (v) {
+    p[wordOf(i)] |= static_cast<uintptr_t>(1) << bitOf(i);
+  } else {
+    p[wordOf(i)] &= ~(static_cast<uintptr_t>(1) << bitOf(i));
+  }
+}
+
+unsigned
+bitsetHasMore(uintptr_t* p)
+{
+  switch (*p) {
+  case 0: return false;
+
+  case BitsetExtensionBit: {
+    uintptr_t length = p[2];
+    uintptr_t word = wordOf(p[1]);
+    for (; word < length; ++word) {
+      if (p[word + 3]) {
+        p[1] = indexOf(word, 0);
+        return true;
+      }
+    }
+    p[1] = indexOf(word, 0);
+    return false;
+  }
+
+  default: return true;
+  }
+}
+
+unsigned
+bitsetNext(Context* c, uintptr_t* p)
+{
+  assert(c, bitsetHasMore(p));
+
+  switch (*p) {
+  case 0: abort(c);
+
+  case BitsetExtensionBit: {
+    uintptr_t i = p[1];
+    uintptr_t word = wordOf(i);
+    assert(c, word < p[2]);
+    for (uintptr_t bit = bitOf(i); bit < BitsPerWord; ++bit) {
+      if (p[word + 3] & (static_cast<uintptr_t>(1) << bit)) {
+        p[1] = indexOf(word, bit) + 1;
+        bitsetSet(p, p[1] + BitsPerWord - 2, false);
+        return p[1] + BitsPerWord - 2;
+      }
+    }
+    abort(c);
+  }
+
+  default: {
+    for (unsigned i = 0; i < BitsPerWord - 1; ++i) {
+      if (*p & (static_cast<uintptr_t>(1) << i)) {
+        bitsetSet(p, i, false);
+        return i;
+      }
+    }
+    abort(c);
+  }
+  }
+}
+
 void
 collect(Context* c, void** p)
 {
@@ -81,7 +719,6 @@ collect(Context* c, void** p)
       // descend
       if (walker.visits > 1) {
         ::parent(original) = parent;
-
         parent = original;
       }
 
@@ -99,7 +736,8 @@ collect(Context* c, void** p)
 
     class Walker : public Heap::Walker {
      public:
-      Walker(uintptr_t* bitset):
+      Walker(Context* c, uintptr_t* bitset):
+        c(c),
         bitset(bitset),
         next(0),
         total(0)
@@ -115,7 +753,7 @@ collect(Context* c, void** p)
           return true;
           
         case 3:
-          next = bitsetNext(bitset);
+          next = bitsetNext(c, bitset);
           return false;
 
         default:
@@ -123,6 +761,7 @@ collect(Context* c, void** p)
         }
       }
 
+      Context* c;
       uintptr_t* bitset;
       unsigned next;
       unsigned total;
@@ -138,11 +777,105 @@ collect(Context* c, void** p)
 
     original = cast<object>(copy, walker.next * sizeof(void*));
     cast<object>(copy, walker.next * sizeof(void*)) = follow(original);
+    goto visit;
   } else {
     return;
   }
 }
 
+void
+collect(Context* c, Segment::Map* map, unsigned start, unsigned end,
+        bool* dirty, bool expectDirty UNUSED)
+{
+  bool wasDirty = false;
+  for (Segment::Map::Iterator it(map, start, end); it.hasMore();) {
+    wasDirty = true;
+    if (map->child) {
+      assert(c, map->scale > 1);
+      unsigned s = it.next();
+      unsigned e = s + map->scale;
+
+      map->clearOnly(s);
+      bool childDirty = false;
+      collect(c, map->child, s, e, &childDirty, true);
+      if (c->collectionMode == OverflowCollection) {
+        return;
+      } else if (childDirty) {
+        map->setOnly(s);
+        *dirty = true;
+      }
+    } else {
+      assert(c, map->scale == 1);
+      object* p = reinterpret_cast<object*>(map->heap->get(it.next()));
+
+      map->clearOnly(p);
+      if (c->nextGen1.contains(*p)) {
+        map->setOnly(p);
+        *dirty = true;
+      } else {
+        collect(c, p);
+
+        if (c->collectionMode == OverflowCollection) {
+          return;
+        } else if (c->gen2.contains(*p)) {
+          // done
+        } else {
+          map->setOnly(p);
+          *dirty = true;
+        }
+      }
+    }
+  }
+
+  assert(c, wasDirty or not expectDirty);
+}
+
+class ObjectSegmentIterator {
+ public:
+  ObjectSegmentIterator(Context* c, Segment* s, unsigned end):
+    c(c), s(s), index(0), end(end)
+  { }
+
+  bool hasNext() {
+    return index < end;
+  }
+
+  object next() {
+    assert(c, hasNext());
+    object p = s->data + (index * BytesPerWord);
+    index += c->client->sizeOf(p) / BytesPerWord;
+    return p;
+  }
+
+  Context* c;
+  Segment* s;
+  unsigned index;
+  unsigned end;
+};
+
+void
+collect(Context* c, Segment* s, unsigned limit)
+{
+  for (ObjectSegmentIterator it(c, s, limit); it.hasNext();) {
+    object p = it.next();
+    collect(c, &objectClass(p));
+
+    class Walker : public Heap::Walker {
+     public:
+      Walker(Context* c, object p): c(c), p(p) { }
+
+      virtual bool visit(unsigned offset) {
+        collect(c, &cast<object>(p, offset * BytesPerWord));
+      }
+
+      Context* c;
+      object p;
+    } walker(c, p);
+
+    c->client->walk(p, &walker);
+  }
+}
+
 void
 collect2(Context* c)
 {
@@ -150,11 +883,11 @@ collect2(Context* c)
     unsigned start = 0;
     unsigned end = start + c->gen2.position();
     bool dirty;
-    collect(m, &(c->map), start, end, &dirty, false);
+    collect(c, &(c->heapMap), start, end, &dirty, false);
   } else if (c->mode == Gen2Collection) {
     unsigned ng2Position = c->nextGen2.position();
-    collect(m, &(c->nextGen1), c->nextGen1.position());
+    collect(c, &(c->nextGen1), c->nextGen1.position());
-    collect(m, &(c->nextGen2), ng2Position);
+    collect(c, &(c->nextGen2), ng2Position);
   }
 
   class Visitor : public Heap::Visitor {
@@ -170,7 +903,7 @@ collect2(Context* c)
 }
 
 void
-collect1(Context* c)
+collect(Context* c)
 {
   switch (c->mode) {
   case MinorCollection: {
@@ -192,7 +925,7 @@ collect1(Context* c)
     initNextGen1(c);
     initNextGen2(c);
     
-    c->map.clear();
+    c->heapMap.clear();
 
     collect2(c);
 

src/system.h

@@ -54,7 +54,7 @@ class System {
   virtual ~System() { }
 
   virtual bool success(Status) = 0;
-  virtual void* allocate(unsigned size) = 0;
+  virtual void* allocate(unsigned* size) = 0;
   virtual void free(void*) = 0;
   virtual Status start(Thread*) = 0;
   virtual Status make(Monitor**) = 0;

src/vm.cpp

@@ -16,9 +16,6 @@ using namespace vm;
 
 namespace {
 
-typedef void* object;
-typedef unsigned Type;
-
 class Thread;
 
 void assert(Thread*, bool);
@@ -30,8 +27,8 @@ void set(Thread*, object&, object);
 inline unsigned
 pad(unsigned n)
 {
-  unsigned extra = n % sizeof(void*);
+  unsigned extra = n % BytesPerWord;
-  return (extra ? n + sizeof(void*) - extra : n);
+  return (extra ? n + BytesPerWord - extra : n);
 }
 
 template <class T>
@@ -996,7 +993,7 @@ fieldSize(Thread* t, object field)
     return 4;
   case 'L':
   case '[':
-    return sizeof(void*);
+    return BytesPerWord;
 
   default: abort(t);
   }
@@ -1011,7 +1008,7 @@ parseFieldTable(Thread* t, Stream& s, object class_, object pool)
   unsigned count = s.read2();
   if (count) {
     unsigned memberOffset
-      = classFixedSize(t, classSuper(t, class_)) * sizeof(void*);
+      = classFixedSize(t, classSuper(t, class_)) * BytesPerWord;
     unsigned staticOffset = 0;
   
     object fieldTable = makeArray(t, count);
@@ -1038,9 +1035,9 @@ parseFieldTable(Thread* t, Stream& s, object class_, object pool)
       if (flags & ACC_STATIC) {
         fieldOffset(t, value) = staticOffset++;
       } else {
-        unsigned excess = memberOffset % sizeof(void*);
+        unsigned excess = memberOffset % BytesPerWord;
         if (excess and isReferenceField(t, value)) {
-          memberOffset += sizeof(void*) - excess;
+          memberOffset += BytesPerWord - excess;
         }
 
         fieldOffset(t, value) = memberOffset;
@@ -1054,7 +1051,7 @@ parseFieldTable(Thread* t, Stream& s, object class_, object pool)
 
     if (staticOffset) {
       object staticTable = makeArray(t, staticOffset);
-      memset(&arrayBody(t, staticTable, 0), 0, staticOffset * sizeof(void*));
+      memset(&arrayBody(t, staticTable, 0), 0, staticOffset * BytesPerWord);
 
       set(t, classStaticTable(t, class_), staticTable);
     }
@@ -1604,7 +1601,7 @@ run(Thread* t)
         push(t, makeInt(t, objectArrayLength(t, array)));
       } else {
         // for all other array types, the length follow the class pointer.
-        push(t, makeInt(t, cast<uint32_t>(array, sizeof(void*))));
+        push(t, makeInt(t, cast<uint32_t>(array, BytesPerWord)));
       }
     } else {
       exception = makeNullPointerException(t);