diff -r 5e3c49013064 -r fb324242a675 jitcraft/Spaces.cpp
--- a/jitcraft/Spaces.cpp	Fri Jul 06 18:57:27 2012 -0400
+++ b/jitcraft/Spaces.cpp	Fri Jul 06 19:24:22 2012 -0400
@@ -23,29 +23,22 @@
 using namespace jc;
 
 HeapStack::HeapStack()
-  : buffer_(NULL),
-    pos_(NULL),
-    end_(NULL)
+  : chunk_(NULL),
+    cursor_(NULL)
 {
 }
 
 HeapStack::~HeapStack()
 {
-    if (buffer_)
-        OS::UnmapAlignedMemory(map_.base(), map_.size());
+    if (chunk_)
+        HeapChunk::Destroy(chunk_);
 }
 
 bool
 HeapStack::initialize()
 {
-    map_ = OS::MapAlignedMemory(kStackSize, kStackSize, OS::Map_Commit);
-    if (!map_.base())
-        return false;
-
-    buffer_ = map_.aligned();
-    pos_ = buffer_;
-    end_ = buffer_ + kStackSize;
-    mask_ = kStackSize - 1;
+    chunk_ = HeapChunk::New(NULL, kStackSize);
+    cursor_ = chunk_->first();
     return true;
 }
 
@@ -61,7 +54,6 @@
     HeapChunk *chunk = reinterpret_cast<HeapChunk *>(map.aligned());
     chunk->base_ = map.base();
     chunk->end_ = map.base() + map.size();
-    chunk->cursor_ = chunk->first();
     if (prev)
         prev->next_ = chunk;
 
@@ -85,6 +77,7 @@
 {
     first_ = HeapChunk::New(first_, HeapChunk::kDefaultSize);
     last_ = first_;
+    cursor_ = first_->first();
 
     return !!first_;
 }
@@ -96,7 +89,14 @@
     if (!chunk)
         return NULL;
 
-    return chunk->allocate(nbytes);
+    last_ = chunk;
+    cursor_ = chunk->first();
+
+    assert(cursor_ + nbytes <= chunk->end());
+
+    Address address = cursor_;
+    cursor_ += nbytes;
+    return address;
 }
 
 OldSpace::~OldSpace()
@@ -143,9 +143,6 @@
         first_ = chunk;
     last_ = chunk;
 
-    Address address = chunk->allocate(nbytes);
-    assert(address);
-
-    return address;
+    return chunk->first();
 }