Reduce space used for stackmaps.

runtime/vm/code_descriptors.h

Index: runtime/vm/code_descriptors.h
diff --git a/runtime/vm/code_descriptors.h b/runtime/vm/code_descriptors.h
index 156b661c8fe8e1fc0bbc2400c06952d5c08620ad..778f10354bbfc01f5986e542bcb7b1c26c23d40b 100644
--- a/runtime/vm/code_descriptors.h
+++ b/runtime/vm/code_descriptors.h
@@ -65,7 +65,8 @@ class DescriptorList : public ZoneAllocated {
 
 class StackmapTableBuilder : public ZoneAllocated {
  public:
-  StackmapTableBuilder() :
+  explicit StackmapTableBuilder(intptr_t entry_length_in_bits) :

[Vyacheslav Egorov (Google), 2012/08/15 14:17:37]

why : is left on this line?

[Kevin Millikin (Google), 2012/08/15 14:41:31]

For historical reasons.

+      entry_length_in_bits_(entry_length_in_bits),
       stack_map_(Stackmap::ZoneHandle()),
       list_(GrowableObjectArray::ZoneHandle(
           GrowableObjectArray::New(Heap::kOld))) { }
@@ -79,8 +80,10 @@ class StackmapTableBuilder : public ZoneAllocated {
 
  private:
   intptr_t Length() const { return list_.Length(); }
-  RawStackmap* Map(int index) const;
+  RawStackmap* MapAt(int index) const;
 
+  // All the stackmaps in a function have the same length.
+  intptr_t entry_length_in_bits_;

[srdjan, 2012/08/15 22:17:08]

const

   Stackmap& stack_map_;
   GrowableObjectArray& list_;
   DISALLOW_COPY_AND_ASSIGN(StackmapTableBuilder);