Skeleton of a linear scan register allocator.

runtime/vm/growable_array.h

Index: runtime/vm/growable_array.h
diff --git a/runtime/vm/growable_array.h b/runtime/vm/growable_array.h
index 49ae5fa230a731d39c1bc72b0a4d9e1d670982ec..2a7fd98be540b81d4a65c51d446fb5376cb47e66 100644
--- a/runtime/vm/growable_array.h
+++ b/runtime/vm/growable_array.h
@@ -59,7 +59,7 @@ class BaseGrowableArray : public B {
   }
 
   void AddArray(const BaseGrowableArray<T, B>& src) {
-    for (int i = 0; i < src.length(); i++) {
+    for (intptr_t i = 0; i < src.length(); i++) {
       Add(src[i]);
     }
   }
@@ -76,6 +76,14 @@ class BaseGrowableArray : public B {
     }
   }
 
+  void InsertAt(intptr_t idx, const T& value) {
+    Resize(length() + 1);
+    for (intptr_t i = length_ - 2; i >= idx; i--) {
+      data_[i + 1] = data_[i];
+    }
+    data_[idx] = value;
+  }
+
   // Sort the array in place.
   inline void Sort(int compare(const T*, const T*));