[Courgette] Reduce AssemblyProgram to reduce Courgette-apply RAM floor and disk churn.

courgette/instruction_utils.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COURGETTE_INSTRUCTION_UTILS_H_
 #define COURGETTE_INSTRUCTION_UTILS_H_
 
 #include <stdint.h>
 
 #include "base/callback.h"
@@ skipping 43 matching lines @@
   virtual CheckBool EmitAbs64(Label* label) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(InstructionReceptor);
 };
 
 // A rerunable callback that emit instructions to a provided receptor. Returns
 // true on success, and false otherwise.
 using InstructionGenerator = base::Callback<CheckBool(InstructionReceptor*)>;
 
+// A counter that increments via .push_back(), so it can be passed via template
+// to substitute std::vector<T>, to count elements instead of storing them.
+template <typename T>
+class CountingVector {
+ public:
+  CountingVector() {}
+
+  void push_back(const T& /* unused */) { ++size_; }
+  size_t size() const { return size_; }
+
+ private:
+  size_t size_ = 0;
+};
+
 }  // namespace courgette
 
 #endif  // COURGETTE_INSTRUCTION_UTILS_H_