Adding a shared scratch arena for compiler passes.

src/alloy/compiler/compiler.cc

@@ -20,6 +20,8 @@ using namespace alloy::runtime;
 
 Compiler::Compiler(Runtime* runtime) :
     runtime_(runtime) {
+  scratch_arena_ = new Arena();
+
   alloy::tracing::WriteEvent(EventType::Init({
   }));
 }
@@ -32,6 +34,8 @@ Compiler::~Compiler() {
     delete pass;
   }
 
+  delete scratch_arena_;
+
   alloy::tracing::WriteEvent(EventType::Deinit({
   }));
 }
@@ -49,6 +53,7 @@ int Compiler::Compile(HIRBuilder* builder) {
   //                 stop changing things, etc.
   for (auto it = passes_.begin(); it != passes_.end(); ++it) {
     CompilerPass* pass = *it;
+    scratch_arena_->Reset();
     if (pass->Run(builder)) {
       return 1;
     }

src/alloy/compiler/compiler.h

@@ -28,6 +28,7 @@ public:
   ~Compiler();
 
   runtime::Runtime* runtime() const { return runtime_; }
+  Arena* scratch_arena() const { return scratch_arena_; }
 
   void AddPass(CompilerPass* pass);
 
@@ -37,6 +38,7 @@ public:
 
 private:
   runtime::Runtime* runtime_;
+  Arena* scratch_arena_;
 
   typedef std::vector<CompilerPass*> PassList;
   PassList passes_;

src/alloy/compiler/compiler_pass.cc

@@ -27,3 +27,7 @@ int CompilerPass::Initialize(Compiler* compiler) {
   compiler_ = compiler;
   return 0;
 }
+
+Arena* CompilerPass::scratch_arena() const {
+  return compiler_->scratch_arena();
+}

src/alloy/compiler/compiler_pass.h

@@ -32,6 +32,9 @@ public:
 
   virtual int Run(hir::HIRBuilder* builder) = 0;
 
+protected:
+  Arena* scratch_arena() const;
+
 protected:
   runtime::Runtime* runtime_;
   Compiler* compiler_;