JSSpecCompiler: Add control flow building pass

Meta/Lagom/Tools/CodeGenerators/JSSpecCompiler/Compiler/Passes/CFGBuildingPass.h

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2023, Dan Klishch <danilklishch@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/TypeCasts.h>
+
+#include "Compiler/ControlFlowGraph.h"
+#include "Compiler/GenericASTPass.h"
+
+namespace JSSpecCompiler {
+
+class CFGBuildingPass
+    : public IntraproceduralCompilerPass
+    , private RecursiveASTVisitor {
+public:
+    inline static constexpr StringView name = "cfg-building"sv;
+
+    using IntraproceduralCompilerPass::IntraproceduralCompilerPass;
+
+protected:
+    void process_function() override;
+    RecursionDecision on_entry(Tree tree) override;
+    void on_leave(Tree tree) override;
+
+private:
+    BasicBlockRef create_empty_block();
+    BasicBlockRef exchange_current_with_empty();
+    void will_be_used_as_expression(Tree const& tree);
+
+    ControlFlowGraph* m_cfg;
+    BasicBlockRef m_current_block;
+    Vector<bool> m_is_expression_stack;
+};
+
+}