JSSpecCompiler: Add SSA form building pass

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

@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2023, Dan Klishch <danilklishch@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/HashMap.h>
+
+#include "Compiler/CompilerPass.h"
+#include "Compiler/ControlFlowGraph.h"
+#include "Compiler/EnableGraphPointers.h"
+
+namespace JSSpecCompiler {
+
+// TODO: Add a LOT of unit tests.
+
+class SSABuildingPass
+    : public IntraproceduralCompilerPass
+    , private EnableGraphPointers<SSABuildingPass, BasicBlockRef> {
+public:
+    inline static constexpr StringView name = "ssa-building"sv;
+
+    using IntraproceduralCompilerPass::IntraproceduralCompilerPass;
+
+protected:
+    void process_function() override;
+
+private:
+    friend EnableGraphPointers;
+
+    class Vertex : public VertexBase {
+    public:
+        using VertexBase::VertexBase;
+
+        BasicBlockRef block() const { return m_instance->m_order[m_index]; }
+    };
+
+    void compute_order(BasicBlockRef u, Vertex parent = invalid_node);
+    void compute_dominator_tree();
+
+    template<typename... Args>
+    Vector<Vertex> unique(Args const&... args);
+    void compute_dtree_tin_tout(Vertex u);
+    bool is_strictly_dominating(Vertex u, Vertex v);
+    void compute_dominance_frontiers();
+
+    void add_phi_node(BasicBlockRef block, NamedVariableDeclarationRef decl);
+    void place_phi_nodes();
+
+    void make_new_ssa_variable_for(NamedVariableDeclarationRef var);
+    void rename_variable(VariableRef var);
+    void rename_variables(Vertex u, Vertex from = invalid_node);
+    void rename_variables();
+
+    struct NodeData {
+        Vector<Vertex> incoming_edges;
+        Vector<Vertex> outgoing_edges;
+
+        Vector<Vertex> buckets;
+
+        bool is_used = false;
+        Vertex parent;
+        Vertex semi_dominator;
+        Vertex immediate_dominator;
+
+        Vector<Vertex> dtree_children;
+        u64 tin, tout;
+
+        Vector<Vertex> d_frontier;
+
+        HashMap<NamedVariableDeclarationRef, Vertex> phi_nodes;
+
+        u64 mark = 0;
+    };
+
+    u64 m_dtree_timer;
+    Vector<NodeData> m_nodes;
+    Vector<NonnullRefPtr<BasicBlock>> m_order;
+
+    u64 m_mark_version;
+
+    HashMap<NamedVariableDeclarationRef, Vector<SSAVariableDeclarationRef>> m_def_stack;
+    HashMap<NamedVariableDeclarationRef, u64> m_next_id;
+    Vector<NamedVariableDeclarationRef> m_undo_vector;
+
+    ControlFlowGraph* m_graph;
+};
+
+}