chore: flat out the file structure

include/furc/middle/ir.hpp

@@ -0,0 +1,455 @@
+#ifndef FURC_MIDDLE_IR_HPP
+#define FURC_MIDDLE_IR_HPP
+
+#include "furc/front/ast.hpp"
+#include "furlang/arena.hpp"
+
+#include <algorithm>
+#include <cstdint>
+#include <initializer_list>
+#include <optional>
+#include <stack>
+#include <stdexcept>
+#include <string>
+#include <type_traits>
+#include <unordered_map>
+#include <utility>
+#include <vector>
+
+namespace furc {
+
+struct ir_operand {
+    enum type_e {
+        Integer = 0,
+        Register,
+        Variable,
+        Global,
+        Function,
+        Block,
+        BlockPair,
+        PhiPair,
+    } type;
+    union value_u {
+        std::uint64_t integer;
+        struct register_s {
+            std::uint64_t name : 54;
+            std::uint64_t ver : 10;
+
+            register_s() = default;
+
+            register_s(std::uint64_t id)
+              : name((id >> 10) & ((1ULL << 54) - 1)), ver((id >> 0) & ((1 << 10) - 1)) {}
+
+            register_s(std::uint64_t name, std::uint64_t ver)
+              : name(name), ver(ver) {}
+
+            operator std::uint64_t() const { return name << 10 | ver; }
+        } reg;
+        std::uint16_t variable;
+        std::uint16_t global;
+        std::uint64_t function;
+        std::uint64_t block;
+        struct block_pair_s {
+            std::uint64_t first;
+            std::uint64_t second;
+        } blockPair;
+        struct phi_pair_s {
+            register_s    reg;
+            std::uint64_t block;
+        } phiPair;
+
+        value_u() = default;
+
+        value_u(std::uint64_t integer)
+          : integer(integer) {}
+
+        value_u(std::uint16_t variable)
+          : variable(variable) {}
+
+        value_u(register_s reg)
+          : reg(reg) {}
+
+        value_u(std::uint64_t first, std::uint64_t second)
+          : blockPair({ first, second }) {}
+
+        value_u(register_s reg, std::uint64_t block)
+          : phiPair({ reg, block }) {}
+    } value;
+
+    template <typename... Args, typename = std::enable_if_t<std::is_constructible_v<value_u, Args...>>>
+    ir_operand(type_e type, Args&&... args)
+      : type(type), value(std::forward<Args>(args)...) {}
+
+    static ir_operand reg(std::uint64_t name, std::uint64_t ver) {
+        return { Register, value_u::register_s{ name, ver } };
+    }
+
+    bool operator==(const ir_operand& rhs) const {
+        if (type != rhs.type) return false;
+        switch (type) {
+        case Integer: return value.integer == rhs.value.integer;
+        case Register: return value.reg.name == rhs.value.reg.name && value.reg.ver == rhs.value.reg.ver;
+        case Variable: return value.variable == rhs.value.variable;
+        case Global: return value.global == rhs.value.global;
+        case Function: return value.function == rhs.value.function;
+        case Block: return value.block == rhs.value.block;
+        case BlockPair:
+            return value.blockPair.first == rhs.value.blockPair.first &&
+                   value.blockPair.second == rhs.value.blockPair.second;
+        case PhiPair:
+            return value.phiPair.block == rhs.value.phiPair.block &&
+                   value.phiPair.reg.name == rhs.value.phiPair.reg.name &&
+                   value.phiPair.reg.ver == rhs.value.phiPair.reg.ver;
+        }
+        throw std::runtime_error("unreachable");
+    }
+};
+
+struct ir_type {
+    enum type_e {
+        Void = 0,
+        S8,
+        U8,
+        S16,
+        U16,
+        S32,
+        U32,
+        S64,
+        U64,
+    } type = Void;
+};
+
+// TODO: Add data types to instructions (like mov QWORD ... in x86 assembly)
+struct ir_instruction {
+    enum type_e {
+        Move = 0,
+        Call,
+        Branch,
+        BranchCond,
+        Return,
+        Phi,
+
+        Add,
+        Sub,
+        Mul,
+        Div,
+        Mod,
+
+        Shl,
+        Shr,
+        BinAnd,
+        BinOr,
+        BinXor,
+        And,
+        Or,
+
+        Eq,
+        NotEq,
+        LessThan,
+        LessEq,
+        GreaterThan,
+        GreaterEq,
+
+        Positive,
+        Negative,
+        Increment,
+        Decrement,
+        BinNot,
+        Not,
+
+        Sizeof,
+        Pointerof,
+        Lenof,
+    } type;
+    std::optional<ir_operand> destination;
+    std::vector<ir_operand>   sources;
+
+    ir_instruction(type_e                 type,
+        std::optional<ir_operand>         destination = {},
+        std::initializer_list<ir_operand> sources     = {})
+      : type(type), destination(destination), sources(sources) {}
+
+    static constexpr bool is_terminating(type_e type) {
+        switch (type) {
+        case Branch:
+        case BranchCond:
+        case Return: return true;
+        default: return false;
+        }
+    }
+
+    bool operator==(const ir_instruction& rhs) const {
+        return type == rhs.type && destination == rhs.destination && sources == rhs.sources;
+    }
+};
+
+struct ir_basic_block {
+    std::vector<ir_instruction> instructions;
+
+    bool is_terminated() const {
+        return !instructions.empty() && ir_instruction::is_terminating(instructions.back().type);
+    }
+};
+
+struct ir_variable {
+    ir_variable() = default;
+
+    ir_variable(ir_type type)
+      : type(type) {}
+
+    virtual ~ir_variable() = default;
+
+    ir_variable(ir_variable&&) noexcept            = default;
+    ir_variable& operator=(ir_variable&&) noexcept = default;
+
+    ir_variable(const ir_variable&)            = default;
+    ir_variable& operator=(const ir_variable&) = default;
+
+    ir_type type;
+
+    virtual ir_operand operand() const = 0;
+};
+
+struct ir_module_variable : ir_variable {
+    ir_module_variable(ir_type type, std::uint16_t name)
+      : ir_variable(type), name(name) {}
+
+    std::uint16_t name;
+
+    ir_operand operand() const final { return { ir_operand::Global, name }; }
+};
+
+struct ir_function_variable : ir_variable {
+    ir_function_variable(ir_type type, std::uint64_t name)
+      : ir_variable(type), name(name) {}
+
+    std::uint64_t name;
+
+    ir_operand operand() const final { return { ir_operand::Variable, name }; }
+};
+
+struct ir_scope {
+    ir_scope()          = default;
+    virtual ~ir_scope() = default;
+
+    ir_scope(ir_scope&&) noexcept            = default;
+    ir_scope& operator=(ir_scope&&) noexcept = default;
+
+    ir_scope(const ir_scope&)            = default;
+    ir_scope& operator=(const ir_scope&) = default;
+
+    ir_scope* previous = nullptr;
+
+    std::unordered_map<std::string, ir_variable*> variables;
+
+    const ir_variable* variable(const std::string& name) const {
+        if (auto it = variables.find(name); it != variables.end()) return it->second;
+        return (previous != nullptr) ? previous->variable(name) : nullptr;
+    }
+
+    virtual const ir_variable* allocate(furlang::arena& arena, const std::string& name, ir_type type) = 0;
+};
+
+struct ir_function : ir_scope {
+    enum type_e {
+        Normal = 0,
+        Import,
+        Native,
+    } type = Normal;
+    enum access_e {
+        Public = 0,
+        Private,
+    } access = Public;
+
+    std::string                 name;
+    std::vector<ir_type>        params;
+    ir_type                     retType;
+    std::vector<ir_basic_block> blocks;
+
+    std::uint64_t regCount = 0;
+    std::uint64_t varCount = 0;
+
+    const ir_variable* allocate(furlang::arena& arena, const std::string& name, ir_type type) final {
+        return variables[name] = arena.allocate<ir_function_variable>(type, varCount++);
+    }
+
+    static ir_function from_name(std::string&& name) {
+        ir_function func;
+        func.name = std::move(name);
+        return func;
+    }
+};
+
+struct ir_module : ir_scope {
+    std::vector<ir_function*> functions;
+    furlang::arena            arena;
+
+    std::uint16_t varCount = 0;
+
+    const ir_variable* allocate(furlang::arena& arena, const std::string& name, ir_type type) final {
+        return variables[name] = arena.allocate<ir_module_variable>(type, varCount);
+    }
+
+    ir_function* add_function(ir_function&& function) {
+        return functions.emplace_back(arena.allocate<ir_function>(std::move(function)));
+    }
+};
+
+struct ir_context {
+    ir_context(ir_function* function)
+      : function(function) {
+        if (function->blocks.empty()) new_last();
+        blockPtr = &function->blocks.front();
+    }
+
+    ~ir_context() {
+        if (blockPtr == nullptr) return;
+        if (!blockPtr->is_terminated()) {
+            if (blockIdx + 1 == function->blocks.size()) {
+                add_instr(ir_instruction::Return);
+            } else {
+                add_instr(ir_instruction::Branch, ir_operand{ ir_operand::Block, blockIdx + 1 });
+            }
+        }
+    }
+
+    ir_context(ir_context&& other) noexcept
+      : function(other.function), blockIdx(other.blockIdx), blockPtr(other.blockPtr) {
+        other.function = nullptr;
+        other.blockIdx = 0;
+        other.blockPtr = nullptr;
+    }
+
+    ir_context& operator=(ir_context&& other) noexcept {
+        if (this == &other) return *this;
+        function = other.function;
+        blockIdx = other.blockIdx;
+        blockPtr = other.blockPtr;
+
+        other.function = nullptr;
+        other.blockIdx = 0;
+        other.blockPtr = nullptr;
+        return *this;
+    }
+
+    ir_context(const ir_context&)            = delete;
+    ir_context& operator=(const ir_context&) = delete;
+
+    template <typename... Args, typename = std::enable_if_t<std::is_constructible_v<ir_instruction, Args...>>>
+    ir_instruction& add_instr(Args&&... args) {
+        auto it = blockPtr->instructions.end();
+        if (!blockPtr->instructions.empty() && ir_instruction::is_terminating(blockPtr->instructions.back().type)) --it;
+        it = blockPtr->instructions.emplace(it, std::forward<Args>(args)...);
+        if (ir_instruction::is_terminating(it->type) && it + 1 != blockPtr->instructions.end())
+            blockPtr->instructions.pop_back();
+        return *it;
+    }
+
+    void terminate() { add_instr(ir_instruction::Return); }
+
+    void terminate(ir_operand value) {
+        ir_instruction instr = { ir_instruction::Return };
+        instr.sources.emplace_back(value);
+        add_instr(std::move(instr));
+    }
+
+    void terminate(std::uint64_t block) { add_instr(ir_instruction::Branch, ir_operand{ ir_operand::Block, block }); }
+
+    ir_instruction* terminate(ir_operand cond, std::uint64_t thenBranch, std::uint64_t elseBranch) {
+        return &add_instr(ir_instruction{ ir_instruction::BranchCond,
+            ir_operand{ ir_operand::BlockPair, thenBranch, elseBranch },
+            { cond } });
+    }
+
+    ir_context& new_next() {
+        if (blockPtr->instructions.empty()) return *this;
+        auto it = function->blocks.begin() + static_cast<std::ptrdiff_t>(++blockIdx);
+        if (!blockPtr->is_terminated()) terminate(blockIdx);
+        blockPtr = &*function->blocks.emplace(it);
+        return *this;
+    }
+
+    ir_context& new_last() {
+        blockIdx = function->blocks.size();
+        blockPtr = &*function->blocks.emplace(function->blocks.end());
+        return *this;
+    }
+
+    ir_context& go(std::uint64_t block) {
+        blockIdx = std::min(block, function->blocks.size() - 1);
+        blockPtr = function->blocks.data() + static_cast<std::ptrdiff_t>(blockIdx);
+        return *this;
+    }
+
+    ir_context& go_next() { return go(blockIdx + 1); }
+    ir_context& go_last() { return go(std::min<std::uint64_t>(0, function->blocks.size() - 1)); }
+
+    ir_operand last_register() const { return { ir_operand::Register, function->regCount - 1 }; }
+    ir_operand next_register() const { return { ir_operand::Register, function->regCount++ }; }
+
+    static ir_operand block_op(std::uint64_t blockIdx) { return { ir_operand::Block, blockIdx }; }
+
+    ir_function*    function = nullptr;
+    std::uint64_t   blockIdx = 0;
+    ir_basic_block* blockPtr = nullptr;
+};
+
+class ir_generator final : public ast_visitor {
+public:
+    ir_generator()
+      : m_initContext(m_module.add_function(ir_function::from_name("module$init"))) {}
+
+    void finalize() {
+        m_module.functions.front()->blocks.emplace_back().instructions.push_back(
+            ir_instruction{ ir_instruction::Return });
+    }
+
+    ir_module build() {
+        m_scope                = nullptr;
+        m_context              = {};
+        m_initContext.blockPtr = nullptr;
+        return std::move(m_module);
+    }
+
+    static ir_module generate(const ast_node& node) {
+        ir_generator gen;
+        node.accept(gen);
+        gen.finalize();
+        return gen.build();
+    }
+
+    static ir_module generate(const ast& tree) {
+        ir_generator gen;
+        for (const auto& node : tree.decls)
+            node->accept(gen);
+        gen.finalize();
+        return gen.build();
+    }
+private:
+    void visit_comp_stmt_node(const comp_stmt_node& node) override;
+    void visit_if_stmt_node(const if_stmt_node& node) override;
+    void visit_while_stmt_node(const while_stmt_node& node) override;
+    void visit_return_stmt_node(const return_stmt_node& node) override;
+    void visit_var_decl_node(const var_decl_node& node) override;
+    void visit_func_decl_node(const func_decl_node& node) override;
+    void visit_var_read_expr_node(const var_read_expr_node& node) override;
+    void visit_func_call_expr_node(const func_call_expr_node& node) override;
+    void visit_group_expr_node(const group_expr_node& node) override;
+    void visit_binary_op_expr_node(const binary_op_expr_node& node) override;
+    void visit_unary_op_expr_node(const unary_op_expr_node& node) override;
+    void visit_if_expr_node(const if_expr_node& node) override;
+    void visit_int_lit_node(const int_lit_node& node) override;
+    void visit_char_lit_node(const char_lit_node& node) override;
+private:
+    ir_context& context() { return m_context.top(); }
+private:
+    ir_module              m_module;
+    ir_scope*              m_scope = &m_module;
+    std::stack<ir_context> m_context;
+
+    ir_context m_initContext;
+};
+
+} // namespace furc
+
+#endif // FURC_MIDDLE_IR_HPP

include/furc/middle/reg_gen.hpp

@@ -0,0 +1,177 @@
+/**
+ * SSA destruction (out-of-SSA phase) for register-based targets based on "Mechanizing Conventional SSA for a
+ * Verified Destruction with Coalescing" by Delphine Demange and Yon Fernandez de Retana
+ * (https://dl.acm.org/doi/pdf/10.1145/2892208.2892222 09/11/2026).
+ */
+#ifndef FURC_MIDDLE_REG_GEN_HPP
+#define FURC_MIDDLE_REG_GEN_HPP
+
+#include "furc/middle/ir.hpp"
+#include "furc/middle/ssa.hpp"
+
+#include <cassert>
+#include <cstdint>
+#include <unordered_set>
+#include <vector>
+
+namespace furc {
+
+class reg_gen {
+public:
+    class disjoint_set {
+    public:
+        std::uint64_t find(std::uint64_t var) {
+            if (m_parents.find(var) == m_parents.end()) m_parents.emplace(var, var);
+            if (m_parents[var] == var) return var;
+            return find(m_parents[var]);
+        }
+
+        void unite(std::uint64_t var1, std::uint64_t var2) {
+            std::uint64_t rep1 = find(var1);
+            std::uint64_t rep2 = find(var2);
+            if (rep1 != rep2) m_parents[rep1] = rep2;
+        }
+    private:
+        std::unordered_map<std::uint64_t, std::uint64_t> m_parents;
+    };
+public:
+    struct block_info {
+        std::unordered_set<std::uint64_t> defs;
+        std::unordered_set<std::uint64_t> uses;
+        std::unordered_set<std::uint64_t> liveIn;
+        std::unordered_set<std::uint64_t> liveOut;
+    };
+public:
+    reg_gen(ir_function& func, ssa& ssa) {
+        std::vector<block_info> lifeBlocks;
+        live_analysis(lifeBlocks, func.blocks, ssa.cfgBlocks);
+        remove_interference(func.blocks, lifeBlocks);
+        merge(func.blocks);
+    }
+public:
+    static void live_analysis(std::vector<block_info>& lifeBlocks,
+        const std::vector<ir_basic_block>&             irBlocks,
+        const std::vector<ssa::cfg_block>&             cfgBlocks) {
+        lifeBlocks.resize(irBlocks.size());
+        for (std::uint64_t i = 0; i < irBlocks.size(); ++i) {
+            const auto& irBlock = irBlocks[i];
+            auto&       block   = lifeBlocks[i];
+
+            for (const auto& instr : irBlock.instructions) {
+                for (const auto& op : instr.sources) {
+                    if (op.type != ir_operand::Register) continue;
+                    if (block.defs.find(op.value.reg) != block.defs.end()) continue;
+                    block.uses.insert(op.value.reg);
+                }
+
+                if (!instr.destination.has_value() || instr.destination->type != ir_operand::Register) continue;
+                block.defs.insert(instr.destination->value.reg);
+            }
+        }
+
+        bool changed = true;
+        while (changed) {
+            changed = false;
+
+            for (std::uint64_t i = 0; i < irBlocks.size(); ++i) {
+                const auto& irBlock = irBlocks[i];
+                auto&       block   = lifeBlocks[i];
+
+                std::unordered_set<std::uint64_t> newSet;
+                for (auto succ : cfgBlocks[i].sucs) {
+                    newSet.insert(lifeBlocks[succ].liveIn.begin(), lifeBlocks[succ].liveIn.end());
+                }
+
+                if (newSet != block.liveOut) {
+                    block.liveOut = newSet;
+                    changed       = true;
+                }
+
+                newSet.clear();
+                newSet.insert(block.uses.begin(), block.uses.end());
+                for (const auto& var : block.liveOut) {
+                    if (block.defs.find(var) != block.defs.end()) continue;
+                    newSet.insert(var);
+                }
+
+                if (newSet != block.liveIn) {
+                    block.liveIn = newSet;
+                    changed      = true;
+                }
+            }
+        }
+    }
+
+    static void remove_interference(std::vector<ir_basic_block>& irBlocks, const std::vector<block_info>& lifeBlocks) {
+        for (std::uint64_t i = 0; i < irBlocks.size(); ++i) {
+            auto& irBlock = irBlocks[i];
+
+            for (auto it = irBlock.instructions.begin(), end = irBlock.instructions.end();
+                it != end && it->type == ir_instruction::Phi;
+                ++it) {
+                assert(it->destination.has_value() && it->destination->type == ir_operand::Register);
+                const auto& phiDst = it->destination->value.reg;
+
+                for (auto& op : it->sources) {
+                    assert(op.type == ir_operand::PhiPair);
+                    const auto& predBlock = lifeBlocks[op.value.phiPair.block];
+                    auto&       phiArg    = op.value.phiPair.reg;
+                    if (predBlock.liveOut.count(phiArg) == 0 || phiArg == phiDst) continue;
+
+                    auto oldArg = phiArg;
+                    phiArg.ver  = 0; // TODO: Allocate temporary registers
+
+                    auto& irBlock = irBlocks[op.value.phiPair.block];
+                    assert(!irBlock.instructions.empty());
+                    auto it = irBlock.instructions.end() - 1;
+                    if (ir_instruction::is_terminating(it->type)) --it;
+                    irBlock.instructions.emplace(it,
+                        ir_instruction{ ir_instruction::Move,
+                            ir_operand::reg(phiArg.name, phiArg.ver),
+                            { ir_operand::reg(oldArg.name, oldArg.ver) } });
+                }
+            }
+        }
+    }
+
+    static void merge(std::vector<ir_basic_block>& irBlocks) {
+        disjoint_set dj;
+
+        for (const auto& block : irBlocks) {
+            for (const auto& instr : block.instructions) {
+                if (instr.type != ir_instruction::Phi) break;
+
+                assert(instr.destination.has_value() && instr.destination->type == ir_operand::Register);
+                const auto& phiDst = instr.destination->value.reg;
+                dj.find(phiDst);
+
+                for (const auto& op : instr.sources) {
+                    assert(op.type == ir_operand::PhiPair);
+                    const auto& predBlock = op.value.phiPair.block;
+                    const auto& phiArg    = op.value.phiPair.reg;
+                    dj.unite(phiDst, phiArg);
+                }
+            }
+        }
+
+        for (auto& block : irBlocks) {
+            auto it = block.instructions.begin();
+            while (it != block.instructions.end() && it->type == ir_instruction::Phi) {
+                it = block.instructions.erase(it);
+            }
+            for (; it != block.instructions.end(); ++it) {
+                for (auto& op : it->sources) {
+                    if (op.type != ir_operand::Register) continue;
+                    op.value.reg = dj.find(op.value.reg);
+                }
+
+                if (!it->destination.has_value() || it->destination->type != ir_operand::Register) continue;
+                it->destination->value.reg = dj.find(it->destination->value.reg);
+            }
+        }
+    }
+};
+
+} // namespace furc
+
+#endif // FURC_MIDDLE_REG_GEN_HPP

include/furc/middle/ssa.hpp

@@ -0,0 +1,101 @@
+#ifndef FURC_MIDDLE_SSA_HPP
+#define FURC_MIDDLE_SSA_HPP
+
+#include "furc/middle/ir.hpp"
+
+#include <cassert>
+#include <limits>
+#include <unordered_map>
+#include <unordered_set>
+#include <vector>
+
+namespace furc {
+
+class ssa {
+public:
+    struct cfg_block {
+        std::unordered_set<std::uint64_t> preds;
+        std::unordered_set<std::uint64_t> sucs;
+    };
+
+    struct ssa_block {
+        std::size_t order = 0;
+
+        std::uint64_t idom = -1;
+
+        std::unordered_set<std::uint64_t> children; // Children of the block in dominator tree
+
+        // Dominance Frontiers
+        std::unordered_set<std::uint64_t> df;
+    };
+
+    struct register_info {
+        std::unordered_set<std::uint64_t> sites; // Definition Sites
+    };
+public:
+    ssa(ir_function& func) {
+        registers.resize(func.regCount);
+        compute_cfg(func.blocks, cfgBlocks);
+        collect_registers(func.blocks, registers, globals);
+
+        std::vector<std::uint64_t> order;
+        compute_rpo(cfgBlocks, ssaBlocks, order);
+
+        build_dtree(cfgBlocks, ssaBlocks, order);
+        compute_dfrontiers(cfgBlocks, ssaBlocks);
+
+        ssaification(func.blocks, cfgBlocks, ssaBlocks, registers, globals);
+        rename(func.blocks, func.regCount, cfgBlocks, ssaBlocks, order);
+    }
+public:
+    static void compute_cfg(const std::vector<ir_basic_block>& irBlocks, std::vector<cfg_block>& cfgBlocks);
+
+    static void collect_registers(const std::vector<ir_basic_block>& irBlocks,
+        std::vector<register_info>&                                  registers,
+        std::unordered_set<std::uint64_t>&                           globals);
+
+    static void build_dtree(const std::vector<cfg_block>& cfgBlocks,
+        std::vector<ssa_block>&                           ssaBlocks,
+        const std::vector<std::size_t>&                   order);
+
+    static void compute_dfrontiers(const std::vector<cfg_block>& cfgBlocks, std::vector<ssa_block>& ssaBlocks);
+
+    static void compute_rpo(std::vector<cfg_block>& cfgBlocks,
+        std::vector<ssa_block>&                     ssaBlocks,
+        std::vector<std::size_t>&                   order);
+
+    static void ssaification(std::vector<ir_basic_block>& irBlocks,
+        const std::vector<cfg_block>&                     cfgBlocks,
+        const std::vector<ssa_block>&                     ssaBlocks,
+        const std::vector<register_info>&                 registers,
+        const std::unordered_set<std::uint64_t>&          globals);
+
+    static void rename(std::vector<ir_basic_block>& irBlocks,
+        std::size_t                                 regCount,
+        const std::vector<cfg_block>&               cfgBlocks,
+        std::vector<ssa_block>&                     ssaBlocks,
+        const std::vector<std::uint64_t>&           order);
+private:
+    static void rename_rec(std::vector<std::uint64_t>& counters,
+        std::vector<std::stack<std::uint64_t>>&        stacks,
+        std::vector<ir_basic_block>&                   irBlocks,
+        const std::vector<cfg_block>&                  cfgBlocks,
+        const std::vector<ssa_block>&                  ssaBlocks,
+        std::size_t                                    blockIdx);
+private:
+    static void rpo_dfs(std::unordered_set<std::size_t>& visited,
+        std::vector<std::size_t>&                        order,
+        std::size_t                                      block,
+        const std::vector<cfg_block>&                    blocks);
+
+    static std::size_t intersect(std::vector<ssa_block>& m_blocks, std::size_t b1, std::size_t b2);
+public:
+    std::vector<cfg_block>            cfgBlocks;
+    std::vector<ssa_block>            ssaBlocks;
+    std::vector<register_info>        registers;
+    std::unordered_set<std::uint64_t> globals;
+};
+
+} // namespace furc
+
+#endif // FURC_MIDDLE_SSA_HPP