hakorune/src/mir/join_ir/lowering/mod.rs

//! JoinIR Lowering Functions
//!
//! Phase 27.9: Modular separation of MIR → JoinIR lowering implementations.
//!
//! このモジュールは各種 MIR 関数を JoinIR に変換する lowering 関数を提供します。
//!
//! ## 構成:
//! - `common.rs`: CFG sanity checks と lowering 共通ユーティリティ（Phase 27.10）
//! - `value_id_ranges.rs`: ValueId 範囲管理（Phase 27.13+）
//! - `min_loop.rs`: JoinIrMin.main/0 専用の最小ループ lowering
//! - `skip_ws.rs`: Main.skip/1 の空白スキップ lowering（手書き版＋MIR自動解析版）
//! - `funcscanner_trim.rs`: FuncScannerBox.trim/1 の trim lowering
//! - `stage1_using_resolver.rs`: Stage1UsingResolverBox.resolve_for_source entries loop lowering（Phase 27.12）
//! - `funcscanner_append_defs.rs`: FuncScannerBox._append_defs/2 の配列結合 lowering（Phase 27.14）
//! - `if_select.rs`: Phase 33 If/Else → Select lowering
//! - `if_dry_runner.rs`: Phase 33-10 If lowering dry-run スキャナー（箱化版）

pub mod common;
pub mod exit_args_resolver;
pub mod funcscanner_append_defs;
pub mod funcscanner_trim;
pub mod generic_case_a;
pub mod generic_type_resolver; // Phase 66: P3-C ジェネリック型推論箱
pub mod method_return_hint; // Phase 83: P3-D 既知メソッド戻り値型推論箱
pub mod if_dry_runner; // Phase 33-10.0
pub mod if_merge; // Phase 33-7
pub mod if_phi_context; // Phase 61-1
pub mod if_phi_spec; // Phase 61-2
pub mod if_select; // Phase 33
pub mod loop_form_intake;
pub mod loop_patterns; // Phase 188: Pattern-based loop lowering (3 patterns)
pub mod loop_scope_shape;
pub mod loop_to_join;
pub mod simple_while_minimal; // Phase 188-Impl-1: Pattern 1 minimal lowerer
pub mod min_loop;
pub mod skip_ws;
pub mod stage1_using_resolver;
pub mod stageb_body;
pub mod stageb_funcscanner;
pub mod type_hint_policy; // Phase 65.5: 型ヒントポリシー箱化
pub mod type_inference; // Phase 65-2-A
pub mod value_id_ranges;

// Re-export public lowering functions
pub use funcscanner_append_defs::lower_funcscanner_append_defs_to_joinir;
pub use funcscanner_trim::lower_funcscanner_trim_to_joinir;
// Phase 31: LoopToJoinLowerer 統一箱
pub use loop_to_join::LoopToJoinLowerer;
// Phase 30 F-3: 旧 lower_case_a_loop_to_joinir_for_minimal_skip_ws は _with_scope に置き換え済みのため削除
pub use min_loop::lower_min_loop_to_joinir;
pub use skip_ws::lower_skip_ws_to_joinir;
pub use stage1_using_resolver::lower_stage1_usingresolver_to_joinir;
pub use stageb_body::lower_stageb_body_to_joinir;
pub use stageb_funcscanner::lower_stageb_funcscanner_to_joinir;

// Phase 33: If/Else → Select lowering entry point
use crate::mir::join_ir::JoinInst;
use crate::mir::loop_form::LoopForm; // Phase 188: Loop pattern lowering
use crate::mir::{BasicBlockId, MirFunction};

/// Phase 33-9.1: Loop lowering対象関数の判定
///
/// これらの関数は Phase 32/33 で LoopToJoinLowerer によって処理されます。
/// If lowering (Select/IfMerge) の対象から除外することで、Loop/If の責務を明確に分離します。
///
/// Phase 82 SSOT: JOINIR_TARGETS テーブルから Exec 対象を参照
/// （テーブルは vm_bridge_dispatch/targets.rs で一元管理）
///
/// ## 対象関数（6本）
/// - Main.skip/1: 空白スキップループ
/// - FuncScannerBox.trim/1: 前後空白削除ループ
/// - FuncScannerBox.append_defs/2: 配列結合ループ
/// - Stage1UsingResolverBox.resolve_for_source/5: using解析ループ
/// - StageBBodyExtractorBox.build_body_src/2: Stage-B本体抽出ループ
/// - StageBFuncScannerBox.scan_all_boxes/1: Stage-B Box走査ループ
///
/// ## 将来の拡張
/// NYASH_JOINIR_LOWER_GENERIC=1 で汎用 Case-A ループにも拡張可能
pub(crate) fn is_loop_lowered_function(name: &str) -> bool {
    // Phase 82 SSOT: vm_bridge_dispatch テーブルから Loop 関数を抽出
    // Phase 33-9.1: If lowering の除外対象は、JOINIR_TARGETS に登録されたすべての関数
    // （Exec/LowerOnly 問わず、ループ専任関数として Loop lowering で処理）
    crate::mir::join_ir_vm_bridge_dispatch::JOINIR_TARGETS
        .iter()
        .any(|t| t.func_name == name)
}

// ============================================================================
// Phase 80: JoinIR Mainline Unification - Core ON 時の本線化判定
// ============================================================================

/// Phase 80: JoinIR 本線化対象（Loop）の判定
///
/// `joinir_core_enabled()=true` の時、これらの関数のループは
/// 必ず JoinIR → MIR 経路を本線として試行します。
pub fn is_loop_mainline_target(name: &str) -> bool {
    is_loop_lowered_function(name)
}

/// Phase 80/184: JoinIR 本線化対象（If）の判定
///
/// `joinir_core_enabled()=true` の時、これらの関数の if/else は
/// 必ず JoinIR → MIR 経路を本線として試行します。
///
/// Phase 184: JOINIR_IF_TARGETS テーブルからの参照に変更
pub fn is_if_mainline_target(name: &str) -> bool {
    crate::mir::join_ir_vm_bridge_dispatch::is_if_lowered_function(name)
}

/// Phase 80: Core ON 時に JoinIR を本線として試行すべきか判定
///
/// Returns true if:
/// - `joinir_core_enabled()=true` AND
/// - 関数が本線化対象 (Loop or If)
pub fn should_try_joinir_mainline(func_name: &str, is_loop: bool) -> bool {
    if !crate::config::env::joinir_core_enabled() {
        return false;
    }
    if is_loop {
        is_loop_mainline_target(func_name)
    } else {
        is_if_mainline_target(func_name)
    }
}

/// Phase 80/81: Strict モードで JoinIR lowering 失敗時にパニックすべきか判定
pub fn should_panic_on_joinir_failure(func_name: &str, is_loop: bool) -> bool {
    if !crate::config::env::joinir_strict_enabled() {
        return false;
    }
    should_try_joinir_mainline(func_name, is_loop)
}

/// Phase 61-4/184: ループ外 If の JoinIR 対象関数判定
///
/// HAKO_JOINIR_IF_TOPLEVEL=1 有効時に、ループ外 if の JoinIR 経路を試行する関数。
/// Phase 184: JOINIR_IF_TARGETS テーブルに統一（SSOT化）
///
/// ## 対象関数（テーブル管理）
/// - IfSelectTest.*: テスト専用関数群
/// - IfMergeTest.*: 複数変数テスト（Phase 33-7）
/// - IfToplevelTest.*: ループ外 if テスト専用（Phase 61-4）
/// - JsonShapeToMap._read_value_from_pair/1: Phase 33-4 Stage-1 実用関数
/// - Stage1JsonScannerBox.value_start_after_key_pos/2: Phase 33-4 Stage-B 実用関数
///
/// ## 使用方法
/// if_form.rs から呼び出され、関数名がテーブルに含まれる場合のみ
/// JoinIR 経路を試行する。
///
/// Phase 184: テーブル参照に変更（プレフィックス判定は併用）
pub fn is_joinir_if_toplevel_target(name: &str) -> bool {
    // Phase 184: JOINIR_IF_TARGETS テーブルから参照（exact match）
    if crate::mir::join_ir_vm_bridge_dispatch::JOINIR_IF_TARGETS
        .iter()
        .any(|t| t.func_name == name)
    {
        return true;
    }

    // Test prefixes (backward compatibility - allows any test function)
    if name.starts_with("IfSelectTest.")
        || name.starts_with("IfToplevelTest.")
        || name.starts_with("IfMergeTest.")
    {
        return true;
    }

    false
}

/// Phase 33-7: Try to lower if/else to JoinIR Select/IfMerge instruction
///
/// Scope:
/// - Only applies to whitelisted functions:
///   - IfSelectTest.* (Phase 33-2/33-3)
///   - IfMergeTest.* (Phase 33-7)
///   - JsonShapeToMap._read_value_from_pair/1 (Phase 33-4 Stage-1)
///   - Stage1JsonScannerBox.value_start_after_key_pos/2 (Phase 33-4 Stage-B)
/// - Requires JoinIR If-select toggle (HAKO_JOINIR_IF_SELECT / joinir_if_select_enabled)
/// - Falls back to traditional if_phi on pattern mismatch
///
/// Pattern selection:
/// - 1 variable → Select
/// - 2+ variables → IfMerge
///
/// Phase 61-1: If-in-loop support
/// - `context` parameter: If-in-loop context (carrier_names for loop variables)
/// - None = Pure If, Some(_) = If-in-loop
///
/// Returns Some(JoinInst::Select) or Some(JoinInst::IfMerge) if pattern matched, None otherwise.
pub fn try_lower_if_to_joinir(
    func: &MirFunction,
    block_id: BasicBlockId,
    debug: bool,
    context: Option<&if_phi_context::IfPhiContext>, // Phase 61-1: If-in-loop context
) -> Option<JoinInst> {
    // 1. dev/Core トグルチェック
    //
    // - Core: joinir_core_enabled() / joinir_if_select_enabled()
    // - Dev:  joinir_dev_enabled()（詳細ログ等）
    //
    // 実際の挙動切り替えは joinir_if_select_enabled() に集約し、
    // Core/Dev ポリシーは config::env 側で判定する。
    if !crate::config::env::joinir_if_select_enabled() {
        return None;
    }
    let core_on = crate::config::env::joinir_core_enabled();
    // Phase 185: strict check moved to caller (if_form.rs)
    // let strict_on = crate::config::env::joinir_strict_enabled();

    // Phase 33-9.1: Loop専任関数の除外（Loop/If責務分離）
    // Loop lowering対象関数はIf loweringの対象外にすることで、
    // 1関数につき1 loweringの原則を保証します
    if is_loop_lowered_function(&func.signature.name) {
        return None;
    }

    // Phase 33-8: デバッグログレベル取得（0-3）
    let debug_level = crate::config::env::joinir_debug_level();
    let _debug = debug || debug_level >= 1;

    // 2. Phase 33-8: 関数名ガード拡張（テスト + Stage-1 rollout + 明示承認）
    let is_allowed =
        // Test functions (always enabled)
        func.signature.name.starts_with("IfSelectTest.") ||
        func.signature.name.starts_with("IfSelectLocalTest.") || // Phase 33-10 test
        func.signature.name.starts_with("IfMergeTest.") ||
        func.signature.name.starts_with("IfToplevelTest.") || // Phase 61-4: loop-outside if test
        func.signature.name.starts_with("Stage1JsonScannerTestBox.") || // Phase 33-5 test

        // Stage-1 rollout (env-controlled)
        (crate::config::env::joinir_stage1_enabled() &&
         func.signature.name.starts_with("Stage1")) ||

        // Explicit approvals (Phase 33-4で検証済み, always on)
        matches!(func.signature.name.as_str(),
            "JsonShapeToMap._read_value_from_pair/1" |
            "Stage1JsonScannerBox.value_start_after_key_pos/2"
        );

    // Phase 80: Core ON のときは許可リストを「JoinIRをまず試す」対象とみなす。
    // Core OFF のときは従来どおり whitelist + env に頼る。
    if !is_allowed || !core_on {
        // Core OFF かつ許可外なら従来のガードでスキップ
        if !is_allowed {
            if debug_level >= 2 {
                eprintln!(
                    "[try_lower_if_to_joinir] skipping non-allowed function: {}",
                    func.signature.name
                );
            }
            return None;
        }
    }
    // Phase 185: strict_allowed removed (strict check moved to caller: if_form.rs)

    if debug_level >= 1 {
        eprintln!(
            "[try_lower_if_to_joinir] trying to lower {}",
            func.signature.name
        );
    }

    // 3. Phase 33-7: IfMerge を優先的に試行（複数変数パターン）
    //    IfMerge が成功すればそれを返す、失敗したら Select を試行
    // Phase 61-1: context がある場合は with_context() を使用
    let if_merge_lowerer = if let Some(ctx) = context {
        if_merge::IfMergeLowerer::with_context(debug_level, ctx.clone())
    } else {
        if_merge::IfMergeLowerer::new(debug_level)
    };

    if if_merge_lowerer.can_lower_to_if_merge(func, block_id) {
        if let Some(result) = if_merge_lowerer.lower_if_to_if_merge(func, block_id) {
            if debug_level >= 1 {
                eprintln!(
                    "[try_lower_if_to_joinir] ✅ IfMerge lowering used for {}",
                    func.signature.name
                );
            }
            return Some(result);
        }
    }

    // 4. IfMerge が失敗したら Select を試行（単一変数パターン）
    // Phase 61-1: context がある場合は with_context() を使用
    let if_select_lowerer = if let Some(ctx) = context {
        if_select::IfSelectLowerer::with_context(debug_level, ctx.clone())
    } else {
        if_select::IfSelectLowerer::new(debug_level)
    };

    // Phase 185: Remove strict checks from lowerer (thin Result-returning box)
    // Strict mode panic should happen at caller level (if_form.rs), not here
    if !if_select_lowerer.can_lower_to_select(func, block_id) {
        if debug_level >= 1 {
            eprintln!(
                "[try_lower_if_to_joinir] pattern not matched for {}",
                func.signature.name
            );
        }
        return None;
    }

    let result = if_select_lowerer.lower_if_to_select(func, block_id);

    if result.is_some() && debug_level >= 1 {
        eprintln!(
            "[try_lower_if_to_joinir] ✅ Select lowering used for {}",
            func.signature.name
        );
    }

    result
}

// ============================================================================
// Phase 188: Loop Pattern-Based Lowering Router
// ============================================================================

/// Phase 188: Try to lower loop to JoinIR using pattern-based approach
///
/// This function routes loop lowering to specific pattern handlers based on
/// loop structure characteristics. It tries patterns in order of complexity:
///
/// 1. **Pattern 1: Simple While** (foundational, easiest)
/// 2. **Pattern 2: Break** (medium complexity)
/// 3. **Pattern 3: If-Else PHI** (leverages existing If lowering)
///
/// # Arguments
///
/// * `loop_form` - The loop structure to lower
/// * `lowerer` - The LoopToJoinLowerer builder (provides ValueId allocation, etc.)
///
/// # Returns
///
/// * `Some(JoinInst)` - Successfully lowered to JoinIR
/// * `None` - No pattern matched (fallback to existing lowering)
///
/// # Pattern Selection Strategy
///
/// Patterns are tried sequentially. First matching pattern wins.
/// If no pattern matches, returns `Ok(None)` to trigger fallback.
///
/// ## Pattern 1: Simple While Loop
/// - **Condition**: Empty break/continue targets, single latch
/// - **Handler**: `loop_patterns::lower_simple_while_to_joinir()`
/// - **Priority**: First (most common, simplest)
///
/// ## Pattern 2: Loop with Conditional Break
/// - **Condition**: Non-empty break_targets, exactly 1 break
/// - **Handler**: `loop_patterns::lower_loop_with_break_to_joinir()`
/// - **Priority**: Second (common, medium complexity)
///
/// ## Pattern 3: Loop with If-Else PHI
/// - **Condition**: Empty break/continue, if-else in body
/// - **Handler**: `loop_patterns::lower_loop_with_conditional_phi_to_joinir()`
/// - **Priority**: Third (reuses If lowering infrastructure)
///
/// # Integration Point
///
/// This function should be called from loop lowering entry points:
/// - `loop_to_join.rs::LoopToJoinLowerer::lower_loop()`
/// - `loop_form_intake.rs::handle_loop_form()`
///
/// # Example Usage
///
/// ```rust,ignore
/// use crate::mir::join_ir::lowering::try_lower_loop_pattern_to_joinir;
///
/// // In loop lowering entry point:
/// if let Some(joinir_inst) = try_lower_loop_pattern_to_joinir(&loop_form, &mut lowerer) {
///     // Pattern matched, use JoinIR
///     return Some(joinir_inst);
/// }
/// // No pattern matched, use existing lowering
/// existing_loop_lowering(&loop_form, &mut lowerer)
/// ```
///
/// # Reference
///
/// See design.md for complete pattern specifications and transformation rules:
/// `docs/private/roadmap2/phases/phase-188-joinir-loop-pattern-expansion/design.md`
///
/// # TODO (Phase 188 Task 188-4 Implementation)
///
/// This function is a skeleton. Implementation steps:
///
/// 1. **Implement Pattern Detection** (Step 1: 6-8h)
///    - Complete `loop_pattern_detection::is_simple_while_pattern()`
///    - Test with `apps/tests/loop_min_while.hako`
///
/// 2. **Implement Pattern 1 Lowering** (Step 1: 6-8h)
///    - Complete `loop_patterns::lower_simple_while_to_joinir()`
///    - Verify no [joinir/freeze] error
///
/// 3. **Implement Pattern 2** (Step 2: 6-10h)
///    - Complete `loop_pattern_detection::is_loop_with_break_pattern()`
///    - Complete `loop_patterns::lower_loop_with_break_to_joinir()`
///    - Test with `apps/tests/joinir_min_loop.hako`
///
/// 4. **Implement Pattern 3** (Step 3: 6-10h)
///    - Complete `loop_pattern_detection::is_loop_with_conditional_phi_pattern()`
///    - Complete `loop_patterns::lower_loop_with_conditional_phi_to_joinir()`
///    - Test with `apps/tests/loop_if_phi.hako`
///
/// 5. **Integration Testing** (Step 4: 2-4h)
///    - Run all 3 tests with JoinIR-only
///    - Verify no regressions
///    - Document results
///
/// **Total Estimated Effort**: 18-28 hours
pub fn try_lower_loop_pattern_to_joinir(
    _loop_form: &LoopForm,
    _lowerer: &mut LoopToJoinLowerer,
) -> Option<JoinInst> {
    // TODO: Implement pattern routing logic
    //
    // Pattern 1: Simple While Loop (easiest, most common)
    // ====================================================
    //
    // ```rust
    // use crate::mir::loop_pattern_detection::is_simple_while_pattern;
    // use crate::mir::join_ir::lowering::loop_patterns::lower_simple_while_to_joinir;
    //
    // if is_simple_while_pattern(loop_form) {
    //     if let Some(inst) = lower_simple_while_to_joinir(loop_form, lowerer) {
    //         return Some(inst);
    //     }
    // }
    // ```
    //
    // Pattern 2: Loop with Conditional Break (medium complexity)
    // ===========================================================
    //
    // ```rust
    // use crate::mir::loop_pattern_detection::is_loop_with_break_pattern;
    // use crate::mir::join_ir::lowering::loop_patterns::lower_loop_with_break_to_joinir;
    //
    // if is_loop_with_break_pattern(loop_form) {
    //     if let Some(inst) = lower_loop_with_break_to_joinir(loop_form, lowerer) {
    //         return Some(inst);
    //     }
    // }
    // ```
    //
    // Pattern 3: Loop with If-Else PHI (leverages existing If lowering)
    // ==================================================================
    //
    // ```rust
    // use crate::mir::loop_pattern_detection::is_loop_with_conditional_phi_pattern;
    // use crate::mir::join_ir::lowering::loop_patterns::lower_loop_with_conditional_phi_to_joinir;
    //
    // if is_loop_with_conditional_phi_pattern(loop_form) {
    //     if let Some(inst) = lower_loop_with_conditional_phi_to_joinir(loop_form, lowerer) {
    //         return Some(inst);
    //     }
    // }
    // ```
    //
    // No Pattern Matched (fallback to existing lowering)
    // ===================================================
    //
    // ```rust
    // // No pattern matched, return None to trigger fallback
    // None
    // ```

    // For now, return None (no pattern matched)
    // This allows existing lowering to continue working
    None
}

#[cfg(test)]
mod tests {
    use super::*;

    /// Phase 33-9.1: is_loop_lowered_function() の動作確認
    #[test]
    fn test_is_loop_lowered_function() {
        // Loop 専任関数（6本）は true を返す
        assert!(is_loop_lowered_function("Main.skip/1"));
        assert!(is_loop_lowered_function("FuncScannerBox.trim/1"));
        assert!(is_loop_lowered_function("FuncScannerBox.append_defs/2"));
        assert!(is_loop_lowered_function(
            "Stage1UsingResolverBox.resolve_for_source/5"
        ));
        assert!(is_loop_lowered_function(
            "StageBBodyExtractorBox.build_body_src/2"
        ));
        assert!(is_loop_lowered_function(
            "StageBFuncScannerBox.scan_all_boxes/1"
        ));

        // If lowering 対象関数は false を返す
        assert!(!is_loop_lowered_function("IfSelectTest.simple_return/0"));
        assert!(!is_loop_lowered_function("IfMergeTest.multiple_true/0"));
        assert!(!is_loop_lowered_function(
            "JsonShapeToMap._read_value_from_pair/1"
        ));
        assert!(!is_loop_lowered_function(
            "Stage1JsonScannerBox.value_start_after_key_pos/2"
        ));

        // 一般的な関数も false を返す
        assert!(!is_loop_lowered_function("SomeBox.some_method/3"));
        assert!(!is_loop_lowered_function("Main.main/0"));
    }
}