hakorune/src/mir/builder/control_flow.rs

//! Control-flow entrypoints (if/loop/try/throw) centralized here.
use super::{Effect, EffectMask, MirInstruction, ValueId};
use crate::ast::ASTNode;

impl super::MirBuilder {
    /// Control-flow: block
    pub(super) fn cf_block(&mut self, statements: Vec<ASTNode>) -> Result<ValueId, String> {
        // identical to build_block; kept here for future policy hooks
        self.build_block(statements)
    }

    /// Control-flow: if
    ///
    /// # Phase 124: JoinIR-Only (hako_check専用化完了)
    ///
    /// If statements are now always routed through the canonical lowering path
    /// (lower_if_form), which internally uses JoinIR-based PHI generation.
    ///
    /// Phase 123 の環境変数による分岐は削除済み。
    pub(super) fn cf_if(
        &mut self,
        condition: ASTNode,
        then_branch: ASTNode,
        else_branch: Option<ASTNode>,
    ) -> Result<ValueId, String> {
        // Phase 124: JoinIR-only path (環境変数分岐削除)
        // lower_if_form は JoinIR ベースの PHI 生成を使用
        self.lower_if_form(condition, then_branch, else_branch)
    }

    /// Control-flow: loop
    ///
    /// # Phase 49: JoinIR Frontend Mainline Integration
    ///
    /// This is the unified entry point for all loop lowering. Specific functions
    /// are routed through JoinIR Frontend instead of the traditional LoopBuilder path
    /// when enabled via dev flags (Phase 49) or Core policy (Phase 80):
    ///
    /// - Core ON (`joinir_core_enabled()`): print_tokens / ArrayExt.filter はまず JoinIR Frontend を試す
    /// - Dev フラグ（既存）:
    ///   - `HAKO_JOINIR_PRINT_TOKENS_MAIN=1`: JsonTokenizer.print_tokens/0
    ///   - `HAKO_JOINIR_ARRAY_FILTER_MAIN=1`: ArrayExtBox.filter/2
    ///
    /// Note: Arity does NOT include implicit `me` receiver.
    pub(super) fn cf_loop(
        &mut self,
        condition: ASTNode,
        body: Vec<ASTNode>,
    ) -> Result<ValueId, String> {
        // Phase 49/80: Try JoinIR Frontend route for mainline targets
        if let Some(result) = self.try_cf_loop_joinir(&condition, &body)? {
            return Ok(result);
        }

        if std::env::var("NYASH_LOOPFORM_DEBUG").is_ok() {
            eprintln!("[cf_loop] CALLED from somewhere");
            eprintln!("[cf_loop] Current stack (simulated): check build_statement vs build_expression_impl");
        }

        // Phase 186: LoopBuilder Hard Freeze - Legacy path disabled
        // Phase 187-2: LoopBuilder module removed - all loops must use JoinIR
        return Err(format!(
            "[joinir/freeze] Loop lowering failed: JoinIR does not support this pattern, and LoopBuilder has been removed.\n\
             Function: {}\n\
             Hint: This loop pattern is not supported. All loops must use JoinIR lowering.",
            self.current_function.as_ref().map(|f| f.signature.name.as_str()).unwrap_or("<unknown>")
        ));
    }

    /// Phase 49: Try JoinIR Frontend for mainline integration
    ///
    /// Returns `Ok(Some(value))` if the current function should use JoinIR Frontend,
    /// `Ok(None)` to fall through to the legacy LoopBuilder path.
    ///
    /// # Phase 49-4: Multi-target support
    ///
    /// Targets are enabled via separate dev flags:
    /// - `HAKO_JOINIR_PRINT_TOKENS_MAIN=1`: JsonTokenizer.print_tokens/0
    /// - `HAKO_JOINIR_ARRAY_FILTER_MAIN=1`: ArrayExtBox.filter/2
    ///
    /// Note: Arity in function names does NOT include implicit `me` receiver.
    /// - Instance method `print_tokens()` → `/0` (no explicit params)
    /// - Static method `filter(arr, pred)` → `/2` (two params)
    fn try_cf_loop_joinir(
        &mut self,
        condition: &ASTNode,
        body: &[ASTNode],
    ) -> Result<Option<ValueId>, String> {
        // Get current function name
        let func_name = self
            .current_function
            .as_ref()
            .map(|f| f.signature.name.clone())
            .unwrap_or_default();

        // Phase 188-Impl-3: Debug logging for function name routing
        if std::env::var("NYASH_JOINIR_MAINLINE_DEBUG").is_ok() {
            eprintln!("[cf_loop/joinir/router] Current function name: '{}'", func_name);
        }

        // Phase 49-4 + Phase 80: Multi-target routing
        // - Core ON なら代表2本（print_tokens / ArrayExt.filter）は JoinIR を優先し、失敗したら LoopBuilder へフォールバック
        // - Core OFF では従来通り dev フラグで opt-in
        // Note: Arity does NOT include implicit `me` receiver
        // Phase 188: Add "main" routing for loop pattern expansion
        let core_on = crate::config::env::joinir_core_enabled();
        let is_target = match func_name.as_str() {
            "main" => true,  // Phase 188-Impl-1: Enable JoinIR for main function (Pattern 1)
            "JoinIrMin.main/0" => true,  // Phase 188-Impl-2: Enable JoinIR for JoinIrMin.main/0 (Pattern 2)
            "JsonTokenizer.print_tokens/0" => {
                if core_on {
                    true
                } else {
                    std::env::var("HAKO_JOINIR_PRINT_TOKENS_MAIN")
                        .ok()
                        .as_deref()
                        == Some("1")
                }
            }
            "ArrayExtBox.filter/2" => {
                if core_on {
                    true
                } else {
                    std::env::var("HAKO_JOINIR_ARRAY_FILTER_MAIN")
                        .ok()
                        .as_deref()
                        == Some("1")
                }
            }
            _ => false,
        };

        if !is_target {
            return Ok(None);
        }

        // Debug log when routing through JoinIR Frontend
        let debug = std::env::var("NYASH_LOOPFORM_DEBUG").is_ok()
            || std::env::var("NYASH_JOINIR_MAINLINE_DEBUG").is_ok();
        if debug {
            eprintln!(
                "[cf_loop/joinir] Routing {} through JoinIR Frontend mainline",
                func_name
            );
        }

        // Phase 49-3: Implement JoinIR Frontend integration
        self.cf_loop_joinir_impl(condition, body, &func_name, debug)
    }

    /// Phase 49-3: JoinIR Frontend integration implementation
    ///
    /// # Pipeline
    /// 1. Build Loop AST → JSON v0 format (with "defs" array)
    /// 2. AstToJoinIrLowerer::lower_program_json() → JoinModule
    /// 3. convert_join_module_to_mir_with_meta() → MirModule
    /// 4. Merge MIR blocks into current_function
    ///
    /// # Phase 49-4 Note
    ///
    /// JoinIR Frontend expects a complete function definition with:
    /// - local variable initializations
    /// - loop body
    /// - return statement
    ///
    /// Since cf_loop only has access to the loop condition and body,
    /// we construct a minimal JSON v0 wrapper with function name "simple"
    /// to match the JoinIR Frontend's expected pattern.
    fn cf_loop_joinir_impl(
        &mut self,
        condition: &ASTNode,
        body: &[ASTNode],
        func_name: &str,
        debug: bool,
    ) -> Result<Option<ValueId>, String> {
        use super::loop_frontend_binding::LoopFrontendBinding;
        use crate::mir::join_ir::frontend::{AstToJoinIrLowerer, JoinFuncMetaMap};
        use crate::mir::join_ir_vm_bridge::convert_join_module_to_mir_with_meta;
        use crate::mir::types::ConstValue;
        use crate::r#macro::ast_json::ast_to_json;

        // Phase 188-Impl-3: Route Pattern 3 (If-Else PHI) - detect by 'sum' variable presence
        // This MUST come before Pattern 1 check to avoid incorrect routing
        // Pattern 3 test (loop_if_phi.hako) uses "main" with 'sum' accumulator variable
        if func_name == "main" && self.variable_map.contains_key("sum") {
            if debug {
                eprintln!("[cf_loop/joinir] Routing 'main' (with sum var) through Pattern 3 minimal lowerer");
            }
            return self.cf_loop_pattern3_with_if_phi(condition, body, func_name, debug);
        }

        // Phase 188-Impl-1-F: Route Pattern 1 (Simple While) - "main" without 'sum' variable
        if func_name == "main" {
            if debug {
                eprintln!("[cf_loop/joinir] Routing '{}' through Pattern 1 minimal lowerer", func_name);
            }
            return self.cf_loop_pattern1_minimal(condition, body, func_name, debug);
        }

        // Phase 188-Impl-2: Route "JoinIrMin.main/0" through Pattern 2 minimal lowerer (Loop with Break)
        if func_name == "JoinIrMin.main/0" {
            if debug {
                eprintln!("[cf_loop/joinir] Routing 'JoinIrMin.main/0' through Pattern 2 minimal lowerer");
            }
            return self.cf_loop_pattern2_with_break(condition, body, func_name, debug);
        }

        // Phase 50: Create appropriate binding based on function name
        let binding = match func_name {
            "JsonTokenizer.print_tokens/0" => LoopFrontendBinding::for_print_tokens(),
            "ArrayExtBox.filter/2" => LoopFrontendBinding::for_array_filter(),
            _ => {
                if debug {
                    eprintln!(
                        "[cf_loop/joinir] No binding defined for {}, falling back",
                        func_name
                    );
                }
                return Ok(None);
            }
        };

        if debug {
            eprintln!(
                "[cf_loop/joinir] Using binding: counter={}, acc={:?}, pattern={:?}",
                binding.counter_var, binding.accumulator_var, binding.pattern
            );
        }

        // Step 1: Convert condition and body to JSON
        let condition_json = ast_to_json(condition);
        let mut body_json: Vec<serde_json::Value> = body.iter().map(|s| ast_to_json(s)).collect();

        // Phase 50: Rename variables in body (e.g., "out" → "acc" for filter)
        binding.rename_body_variables(&mut body_json);

        // Phase 50: Generate Local declarations from binding
        let (i_local, acc_local, n_local) = binding.generate_local_declarations();

        // Phase 52/56: Build params from external_refs
        // Instance methods need `me`, static methods need their parameters (arr, pred, etc.)
        let mut params: Vec<serde_json::Value> = Vec::new();

        // Phase 52: Add 'me' for instance methods
        if binding.needs_me_receiver() {
            if debug {
                eprintln!("[cf_loop/joinir] Adding 'me' to params (instance method)");
            }
            params.push(serde_json::json!("me"));
        }

        // Phase 56: Add external_refs as parameters (arr, pred for filter)
        for ext_ref in &binding.external_refs {
            // Skip "me" and "me.*" as they're handled above
            if ext_ref == "me" || ext_ref.starts_with("me.") {
                continue;
            }
            if debug {
                eprintln!(
                    "[cf_loop/joinir] Adding '{}' to params (external_ref)",
                    ext_ref
                );
            }
            params.push(serde_json::json!(ext_ref));
        }

        // Step 2: Construct JSON v0 format with "defs" array
        // The function is named "simple" to match JoinIR Frontend's pattern matching
        // Phase 50: Include i/acc/n Local declarations to satisfy JoinIR Frontend expectations
        let program_json = serde_json::json!({
            "defs": [
                {
                    "name": "simple",
                    "params": params,
                    "body": {
                        "type": "Block",
                        "body": [
                            // Phase 50: Inject i/acc/n Local declarations
                            i_local,
                            acc_local,
                            n_local,
                            {
                                "type": "Loop",
                                "cond": condition_json,  // JoinIR Frontend expects "cond" not "condition"
                                "body": body_json
                            },
                            // Return the accumulator (or null for side-effect loops)
                            {
                                "type": "Return",
                                "value": { "kind": "Variable", "name": "acc" }
                            }
                        ]
                    }
                }
            ]
        });

        if debug {
            eprintln!(
                "[cf_loop/joinir] Generated JSON v0 for {}: {}",
                func_name,
                serde_json::to_string_pretty(&program_json).unwrap_or_default()
            );
        }

        // Step 3: Lower to JoinIR
        // Phase 49-4: Use catch_unwind for graceful fallback on unsupported patterns
        // The JoinIR Frontend may panic if the loop doesn't match expected patterns
        // (e.g., missing variable initializations like "i must be initialized")
        let join_module = {
            let json_clone = program_json.clone();
            let result = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
                let mut lowerer = AstToJoinIrLowerer::new();
                lowerer.lower_program_json(&json_clone)
            }));

            match result {
                Ok(module) => module,
                Err(e) => {
                    // Extract panic message for debugging
                    let panic_msg = if let Some(s) = e.downcast_ref::<&str>() {
                        s.to_string()
                    } else if let Some(s) = e.downcast_ref::<String>() {
                        s.clone()
                    } else {
                        "unknown panic".to_string()
                    };

                    if debug {
                        eprintln!(
                            "[cf_loop/joinir] JoinIR lowering failed for {}: {}, falling back to legacy",
                            func_name, panic_msg
                        );
                    }
                    // Return None to fall back to legacy LoopBuilder
                    return Ok(None);
                }
            }
        };
        // Phase 49-3 MVP: Use empty meta map (full if-analysis is Phase 40+ territory)
        let join_meta = JoinFuncMetaMap::new();

        if debug {
            eprintln!(
                "[cf_loop/joinir] JoinModule has {} functions, entry={:?}",
                join_module.functions.len(),
                join_module.entry
            );
        }

        // Step 4: Convert JoinModule to MIR
        let mir_module = convert_join_module_to_mir_with_meta(&join_module, &join_meta)
            .map_err(|e| format!("JoinIR→MIR conversion failed: {}", e.message))?;

        if debug {
            eprintln!(
                "[cf_loop/joinir] MirModule has {} functions",
                mir_module.functions.len()
            );
            for (name, func) in &mir_module.functions {
                eprintln!(
                    "[cf_loop/joinir]   - {}: {} blocks, entry={:?}",
                    name,
                    func.blocks.len(),
                    func.entry_block
                );
                // Phase 189: Debug - show block contents
                for (block_id, block) in &func.blocks {
                    eprintln!("[cf_loop/joinir]     Block {:?}: {} instructions", block_id, block.instructions.len());
                    for (i, inst) in block.instructions.iter().enumerate() {
                        eprintln!("[cf_loop/joinir]       [{}] {:?}", i, inst);
                    }
                    if let Some(ref term) = block.terminator {
                        eprintln!("[cf_loop/joinir]       terminator: {:?}", term);
                    }
                }
            }
        }

        // Step 5: Merge MIR blocks into current_function
        // For Phase 49-3, we'll use a simplified approach:
        // - Add generated blocks to current_function
        // - Jump from current_block to the entry of generated loop
        // - The loop exit becomes the new current_block
        // Phase 188-Impl-3: Pass None for boundary (legacy path without boundary)
        self.merge_joinir_mir_blocks(&mir_module, None, debug)?;

        // Return void for now (loop doesn't have a meaningful return value in this context)
        let void_val = self.next_value_id();
        self.emit_instruction(MirInstruction::Const {
            dst: void_val,
            value: ConstValue::Void,
        })?;

        Ok(Some(void_val))
    }

    /// Phase 188-Impl-1-F: Pattern 1 (Simple While Loop) minimal lowerer
    ///
    /// This bypasses the LoopFrontendBinding JSON path and directly calls
    /// the Pattern 1 minimal lowerer for apps/tests/loop_min_while.hako
    ///
    /// # Phase 188-Impl-2: Host Variable Integration
    ///
    /// Extracts the loop variable from the host function (e.g., `i` from `i < 3`)
    /// and passes it to the Pattern 1 lowerer along with a ValueId allocator.
    ///
    /// # Pipeline
    /// 1. Extract loop variable name from condition
    /// 2. Look up ValueId in host variable_map
    /// 3. Create Pattern1Context with host variable + allocator
    /// 4. Call simple_while_minimal::lower_simple_while_minimal() → JoinModule
    /// 5. convert_join_module_to_mir_with_meta() → MirModule
    /// 6. Merge MIR blocks into current_function
    fn cf_loop_pattern1_minimal(
        &mut self,
        condition: &ASTNode,
        _body: &[ASTNode],
        _func_name: &str,
        debug: bool,
    ) -> Result<Option<ValueId>, String> {
        use crate::mir::join_ir::lowering::simple_while_minimal::{
            lower_simple_while_minimal, Pattern1Context,
        };
        use crate::mir::join_ir_vm_bridge::convert_join_module_to_mir_with_meta;
        use crate::mir::BasicBlockId;
        use std::collections::{BTreeMap, BTreeSet};

        if debug {
            eprintln!("[cf_loop/joinir/pattern1] Calling Pattern 1 minimal lowerer");
        }

        // Phase 188-Impl-2: Extract loop variable from condition
        // For `i < 3`, extract `i` and look up its ValueId in variable_map
        let loop_var_name = self.extract_loop_variable_from_condition(condition)?;
        let loop_var_id = self
            .variable_map
            .get(&loop_var_name)
            .copied()
            .ok_or_else(|| {
                format!(
                    "[cf_loop/pattern1] Loop variable '{}' not found in variable_map",
                    loop_var_name
                )
            })?;

        if debug {
            eprintln!(
                "[cf_loop/joinir/pattern1] Loop variable '{}' → {:?}",
                loop_var_name, loop_var_id
            );
        }

        // Create a minimal LoopScopeShape (Phase 188: hardcoded for loop_min_while.hako)
        // Pattern 1 lowerer ignores the scope anyway, so this is just a placeholder
        use crate::mir::join_ir::lowering::loop_scope_shape::LoopScopeShape;
        let scope = LoopScopeShape {
            header: BasicBlockId(0),
            body: BasicBlockId(0),
            latch: BasicBlockId(0),
            exit: BasicBlockId(0),
            pinned: BTreeSet::new(),
            carriers: BTreeSet::new(),
            body_locals: BTreeSet::new(),
            exit_live: BTreeSet::new(),
            progress_carrier: None,
            variable_definitions: BTreeMap::new(),
        };

        // Phase 188-Impl-2: Create Pattern1Context with host variable + allocator
        // Clone value_gen to move into closure
        let mut value_gen_clone = self.value_gen.clone();
        let ctx = Pattern1Context {
            loop_var: loop_var_id,
            value_allocator: Box::new(move || value_gen_clone.next()),
        };

        // Call Pattern 1 lowerer with host context
        let join_module = match lower_simple_while_minimal(scope, Some(ctx)) {
            Some(module) => module,
            None => {
                if debug {
                    eprintln!("[cf_loop/joinir/pattern1] Pattern 1 lowerer returned None");
                }
                return Ok(None);
            }
        };

        if debug {
            eprintln!(
                "[cf_loop/joinir/pattern1] JoinModule generated with {} functions",
                join_module.functions.len()
            );
        }

        // Convert JoinModule to MirModule
        // Phase 188: Pass empty meta map since Pattern 1 lowerer doesn't use metadata
        use crate::mir::join_ir::frontend::JoinFuncMetaMap;
        let empty_meta: JoinFuncMetaMap = BTreeMap::new();

        let mir_module = convert_join_module_to_mir_with_meta(&join_module, &empty_meta)
            .map_err(|e| format!("[cf_loop/joinir/pattern1] MIR conversion failed: {:?}", e))?;

        if debug {
            eprintln!(
                "[cf_loop/joinir/pattern1] MirModule generated with {} functions",
                mir_module.functions.len()
            );
        }

        // Merge JoinIR blocks into current function
        // Phase 188-Impl-3: Create and pass JoinInlineBoundary for Pattern 1
        let boundary = crate::mir::join_ir::lowering::inline_boundary::JoinInlineBoundary::new_inputs_only(
            vec![ValueId(0)],      // JoinIR's main() parameter (loop variable)
            vec![loop_var_id],     // Host's loop variable
        );
        self.merge_joinir_mir_blocks(&mir_module, Some(&boundary), debug)?;

        // Phase 188-Impl-4-FIX: Return Void instead of trying to emit Const
        //
        // PROBLEM: Emitting instructions after merge_joinir_mir_blocks is fragile because:
        // 1. merge creates exit block and switches to it
        // 2. We try to add Const to exit block
        // 3. But subsequent code (return statement) might overwrite the block
        //
        // SOLUTION: Loops don't produce values - they return Void.
        // The subsequent "return 0" statement will emit its own Const + Return.
        //
        // This is cleaner because:
        // - Loop lowering doesn't need to know about the return value
        // - The return statement handles its own code generation
        // - No risk of instructions being lost due to block management issues

        let void_val = crate::mir::builder::emission::constant::emit_void(self);

        if debug {
            eprintln!(
                "[cf_loop/joinir/pattern1] Loop complete, returning Void {:?}",
                void_val
            );
        }

        Ok(Some(void_val))
    }

    /// Phase 188-Impl-2: Pattern 2 (Loop with Conditional Break) minimal lowerer
    ///
    /// Similar to Pattern 1, but handles loops with break statements.
    ///
    /// # Steps
    /// 1. Extract loop variable from condition
    /// 2. Generate JoinIR using loop_with_break_minimal
    /// 3. Convert JoinModule → MirModule
    /// 4. Create JoinInlineBoundary for input mapping
    /// 5. Merge MIR blocks into current_function
    /// 6. Return Void (loop doesn't produce values)
    fn cf_loop_pattern2_with_break(
        &mut self,
        condition: &ASTNode,
        _body: &[ASTNode],
        _func_name: &str,
        debug: bool,
    ) -> Result<Option<ValueId>, String> {
        use crate::mir::join_ir::lowering::loop_with_break_minimal::lower_loop_with_break_minimal;
        use crate::mir::join_ir_vm_bridge::convert_join_module_to_mir_with_meta;
        use crate::mir::BasicBlockId;
        use std::collections::{BTreeMap, BTreeSet};

        if debug {
            eprintln!("[cf_loop/joinir/pattern2] Calling Pattern 2 minimal lowerer");
        }

        // Phase 188-Impl-2: Extract loop variable from condition
        // For `i < 3`, extract `i` and look up its ValueId in variable_map
        let loop_var_name = self.extract_loop_variable_from_condition(condition)?;
        let loop_var_id = self
            .variable_map
            .get(&loop_var_name)
            .copied()
            .ok_or_else(|| {
                format!(
                    "[cf_loop/pattern2] Loop variable '{}' not found in variable_map",
                    loop_var_name
                )
            })?;

        if debug {
            eprintln!(
                "[cf_loop/joinir/pattern2] Loop variable '{}' → {:?}",
                loop_var_name, loop_var_id
            );
        }

        // Create a minimal LoopScopeShape (Phase 188: hardcoded for joinir_min_loop.hako)
        // Pattern 2 lowerer ignores the scope anyway, so this is just a placeholder
        use crate::mir::join_ir::lowering::loop_scope_shape::LoopScopeShape;
        let scope = LoopScopeShape {
            header: BasicBlockId(0),
            body: BasicBlockId(0),
            latch: BasicBlockId(0),
            exit: BasicBlockId(0),
            pinned: BTreeSet::new(),
            carriers: BTreeSet::new(),
            body_locals: BTreeSet::new(),
            exit_live: BTreeSet::new(),
            progress_carrier: None,
            variable_definitions: BTreeMap::new(),
        };

        // Call Pattern 2 lowerer
        let join_module = match lower_loop_with_break_minimal(scope) {
            Some(module) => module,
            None => {
                if debug {
                    eprintln!("[cf_loop/joinir/pattern2] Pattern 2 lowerer returned None");
                }
                return Ok(None);
            }
        };

        if debug {
            eprintln!(
                "[cf_loop/joinir/pattern2] JoinModule generated with {} functions",
                join_module.functions.len()
            );
        }

        // Convert JoinModule to MirModule
        // Phase 188: Pass empty meta map since Pattern 2 lowerer doesn't use metadata
        use crate::mir::join_ir::frontend::JoinFuncMetaMap;
        let empty_meta: JoinFuncMetaMap = BTreeMap::new();

        let mir_module = convert_join_module_to_mir_with_meta(&join_module, &empty_meta)
            .map_err(|e| format!("[cf_loop/joinir/pattern2] MIR conversion failed: {:?}", e))?;

        if debug {
            eprintln!(
                "[cf_loop/joinir/pattern2] MirModule generated with {} functions",
                mir_module.functions.len()
            );
        }

        // Merge JoinIR blocks into current function
        // Phase 188-Impl-2: Create and pass JoinInlineBoundary for Pattern 2
        let boundary = crate::mir::join_ir::lowering::inline_boundary::JoinInlineBoundary::new_inputs_only(
            vec![ValueId(0)],      // JoinIR's main() parameter (loop variable init)
            vec![loop_var_id],     // Host's loop variable
        );
        self.merge_joinir_mir_blocks(&mir_module, Some(&boundary), debug)?;

        // Phase 188-Impl-2: Return Void (loops don't produce values)
        // The subsequent "return i" statement will emit its own Load + Return
        let void_val = crate::mir::builder::emission::constant::emit_void(self);

        if debug {
            eprintln!(
                "[cf_loop/joinir/pattern2] Loop complete, returning Void {:?}",
                void_val
            );
        }

        Ok(Some(void_val))
    }

    /// Phase 188-Impl-3: Pattern 3 (Loop with If-Else PHI) minimal lowerer
    ///
    /// Handles loops with if-else statements that assign to carrier variables.
    ///
    /// # Steps
    /// 1. Extract loop variables (carriers: i + sum)
    /// 2. Generate JoinIR using loop_with_if_phi_minimal
    /// 3. Convert JoinModule → MirModule
    /// 4. Create JoinInlineBoundary for input mapping
    /// 5. Merge MIR blocks into current_function
    /// 6. Return Void (loop doesn't produce values)
    fn cf_loop_pattern3_with_if_phi(
        &mut self,
        condition: &ASTNode,
        _body: &[ASTNode],
        _func_name: &str,
        debug: bool,
    ) -> Result<Option<ValueId>, String> {
        use crate::mir::join_ir::lowering::loop_with_if_phi_minimal::lower_loop_with_if_phi_pattern;
        use crate::mir::join_ir_vm_bridge::convert_join_module_to_mir_with_meta;
        use crate::mir::BasicBlockId;
        use std::collections::{BTreeMap, BTreeSet};

        if debug {
            eprintln!("[cf_loop/joinir/pattern3] Calling Pattern 3 minimal lowerer");
        }

        // Phase 188-Impl-3: Extract loop variable from condition
        // For `i <= 5`, extract `i` and look up its ValueId in variable_map
        let loop_var_name = self.extract_loop_variable_from_condition(condition)?;
        let loop_var_id = self
            .variable_map
            .get(&loop_var_name)
            .copied()
            .ok_or_else(|| {
                format!(
                    "[cf_loop/pattern3] Loop variable '{}' not found in variable_map",
                    loop_var_name
                )
            })?;

        // Phase 188-Impl-3: Also get the accumulator variable (sum)
        // For Pattern 3, we need both i and sum
        let sum_var_id = self
            .variable_map
            .get("sum")
            .copied()
            .ok_or_else(|| {
                format!(
                    "[cf_loop/pattern3] Accumulator variable 'sum' not found in variable_map"
                )
            })?;

        if debug {
            eprintln!(
                "[cf_loop/joinir/pattern3] Loop variables: '{}' → {:?}, 'sum' → {:?}",
                loop_var_name, loop_var_id, sum_var_id
            );
        }

        // Create a minimal LoopScopeShape (Phase 188: hardcoded for loop_if_phi.hako)
        // Pattern 3 lowerer ignores the scope anyway, so this is just a placeholder
        use crate::mir::join_ir::lowering::loop_scope_shape::LoopScopeShape;
        let scope = LoopScopeShape {
            header: BasicBlockId(0),
            body: BasicBlockId(0),
            latch: BasicBlockId(0),
            exit: BasicBlockId(0),
            pinned: BTreeSet::new(),
            carriers: BTreeSet::new(),
            body_locals: BTreeSet::new(),
            exit_live: BTreeSet::new(),
            progress_carrier: None,
            variable_definitions: BTreeMap::new(),
        };

        // Call Pattern 3 lowerer
        let join_module = match lower_loop_with_if_phi_pattern(scope) {
            Some(module) => module,
            None => {
                if debug {
                    eprintln!("[cf_loop/joinir/pattern3] Pattern 3 lowerer returned None");
                }
                return Ok(None);
            }
        };

        if debug {
            eprintln!(
                "[cf_loop/joinir/pattern3] JoinModule generated with {} functions",
                join_module.functions.len()
            );
        }

        // Convert JoinModule to MirModule
        // Phase 188: Pass empty meta map since Pattern 3 lowerer doesn't use metadata
        use crate::mir::join_ir::frontend::JoinFuncMetaMap;
        let empty_meta: JoinFuncMetaMap = BTreeMap::new();

        let mir_module = convert_join_module_to_mir_with_meta(&join_module, &empty_meta)
            .map_err(|e| format!("[cf_loop/joinir/pattern3] MIR conversion failed: {:?}", e))?;

        if debug {
            eprintln!(
                "[cf_loop/joinir/pattern3] MirModule generated with {} functions",
                mir_module.functions.len()
            );
        }

        // Merge JoinIR blocks into current function
        // Phase 188-Impl-3: Create and pass JoinInlineBoundary for Pattern 3
        // Pattern 3 has TWO carriers: i and sum
        let boundary = crate::mir::join_ir::lowering::inline_boundary::JoinInlineBoundary::new_inputs_only(
            vec![ValueId(0), ValueId(1)],      // JoinIR's main() parameters (i, sum init)
            vec![loop_var_id, sum_var_id],     // Host's loop variables
        );
        self.merge_joinir_mir_blocks(&mir_module, Some(&boundary), debug)?;

        // Phase 188-Impl-3: Return Void (loops don't produce values)
        let void_val = crate::mir::builder::emission::constant::emit_void(self);

        if debug {
            eprintln!(
                "[cf_loop/joinir/pattern3] Loop complete, returning Void {:?}",
                void_val
            );
        }

        Ok(Some(void_val))
    }

    /// Phase 49-3.2: Merge JoinIR-generated MIR blocks into current_function
    ///
    /// # Phase 189: Multi-Function MIR Merge
    ///
    /// This merges JoinIR-generated blocks by:
    /// 1. Remapping all block IDs across ALL functions to avoid conflicts
    /// 2. Remapping all value IDs across ALL functions to avoid conflicts
    /// 3. Adding all blocks from all functions to current_function
    /// 4. Jumping from current_block to the entry block
    /// 5. Converting Return → Jump to exit block for all functions
    ///
    /// **Multi-Function Support** (Phase 189):
    /// - Pattern 1 (Simple While) generates 3 functions: entry + loop_step + k_exit
    /// - All functions are flattened into current_function with global ID remapping
    /// - Single exit block receives all Return instructions from all functions
    ///
    /// # Phase 188-Impl-3: JoinInlineBoundary Support
    ///
    /// When `boundary` is provided, injects Copy instructions at the entry block
    /// to connect host ValueIds to JoinIR local ValueIds:
    ///
    /// ```text
    /// entry_block:
    ///   // Injected by boundary
    ///   ValueId(100) = Copy ValueId(4)  // join_input → host_input
    ///   // Original JoinIR instructions follow...
    /// ```
    ///
    /// This enables clean separation: JoinIR uses local IDs (0,1,2...),
    /// host uses its own IDs, and Copy instructions bridge the gap.
    fn merge_joinir_mir_blocks(
        &mut self,
        mir_module: &crate::mir::MirModule,
        boundary: Option<&crate::mir::join_ir::lowering::inline_boundary::JoinInlineBoundary>,
        debug: bool,
    ) -> Result<(), String> {
        use crate::mir::{BasicBlock, BasicBlockId, MirInstruction, ValueId};
        use std::collections::HashMap;
        // Phase 189: Use new ID remapper Box
        use super::joinir_id_remapper::JoinIrIdRemapper;

        if debug {
            eprintln!(
                "[cf_loop/joinir] merge_joinir_mir_blocks called with {} functions",
                mir_module.functions.len()
            );
        }

        // Phase 189: Create ID remapper for ValueId/BlockId translation
        let mut remapper = JoinIrIdRemapper::new();

        // Phase 189: Map function names to their entry blocks (for Call→Jump conversion)
        let mut function_entry_map: HashMap<String, BasicBlockId> = HashMap::new();

        // 1. Allocate new block IDs for ALL functions (Phase 189)
        // DETERMINISM FIX: Sort functions by name to ensure consistent iteration order
        if debug {
            eprintln!("[cf_loop/joinir] Phase 189: Allocating block IDs for all functions");
        }
        let mut functions: Vec<_> = mir_module.functions.iter().collect();
        functions.sort_by_key(|(name, _)| name.as_str());
        for (func_name, func) in functions {
            if debug {
                eprintln!("[cf_loop/joinir]   Function: {}", func_name);
            }
            // DETERMINISM FIX: Sort blocks by ID to ensure consistent iteration order
            let mut blocks: Vec<_> = func.blocks.iter().collect();
            blocks.sort_by_key(|(id, _)| id.0);
            for (old_block_id, _) in blocks {
                let new_block_id = self.block_gen.next();
                // Use remapper to store composite key mapping
                remapper.set_block(func_name.clone(), *old_block_id, new_block_id);
                if debug {
                    eprintln!(
                        "[cf_loop/joinir]   Block remap: {}:{:?} → {:?}",
                        func_name, old_block_id, new_block_id
                    );
                }
            }
            // Map function entry blocks for Call→Jump conversion
            let entry_block_new = remapper.get_block(func_name, func.entry_block)
                .ok_or_else(|| format!("Entry block not found for {}", func_name))?;
            function_entry_map.insert(func_name.clone(), entry_block_new);
            if debug {
                eprintln!(
                    "[cf_loop/joinir]   Entry map: {} → {:?}",
                    func_name, entry_block_new
                );
            }
        }

        // 2. Create exit block for Return conversion (single for all functions)
        let exit_block_id = self.block_gen.next();
        if debug {
            eprintln!("[cf_loop/joinir]   Exit block: {:?}", exit_block_id);
        }

        // 3. Collect all ValueIds used across ALL functions (Phase 189)
        // Also build a map of ValueId → function name for Call→Jump conversion
        // Phase 188-Impl-3: Also collect function parameters for tail call conversion
        if debug {
            eprintln!("[cf_loop/joinir] Phase 189: Collecting value IDs from all functions");
        }
        let mut used_values: std::collections::BTreeSet<ValueId> =
            std::collections::BTreeSet::new();
        let mut value_to_func_name: HashMap<ValueId, String> = HashMap::new();
        let mut function_params: HashMap<String, Vec<ValueId>> = HashMap::new();

        for (func_name, func) in &mir_module.functions {
            // Phase 188-Impl-3: Collect function parameters for tail call conversion
            function_params.insert(func_name.clone(), func.params.clone());

            for block in func.blocks.values() {
                // Phase 189: Use remapper to collect values
                let block_values = remapper.collect_values_in_block(block);
                used_values.extend(block_values);

                // Phase 189: Track Const String instructions that define function names
                for inst in &block.instructions {
                    if let MirInstruction::Const { dst, value } = inst {
                        if let crate::mir::types::ConstValue::String(s) = value {
                            if function_entry_map.contains_key(s) {
                                value_to_func_name.insert(*dst, s.clone());
                                if debug {
                                    eprintln!(
                                        "[cf_loop/joinir]   Found function name constant: {:?} = '{}'",
                                        dst, s
                                    );
                                }
                            }
                        }
                    }
                }
            }
            // Also collect parameter ValueIds
            for param in &func.params {
                used_values.insert(*param);
            }
        }

        // 4. Allocate new ValueIds for all collected values
        for old_value in used_values {
            let new_value = self.next_value_id();
            remapper.set_value(old_value, new_value);
            if debug {
                eprintln!(
                    "[cf_loop/joinir]   Value remap: {:?} → {:?}",
                    old_value, new_value
                );
            }
        }

        // 5. Merge ALL functions (Phase 189: iterate over all, not just first)
        // DETERMINISM FIX: Sort functions by name to ensure consistent iteration order
        if debug {
            eprintln!("[cf_loop/joinir] Phase 189: Merging {} functions", mir_module.functions.len());
        }
        // Phase 189: Iterate over both names and functions (need name for composite keys)
        let mut functions_merge: Vec<_> = mir_module.functions.iter().collect();
        functions_merge.sort_by_key(|(name, _)| name.as_str());
        for (func_name, func) in functions_merge {
            if debug {
                eprintln!(
                    "[cf_loop/joinir]   Merging function '{}' with {} blocks, entry={:?}",
                    func_name,
                    func.blocks.len(),
                    func.entry_block
                );
            }

            // Build a local block map for this function (for remap_instruction compatibility)
            let mut local_block_map: HashMap<BasicBlockId, BasicBlockId> = HashMap::new();
            for old_block_id in func.blocks.keys() {
                let new_block_id = remapper.get_block(func_name, *old_block_id)
                    .ok_or_else(|| format!("Block {:?} not found for {}", old_block_id, func_name))?;
                local_block_map.insert(*old_block_id, new_block_id);
            }

            // Clone and remap all blocks from this function
            // DETERMINISM FIX: Sort blocks by ID to ensure consistent iteration order
            let mut blocks_merge: Vec<_> = func.blocks.iter().collect();
            blocks_merge.sort_by_key(|(id, _)| id.0);
            for (old_block_id, old_block) in blocks_merge {
                // Use remapper to get correct mapping for this function's block
                let new_block_id = remapper.get_block(func_name, *old_block_id)
                    .ok_or_else(|| format!("Block {:?} not found for {}", old_block_id, func_name))?;
                let mut new_block = BasicBlock::new(new_block_id);

                // Remap instructions (Phase 189: Convert inter-function Calls to control flow)
                let mut found_tail_call = false;
                let mut tail_call_target: Option<(BasicBlockId, Vec<ValueId>)> = None;

                // First pass: Process all instructions, identify tail calls
                for inst in &old_block.instructions {
                    // Phase 189: Skip Const String instructions that define function names
                    if let MirInstruction::Const { dst, value } = inst {
                        if let crate::mir::types::ConstValue::String(_) = value {
                            if value_to_func_name.contains_key(dst) {
                                if debug {
                                    eprintln!("[cf_loop/joinir]   Skipping function name const: {:?}", inst);
                                }
                                continue; // Skip this instruction
                            }
                        }
                    }

                    // Phase 189: Detect tail calls and save parameters
                    if let MirInstruction::Call { func, args, .. } = inst {
                        if let Some(func_name) = value_to_func_name.get(func) {
                            if let Some(&target_block) = function_entry_map.get(func_name) {
                                // This is a tail call - save info and skip the Call instruction itself
                                let remapped_args: Vec<ValueId> = args
                                    .iter()
                                    .map(|&v| remapper.get_value(v).unwrap_or(v))
                                    .collect();
                                tail_call_target = Some((target_block, remapped_args));
                                found_tail_call = true;

                                if debug {
                                    eprintln!(
                                        "[cf_loop/joinir]   Detected tail call to '{}' (args={:?}), will convert to Jump",
                                        func_name, args
                                    );
                                }
                                continue; // Skip the Call instruction itself
                            }
                        }
                    }

                    // Process regular instructions - Phase 189: Use remapper.remap_instruction() + manual block remapping
                    let remapped = remapper.remap_instruction(inst);

                    // Phase 189 FIX: Manual block remapping for Branch/Phi (JoinIrIdRemapper doesn't know func_name)
                    let remapped_with_blocks = match remapped {
                        MirInstruction::Branch { condition, then_bb, else_bb } => {
                            MirInstruction::Branch {
                                condition,
                                then_bb: local_block_map.get(&then_bb).copied().unwrap_or(then_bb),
                                else_bb: local_block_map.get(&else_bb).copied().unwrap_or(else_bb),
                            }
                        }
                        MirInstruction::Phi { dst, inputs, type_hint: None } => {
                            MirInstruction::Phi {
                                dst,
                                inputs: inputs.iter().map(|(bb, val)| {
                                    (local_block_map.get(bb).copied().unwrap_or(*bb), *val)
                                }).collect(),
                                type_hint: None,
                            }
                        }
                        other => other,
                    };

                    if debug {
                        match inst {
                            MirInstruction::BoxCall { .. } => {
                                eprintln!("[cf_loop/joinir]   Adding BoxCall to block {:?}: {:?}", new_block_id, inst);
                            }
                            _ => {}
                        }
                    }

                    new_block.instructions.push(remapped_with_blocks);
                }

                // Second pass: Insert parameter bindings for tail calls
                // Phase 188-Impl-3: Use actual parameter ValueIds from target function
                if let Some((target_block, args)) = tail_call_target {
                    if debug {
                        eprintln!(
                            "[cf_loop/joinir]   Inserting param bindings for tail call to {:?}",
                            target_block
                        );
                    }

                    // Find the target function name from the target_block
                    // We need to reverse-lookup the function name from the entry block
                    let mut target_func_name: Option<String> = None;
                    for (fname, &entry_block) in &function_entry_map {
                        if entry_block == target_block {
                            target_func_name = Some(fname.clone());
                            break;
                        }
                    }

                    if let Some(target_func_name) = target_func_name {
                        if let Some(target_params) = function_params.get(&target_func_name) {
                            // Insert Copy instructions for parameter binding
                            for (i, arg_val_remapped) in args.iter().enumerate() {
                                if i < target_params.len() {
                                    let param_val_original = target_params[i];
                                    if let Some(param_val_remapped) = remapper.get_value(param_val_original) {
                                        new_block.instructions.push(MirInstruction::Copy {
                                            dst: param_val_remapped,
                                            src: *arg_val_remapped,
                                        });

                                        if debug {
                                            eprintln!(
                                                "[cf_loop/joinir]     Param binding: arg {:?} → param {:?}",
                                                arg_val_remapped, param_val_remapped
                                            );
                                        }
                                    }
                                }
                            }
                        }
                    }

                    // Set terminator to Jump
                    new_block.terminator = Some(MirInstruction::Jump {
                        target: target_block,
                    });
                }
                new_block.instruction_spans = old_block.instruction_spans.clone();

                // Remap terminator (convert Return → Jump to exit) if not already set by tail call
                if !found_tail_call {
                    if let Some(ref term) = old_block.terminator {
                        let remapped_term = match term {
                            MirInstruction::Return { value } => {
                                // Convert Return to Jump to exit block
                                // All functions return to same exit block (Phase 189)
                                if let Some(ret_val) = value {
                                    let remapped_val = remapper.get_value(*ret_val).unwrap_or(*ret_val);
                                    if debug {
                                        eprintln!(
                                            "[cf_loop/joinir]   Return({:?}) → Jump to exit",
                                            remapped_val
                                        );
                                    }
                                }
                                MirInstruction::Jump {
                                    target: exit_block_id,
                                }
                            }
                            MirInstruction::Jump { target } => {
                                // Phase 189 FIX: Remap block ID for Jump
                                MirInstruction::Jump {
                                    target: local_block_map.get(target).copied().unwrap_or(*target),
                                }
                            }
                            MirInstruction::Branch { condition, then_bb, else_bb } => {
                                // Phase 189 FIX: Remap block IDs for Branch
                                let remapped = remapper.remap_instruction(term);
                                match remapped {
                                    MirInstruction::Branch { condition, then_bb, else_bb } => {
                                        MirInstruction::Branch {
                                            condition,
                                            then_bb: local_block_map.get(&then_bb).copied().unwrap_or(then_bb),
                                            else_bb: local_block_map.get(&else_bb).copied().unwrap_or(else_bb),
                                        }
                                    }
                                    other => other,
                                }
                            }
                            _ => remapper.remap_instruction(term),
                        };
                        new_block.terminator = Some(remapped_term);
                    }
                }

                // Add block to current function
                if let Some(ref mut current_func) = self.current_function {
                    current_func.add_block(new_block);
                }
            }
        }

        // Phase 188-Impl-3: Inject Copy instructions for boundary inputs using BoundaryInjector
        if let Some(boundary) = boundary {
            use super::joinir_inline_boundary_injector::BoundaryInjector;

            // Get entry function's entry block (first function by convention)
            let (entry_func_name, entry_func) = mir_module
                .functions
                .iter()
                .next()
                .ok_or("JoinIR module has no functions")?;
            let entry_block_remapped = remapper.get_block(entry_func_name, entry_func.entry_block)
                .ok_or_else(|| format!("Entry block not found for {}", entry_func_name))?;

            // Create HashMap from remapper for BoundaryInjector (temporary adapter)
            let mut value_map_for_injector = HashMap::new();
            for join_in in &boundary.join_inputs {
                if let Some(remapped) = remapper.get_value(*join_in) {
                    value_map_for_injector.insert(*join_in, remapped);
                }
            }

            // Use BoundaryInjector to inject Copy instructions
            if let Some(ref mut current_func) = self.current_function {
                BoundaryInjector::inject_boundary_copies(
                    current_func,
                    entry_block_remapped,
                    boundary,
                    &value_map_for_injector,
                    debug,
                )?;
            }
        }

        // 6. Create exit block (empty for now, will be populated after loop)
        if let Some(ref mut func) = self.current_function {
            let exit_block = BasicBlock::new(exit_block_id);
            func.add_block(exit_block);
        }

        // 7. Jump from current block to entry function's entry block
        // Entry function is first function by convention
        let (entry_func_name, entry_func) = mir_module
            .functions
            .iter()
            .next()
            .ok_or("JoinIR module has no functions")?;
        // Use remapper to get entry block mapping
        let entry_block = remapper.get_block(entry_func_name, entry_func.entry_block)
            .ok_or_else(|| format!("Entry block not found for {}", entry_func_name))?;
        if debug {
            eprintln!("[cf_loop/joinir]   Jumping to entry block: {:?}", entry_block);
        }
        crate::mir::builder::emission::branch::emit_jump(self, entry_block)?;

        // 8. Switch to exit block for subsequent code
        self.start_new_block(exit_block_id)?;

        if debug {
            eprintln!(
                "[cf_loop/joinir] Phase 189: Merge complete: {} functions merged, continuing from {:?}",
                mir_module.functions.len(),
                exit_block_id
            );
        }

        Ok(())
    }

    // Phase 189: collect_values_in_block/collect_values_in_instruction removed
    // These functions are now provided by JoinIrIdRemapper::collect_values_in_block()

    // Phase 189: remap_joinir_instruction/remap_instruction removed
    // These functions are now provided by JoinIrIdRemapper::remap_instruction()

    /// Control-flow: try/catch/finally
    pub(super) fn cf_try_catch(
        &mut self,
        try_body: Vec<ASTNode>,
        catch_clauses: Vec<crate::ast::CatchClause>,
        finally_body: Option<Vec<ASTNode>>,
    ) -> Result<ValueId, String> {
        if std::env::var("NYASH_BUILDER_DISABLE_TRYCATCH")
            .ok()
            .as_deref()
            == Some("1")
        {
            let try_ast = ASTNode::Program {
                statements: try_body,
                span: crate::ast::Span::unknown(),
            };
            let result = self.build_expression(try_ast)?;
            return Ok(result);
        }

        let try_block = self.block_gen.next();
        let catch_block = self.block_gen.next();
        let finally_block = if finally_body.is_some() {
            Some(self.block_gen.next())
        } else {
            None
        };
        let exit_block = self.block_gen.next();

        // Snapshot deferred-return state
        let saved_defer_active = self.return_defer_active;
        let saved_defer_slot = self.return_defer_slot;
        let saved_defer_target = self.return_defer_target;
        let saved_deferred_flag = self.return_deferred_emitted;
        let saved_in_cleanup = self.in_cleanup_block;
        let saved_allow_ret = self.cleanup_allow_return;
        let saved_allow_throw = self.cleanup_allow_throw;

        let ret_slot = self.next_value_id();
        self.return_defer_active = true;
        self.return_defer_slot = Some(ret_slot);
        self.return_deferred_emitted = false;
        self.return_defer_target = Some(finally_block.unwrap_or(exit_block));

        if let Some(catch_clause) = catch_clauses.first() {
            if std::env::var("NYASH_DEBUG_TRYCATCH").ok().as_deref() == Some("1") {
                eprintln!(
                    "[BUILDER] Emitting catch handler for {:?}",
                    catch_clause.exception_type
                );
            }
            let exception_value = self.next_value_id();
            self.emit_instruction(MirInstruction::Catch {
                exception_type: catch_clause.exception_type.clone(),
                exception_value,
                handler_bb: catch_block,
            })?;
        }

        // Enter try block
        crate::mir::builder::emission::branch::emit_jump(self, try_block)?;
        self.start_new_block(try_block)?;
        let try_ast = ASTNode::Program {
            statements: try_body,
            span: crate::ast::Span::unknown(),
        };
        let _try_result = self.build_expression(try_ast)?;
        if !self.is_current_block_terminated() {
            let next_target = finally_block.unwrap_or(exit_block);
            crate::mir::builder::emission::branch::emit_jump(self, next_target)?;
        }

        // Catch block
        self.start_new_block(catch_block)?;
        if std::env::var("NYASH_DEBUG_TRYCATCH").ok().as_deref() == Some("1") {
            eprintln!("[BUILDER] Enter catch block {:?}", catch_block);
        }
        if let Some(catch_clause) = catch_clauses.first() {
            let catch_ast = ASTNode::Program {
                statements: catch_clause.body.clone(),
                span: crate::ast::Span::unknown(),
            };
            self.build_expression(catch_ast)?;
        }
        if !self.is_current_block_terminated() {
            let next_target = finally_block.unwrap_or(exit_block);
            crate::mir::builder::emission::branch::emit_jump(self, next_target)?;
        }

        // Finally
        let mut cleanup_terminated = false;
        if let (Some(finally_block_id), Some(finally_statements)) = (finally_block, finally_body) {
            self.start_new_block(finally_block_id)?;
            self.in_cleanup_block = true;
            self.cleanup_allow_return = crate::config::env::cleanup_allow_return();
            self.cleanup_allow_throw = crate::config::env::cleanup_allow_throw();
            self.return_defer_active = false; // do not defer inside cleanup

            let finally_ast = ASTNode::Program {
                statements: finally_statements,
                span: crate::ast::Span::unknown(),
            };
            self.build_expression(finally_ast)?;
            cleanup_terminated = self.is_current_block_terminated();
            if !cleanup_terminated {
                crate::mir::builder::emission::branch::emit_jump(self, exit_block)?;
            }
            self.in_cleanup_block = false;
        }

        // Exit block
        self.start_new_block(exit_block)?;
        let result = if self.return_deferred_emitted && !cleanup_terminated {
            self.emit_instruction(MirInstruction::Return {
                value: Some(ret_slot),
            })?;
            crate::mir::builder::emission::constant::emit_void(self)
        } else {
            crate::mir::builder::emission::constant::emit_void(self)
        };

        // Restore context
        self.return_defer_active = saved_defer_active;
        self.return_defer_slot = saved_defer_slot;
        self.return_defer_target = saved_defer_target;
        self.return_deferred_emitted = saved_deferred_flag;
        self.in_cleanup_block = saved_in_cleanup;
        self.cleanup_allow_return = saved_allow_ret;
        self.cleanup_allow_throw = saved_allow_throw;

        Ok(result)
    }

    /// Phase 188-Impl-2: Extract loop variable name from condition
    ///
    /// For `i < 3`, extracts `i`.
    /// For `arr.length() > 0`, extracts `arr`.
    ///
    /// This is a minimal implementation that handles simple comparison patterns.
    fn extract_loop_variable_from_condition(&self, condition: &ASTNode) -> Result<String, String> {
        use crate::ast::BinaryOperator;

        match condition {
            ASTNode::BinaryOp {
                operator, left, ..
            } if matches!(
                operator,
                BinaryOperator::Less
                    | BinaryOperator::Greater
                    | BinaryOperator::LessEqual
                    | BinaryOperator::GreaterEqual
            ) =>
            {
                // Binary comparison: extract variable from left side
                match &**left {
                    ASTNode::Variable { name, .. } => Ok(name.clone()),
                    _ => Err(format!(
                        "[cf_loop/pattern1] Cannot extract loop variable from condition: {:?}",
                        condition
                    )),
                }
            }
            _ => Err(format!(
                "[cf_loop/pattern1] Unsupported loop condition pattern: {:?}",
                condition
            )),
        }
    }

    /// Control-flow: throw
    pub(super) fn cf_throw(&mut self, expression: ASTNode) -> Result<ValueId, String> {
        if self.in_cleanup_block && !self.cleanup_allow_throw {
            return Err("throw is not allowed inside cleanup block (enable NYASH_CLEANUP_ALLOW_THROW=1 to permit)".to_string());
        }
        if std::env::var("NYASH_BUILDER_DISABLE_THROW").ok().as_deref() == Some("1") {
            let v = self.build_expression(expression)?;
            self.emit_instruction(MirInstruction::ExternCall {
                dst: None,
                iface_name: "env.debug".to_string(),
                method_name: "trace".to_string(),
                args: vec![v],
                effects: EffectMask::PURE.add(Effect::Debug),
            })?;
            return Ok(v);
        }
        let exception_value = self.build_expression(expression)?;
        self.emit_instruction(MirInstruction::Throw {
            exception: exception_value,
            effects: EffectMask::PANIC,
        })?;
        Ok(exception_value)
    }
}