feat(joinir): FuncScannerBox.trim/1 JoinIR VM Bridge A/B test

Phase 30.x: JoinIR VM Bridge でPHI問題を設計で解決できることを実証

変更内容:
- src/runner/modes/vm.rs: FuncScannerBox.trim/1 検出時にJoinIR経由実行
- src/mir/join_ir_vm_bridge.rs: Non-tail call サポート追加
  - dst=Some(id) の場合、結果を格納して次の命令へ継続
- src/tests/joinir_vm_bridge_trim.rs: A/Bテスト新規作成
  - メインテスト: Route A (VM) → "void" (PHI bug), Route C (JoinIR) → "abc" ✅
  - エッジケース: 5パターン全てPASS
- src/config/env.rs: joinir_vm_bridge_debug() 追加
- docs: Phase 30 TASKS.md に L-0.4 追加

テスト結果:
  Route A (MIR→VM直接):     "void"  ← PHI バグ
  Route C (MIR→JoinIR→VM):  "abc"   ← 正解 ✅

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/runner/modes/vm.rs

@@ -2,6 +2,13 @@ use super::super::NyashRunner;
 use nyash_rust::{ast::ASTNode, mir::MirCompiler, parser::NyashParser};
 use std::{fs, process};
 
+// Phase 30.x: JoinIR VM Bridge integration (experimental)
+// Used only when NYASH_JOINIR_EXPERIMENT=1 AND NYASH_JOINIR_VM_BRIDGE=1
+use crate::config::env::{joinir_experiment_enabled, joinir_vm_bridge_enabled};
+use crate::mir::join_ir::{lower_funcscanner_trim_to_joinir, lower_skip_ws_to_joinir, JoinFuncId};
+use crate::mir::join_ir_ops::JoinValue;
+use crate::mir::join_ir_vm_bridge::run_joinir_via_vm;
+
 impl NyashRunner {
     /// Execute VM mode with full plugin initialization and AST prelude merge
     pub(crate) fn execute_vm_mode(&self, filename: &str) {
@@ -495,6 +502,106 @@ impl NyashRunner {
             }
         }
 
+        // Phase 30.x: JoinIR VM Bridge experimental path
+        // Activated when NYASH_JOINIR_EXPERIMENT=1 AND NYASH_JOINIR_VM_BRIDGE=1
+        // Currently only supports minimal_ssa_skip_ws.hako (Main.skip function)
+        let joinir_path_attempted = if joinir_experiment_enabled() && joinir_vm_bridge_enabled() {
+            // Check if this module contains Main.skip/1 (minimal_ssa_skip_ws target)
+            // Note: function names include arity suffix like "Main.skip/1"
+            let has_main_skip = module_vm.functions.contains_key("Main.skip/1");
+            let has_trim = module_vm.functions.contains_key("FuncScannerBox.trim/1");
+
+            if has_main_skip {
+                eprintln!("[joinir/vm_bridge] Attempting JoinIR path for Main.skip");
+                match lower_skip_ws_to_joinir(&module_vm) {
+                    Some(join_module) => {
+                        // Get input argument from NYASH_JOINIR_INPUT or use default
+                        let input = std::env::var("NYASH_JOINIR_INPUT")
+                            .unwrap_or_else(|_| "   abc".to_string());
+                        eprintln!("[joinir/vm_bridge] Input: {:?}", input);
+
+                        match run_joinir_via_vm(
+                            &join_module,
+                            JoinFuncId::new(0),
+                            &[JoinValue::Str(input)],
+                        ) {
+                            Ok(result) => {
+                                let exit_code = match &result {
+                                    JoinValue::Int(v) => *v as i32,
+                                    JoinValue::Bool(b) => if *b { 1 } else { 0 },
+                                    _ => 0,
+                                };
+                                eprintln!("[joinir/vm_bridge] ✅ JoinIR result: {:?}", result);
+                                if !quiet_pipe {
+                                    println!("RC: {}", exit_code);
+                                }
+                                process::exit(exit_code);
+                            }
+                            Err(e) => {
+                                eprintln!("[joinir/vm_bridge] ❌ JoinIR execution failed: {:?}", e);
+                                eprintln!("[joinir/vm_bridge] Falling back to normal VM path");
+                                false // Continue to normal VM execution
+                            }
+                        }
+                    }
+                    None => {
+                        eprintln!("[joinir/vm_bridge] lower_skip_ws_to_joinir returned None");
+                        eprintln!("[joinir/vm_bridge] Falling back to normal VM path");
+                        false
+                    }
+                }
+            } else if has_trim {
+                // Phase 30.x: FuncScannerBox.trim/1 JoinIR path
+                eprintln!("[joinir/vm_bridge] Attempting JoinIR path for FuncScannerBox.trim");
+                match lower_funcscanner_trim_to_joinir(&module_vm) {
+                    Some(join_module) => {
+                        // Get input argument from NYASH_JOINIR_INPUT or use default
+                        let input = std::env::var("NYASH_JOINIR_INPUT")
+                            .unwrap_or_else(|_| "   abc  ".to_string());
+                        eprintln!("[joinir/vm_bridge] Input: {:?}", input);
+
+                        match run_joinir_via_vm(
+                            &join_module,
+                            JoinFuncId::new(0),
+                            &[JoinValue::Str(input)],
+                        ) {
+                            Ok(result) => {
+                                // trim returns a string, print it and exit with 0
+                                eprintln!("[joinir/vm_bridge] ✅ JoinIR trim result: {:?}", result);
+                                if !quiet_pipe {
+                                    match &result {
+                                        JoinValue::Str(s) => println!("{}", s),
+                                        _ => println!("{:?}", result),
+                                    }
+                                }
+                                process::exit(0);
+                            }
+                            Err(e) => {
+                                eprintln!("[joinir/vm_bridge] ❌ JoinIR trim failed: {:?}", e);
+                                eprintln!("[joinir/vm_bridge] Falling back to normal VM path");
+                                false
+                            }
+                        }
+                    }
+                    None => {
+                        eprintln!("[joinir/vm_bridge] lower_funcscanner_trim_to_joinir returned None");
+                        eprintln!("[joinir/vm_bridge] Falling back to normal VM path");
+                        false
+                    }
+                }
+            } else {
+                false // No supported JoinIR target function
+            }
+        } else {
+            false
+        };
+
+        // Normal VM execution path (fallback or default)
+        if joinir_path_attempted {
+            // This branch is never reached because successful JoinIR path calls process::exit()
+            unreachable!("JoinIR path should have exited");
+        }
+
         match vm.execute_module(&module_vm) {
             Ok(ret) => {
                 use crate::box_trait::{BoolBox, IntegerBox};