llvm(py): introduce BuildCtx + trace hub; refactor if-merge prepass + PHI wiring into module; unify logs; ctx-enable compare/ret/call/boxcall/externcall/typeop/newbox/safepoint; curated smoke option for if-merge; README updates; keep behavior stable

src/runner/modes/bench.rs

@@ -236,3 +236,4 @@ impl NyashRunner {
         Ok(())
     }
 }
+#![cfg(feature = "vm-legacy")]

src/runner/modes/mir_interpreter.rs

@@ -101,4 +101,4 @@ impl NyashRunner {
         let _ = runtime; // reserved for future GC/safepoint integration
     }
 }
-
+#![cfg(feature = "interpreter-legacy")]

src/runner/modes/mod.rs

@@ -1,8 +1,12 @@
+#[cfg(feature = "vm-legacy")]
 pub mod bench;
+#[cfg(feature = "interpreter-legacy")]
 pub mod interpreter;
 pub mod llvm;
 pub mod mir;
+#[cfg(feature = "vm-legacy")]
 pub mod vm;
+pub mod pyvm;
 
 #[cfg(feature = "cranelift-jit")]
 pub mod aot;

src/runner/modes/pyvm.rs

@@ -0,0 +1,102 @@
+use super::super::NyashRunner;
+use nyash_rust::{mir::MirCompiler, parser::NyashParser};
+use std::{fs, process};
+
+/// Execute using PyVM only (no Rust VM runtime). Emits MIR(JSON) and invokes tools/pyvm_runner.py.
+pub fn execute_pyvm_only(_runner: &NyashRunner, filename: &str) {
+    // Read the file
+    let code = match fs::read_to_string(filename) {
+        Ok(content) => content,
+        Err(e) => {
+            eprintln!("❌ Error reading file {}: {}", filename, e);
+            process::exit(1);
+        }
+    };
+
+    // Parse to AST
+    let ast = match NyashParser::parse_from_string(&code) {
+        Ok(ast) => ast,
+        Err(e) => {
+            eprintln!("❌ Parse error: {}", e);
+            process::exit(1);
+        }
+    };
+
+    // Compile to MIR (respect default optimizer setting)
+    let mut mir_compiler = MirCompiler::with_options(true);
+    let mut compile_result = match mir_compiler.compile(ast) {
+        Ok(result) => result,
+        Err(e) => {
+            eprintln!("❌ MIR compilation error: {}", e);
+            process::exit(1);
+        }
+    };
+
+    // Optional: VM-only escape analysis elision pass retained for parity with VM path
+    if std::env::var("NYASH_VM_ESCAPE_ANALYSIS").ok().as_deref() == Some("1") {
+        let removed = nyash_rust::mir::passes::escape::escape_elide_barriers_vm(&mut compile_result.module);
+        if removed > 0 && std::env::var("NYASH_CLI_VERBOSE").ok().as_deref() == Some("1") {
+            eprintln!("[PyVM] escape_elide_barriers: removed {} barriers", removed);
+        }
+    }
+
+    // Emit MIR JSON for PyVM harness
+    let tmp_dir = std::path::Path::new("tmp");
+    let _ = std::fs::create_dir_all(tmp_dir);
+    let mir_json_path = tmp_dir.join("nyash_pyvm_mir.json");
+    if let Err(e) = crate::runner::mir_json_emit::emit_mir_json_for_harness(
+        &compile_result.module,
+        &mir_json_path,
+    ) {
+        eprintln!("❌ PyVM MIR JSON emit error: {}", e);
+        process::exit(1);
+    }
+
+    // Pick entry: prefer Main.main or main
+    let entry = if compile_result.module.functions.contains_key("Main.main") {
+        "Main.main"
+    } else if compile_result.module.functions.contains_key("main") {
+        "main"
+    } else {
+        "Main.main"
+    };
+
+    // Locate python3 and run harness
+    let py = which::which("python3").ok();
+    if let Some(py3) = py {
+        let runner = std::path::Path::new("tools/pyvm_runner.py");
+        if !runner.exists() {
+            eprintln!("❌ PyVM runner not found: {}", runner.display());
+            process::exit(1);
+        }
+        if std::env::var("NYASH_CLI_VERBOSE").ok().as_deref() == Some("1") {
+            eprintln!(
+                "[Runner/PyVM] {} (mir={})",
+                filename,
+                mir_json_path.display()
+            );
+        }
+        let status = std::process::Command::new(py3)
+            .args([
+                runner.to_string_lossy().as_ref(),
+                "--in",
+                &mir_json_path.display().to_string(),
+                "--entry",
+                entry,
+            ])
+            .status()
+            .map_err(|e| format!("spawn pyvm: {}", e))
+            .unwrap();
+        let code = status.code().unwrap_or(1);
+        if !status.success() {
+            if std::env::var("NYASH_CLI_VERBOSE").ok().as_deref() == Some("1") {
+                eprintln!("❌ PyVM failed (status={})", code);
+            }
+        }
+        process::exit(code);
+    } else {
+        eprintln!("❌ python3 not found in PATH. Install Python 3 to use PyVM.");
+        process::exit(1);
+    }
+}
+