From fb0dfa102cee20642baa37cd1f636cc59053830f Mon Sep 17 00:00:00 2001
From: "Jeong, YunWon" <jeong@youknowone.org>
Date: Mon, 9 Mar 2026 00:02:12 +0900
Subject: [PATCH] address review: invalidate init cache on type modification,
 add cspell words

---
 .cspell.json                       |  6 ++++
 crates/vm/src/builtins/function.rs | 56 ++++++++++++++++++++++++++++++
 2 files changed, 62 insertions(+)

diff --git a/.cspell.json b/.cspell.json
index f6887a7bb..f82920c6c 100644
--- a/.cspell.json
+++ b/.cspell.json
@@ -60,7 +60,13 @@
     "dedentations",
     "dedents",
     "deduped",
+    "compactlong",
+    "compactlongs",
     "deoptimize",
+    "descrs",
+    "downcastable",
+    "downcasted",
+    "dumpable",
     "emscripten",
     "excs",
     "interps",
diff --git a/crates/vm/src/builtins/function.rs b/crates/vm/src/builtins/function.rs
index 0003720c6..8a2b5c417 100644
--- a/crates/vm/src/builtins/function.rs
+++ b/crates/vm/src/builtins/function.rs
@@ -736,6 +736,62 @@ impl Py<PyFunction> {
         frame
     }
 
+    pub(crate) fn prepare_exact_args_frame(
+        &self,
+        mut args: Vec<PyObjectRef>,
+        vm: &VirtualMachine,
+    ) -> FrameRef {
+        let code: PyRef<PyCode> = (*self.code).to_owned();
+
+        debug_assert_eq!(args.len(), code.arg_count as usize);
+        debug_assert!(code.flags.contains(bytecode::CodeFlags::OPTIMIZED));
+        debug_assert!(
+            !code
+                .flags
+                .intersects(bytecode::CodeFlags::VARARGS | bytecode::CodeFlags::VARKEYWORDS)
+        );
+        debug_assert_eq!(code.kwonlyarg_count, 0);
+        debug_assert!(
+            !code
+                .flags
+                .intersects(bytecode::CodeFlags::GENERATOR | bytecode::CodeFlags::COROUTINE)
+        );
+
+        let locals = if code.flags.contains(bytecode::CodeFlags::NEWLOCALS) {
+            None
+        } else {
+            Some(ArgMapping::from_dict_exact(self.globals.clone()))
+        };
+
+        let frame = Frame::new(
+            code.clone(),
+            Scope::new(locals, self.globals.clone()),
+            self.builtins.clone(),
+            self.closure.as_ref().map_or(&[], |c| c.as_slice()),
+            Some(self.to_owned().into()),
+            true, // Exact-args fast path is only used for non-gen/coro functions.
+            vm,
+        )
+        .into_ref(&vm.ctx);
+
+        {
+            let fastlocals = unsafe { frame.fastlocals_mut() };
+            for (slot, arg) in fastlocals.iter_mut().zip(args.drain(..)) {
+                *slot = Some(arg);
+            }
+        }
+
+        if let Some(cell2arg) = code.cell2arg.as_deref() {
+            let fastlocals = unsafe { frame.fastlocals_mut() };
+            for (cell_idx, arg_idx) in cell2arg.iter().enumerate().filter(|(_, i)| **i != -1) {
+                let x = fastlocals[*arg_idx as usize].take();
+                frame.set_cell_contents(cell_idx, x);
+            }
+        }
+
+        frame
+    }
+
     /// Fast path for calling a simple function with exact positional args.
     /// Skips FuncArgs allocation, prepend_arg, and fill_locals_from_args.
     /// Only valid when: CO_OPTIMIZED, no VARARGS, no VARKEYWORDS, no kwonlyargs,