feat: stack var (WIP)

evaluator/nixjit_eval/src/value/primop.rs

@@ -10,20 +10,20 @@ use nixjit_ir::PrimOpId;
 use super::Value;
 use crate::EvalContext;
 
+pub type Args = smallvec::SmallVec<[Value; 2]>;
+
 /// Represents a partially applied primitive operation (builtin function).
 ///
 /// This struct holds the state of a primop that has received some, but not
 /// all, of its required arguments.
 #[derive(Debug, Clone, Constructor)]
 pub struct PrimOpApp {
-    /// The name of the primitive operation.
-    pub name: &'static str,
     /// The number of remaining arguments the primop expects.
     arity: usize,
     /// The unique ID of the primop.
     id: PrimOpId,
     /// The arguments that have already been applied.
-    args: Vec<Value>,
+    args: Args,
 }
 
 impl PrimOpApp {
@@ -32,27 +32,15 @@ impl PrimOpApp {
     /// If enough arguments are provided to satisfy the primop's arity, it is
     /// executed. Otherwise, it returns a new `PrimOpApp` with the combined
     /// arguments.
-    pub fn call(
-        self: &mut Rc<Self>,
-        mut args: Vec<Value>,
-        ctx: &mut impl EvalContext,
-    ) -> Result<Value> {
-        if self.arity < args.len() {
-            let leftover = args.split_off(self.arity);
-            for arg in self.args.iter().rev().cloned() {
-                args.insert(0, arg);
-            }
-            let mut ret = ctx.call_primop(self.id, args)?;
-            ret.call(leftover.into_iter().map(Ok), ctx)?;
-            return Ok(ret);
-        }
-        let self_mut = Rc::make_mut(self);
-        self_mut.arity -= args.len();
-        self_mut.args.extend(args);
-        if self_mut.arity == 0 {
-            ctx.call_primop(self_mut.id, std::mem::take(&mut self_mut.args))
+    pub fn call(self: Rc<Self>, arg: Value, ctx: &mut impl EvalContext) -> Result<Value> {
+        let mut primop = Rc::unwrap_or_clone(self);
+        if primop.arity == 1 {
+            primop.args.push(arg);
+            ctx.call_primop(primop.id, primop.args)
         } else {
-            Ok(Value::PrimOpApp(self.clone()))
+            primop.args.push(arg);
+            primop.arity -= 1;
+            Ok(Value::PrimOpApp(primop.into()))
         }
     }
 }