RustPython · youknowone · Feb 5, 2026 · Feb 5, 2026
diff --git a/crates/codegen/src/compile.rs b/crates/codegen/src/compile.rs
@@ -30,8 +30,8 @@ use rustpython_compiler_core::{
     bytecode::{
         self, AnyInstruction, Arg as OpArgMarker, BinaryOperator, BuildSliceArgCount, CodeObject,
         ComparisonOperator, ConstantData, ConvertValueOparg, Instruction, IntrinsicFunction1,
-        Invert, OpArg, OpArgType, PseudoInstruction, SpecialMethod, UnpackExArgs,
-        encode_load_attr_arg, encode_load_super_attr_arg,
+        Invert, LoadSuperAttr, OpArg, OpArgType, PseudoInstruction, SpecialMethod, UnpackExArgs,
+        encode_load_attr_arg,
     },
 };
 use rustpython_wtf8::Wtf8Buf;
@@ -7818,28 +7818,44 @@ impl Compiler {
     /// Emit LOAD_SUPER_ATTR for 2-arg super().attr access.
     /// Encodes: (name_idx << 2) | 0b10 (method=0, class=1)
     fn emit_load_super_attr(&mut self, name_idx: u32) {
-        let encoded = encode_load_super_attr_arg(name_idx, false, true);
+        let encoded = LoadSuperAttr::builder()
+            .name_idx(name_idx)
+            .is_load_method(false)
+            .has_class(true)
+            .build();
         self.emit_arg(encoded, |arg| Instruction::LoadSuperAttr { arg })
     }
 
     /// Emit LOAD_SUPER_ATTR for 2-arg super().method() call.
     /// Encodes: (name_idx << 2) | 0b11 (method=1, class=1)
     fn emit_load_super_method(&mut self, name_idx: u32) {
-        let encoded = encode_load_super_attr_arg(name_idx, true, true);
+        let encoded = LoadSuperAttr::builder()
+            .name_idx(name_idx)
+            .is_load_method(true)
+            .has_class(true)
+            .build();
         self.emit_arg(encoded, |arg| Instruction::LoadSuperAttr { arg })
     }
 
     /// Emit LOAD_SUPER_ATTR for 0-arg super().attr access.
     /// Encodes: (name_idx << 2) | 0b00 (method=0, class=0)
     fn emit_load_zero_super_attr(&mut self, name_idx: u32) {
-        let encoded = encode_load_super_attr_arg(name_idx, false, false);
+        let encoded = LoadSuperAttr::builder()
+            .name_idx(name_idx)
+            .is_load_method(false)
+            .has_class(false)
+            .build();
         self.emit_arg(encoded, |arg| Instruction::LoadSuperAttr { arg })
     }
 
     /// Emit LOAD_SUPER_ATTR for 0-arg super().method() call.
     /// Encodes: (name_idx << 2) | 0b01 (method=1, class=0)
     fn emit_load_zero_super_method(&mut self, name_idx: u32) {
-        let encoded = encode_load_super_attr_arg(name_idx, true, false);
+        let encoded = LoadSuperAttr::builder()
+            .name_idx(name_idx)
+            .is_load_method(true)
+            .has_class(false)
+            .build();
         self.emit_arg(encoded, |arg| Instruction::LoadSuperAttr { arg })
     }
 

diff --git a/crates/compiler-core/src/bytecode.rs b/crates/compiler-core/src/bytecode.rs
@@ -17,13 +17,13 @@ use rustpython_wtf8::{Wtf8, Wtf8Buf};
 pub use crate::bytecode::{
     instruction::{
         AnyInstruction, Arg, Instruction, InstructionMetadata, PseudoInstruction, StackEffect,
-        decode_load_attr_arg, decode_load_super_attr_arg, encode_load_attr_arg,
-        encode_load_super_attr_arg,
+        decode_load_attr_arg, encode_load_attr_arg,
     },
     oparg::{
         BinaryOperator, BuildSliceArgCount, CommonConstant, ComparisonOperator, ConvertValueOparg,
-        IntrinsicFunction1, IntrinsicFunction2, Invert, Label, MakeFunctionFlags, NameIdx, OpArg,
-        OpArgByte, OpArgState, OpArgType, RaiseKind, ResumeType, SpecialMethod, UnpackExArgs,
+        IntrinsicFunction1, IntrinsicFunction2, Invert, Label, LoadSuperAttr, MakeFunctionFlags,
+        NameIdx, OpArg, OpArgByte, OpArgState, OpArgType, RaiseKind, ResumeType, SpecialMethod,
+        UnpackExArgs,
     },
 };
 

diff --git a/crates/compiler-core/src/bytecode/instruction.rs b/crates/compiler-core/src/bytecode/instruction.rs
@@ -6,8 +6,8 @@ use crate::{
         oparg::{
             BinaryOperator, BuildSliceArgCount, CommonConstant, ComparisonOperator,
             ConvertValueOparg, IntrinsicFunction1, IntrinsicFunction2, Invert, Label,
-            MakeFunctionFlags, NameIdx, OpArg, OpArgByte, OpArgType, RaiseKind, SpecialMethod,
-            UnpackExArgs,
+            LoadSuperAttr, MakeFunctionFlags, NameIdx, OpArg, OpArgByte, OpArgType, RaiseKind,
+            SpecialMethod, UnpackExArgs,
         },
     },
     marshal::MarshalError,
@@ -198,7 +198,7 @@ pub enum Instruction {
         method: Arg<SpecialMethod>,
     } = 95,
     LoadSuperAttr {
-        arg: Arg<u32>,
+        arg: Arg<LoadSuperAttr>,
     } = 96,
     MakeCell(Arg<NameIdx>) = 97,
     MapAdd {
@@ -862,13 +862,15 @@ impl InstructionMetadata for Instruction {
             Self::LoadName(idx) => w!(LOAD_NAME, name = idx),
             Self::LoadSpecial { method } => w!(LOAD_SPECIAL, method),
             Self::LoadSuperAttr { arg: idx } => {
-                let encoded = idx.get(arg);
-                let (name_idx, load_method, has_class) = decode_load_super_attr_arg(encoded);
-                let attr_name = name(name_idx);
+                let oparg = idx.get(arg);
                 write!(
                     f,
                     "{:pad$}({}, {}, method={}, class={})",
-                    "LOAD_SUPER_ATTR", encoded, attr_name, load_method, has_class
+                    "LOAD_SUPER_ATTR",
+                    u32::from(oparg),
+                    name(oparg.name_idx()),
+                    oparg.is_load_method(),
+                    oparg.has_class()
                 )
             }
             Self::MakeFunction => w!(MAKE_FUNCTION),
@@ -1304,18 +1306,3 @@ pub const fn decode_load_attr_arg(oparg: u32) -> (u32, bool) {
     let name_idx = oparg >> 1;
     (name_idx, is_method)
 }
-
-/// Encode LOAD_SUPER_ATTR oparg: bit 0 = load_method, bit 1 = has_class, bits 2+ = name index.
-#[inline]
-pub const fn encode_load_super_attr_arg(name_idx: u32, load_method: bool, has_class: bool) -> u32 {
-    (name_idx << 2) | ((has_class as u32) << 1) | (load_method as u32)
-}
-
-/// Decode LOAD_SUPER_ATTR oparg: returns (name_idx, load_method, has_class).
-#[inline]
-pub const fn decode_load_super_attr_arg(oparg: u32) -> (u32, bool, bool) {
-    let load_method = (oparg & 1) == 1;
-    let has_class = (oparg & 2) == 2;
-    let name_idx = oparg >> 2;
-    (name_idx, load_method, has_class)
-}
diff --git a/crates/compiler-core/src/bytecode/oparg.rs b/crates/compiler-core/src/bytecode/oparg.rs
@@ -655,3 +655,97 @@ impl fmt::Display for UnpackExArgs {
         write!(f, "before: {}, after: {}", self.before, self.after)
     }
 }
+
+#[derive(Clone, Copy)]
+pub struct LoadSuperAttr(u32);
+
+impl LoadSuperAttr {
+    #[must_use]
+    pub const fn new(value: u32) -> Self {
+        Self(value)
+    }
+
+    #[must_use]
+    pub fn builder() -> LoadSuperAttrBuilder {
+        LoadSuperAttrBuilder::default()
+    }
+
+    #[must_use]
+    pub const fn name_idx(self) -> u32 {
+        self.0 >> 2
+    }
+
+    #[must_use]
+    pub const fn is_load_method(self) -> bool {
+        (self.0 & 1) == 1
+    }
+
+    #[must_use]
+    pub const fn has_class(self) -> bool {
+        (self.0 & 2) == 2
+    }
+}
+
+impl OpArgType for LoadSuperAttr {
+    #[inline(always)]
+    fn from_op_arg(x: u32) -> Result<Self, MarshalError> {
+        Ok(x.into())
+    }
+
+    #[inline(always)]
+    fn to_op_arg(self) -> u32 {
+        self.into()
+    }
+}
+
+impl From<u32> for LoadSuperAttr {
+    fn from(value: u32) -> Self {
+        Self::new(value)
+    }
+}
+
+impl From<LoadSuperAttr> for u32 {
+    fn from(value: LoadSuperAttr) -> Self {
+        value.0
+    }
+}
+
+#[derive(Clone, Copy, Default)]
+pub struct LoadSuperAttrBuilder {
+    name_idx: u32,
+    is_load_method: bool,
+    has_class: bool,
+}
+
+impl LoadSuperAttrBuilder {
+    #[must_use]
+    pub const fn build(self) -> LoadSuperAttr {
+        let value =
+            (self.name_idx << 2) | ((self.has_class as u32) << 1) | (self.is_load_method as u32);
+        LoadSuperAttr::new(value)
+    }
+
+    #[must_use]
+    pub const fn name_idx(mut self, value: u32) -> Self {
+        self.name_idx = value;
+        self
+    }
+
+    #[must_use]
+    pub const fn is_load_method(mut self, value: bool) -> Self {
+        self.is_load_method = value;
+        self
+    }
+
+    #[must_use]
+    pub const fn has_class(mut self, value: bool) -> Self {
+        self.has_class = value;
+        self
+    }
+}
+
+impl From<LoadSuperAttrBuilder> for LoadSuperAttr {
+    fn from(builder: LoadSuperAttrBuilder) -> Self {
+        builder.build()
+    }
+}
diff --git a/crates/vm/src/frame.rs b/crates/vm/src/frame.rs
@@ -10,7 +10,7 @@ use crate::{
         function::{PyCell, PyCellRef, PyFunction},
         tuple::{PyTuple, PyTupleRef},
     },
-    bytecode::{self, Instruction},
+    bytecode::{self, Instruction, LoadSuperAttr},
     convert::{IntoObject, ToPyResult},
     coroutine::Coro,
     exceptions::ExceptionCtor,
@@ -2859,9 +2859,8 @@ impl ExecutingFrame<'_> {
         Ok(None)
     }
 
-    fn load_super_attr(&mut self, vm: &VirtualMachine, oparg: u32) -> FrameResult {
-        let (name_idx, load_method, has_class) = bytecode::decode_load_super_attr_arg(oparg);
-        let attr_name = self.code.names[name_idx as usize];
+    fn load_super_attr(&mut self, vm: &VirtualMachine, oparg: LoadSuperAttr) -> FrameResult {
+        let attr_name = self.code.names[oparg.name_idx() as usize];
 
         // Stack layout (bottom to top): [super, class, self]
         // Pop in LIFO order: self, class, super
@@ -2871,13 +2870,13 @@ impl ExecutingFrame<'_> {
 
         // Create super object - pass args based on has_class flag
         // When super is shadowed, has_class=false means call with 0 args
-        let super_obj = if has_class {
+        let super_obj = if oparg.has_class() {
             global_super.call((class.clone(), self_obj.clone()), vm)?
         } else {
             global_super.call((), vm)?
         };
 
-        if load_method {
+        if oparg.is_load_method() {
             // Method load: push [method, self_or_null]
             let method = PyMethod::get(super_obj, attr_name, vm)?;
             match method {