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Merged
youknowone merged 3 commits into from
Dec 28, 2025
Merged

impl basicsize #6557

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e0541fb
shape_differs
youknowone Dec 28, 2025
a3c3ea0
may_add_dict
youknowone Jul 21, 2025
63c3ba3
basicsize
youknowone Dec 28, 2025
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shape_differs
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@youknowone
youknowone committed Dec 28, 2025
commit e0541fb18f38b530e0e87ca7ea6f45227a7032f5
17 changes: 7 additions & 10 deletions crates/vm/src/builtins/type.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1349,6 +1349,7 @@ impl Constructor for PyType {
let slots = PyTypeSlots {
flags,
member_count,
itemsize: base.slots.itemsize,
..PyTypeSlots::heap_default()
};
let heaptype_ext = HeapTypeExt {
Expand Down Expand Up @@ -2009,23 +2010,19 @@ fn calculate_meta_class(
Ok(winner)
}

/// Returns true if the two types have different instance layouts.
fn shape_differs(t1: &Py<PyType>, t2: &Py<PyType>) -> bool {
t1.__basicsize__() != t2.__basicsize__() || t1.slots.itemsize != t2.slots.itemsize
}

fn solid_base<'a>(typ: &'a Py<PyType>, vm: &VirtualMachine) -> &'a Py<PyType> {
let base = if let Some(base) = &typ.base {
solid_base(base, vm)
} else {
vm.ctx.types.object_type
};

// Check for extra instance variables (CPython's extra_ivars)
let t_size = typ.__basicsize__();
let b_size = base.__basicsize__();
let t_itemsize = typ.slots.itemsize;
let b_itemsize = base.slots.itemsize;

// Has extra ivars if: sizes differ AND (has items OR t_size > b_size)
let has_extra_ivars = t_size != b_size && (t_itemsize > 0 || b_itemsize > 0 || t_size > b_size);

if has_extra_ivars { typ } else { base }
if shape_differs(typ, base) { typ } else { base }
}

fn best_base<'a>(bases: &'a [PyTypeRef], vm: &VirtualMachine) -> PyResult<&'a Py<PyType>> {
Expand Down