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lookup slot in hash() #6102

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Merged
coolreader18 merged 3 commits into from
Sep 4, 2025
Merged

lookup slot in hash() #6102

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41a956a
fast-path hash() for exact PyStr
giammirove Aug 18, 2025
6a29c4c
avoid get_class_attr for __hash__; read hash slot via mro_find_map
giammirove Aug 20, 2025
32c74b8
fix linting in hash function
giammirove Aug 20, 2025
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fast-path hash() for exact PyStr 
str.__hash__ can’t be overridden, so for exact PyStr instances we
skip the attribute lookup and MRO walk and call the string hash directly.
This reduces overhead on hot paths (e.g. dict/set key hashing) while keeping
subclass semantics intact (downcast_ref_if_exact).
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@giammirove
giammirove committed Aug 18, 2025
commit 41a956a914ca92ebb5f8a482cf348efb9dd43f2e
5 changes: 5 additions & 0 deletions vm/src/protocol/object.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -642,6 +642,11 @@ impl PyObject {
}

pub fn hash(&self, vm: &VirtualMachine) -> PyResult<PyHash> {
// __hash__ function in str cannot be overwritten
if let Some(pystr) = self.downcast_ref_if_exact::<PyStr>(vm) {
return Ok(pystr.hash(vm));
}

let hash = self.get_class_attr(identifier!(vm, __hash__)).unwrap();
if vm.is_none(&hash) {
return Err(vm.new_exception_msg(
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