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Optimize frozenset construction #150027
Description
Feature or enhancement
Proposal:
Many cases of frozenset look like this:
xyz = frozenset({1, 2, 3})Currently, this constructs a new frozenset and copies the set object created by the literal. We can optimize this by detecting that it's a set literal via PyUnstable_Object_IsUniqueReferencedTemporary, and then simply move the mutable set 's memory into the frozenset without a copy.
Additionally, we have some optimizations for generator expressions inside sets. For example, this will be optimized by the compiler into some bytecode magic:
xyz = set((index for index in range(5))We can extend this optimization to frozensets as well.
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gh-150027: Avoid copying during construction of `frozenset` objects (G…
MojoVampire commentedon May 19, 2026
Heh, I'd been looking at making a similar change a few months ago at work, then forgot to follow up at home. Way more work to accomplish it than I expected. 👍 If I'm reading it correctly, it's doing it smarter than I would have, generating op codes that directly construct a frozenset from a set literal or set comprehension, correct?
MojoVampire commentedon May 19, 2026
Seems like an optimization that would apply to
frozendict({dictliteral})andfrozendict({dictcomp})s as well, right?