LoadClosure as pseudo op by youknowone · Pull Request #6789 · RustPython/RustPython

youknowone

📝 Walkthrough

Walkthrough

The PR migrates the LoadClosure opcode from the concrete Instruction enum to the PseudoInstruction enum, updating bytecode emission, IR lowering, decoding logic, instruction metadata, and VM frame execution paths to accommodate this structural change.

Changes

Cohort / File(s)	Summary
Bytecode Definition and Conversion `crates/compiler-core/src/bytecode/instruction.rs`	Moves `LoadClosure(Arg<NameIdx>)` from `Instruction` to `PseudoInstruction` (discriminant 268); updates `TryFrom` bounds and removes `LoadClosure` handling from `Instruction` paths; removes stack effects and formatting for `LoadClosure` from `Instruction`, adds stack effect of 1 to `PseudoInstruction`.
Code Generation and IR Lowering `crates/codegen/src/compile.rs`, `crates/codegen/src/ir.rs`	Updates closure variable emission to use `PseudoInstruction::LoadClosure` instead of `Instruction::LoadClosure`; adds IR lowering to convert `PseudoInstruction::LoadClosure` to `LOAD_FAST` with index adjusted by varnames count.
Opcode Metadata `crates/stdlib/src/opcode.rs`	Removes `LoadClosure(_)` from the `has_free` instruction pattern match, no longer treating it as a free-variable instruction.
Frame Execution and Locals `crates/vm/src/frame.rs`	Restructures frame locals initialization to combine varnames, cellvars, and freevars into a single `fastlocals` array with pre-filled cell objects; removes the `Instruction::LoadClosure` execution path from frame dispatch.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~22 minutes

Possibly related PRs

Bytecode instrumented placeholder #6741: Directly migrates the same LoadClosure opcode out of Instruction into PseudoInstruction with coordinated enum and handling updates.
LoadClassDeref -> LoadFromDictOrDeref #6692: Performs analogous opcode migration (e.g., LoadClassDeref) affecting bytecode enums, codegen, IR, and frame execution.
Pseudo ops #6678: Refactors the broader pseudo-instruction pipeline with similar opcode relocation and IR lowering patterns.

Suggested reviewers

ShaharNaveh

Poem

🐰 A closure hops from Instruction's gate,
To Pseudo's burrow, a lighter fate!
Fastlocals swell with cells in place,
No more dispatch—just stack-bound grace.

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: moving LoadClosure from a regular Instruction to a PseudoInstruction, which is the primary focus across all modified files.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

📝 Generate docstrings

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

_{Comment @coderabbitai help to get the list of available commands and usage tips.}