Newtype `var_nums` oparg by ShaharNaveh · Pull Request #7431

Newtype `var_nums` oparg by ShaharNaveh · Pull Request #7431 · RustPython/RustPython

📝 Walkthrough

Walkthrough

This PR refactors the bytecode instruction type system by introducing a new VarNums type for encoding multiple variable operands and replacing manual bit-shifting logic with a dedicated indexes() method. The changes propagate through instruction variants, display logic, JIT, and VM frame handling to use the new type-safe accessor pattern.

Changes

Cohort / File(s)	Summary
Oparg Type System Refactoring `crates/compiler-core/src/bytecode/oparg.rs`	Type names reorganized: `LoadAttr → VarNums`, `LoadSuperAttr → LoadAttr`, `Label → LoadSuperAttr`, `StoreFastLoadFast → Label`. New `VarNums` impl provides `idx_1()`, `idx_2()`, and `indexes()` accessors replacing separate `store_idx`/`load_idx` logic.
Instruction Variant Updates `crates/compiler-core/src/bytecode/instruction.rs`	Several bytecode instructions updated to use `Arg<oparg::VarNums>` for var_nums fields instead of `Arg<u32>` or custom types. Display logic for `LOAD_FAST_LOAD_FAST`, `LOAD_FAST_BORROW_LOAD_FAST_BORROW`, `STORE_FAST_LOAD_FAST`, and `STORE_FAST_STORE_FAST` now calls `oparg.indexes()` instead of manual bit-shifting. Removed `StoreFastLoadFast` from public imports.
Index Extraction Simplification `crates/jit/src/instructions.rs`, `crates/vm/src/frame.rs`	Replaced manual index extraction via bit-shift operations (`idx = oparg >> 4`; `idx = oparg & 0xF`) with structured `oparg.indexes()` calls. Frame handling updated to use `var_nums.get(arg).indexes()` for loading and storing variable pairs.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

Newtype var_num oparg #7400: Introduces VarNum/VarNums types and refactors oparg newtype encoding, directly paralleling the type system changes in this PR.
slice ops and a little bit of peephole #6860: Introduces the fused two-variable instructions (LoadFastLoadFast, StoreFastStoreFast, etc.) that this PR refactors to use the new VarNums/indexes() API.
Use num_enum crate for oparg types #6980: Modifies the oparg type system with new accessor methods and conversion traits that establish the foundation for the centralized index extraction approach.

Suggested reviewers

youknowone

Poem

🐰 Hop, skip, and a bound—old bit-shifts retire,
New indexes() dance where opcodes conspire!
VarNums embrace the variables with grace,
No more shifting masks all over the place! ✨

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Newtype `var_nums` oparg' accurately describes the main change: introducing a new VarNums type that replaces several oparg-like types and consolidates their accessor logic.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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