Remove ReturnConst/Break/Continue ops by youknowone · Pull Request #6816 · RustPython/RustPython

youknowone

📝 Walkthrough

Walkthrough

This PR removes three specialized bytecode instruction variants (Break, Continue, and ReturnConst) from the instruction set and consolidates their functionality into generic alternatives (Jump for break/continue control flow, ReturnValue for constant returns), simplifying the bytecode instruction architecture.

Changes

Cohort / File(s)	Summary
Instruction Definition `crates/compiler-core/src/bytecode/instruction.rs`	Removes `Break`, `Continue`, and `ReturnConst` enum variants and all associated metadata handling (label arguments, unconditional branch detection, stack effect calculations, and disassembler formatting).
Code Generation `crates/codegen/src/compile.rs`	Replaces `emit_return_const()` to load constants and emit `ReturnValue` instead; removes optimization in `emit_return_value()` that reused trailing `LoadConst` as `ReturnConst`; updates `emit_jump()` for break/continue to emit generic `Jump` to computed targets.
Opcode Predicates `crates/stdlib/src/opcode.rs`	Updates `has_const()` to exclude `ReturnConst` from constant-returning opcodes; removes `Break` and `Continue` from `has_jump()` matching.
VM Runtime Execution `crates/vm/src/frame.rs`	Removes `Break` and `Continue` variants from `UnwindReason` enum; deletes instruction handling for `Break`, `Continue`, and `ReturnConst` in `execute_instruction()`; eliminates break/continue unwinding paths.
JIT Instruction Handling `crates/jit/src/instructions.rs`	Removes `ReturnConst` from instruction termination recognition and instruction emitter logic.
Test Utilities `crates/jit/tests/common.rs`	Removes `ReturnConst` handling from annotation extraction and `StackMachine` execution flow.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

Instruction 3.14 #6805: Directly inverse operation—adds Break, Continue, and ReturnConst variants that this PR removes.
Bytecode pseudo opcodes #6715: Introduces PseudoInstruction and instruction enum consolidation that likely motivates this removal.
Fix opcode args #6649: Modifies the same opcode predicate functions (has_const, has_jump) in crates/stdlib/src/opcode.rs.

Suggested reviewers

ShaharNaveh

Poem

🐰 Hops along with glee,
Break and Continue—now set free!
ReturnConst fades from bytecode bright,
Jump and ReturnValue shine so right. ✨

🚥 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 precisely summarizes the main change: removing three instruction variants (ReturnConst, Break, Continue) from the bytecode instruction set across multiple crates.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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✨ Finishing touches

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