Return opcode

As explained in Rust in Action: Systems programming concepts and techniques

The RETURN opcode restores CPU execution to the address saved by a preceding function call.

How Rust in Action: Systems programming concepts and techniques covers it

How deep it goes

Implements stack popping and execution restoration, while stopping short of language-level function support.

Examples

Uses the add_twice function, two addition opcodes, the 0x00EE encoding, and illustrated control flow.

What it assumes

Assumes opcode execution and CALL behavior, while introducing the stack as address storage for function control flow.

What you can do after

Build a Rust emulator method that safely returns from functions and detects stack underflow.

How it connects

Connects function calls, the CALL opcode, the stack, the stack pointer, and CPU instruction execution.

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Related concepts

• execution context stackuses · An execution context stack is a runtime last-in-first-out structure that records active function or method calls and their execution state and return information.
• opcodekind of · An opcode is the encoded portion of an instruction that identifies the operation an execution system is to perform.

This explainer was generated by Manning's knowledge graph from the text of Rust in Action: Systems programming concepts and techniques. The section links point to the parts of the book it draws on.