FuelLabs/sway

Allow use of `consts` in place of immediates in asm blocks

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#810 opened on Feb 17, 2022

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P: lowcompilerenhancementgood first issuelanguage featureteam:compiler

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Description

Motivation

https://github.com/FuelLabs/sway-lib-std/pull/46 We should be able to directly use the const in the asm block if it is small enough to fit in that immediate size.

Summary

Currently, immediates are size-checked in the compiler. If an opcode takes a 12-bit immediate, the size of that immediate is checked at compile time. Since we also know the value of consts at compile time, we should be able to directly allow the use of consts inside of asm blocks instead of passing them in. This will require a modification to the grammar and then size checking the const.

Contributor guide

Research direction
Understand how immediate values are currently size checked in the Sway compiler, then extend the grammar to allow const identifiers in asm blocks, ensuring the const value fits the immediate size.
Tech stack
rust
Domain
backend
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
RustGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40