JuliaLang/julia

Granular `@fastmath` flags

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#49,890 opened on May 19, 2023

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Description

@fastmath is currently an all-or-nothing construct: one opts into every available flag (which is subject to change with new LLVM versions) by using this macro. There is no syntax to invoke a specific subset of the available flags.

A syntax for opt-in flags like @fastmath (;reassoc=true,contract=true,nsz=true) EXPR would be welcome for a more controlled @fastmath experience.

Contributor guide

Research direction
Explore Julia's macro system to understand how `@fastmath` is implemented. Investigate LLVM's fast math flags and propose a syntax for selective flags, ensuring compatibility with current code generation.
Tech stack
julia
Domain
compilers
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
Julia
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40