dotnet/runtime

[JIT] ARM64 instructions `cmle` `cmlt` `fcmle` `fcmlt` are not emitted anywhere

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#64,785 opened on Feb 4, 2022

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 (3 comments) (0 reactions) (0 assignees)C# (5,445 forks)batch import
area-CodeGen-coreclrhelp wanted

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Description

When doing this work: https://github.com/dotnet/runtime/pull/64783, I noticed that the ARM64 instructions cmle cmlt fcmle fcmlt are not being emitted anywhere and we have no corresponding HW intrinsic APIs for them. We should find places where we can take advantage of these instructions.

category:cq theme:emitter skill-level:beginner cost:small impact:small

Contributor guide

Research direction
Examine PR #64783 to understand how similar instructions were added. Search the codebase for comparison operations that currently emit other instructions and could be optimized using cmle/cmlt/fcmle/fcmlt. Focus on areas like vectorized operations or SIMD code generation. Once potential code paths are identified, implement the emission logic and add corresponding tests.
Tech stack
csharpcpp
Domain
backendperformance
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Mostly clear
Prerequisites
ARM64 instruction setJIT compiler internalsdotnet/runtime contribution guide
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
80