llvm/llvm-project

[ARM][AArch64] Remove CLS special handling and use generic ISD::CTLS node

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#174,337 opened on Jan 4, 2026

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backend:AArch64backend:ARMgood first issue

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Description

Once #173417 has landed, the arm/aarch64 intrinsics (int_arm_mve_vcls/int_arm_neon_vcls/int_aarch64_cls/int_aarch64_cls64 etc.) can be expanded to ISD::CTLS in DAG/GISel and the remaining patterns/setOperationAction calls converted to use ISD::CTLS

Contributor guide

Research direction
Review the linked PR #173417 to understand the introduction of ISD::CTLS. Then identify all remaining uses of CLS special handling in ARM/AArch64 backend code, including patterns in .td files and setOperationAction calls, and replace them with ISD::CTLS.
Tech stack
cpp
Domain
backend
Issue type
Refactor
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.
1-2 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.
Mostly clear
Prerequisites
C++LLVM compiler backend
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30