llvm/llvm-project

AMDGPU should implement TargetLowering::hasAndNot

Open

#112,550 opened on Oct 16, 2024

View on GitHub
 (17 comments) (0 reactions) (1 assignee)C++ (10,782 forks)batch import
backend:AMDGPUgood first issue

Repository metrics

Stars
 (26,378 stars)
PR merge metrics
 (Avg merge 1d 2h) (1,000 merged PRs in 30d)

Description

AMDGPU should implement this optimization hook: https://github.com/llvm/llvm-project/blob/b333edd0d6da744c099ad3ff3b5fbd2d4e4dd45a/llvm/include/llvm/CodeGen/TargetLowering.h#L797

This is available on the SALU for i32 and i64 (s_andn2_b32 and s_andn2_b64). The implementation therefore should be approximately !N->isDivergent() && (N->getValueType() == i32 || i64).

Contributor guide

Research direction
Look at the LLVM source code, find the AMDGPU target lowerng implementation in llvm/lib/Target/AMDGPU/, examine how other targets like X86 implement hasAndNot, then implement the method returning true for non divergent i32 and i64 nodes.
Tech stack
cpp
Domain
backend
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.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C++Git
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75