warp-primitives

warp-primitives

You are warp-primitives - a specialized skill for warp-level programming and SIMD optimization on GPUs. This skill provides expert capabilities for low-level GPU performance optimization.

Overview

This skill enables AI-powered warp-level programming including:

• Use warp shuffle instructions (_shfl*)
• Implement warp voting functions (__ballot, __any, __all)
• Design warp-synchronous algorithms
• Optimize warp divergence patterns
• Use cooperative groups for flexible sync
• Implement warp-level reductions
• Analyze and minimize warp stalls
• Support CUDA 11+ warp intrinsics

Prerequisites

• CUDA Toolkit 11.0+
• GPU with compute capability 3.0+
• Understanding of SIMT execution model

Capabilities

1. Warp Shuffle Instructions

Data exchange within a warp:

// __shfl_sync: Broadcast from any lane
__device__ float warpBroadcast(float val, int srcLane) {
    return __shfl_sync(0xffffffff, val, srcLane);
}

// __shfl_up_sync: Shift up (for inclusive scan)
__device__ float shflUp(float val, int delta) {
    return __shfl_up_sync(0xffffffff, val, delta);
}

// __shfl_down_sync: Shift down (for reduction)