There are some useful intrinsic functions in the NVIDIA GPU instruction set that are not included in standard graphics APIs. Updated from the original 2016 post…
Overview
The article discusses the use of NVIDIA GPU intrinsics in HLSL, highlighting how these functions can enhance shader performance by enabling operations that are not available in standard graphics APIs. It provides detailed guidance on implementing these intrinsics in DirectX 11 and 12, including code examples and best practices.
What You'll Learn
1
How to use NVIDIA GPU intrinsics in HLSL shaders
2
How to create extended shaders in DirectX 11 with NVAPI
3
How to create extended pipeline state objects in DirectX 12
4
How to query GPU feature support for intrinsics
Prerequisites & Requirements
- Understanding of HLSL and shader programming
- Familiarity with NVAPI and DirectX(optional)
Key Questions Answered
What are GPU intrinsics and how can they be used in HLSL?
GPU intrinsics are special functions in the NVIDIA GPU instruction set that enhance shader performance by allowing operations like warp shuffle and atomic additions. They can be used in HLSL shaders to optimize data exchange between threads and improve memory access patterns.
How do you create extended shaders in DirectX 11 using NVAPI?
To create extended shaders in DirectX 11, you must use the NvAPI_D3D11_SetNvShaderExtnSlot function to specify the UAV slot before creating the pixel shader. This informs the driver that the shader will utilize intrinsics, ensuring proper compilation and execution.
What is the process for creating pipeline state objects in DirectX 12?
In DirectX 12, pipeline state objects (PSOs) are created using the NvAPI_D3D12_CreateGraphicsPipelineState function. You must provide a PSO description and include an extension structure that specifies the UAV slot used in the shaders, allowing for the use of intrinsics.
How can you check if a GPU supports specific intrinsics?
You can check GPU support for specific intrinsics using the NVAPI_D3D11_IsNvShaderExtnOpCodeSupported or NVAPI_D3D12_IsNvShaderExtnOpCodeSupported functions. These functions return a boolean indicating whether the specified operation code is supported by the device.
Technologies & Tools
Software
Nvidia Nvapi
Used to access NVIDIA-specific extensions and functionalities in DirectX.
Graphics API
Directx
Used for rendering graphics and utilizing GPU intrinsics.
Key Actionable Insights
1Implementing warp shuffle instructions can significantly optimize data exchange in pixel shaders, especially where shared memory is unavailable.This is particularly useful in scenarios where multiple threads need to share data efficiently without incurring the overhead of shared memory access.
2Utilizing atomic operations on half-precision floating-point numbers can enhance performance in graphics applications like VXGI.This allows for efficient accumulation of values during operations such as voxelization, which is critical for real-time rendering applications.
3Ensure that shaders are compiled without optimizations when using NVAPI intrinsics to prevent unintended alterations by the compiler.This is crucial because the compiler may not recognize the intrinsic sequences, leading to incorrect shader behavior.
Common Pitfalls
1
Compiling shaders with the D3DCOMPILE_SKIP_OPTIMIZATION flag can lead to non-functional intrinsics.
This occurs because the compiler may optimize away crucial instructions that are necessary for the intrinsics to operate correctly, resulting in unexpected shader behavior.
Related Concepts
Shader Optimization Techniques
Directx 11 And 12 Features
Atomic Operations In Graphics Programming