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| -rw-r--r-- | docs/language-reference/08-attributes.md | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/docs/language-reference/08-attributes.md b/docs/language-reference/08-attributes.md index 4098303cf..76a739315 100644 --- a/docs/language-reference/08-attributes.md +++ b/docs/language-reference/08-attributes.md @@ -2,3 +2,29 @@ Attributes ========== > Note: This section is not yet complete. + +## [[vk::spirv_instruction]] + +** SPIR-V only ** + +This attribute is only available for Vulkan SPIR-V output via GLSLANG. In the future it could be supported via the `direct-spirv` option. The attribute will be ignored for any other target. This attribute requires the `GL_EXT_spirv_intrinsics` GLSL extension. + +The attibute allows access to SPIR-V intrinsics, by supplying a function declaration with the appropriate signature for the SPIR-V op and no body. The intrinsic takes a single parameter which is the integer value for the SPIR-V op. + +In the example below the add function, uses the mechanism to directly use the SPIR-V integer add 'op' which is 128 in this case. + +```HLSL +// 128 is OpIAdd in SPIR-V +[[vk::spirv_instruction(128)]] +uint add(uint a, uint b); + +RWStructuredBuffer<uint> resultBuffer; + +[numthreads(4,1,1)] +void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID) +{ + uint threadId = dispatchThreadID.x; + resultBuffer[threadId] = add(threadId, threadId); +} +``` + |