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hlslvulkancompute-shaderspir-v

SPIR-V error with InterlockedMax after upgrading to LunarG SDK 1.0.68.0

My compute shader (written in HLSL) compiled and worked with the earlier SDK 1.0.65.0. I updated to 1.0.68.0 and recompiled it, now I get this error when calling vkCreateShaderModule:

Vulkan error: [SC], code: 5: SPIR-V module not valid: AtomicSMax: expected Result Type to be int scalar type

I verified that the error comes from this function in my shader:

groupshared uint ldsZMax;
groupshared uint ldsZMin;
...

void CalculateMinMaxDepthInLds( uint3 globalThreadIdx, uint depthBufferSampleIdx )
{
    float viewPosZ = depthTexture.Load( uint3( globalThreadIdx.x, globalThreadIdx.y, 0 ) ).x;

    uint z = asuint( viewPosZ );

    if (viewPosZ != 0.f)
    {
        InterlockedMax( ldsZMax, z );
        InterlockedMin( ldsZMin, z );
    }
}

I compile the shader with this command:

C:\VulkanSDK\1.0.68.0\Bin\glslangValidator -D -V -S comp -e CSMain LightCuller.hlsl -o LightCuller.spv

The error goes away if I don't use those Interlocked* methods. I also tried to use ints instead of uints but the problem persists. What am I doing wrong or could this be a codegen bug?

Solution

  • If the SPIR-V validator says that something generated by glslangValidator is invalid, then that is either a glslangValidator bug or a SPIR-V validator bug. Probably best to file a bug at https://github.com/KhronosGroup/glslang; if the maintainers there think they're doing the right thing, they'll follow up with the spirv-tools people.

    Though looking at the HLSL InterlockedMax docs, isn't it supposed to have three parameters? The glslangValidator bug here may just be a failure to issue an error for invalid input. But I'm not an HLSL expert, maybe there some other variant with two parameters and a return value.