microsoft / microsoft/DirectXShaderCompiler

[SM6.9] Invalid DXIL generation

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Since Sep 9, 2026.

bug needs-triage
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Description

Description
A previously valid HLSL shader generates invalid DXIL under SM 6.9:

StructuredBuffer<uint3> In;
RWStructuredBuffer<float3> Out;

[numthreads(8, 1, 1)]
void main(uint3 dtid : SV_DispatchThreadID)
{
    float3 v[2];
    v[0] = asfloat(In[0]);

    if (dtid.x > 1)
        v[dtid.x & 1] = asfloat(In[1]);

    Out[0] = v[0];
}

Steps to Reproduce
Compiler Explorer

Environment

  • DXC version: main & all 1.9-1.10 releases
  • Host Operating System: Any

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