DISubprogram not attached to function directly

[czw831024]

We found that ray tracing shaders from D3D12RaytracingRealTimeDenoisedAmbientOcclusion in MSFT's DirectX-Graphics-Samples from Github don't have DISubprogram s attached to their corresponding functions in DXIL. For example, in Pathtracer.hlsl

define void @MyMissShader_RadianceRay() {
%WorldRayDirection.i = call float @dx.op.worldRayDirection.f32(i32 148, i8 0) #3, !dbg !344
%WorldRayDirection1.i = call float @dx.op.worldRayDirection.f32(i32 148, i8 1) #3, !dbg !344
%WorldRayDirection2.i = call float @dx.op.worldRayDirection.f32(i32 148, i8 2) #3, !dbg !344
%1 = call %dx.types.Handle @dx.op.createHandle(i32 57, i8 0, i32 0, i32 12, i1 false), !dbg !362
%2 = call %dx.types.Handle @dx.op.createHandle(i32 57, i8 3, i32 0, i32 0, i1 false), !dbg !362
...

!481 = !DISubprogram(name: "MyMissShader_RadianceRay", linkageName: "\01?MyMissShader_RadianceRay@@YAXUPathtracerRayPayload@@@z", scope: !1, file: !1, line: 536, type: !482, isLocal: false, isDefinition: true, scopeLine: 537, flags: DIFlagPrototyped, isOptimized: false, function: void (%struct.PathtracerRayPayload*)* @"\01?MyMissShader_RadianceRay@@YAXUPathtracerRayPayload@@@z")

We expect something like

define void @MyMissShader_RadianceRay() !dbg !481{

to connect the DISubprogram and its function directly.

To compile the shader and reproduce, you can modify the following command, which I got from the build

D:\Codes\MSFT\DirectX-Graphics-Samples\Samples\Desktop\D3D12Raytracing\src\D3D12RaytracingRealTimeDenoisedAmbientOcclusion>D:\Downloads\dxc_2024_07_31\bin\x64\dxc.exe /I"D:\Codes\MSFT\DirectX-Graphics-Samples\Samples\Desktop\D3D12Raytracing\src\D3D12RaytracingRealTimeDenoisedAmbientOcclusion\" /I"D:\Codes\MSFT\DirectX-Graphics-Samples\Samples\Desktop\D3D12Raytracing\src\D3D12RaytracingRealTimeDenoisedAmbientOcclusion\" /IRTAO/shaders /ISampleCore/shaders /ISampleCore/shaders/util /nologo /T lib_6_3 /Fh "obj\x64\Debug\CompiledShaders\Pathtracer.hlsl.h" /Vn "g_pPathtracer" /Zi /Zpr -Qembed_debug -HV 2021 SampleCore\Shaders\Pathtracer.hlsl

[damyanp]

From our initial look at this we think that this is working as expected. Is there some functionality not working as a result of this?

@AdamJMiles, @jeffnn - do you have any insights as to whether or not this is a bug?

[damyanp]

Oops, meant to tag @adam-yang in this. But other Adam if you have any insights they'd also be appreciated :)

[czw831024]

Any update?

[damyanp]

Other than the update above, I'm afraid not. We've triaged this as "Dormant" which means that we don't currently think it reaches the bar for us to actively investigate it - but we would be prepared to accept a pull request with a proposed fix if one were submitted.