[SPIR-V] Shader failes to compile when activating debug infos

[Clothoid1]

The following reproducer does not compile, leading to the error message:

fatal error : generated SPIR-V is invalid: ID '52[%52]' has not been defined
1>  %51 = OpExtInst %void %1 DebugTypeFunction %uint_3 %52 %48 %49
1>
1>note: please file a bug report on https://github.com/Microsoft/DirectXShaderCompiler/issues with source code if possible

Reproducer:

StructuredBuffer<uint16_t> myIntersectionMaskBuffer_BitCompressed : register(t0);

class CompressedIntersectionBits
{
	uint16_t myCompressedData;

	static CompressedIntersectionBits read_const(StructuredBuffer<uint16_t> aIntersectionMaskBuffer_BitCompressed_in, const uint aRayIndex_in)
	{
		CompressedIntersectionBits aCompressedIntersectionBits;
		aCompressedIntersectionBits.myCompressedData = aIntersectionMaskBuffer_BitCompressed_in[aRayIndex_in];
		return aCompressedIntersectionBits;
	}
};

class CompressedIntersectionBits_Test
{
	static CompressedIntersectionBits read_const(StructuredBuffer<uint16_t> aIntersectionMaskBuffer_BitCompressed_in, const uint aRayIndex_in)
	{
		CompressedIntersectionBits aCompressedIntersectionBits;
		aCompressedIntersectionBits.myCompressedData = aIntersectionMaskBuffer_BitCompressed_in[aRayIndex_in];
		return aCompressedIntersectionBits;
	}
};

void runKernel(const uint aIndexX_in, const uint aIndexY_in)
{
	uint aRayIndex = aIndexY_in * 512 + aIndexX_in;

	CompressedIntersectionBits aCompressedIntersectionBits = CompressedIntersectionBits::read_const(myIntersectionMaskBuffer_BitCompressed, aRayIndex);
	//CompressedIntersectionBits aCompressedIntersectionBits = CompressedIntersectionBits_Test::read_const(myIntersectionMaskBuffer_BitCompressed, aRayIndex);
}

[numthreads(8, 8, 1)]
void main(uint3 GlobalInvocationID : SV_DispatchThreadID, uint3 LocalInvocationID : SV_GroupThreadID)
{
	runKernel(GlobalInvocationID[0], GlobalInvocationID[1]);
}

Command Line used:
dxc.exe -spirv -T cs_6_7 -fvk-use-scalar-layout -enable-16bit-types -fspv-target-env=vulkan1.3 -fspv-debug=vulkan-with-source -E main

dxc version used:
dxcompiler.dll: 1.7 - 1.7.0.3774 (2168dcb4f)

Operating System used:
Windows 10

When removing the option
-fspv-debug=vulkan-with-source
the file compiles without a problem.

The issue also vanishes, when calling

CompressedIntersectionBits_Test::read_const(myIntersectionMaskBuffer_BitCompressed, aRayIndex);

instead of

CompressedIntersectionBits::read_const(myIntersectionMaskBuffer_BitCompressed, aRayIndex);

[Keenuts]

Hi! Thanks for complete the report!

Was able to reproduce at head with:

class MyClass
{
	static MyClass my_func()
	{
		MyClass tmp;
		return tmp;
	}
};

[numthreads(1, 1, 1)]
void main(uint3 GlobalInvocationID : SV_DispatchThreadID)
{
  const uint index = GlobalInvocationID[0];
	MyClass::my_func();
}

./build/bin/dxc -spirv -T cs_6_7 -fspv-debug=vulkan-with-source -E main repro.hlsl

The issue seems to be linked to the optimizer, and the compact-ids pass, IDs gets rearranged, and the ID ends up being used before being defined:

10747 %26 = OpExtInst %void %1 DebugLexicalBlock %12 %uint_4 %uint_2 %22
10748 %28 = OpExtInst %void %1 DebugLocalVariable %27 %19 %12 %uint_5 %uint_11 %26 %uint_4

10853 %24 = OpExtInst %void %1 DebugTypeFunction %uint_3 %26
[...]
10855 %26 = OpExtInst %void %1 DebugTypeComposite %8 %uint_0 %19 %uint_1 %uint_7 %20 %8 %uint_0 %uint_3 %27

[Keenuts]

Not a compact-ids pass issue, the initial code also contains other debug instructions with IDs defined later on. Also, from other generated spv, the use-before-declaration seems to be OK. Looking into it.

[webez]

Hi.
I could reproduce the same bug with this code

class ClassA {
  void FuncA()   {
      this.FuncB();
  }
  
    void FuncB()   {
  }
};

void main() {
    ClassA var;
    var.FuncA();
}

[Keenuts]

Hello! Sorry haven't had much time for DXC.
Seems like this issue is related to KhronosGroup/SPIRV-Tools#5229 but this is not enough to fix it.
Seems like there is also a fix to do in the debug instruction ordering code.

[Clothoid1]

I just tested this issue with latest DXC compiler.
I can now no longer reproduce this issue.
Instead i only get the warning:
warning : Member functions will not be linked to their class in the debug information. See KhronosGroup/SPIRV-Registry#203

Theoretically this issue could now be closed.
Or should it be kept open until also the warning is solved?

[Clothoid1]

When activating debug infos now all of our shaders compile - with the exception of our raytracing shaders.
But it seems to me that this remaining issue was already reported:
#5113

[Keenuts]

Hello! So yes, thanks, for now, the issue is "resolved" as "it doesn't crash".
We can close this, but we now need to change the SPIR-V spec to solve this long-term.
(This will take longer, as we need to define the spec, and figure out how to propagate it, maybe wait a spirv release?)

For the second issue, seems unrelated to this (as in it's a different error/crash).