Shader reflection broken in DXIL if struct's name starts with "Buffer"

[jbourdon-msft]

Description
The information gathered from a RWStructuredBuffer using ID3D12ShaderReflection isn't the same for DXBC and DXIL if the template argument type name starts with "Buffer". The DXBC information is the expected one.

After a very quick investigation, the problem seems to come from here:

DirectXShaderCompiler/lib/HLSL/DxilContainerReflection.cpp

Line 1258 in ef1472a

if (TryToDetectObjectType(structType, &m_Desc.Type)) {

DirectXShaderCompiler/lib/HLSL/DxilContainerReflection.cpp

Line 941 in ef1472a

PREFIX_MATCH(Buffer, D3D_SVT_BUFFER);

Steps to Reproduce
Build a shader with a declaration like:

struct BufferData { int i; int j; };
RWStructuredBuffer<BufferData> resource;

Accessing the information about that resource through ID3D12ShaderReflection will not get you the correct information about BufferData if the reflection is on DXIL. Getting to the D3D12_SHADER_TYPE_DESC of the BufferData struct through the ID3D12ShaderReflectionConstantBuffer associated to the declared RWStructuredBuffer will give you different results whether you're reflecting on DXBC or DXIL.

DXBC:

DXIL:

Actual Behavior
Note that if the struct name does not start with "Buffer", the behavior is the same for both DXIL and DXBC.
The DXIL information should be the same as that of DXBC in all cases.

Environment

• DXC version: dxcompiler.dll: 1.8.2407.12; dxil.dll: 101.8.2407.17
• Host Operating System: Windows 11