NULL pointer access when retrieving field layout

[chaoticbob]

The shader below is causing a NULL pointer access when retrieving the field layout at slang-ir-insts.h::getFieldLayout(), the element at index is null. This may be related to https://github.com/shader-slang/slang/issues/4451.

CMD:

slangc -target spirv -lang slang -D__spirv__ -emit-spirv-directly -profile vs_6_0 -entry main shader.hlsl

Shader

struct S {
    float4 m : MMM;
};

struct T {
    float3 n : NNN;
};

struct Base {
    float4 a : AAA;
    float4 b : BBB;
    S      s;
    float4 p : SV_Position;
};

struct Derived : Base {
    T      t;
    float4 c : CCC;
    float4 d : DDD;
};

void main(in Derived input, out Derived output) {
    output = input;
}

[csyonghe]

Can you provide the host API calls so we can know which type and which field you are querying?

[chaoticbob]

Sorry, should've included this initially, here's the call stack:

slang.dll!Slang::IRInst::getOperandCount() Line 602
    at C:\code\source\slang\source\slang\slang-ir.h(602)
slang.dll!Slang::IRInst::getOperand(unsigned __int64 index) Line 756
    at C:\code\source\slang\source\slang\slang-ir.h(756)
slang.dll!Slang::IRStructFieldLayoutAttr::getLayout() Line 1931
    at C:\code\source\slang\source\slang\slang-ir-insts.h(1931)
slang.dll!Slang::IRStructTypeLayout::getFieldLayout(unsigned __int64 index) Line 1958
    at C:\code\source\slang\source\slang\slang-ir-insts.h(1958)
slang.dll!Slang::createGLSLGlobalVaryingsImpl(Slang::GLSLLegalizationContext * context, Slang::CodeGenContext * codeGenContext, Slang::IRBuilder * builder, Slang::IRType * type, Slang::IRVarLayout * varLayout, Slang::IRTypeLayout * typeLayout, slang::ParameterCategory kind, Slang::Stage stage, unsigned __int64 bindingIndex, unsigned __int64 bindingSpace, Slang::GlobalVaryingDeclarator * declarator, Slang::OuterParamInfoLink * outerParamInfo, Slang::IRInst * leafVar, Slang::StringBuilder & nameHintSB) Line 1717
    at C:\code\source\slang\source\slang\slang-ir-glsl-legalize.cpp(1717)
slang.dll!Slang::createGLSLGlobalVaryingsImpl(Slang::GLSLLegalizationContext * context, Slang::CodeGenContext * codeGenContext, Slang::IRBuilder * builder, Slang::IRType * type, Slang::IRVarLayout * varLayout, Slang::IRTypeLayout * typeLayout, slang::ParameterCategory kind, Slang::Stage stage, unsigned __int64 bindingIndex, unsigned __int64 bindingSpace, Slang::GlobalVaryingDeclarator * declarator, Slang::OuterParamInfoLink * outerParamInfo, Slang::IRInst * leafVar, Slang::StringBuilder & nameHintSB) Line 1734
    at C:\code\source\slang\source\slang\slang-ir-glsl-legalize.cpp(1734)
slang.dll!Slang::createGLSLGlobalVaryings(Slang::GLSLLegalizationContext * context, Slang::CodeGenContext * codeGenContext, Slang::IRBuilder * builder, Slang::IRType * type, Slang::IRVarLayout * layout, slang::ParameterCategory kind, Slang::Stage stage, Slang::IRInst * leafVar) Line 1812
    at C:\code\source\slang\source\slang\slang-ir-glsl-legalize.cpp(1812)
slang.dll!Slang::legalizeEntryPointParameterForGLSL(Slang::GLSLLegalizationContext * context, Slang::CodeGenContext * codeGenContext, Slang::IRFunc * func, Slang::IRParam * pp, Slang::IRVarLayout * paramLayout) Line 3119
    at C:\code\source\slang\source\slang\slang-ir-glsl-legalize.cpp(3119)
slang.dll!Slang::legalizeEntryPointForGLSL(Slang::Session * session, Slang::IRModule * module, Slang::IRFunc * func, Slang::CodeGenContext * codeGenContext, Slang::GLSLExtensionTracker * glslExtensionTracker) Line 3517
    at C:\code\source\slang\source\slang\slang-ir-glsl-legalize.cpp(3517)
slang.dll!Slang::legalizeEntryPointsForGLSL(Slang::Session * session, Slang::IRModule * module, const Slang::List<Slang::IRFunc *,Slang::StandardAllocator> & funcs, Slang::CodeGenContext * context, Slang::GLSLExtensionTracker * glslExtensionTracker) Line 3624
    at C:\code\source\slang\source\slang\slang-ir-glsl-legalize.cpp(3624)
slang.dll!Slang::linkAndOptimizeIR(Slang::CodeGenContext * codeGenContext, const Slang::LinkingAndOptimizationOptions & options, Slang::LinkedIR & outLinkedIR) Line 1127
    at C:\code\source\slang\source\slang\slang-emit.cpp(1127)
slang.dll!Slang::emitSPIRVForEntryPointsDirectly(Slang::CodeGenContext * codeGenContext, Slang::ComPtr<Slang::IArtifact> & outArtifact) Line 1648
    at C:\code\source\slang\source\slang\slang-emit.cpp(1648)
slang.dll!Slang::CodeGenContext::_emitEntryPoints(Slang::ComPtr<Slang::IArtifact> & outArtifact) Line 1618
    at C:\code\source\slang\source\slang\slang-compiler.cpp(1618)
slang.dll!Slang::CodeGenContext::emitEntryPoints(Slang::ComPtr<Slang::IArtifact> & outArtifact) Line 1664
    at C:\code\source\slang\source\slang\slang-compiler.cpp(1664)
slang.dll!Slang::TargetProgram::_createWholeProgramResult(Slang::DiagnosticSink * sink, Slang::EndToEndCompileRequest * endToEndReq) Line 1817
    at C:\code\source\slang\source\slang\slang-compiler.cpp(1817)
slang.dll!Slang::EndToEndCompileRequest::generateOutput(Slang::TargetProgram * targetProgram) Line 1906
    at C:\code\source\slang\source\slang\slang-compiler.cpp(1906)
slang.dll!Slang::EndToEndCompileRequest::generateOutput(Slang::ComponentType * program) Line 2246
    at C:\code\source\slang\source\slang\slang-compiler.cpp(2246)
slang.dll!Slang::EndToEndCompileRequest::generateOutput() Line 2257
    at C:\code\source\slang\source\slang\slang-compiler.cpp(2257)
slang.dll!Slang::EndToEndCompileRequest::executeActionsInner() Line 3145
    at C:\code\source\slang\source\slang\slang.cpp(3145)
slang.dll!Slang::EndToEndCompileRequest::executeActions() Line 3154
    at C:\code\source\slang\source\slang\slang.cpp(3154)
slang.dll!Slang::EndToEndCompileRequest::compile() Line 6135
    at C:\code\source\slang\source\slang\slang.cpp(6135)
slang.dll!spCompile(slang::ICompileRequest * request) Line 636
    at C:\code\source\slang\source\slang\slang-api.cpp(636)
slangc.exe!_compile(slang::ICompileRequest * compileRequest, int argc, const char * const * argv) Line 53
    at C:\code\source\slang\source\slangc\main.cpp(53)
slangc.exe!innerMain(Slang::StdWriters * stdWriters, slang::IGlobalSession * sharedSession, int argc, const char * const * argv) Line 104
    at C:\code\source\slang\source\slangc\main.cpp(104)
slangc.exe!slangc_main(int argc, char * * argv) Line 114
    at C:\code\source\slang\source\slangc\main.cpp(114)
slangc.exe!wmain(int argc, wchar_t * * argv) Line 138
    at C:\code\source\slang\source\slangc\main.cpp(138)

[csyonghe]

Sorry I was asking for the host code in addition to the shader code so we can reproduce this.

[chaoticbob]

IIUC: this is happening just during the compilation from the command line. I'm currently not using any API calls.

[csyonghe]

I see, this is likely due to use of inheritance here. Our implementation of inheritance is closer to none than to complete so it shall be considered as not supported right now.

[chaoticbob]

Got it, thanks. I saw the mention in the docs of limited inheritance, I couldn't figure out if the docs were out of date or not. It's good to have this clarification.

[jkwak-work]

@swoods-nv I think we should close this for now and keep track it as a long term task, "Implement inheritance".