Internal llvm::cast<X> due to particular combination of class fields and methods

[siliconvoodoo]

(reduced to minimum crashing example) code:

struct PSInput
{
};

class SurfaceData_BasePBR
{
    float3 albedo;
};

interface ISpecRough
{
    void ApplySpecularAA();
};

class SurfaceData_NewPBR : SurfaceData_BasePBR, ISpecRough
{
    float3 emissiveLighting;

    void ApplySpecularAA()
    {
    } 
};

float4 PSMain( PSInput input ) : SV_TARGET
{
    SurfaceData_NewPBR obj ;
    obj . albedo . x = 1 ;
    return float4 ( obj . albedo , 1 ) ;
} 

Example command line:

-T ps_6_5 -E PSMain -HV 2021

Effect:

Internal Compiler error: llvm::cast() argument of incompatible type!

[damyanp]

Stil reproduces: https://godbolt.org/z/zv4WKPjdn

[llvm-beanz]

Callstack for the bad cast:

* thread #1, name = 'dxc', stop reason = signal SIGILL: illegal instruction operand
  * frame #0: 0x00007ffff0e036cd libdxcompiler.so ::llvm_assert(const char *, const char *, unsigned int, const char *):`::llvm_assert(Message="false && \"expected struct bitcast to only be used by lifetime intrinsics\"", File="/home/cbieneman/dev/DirectXShaderCompiler/lib/Transforms/Scalar/ScalarReplAggregatesHLSL.cpp", Line=2578 0x00000a12, Function="RewriteBitCast") + 429 at assert.cpp:33
    frame #1: 0x00007ffff0c36d2b libdxcompiler.so (anonymous namespace)::SROA_Helper::RewriteBitCast:`(anonymous namespace)::SROA_Helper::RewriteBitCast(this=0x00007fffffff5c60, BCI=0x00005555570f1f08) + 859 at ScalarReplAggregatesHLSL.cpp:2577
    frame #2: 0x00007ffff0c30ca8 libdxcompiler.so (anonymous namespace)::SROA_Helper::RewriteForScalarRepl:`(anonymous namespace)::SROA_Helper::RewriteForScalarRepl(this=0x00007fffffff5c60, V=0x00005555570efbf8, Builder=0x00007fffffff6938) + 984 at ScalarReplAggregatesHLSL.cpp:2899
    frame #3: 0x00007ffff0c280ae libdxcompiler.so (anonymous namespace)::SROA_Helper::DoScalarReplacement:`(anonymous namespace)::SROA_Helper::DoScalarReplacement(V=0x00005555570efbf8, Elts=size=1, BrokenUpTy=0x00007fffffff6928, NumInstances=0x00007fffffff6920, Builder=0x00007fffffff6938, bFlatVector=true, hasPrecise=false, typeSys=0x000055555709b340, DL=0x00005555570860e0, DeadInsts=0x00007fffffff6aa0, DT=0x0000555557153508) + 6542 at ScalarReplAggregatesHLSL.cpp:3060
    frame #4: 0x00007ffff0c16c21 libdxcompiler.so (anonymous namespace)::SROAGlobalAndAllocas:`(anonymous namespace)::SROAGlobalAndAllocas(HLM=0x000055555708d680, bHasDbgInfo=false) + 6321 at ScalarReplAggregatesHLSL.cpp:1879
    frame #5: 0x00007ffff0c0d5a5 libdxcompiler.so (anonymous namespace)::SROA_Parameter_HLSL::runOnModule:`(anonymous namespace)::SROA_Parameter_HLSL::runOnModule(this=0x00005555570fe350, M=0x0000555557085fe0) + 4613 at ScalarReplAggregatesHLSL.cpp:4370
    frame #6: 0x00007fffefdc37b5 libdxcompiler.so (anonymous namespace)::MPPassManager::runOnModule:`(anonymous namespace)::MPPassManager::runOnModule(this=0x0000555557079a90, M=0x0000555557085fe0) + 1797 at LegacyPassManager.cpp:1669
    frame #7: 0x00007fffefdc2c28 libdxcompiler.so llvm::legacy::PassManagerImpl::run:`llvm::legacy::PassManagerImpl::run(this=0x00005555570f7cc0, M=0x0000555557085fe0) + 776 at LegacyPassManager.cpp:1771
    frame #8: 0x00007fffefdc469a libdxcompiler.so llvm::legacy::PassManager::run:`llvm::legacy::PassManager::run(this=0x00005555570f7c30, M=0x0000555557085fe0) + 138 at LegacyPassManager.cpp:1814
    frame #9: 0x00007ffff0ffc781 libdxcompiler.so (anonymous namespace)::EmitAssemblyHelper::EmitAssembly:`(anonymous namespace)::EmitAssemblyHelper::EmitAssembly(this=0x00007fffffff8048, Action=Backend_EmitBC, OS=0x0000555557085440) + 3761 at BackendUtil.cpp:760
    frame #10: 0x00007ffff0ffb09b libdxcompiler.so clang::EmitBackendOutput:`clang::EmitBackendOutput(Diags=0x00005555570496a0, CGOpts=0x0000555557048150, TOpts=0x0000555557048d80, LOpts=0x0000555557048c00, TDesc=(Data = "e-m:e-p:32:32-i1:32-i8:32-i16:32-i32:32-i64:64-f16:32-f32:32-f64:64-n8:16:32:64", Length = 79), M=0x0000555557085fe0, Action=Backend_EmitBC, OS=0x0000555557085440) + 411 at BackendUtil.cpp:783
    frame #11: 0x00007ffff0ff28d6 libdxcompiler.so clang::BackendConsumer::HandleTranslationUnit:`clang::BackendConsumer::HandleTranslationUnit(this=0x0000555557085610, C=0x000055555706f5c0) + 2150 at CodeGenAction.cpp:191
    frame #12: 0x00007ffff39a0ec3 libdxcompiler.so clang::ParseAST:`clang::ParseAST(S=0x00005555570862a0, PrintStats=false, SkipFunctionBodies=false) + 2547 at ParseAST.cpp:164
    frame #13: 0x00007ffff1780315 libdxcompiler.so clang::ASTFrontendAction::ExecuteAction:`clang::ASTFrontendAction::ExecuteAction(this=0x00007fffffffa5d0) + 725 at FrontendAction.cpp:554
    frame #14: 0x00007ffff0feed07 libdxcompiler.so clang::CodeGenAction::ExecuteAction:`clang::CodeGenAction::ExecuteAction(this=0x00007fffffffa5d0) + 3703 at CodeGenAction.cpp:807
    frame #15: 0x00007ffff177f7ff libdxcompiler.so clang::FrontendAction::Execute:`clang::FrontendAction::Execute(this=0x00007fffffffa5d0) + 303 at FrontendAction.cpp:455
    frame #16: 0x00007fffef74f0b3 libdxcompiler.so DxcCompiler::Compile:`DxcCompiler::Compile(this=0x00005555570458a0, pSource=0x00007fffffffcd60, pArguments=0x00005555570460f0, argCount=5 0x00000005, pIncludeHandler=0x0000555557045570, riid=0x0000555555ae6d10, ppResult=0x00007fffffffc250) + 22435 at dxcompilerobj.cpp:984
    frame #17: 0x00007fffef73ade0 libdxcompiler.so hlsl::DxcCompilerAdapter::WrapCompile:`hlsl::DxcCompilerAdapter::WrapCompile(this=0x0000555557045cc0, bPreprocess=NO, pSource=0x0000555557045d70, pSourceName=L"./4629.hlsl", pEntryPoint=L"main", pTargetProfile=L"ps_6_6", pArguments=0x0000555557045550, argCount=2 0x00000002, pDefines=0x00007fffffffdbe0, defineCount=0 0x00000000, pIncludeHandler=0x0000555557045570, ppResult=0x00007fffffffd710, ppDebugBlobName=0x0000000000000000, ppDebugBlob=0x0000000000000000) + 4288 at dxcompilerobj.cpp:1845
    frame #18: 0x00007fffef73c938 libdxcompiler.so hlsl::DxcCompilerAdapter::CompileWithDebug:`hlsl::DxcCompilerAdapter::CompileWithDebug(this=0x0000555557045cc0, pSource=0x0000555557045d70, pSourceName=L"./4629.hlsl", pEntryPoint=L"main", pTargetProfile=L"ps_6_6", pArguments=0x0000555557045550, argCount=2 0x00000002, pDefines=0x00007fffffffdbe0, defineCount=0 0x00000000, pIncludeHandler=0x0000555557045570, ppResult=0x00007fffffffd710, ppDebugBlobName=0x0000000000000000, ppDebugBlob=0x0000000000000000) + 360 at dxcompilerobj.cpp:1748
    frame #19: 0x00007fffef743e18 libdxcompiler.so hlsl::DxcCompilerAdapter::Compile:`hlsl::DxcCompilerAdapter::Compile(this=0x0000555557045cc0, pSource=0x0000555557045d70, pSourceName=L"./4629.hlsl", pEntryPoint=L"main", pTargetProfile=L"ps_6_6", pArguments=0x0000555557045550, argCount=2 0x00000002, pDefines=0x00007fffffffdbe0, defineCount=0 0x00000000, pIncludeHandler=0x0000555557045570, ppResult=0x00007fffffffd710) + 184 at dxcompileradapter.h:75
    frame #20: 0x0000555555df6490 dxc DxcContext::Compile:`DxcContext::Compile(this=0x00007fffffffda40) + 5344 at dxc.cpp:874
    frame #21: 0x0000555555dfc738 dxc dxc::main:`dxc::main(argc=4 0x00000004, argv_=0x00007fffffffe728) + 2744 at dxc.cpp:1502
    frame #22: 0x0000555555deb722 dxc main:`main(argc=4 0x00000004, argv_=0x00007fffffffe728) + 34 at dxcmain.cpp:19
    frame #23: 0x00007fffe6a9bd90 libc.so.6 __libc_start_call_main:`__libc_start_call_main(main=(dxc`main at dxcmain.cpp:18), argc=4 0x00000004, argv=0x00007fffffffe728) + 128 at libc_start_call_main.h:58
    frame #24: 0x00007fffe6a9be40 libc.so.6 __libc_start_main_impl:`__libc_start_main_impl(main=(dxc`main at dxcmain.cpp:18), argc=4 0x00000004, argv=0x00007fffffffe728, init=0x00007ffff7ffd040, fini=<unavailable>, rtld_fini=<unavailable>, stack_end=0x00007fffffffe718) + 128 at libc-start.c:392
    frame #25: 0x0000555555dc30b5 dxc _start:`_start + 37

[llvm-beanz]

I've also filed an issue to track removing interfaces in a future version of HLSL. They are broken and can't be used in many of the contexts that would make them interesting (see: microsoft/hlsl-specs#291).