Segfault when trying to use hull shader as lib.

Description
This is generated code from a tool I built. Expectation is an error that this is only supported on hull shader stages. The issue seems to be because of the patchconstantfunc .

Steps to Reproduce
Run DXC_Debug_BUILD/bin/dxc -T lib_6_8 -enable-16bit-types -O0 test.hlsl

RWStructuredBuffer<float> buffer : register(u0);
void fn () {}

[domain("tri")]
[outputtopology("triangle_cw")]
[patchconstantfunc("fn")]
[outputcontrolpoints(3)]
[partitioning("pow2")]
void main( const uint index : SV_OutputControlPointID) {
	buffer[index] = 1;
}

Actual Behavior

Process 1116521 launched: '/mnt/DevDrive/projects/HLSLDocGenerator/DXC_Debug_BUILD/bin/dxc' (x86_64)
Process 1116521 stopped
* thread #1, name = 'dxc', stop reason = signal SIGSEGV: address not mapped to object (fault address: 0x20)
    frame #0: 0x00007ffff446a15c libdxcompiler.so`llvm::GlobalValue::getLinkage(this=0x0000000000000000) const at GlobalValue.h:289:44
   286        Visibility = DefaultVisibility;
   287      Linkage = LT;
   288    }
-> 289    LinkageTypes getLinkage() const { return Linkage; }
   290 
   291    bool isDiscardableIfUnused() const {
   292      return isDiscardableIfUnused(Linkage);
(lldb) bt
* thread #1, name = 'dxc', stop reason = signal SIGSEGV: address not mapped to object (fault address: 0x20)
  * frame #0: 0x00007ffff446a15c libdxcompiler.so`llvm::GlobalValue::getLinkage(this=0x0000000000000000) const at GlobalValue.h:289:44
    frame #1: 0x00007ffff50778c7 libdxcompiler.so`CGHLSLMSHelper::UpdateLinkage(HLM=0x0000555555a220b0, CGM=0x0000555555a1f1c0, exportMap=0x0000555555a21ba0, entryFunctionMap=0x0000555555a21d68, patchConstantFunctionMap=0x0000555555a21cd8) at CGHLSLMSFinishCodeGen.cpp:3474:17
    frame #2: 0x00007ffff50281a1 libdxcompiler.so`(anonymous namespace)::CGMSHLSLRuntime::FinishCodeGen(this=0x0000555555a21820) at CGHLSLMS.cpp:3980:3
    frame #3: 0x00007ffff4df5fed libdxcompiler.so`clang::CodeGen::CodeGenModule::FinishCodeGen(this=0x0000555555a1f1c0) at CodeGenModule.cpp:246:16
    frame #4: 0x00007ffff4df7855 libdxcompiler.so`clang::CodeGen::CodeGenModule::Release(this=0x0000555555a1f1c0) at CodeGenModule.cpp:447:5
    frame #5: 0x00007ffff4d75477 libdxcompiler.so`(anonymous namespace)::CodeGeneratorImpl::HandleTranslationUnit(this=0x0000555555a1a0f0, Ctx=0x0000555555a03ec0) at ModuleBuilder.cpp:232:18
    frame #6: 0x00007ffff4d56425 libdxcompiler.so`clang::BackendConsumer::HandleTranslationUnit(this=0x0000555555a19ff0, C=0x0000555555a03ec0) at CodeGenAction.cpp:147:14
    frame #7: 0x00007ffff62be9d4 libdxcompiler.so`clang::ParseAST(S=0x0000555555a1ad50, PrintStats=false, SkipFunctionBodies=false) at ParseAST.cpp:164:13
    frame #8: 0x00007ffff50ff656 libdxcompiler.so`clang::ASTFrontendAction::ExecuteAction(this=0x00007fffffff9ea0) at FrontendAction.cpp:554:3
    frame #9: 0x00007ffff4d54d41 libdxcompiler.so`clang::CodeGenAction::ExecuteAction(this=0x00007fffffff9ea0) at CodeGenAction.cpp:807:28
    frame #10: 0x00007ffff50ff14c libdxcompiler.so`clang::FrontendAction::Execute(this=0x00007fffffff9ea0) at FrontendAction.cpp:455:8
    frame #11: 0x00007ffff43e5459 libdxcompiler.so`DxcCompiler::Compile(this=0x00005555559d9af0, pSource=0x00007fffffffc540, pArguments=0x00005555559d9a10, argCount=7, pIncludeHandler=0x00005555559d9640, riid=0x00005555557fd6b0, ppResult=0x00007fffffffba38) at dxcompilerobj.cpp:984:18
    frame #12: 0x00007ffff43d9dbd libdxcompiler.so`hlsl::DxcCompilerAdapter::WrapCompile(this=0x00005555559d9f10, bPreprocess=NO, pSource=0x00005555559da1d0, pSourceName=L"scratch/GSInstanceID_test.hlsl", pEntryPoint=L"lib.no::entry", pTargetProfile=L"lib_6_8", pArguments=0x00005555559d99b0, argCount=4, pDefines=0x00007fffffffd188, defineCount=0, pIncludeHandler=0x00005555559d9640, ppResult=0x00007fffffffcd40, ppDebugBlobName=0x0000000000000000, ppDebugBlob=0x0000000000000000) at dxcompilerobj.cpp:1845:5
    frame #13: 0x00007ffff43db2ac libdxcompiler.so`hlsl::DxcCompilerAdapter::CompileWithDebug(this=0x00005555559d9f10, pSource=0x00005555559da1d0, pSourceName=L"scratch/GSInstanceID_test.hlsl", pEntryPoint=L"lib.no::entry", pTargetProfile=L"lib_6_8", pArguments=0x00005555559d99b0, argCount=4, pDefines=0x00007fffffffd188, defineCount=0, pIncludeHandler=0x00005555559d9640, ppResult=0x00007fffffffcd40, ppDebugBlobName=0x0000000000000000, ppDebugBlob=0x0000000000000000) at dxcompilerobj.cpp:1748:10
    frame #14: 0x00007ffff43df066 libdxcompiler.so`hlsl::DxcCompilerAdapter::Compile(this=0x00005555559d9f10, pSource=0x00005555559da1d0, pSourceName=L"scratch/GSInstanceID_test.hlsl", pEntryPoint=L"lib.no::entry", pTargetProfile=L"lib_6_8", pArguments=0x00005555559d99b0, argCount=4, pDefines=0x00007fffffffd188, defineCount=0, pIncludeHandler=0x00005555559d9640, ppResult=0x00007fffffffcd40) at dxcompileradapter.h:75:12
    frame #15: 0x00005555555c1c17 dxc`DxcContext::Compile(this=0x00007fffffffcfe8) at dxc.cpp:874:9
    frame #16: 0x00005555555c5db3 dxc`dxc::main(argc=6, argv_=0x00007fffffffdcc8) at dxc.cpp:1502:24
    frame #17: 0x00005555555ba732 dxc`main(argc=6, argv_=0x00007fffffffdcc8) at dxcmain.cpp:19:10
    frame #18: 0x00007ffff3a29d90 libc.so.6`__libc_start_call_main(main=(dxc`main at dxcmain.cpp:18), argc=6, argv=0x00007fffffffdcc8) at libc_start_call_main.h:58:16
    frame #19: 0x00007ffff3a29e40 libc.so.6`__libc_start_main_impl(main=(dxc`main at dxcmain.cpp:18), argc=6, argv=0x00007fffffffdcc8, init=<unavailable>, fini=<unavailable>, rtld_fini=<unavailable>, stack_end=0x00007fffffffdcb8) at libc-start.c:392:3
    frame #20: 0x00005555555ba645 dxc`_start + 37

Environment

• DXC version e7b78ff9c99c19a6a0c98256db9794e0af4eb59d
• Host Operating System Ubuntu 22.04

Start with CGHLSLMSFinishCodeGen.cpp at CGHLSLMSHelper::UpdateLinkage, line 3474, and trace how patchConstantFunctionMap is handled during FinishCodeGen. Reproduce with the supplied dxc command and HLSL input. Done means the invalid hull-shader usage produces the expected diagnostic instead of a segmentation fault.