[HLSL][DirectX][SPIR-V] `llvm.copysign` fails to lower

[kmpeng]

https://godbolt.org/z/xdsqYdYeh

Code that reproduces the error:

// RUN: %clang-dxc -T cs_6_5 %s
// RUN: %clang-dxc -spirv -T cs_6_5 %s
RWStructuredBuffer<float> Out : register(u0);

[numthreads(1,1,1)]
void main(uint3 id : SV_DispatchThreadID) {
  float x = Out[id.x];
  Out[0] = x / abs(x);
}

x / abs(x) is optimized into @llvm.copysign.f32, which fails to lower on both backends:

error: Unsupported intrinsic llvm.copysign.f32 for DXIL lowering

fatal error: error in backend: cannot select: %19:fid(s64) = nnan ninf nsz arcp afn reassoc G_FCOPYSIGN %18:fid, %17:fid(s64) (in function: main)
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace and dumped files.
Stack dump:
0.	Program arguments: /opt/compiler-explorer/clang-assertions-trunk/bin/clang --driver-mode=dxc -Zi -Qembed_debug -Fc /app/output.s -fcolor-diagnostics -fno-crash-diagnostics -T cs_6_5 -spirv <source>
1.	<eof> parser at end of file
2.	Code generation
3.	Running pass 'Function Pass Manager' on module '<source>'.
4.	Running pass 'InstructionSelect' on function '@main'
 #0 0x000000000446f2a8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x446f2a8)
 #1 0x000000000446c154 llvm::sys::RunSignalHandlers() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x446c154)
 #2 0x000000000446c78c llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x446c78c)
 #3 0x00000000043ab586 llvm::CrashRecoveryContext::HandleExit(int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x43ab586)
 #4 0x0000000004463cfe llvm::sys::Process::Exit(int, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x4463cfe)
 #5 0x0000000000da8810 LLVMErrorHandler(void*, char const*, bool) cc1_main.cpp:0:0
 #6 0x00000000043b5003 llvm::report_fatal_error(llvm::Twine const&, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x43b5003)
 #7 0x00000000043b521b (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x43b521b)
 #8 0x0000000005a44cb2 reportGISelDiagnostic(llvm::DiagnosticSeverity, llvm::MachineFunction&, llvm::MachineOptimizationRemarkEmitter&, llvm::MachineOptimizationRemarkMissed&) Utils.cpp:0:0
 #9 0x0000000005a521c1 llvm::reportGISelFailure(llvm::MachineFunction&, llvm::MachineOptimizationRemarkEmitter&, char const*, llvm::StringRef, llvm::MachineInstr const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x5a521c1)
#10 0x00000000059acd3d llvm::InstructionSelect::selectMachineFunction(llvm::MachineFunction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x59acd3d)
#11 0x00000000059ae2f8 llvm::InstructionSelect::runOnMachineFunction(llvm::MachineFunction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x59ae2f8)
#12 0x000000000370136d llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (.part.0) MachineFunctionPass.cpp:0:0
#13 0x0000000003d4ae21 llvm::FPPassManager::runOnFunction(llvm::Function&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x3d4ae21)
#14 0x0000000003d4b351 llvm::FPPassManager::runOnModule(llvm::Module&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x3d4b351)
#15 0x0000000003d4bd11 llvm::legacy::PassManagerImpl::run(llvm::Module&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x3d4bd11)
#16 0x0000000004883b68 (anonymous namespace)::EmitAssemblyHelper::TimeCodegenPasses(llvm::function_ref<void ()>) (.isra.0) BackendUtil.cpp:0:0
#17 0x0000000004893d96 (anonymous namespace)::EmitAssemblyHelper::emitAssembly(clang::BackendAction, std::unique_ptr<llvm::raw_pwrite_stream, std::default_delete<llvm::raw_pwrite_stream>>, clang::BackendConsumer*) BackendUtil.cpp:0:0
#18 0x00000000048942e4 clang::emitBackendOutput(clang::CompilerInstance&, clang::CodeGenOptions&, llvm::StringRef, llvm::Module*, clang::BackendAction, llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem>, std::unique_ptr<llvm::raw_pwrite_stream, std::default_delete<llvm::raw_pwrite_stream>>, clang::BackendConsumer*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x48942e4)
#19 0x0000000004f6a677 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x4f6a677)
#20 0x0000000006d8315c clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x6d8315c)
#21 0x0000000004f6aab8 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x4f6aab8)
#22 0x00000000052b2f1d clang::HLSLFrontendAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x52b2f1d)
#23 0x00000000052951d8 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x52951d8)
#24 0x000000000522357d clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x522357d)
#25 0x000000000536a20d clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x536a20d)
#26 0x0000000000daafbc cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xdaafbc)
#27 0x0000000000da1bda ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&, llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem>) driver.cpp:0:0
#28 0x0000000000da1d5d int llvm::function_ref<int (llvm::SmallVectorImpl<char const*>&)>::callback_fn<clang_main(int, char**, llvm::ToolContext const&)::'lambda'(llvm::SmallVectorImpl<char const*>&)>(long, llvm::SmallVectorImpl<char const*>&) driver.cpp:0:0
#29 0x0000000004fe3789 void llvm::function_ref<void ()>::callback_fn<clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const::'lambda'()>(long) Job.cpp:0:0
#30 0x00000000043ab4c4 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x43ab4c4)
#31 0x0000000004fe42f5 clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const (.part.0) Job.cpp:0:0
#32 0x0000000004f9bfa2 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x4f9bfa2)
#33 0x0000000004fa0907 clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x4fa0907)
#34 0x0000000004faafd5 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x4faafd5)
#35 0x0000000000da74ba clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xda74ba)
#36 0x0000000000cc320a main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xcc320a)
#37 0x00007adba6e2a1ca (/lib/x86_64-linux-gnu/libc.so.6+0x2a1ca)
#38 0x00007adba6e2a28b __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2a28b)
#39 0x0000000000da1585 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xda1585)
Compiler returned: 1