[x86_64/GlobalISel] Returning half type causes error "Cannot emit physreg copy instruction"

[HazyFish]

Description

Returning half type will crash the x86_64 Global ISel backend with LLVM ERROR: Cannot emit physreg copy instruction during Post-RA pseudo instruction expansion pass.

The problem does not exist when targeting i686 or aarch64.
The problem also does not exist when not using Global ISel.

Minimal Reproduction

https://godbolt.org/z/G1rszzf1n

Code

define half @f(ptr %0) {
  %h = load half, ptr %0
  ret half %h
}

Stack Trace

LLVM ERROR: Cannot emit physreg copy instruction
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.	Program arguments: /opt/compiler-explorer/clang-assertions-trunk/bin/llc -o /app/output.s -x86-asm-syntax=intel -mtriple=x86_64 --global-isel <source>
1.	Running pass 'Function Pass Manager' on module '<source>'.
2.	Running pass 'Post-RA pseudo instruction expansion pass' on function '@f'
 #0 0x0000000003398418 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x3398418)
 #1 0x0000000003395d0c SignalHandler(int) Signals.cpp:0:0
 #2 0x00007f6d11af4420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #3 0x00007f6d115b700b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4300b)
 #4 0x00007f6d11596859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859)
 #5 0x0000000000695331 (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x695331)
 #6 0x00000000032ee9e8 (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x32ee9e8)
 #7 0x0000000001d4ef15 llvm::X86InstrInfo::copyPhysReg(llvm::MachineBasicBlock&, llvm::MachineInstrBundleIterator<llvm::MachineInstr, false>, llvm::DebugLoc const&, llvm::MCRegister, llvm::MCRegister, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x1d4ef15)
 #8 0x0000000002937b38 llvm::TargetInstrInfo::lowerCopy(llvm::MachineInstr*, llvm::TargetRegisterInfo const*) const (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x2937b38)
 #9 0x000000000253ff67 (anonymous namespace)::ExpandPostRA::runOnMachineFunction(llvm::MachineFunction&) ExpandPostRAPseudos.cpp:0:0
#10 0x0000000002680049 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (.part.0) MachineFunctionPass.cpp:0:0
#11 0x0000000002bf8bb9 llvm::FPPassManager::runOnFunction(llvm::Function&) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x2bf8bb9)
#12 0x0000000002bf8df1 llvm::FPPassManager::runOnModule(llvm::Module&) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x2bf8df1)
#13 0x0000000002bf9612 llvm::legacy::PassManagerImpl::run(llvm::Module&) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x2bf9612)
#14 0x000000000075e092 compileModule(char**, llvm::LLVMContext&) llc.cpp:0:0
#15 0x000000000069a7e6 main (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x69a7e6)
#16 0x00007f6d11598083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083)
#17 0x0000000000754a4e _start (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x754a4e)
Program terminated with signal: SIGSEGV
Compiler returned: 139

[HazyFish]

@DataCorrupted

[llvmbot]

@llvm/issue-subscribers-backend-x86