<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/93894>93894</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            loongarch64 half (f16) failure to select with `+f` and `+d`
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          tgross35
      </td>
    </tr>
</table>

<pre>
    ```llvm
define half @half_add(half %a, half %b) unnamed_addr #0 {
start:
  %_0 = fadd half %a, %b
  ret half %_0
}
```

With `-mtriple=loongarch64-unknown-linux-gnu -mattr=+f,+d`:

```text
LLVM ERROR: Cannot select: t23: f32 = fp16_to_fp t21
  t21: i64 = fp_to_fp16 t4
    t4: f32,ch = CopyFromReg t0, Register:f32 %1
      t3: f32 = Register %1
In function: half_add
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=loongarch64-unknown-linux-gnu -mattr=+f,+d <source>
1.      Running pass 'Function Pass Manager' on module '<source>'.
2.      Running pass 'LoongArch DAG->DAG Pattern Instruction Selection' on function '@half_add'
 #0 0x00000000039e9678 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x39e9678)
 #1 0x00000000039e6dbc SignalHandler(int) Signals.cpp:0:0
 #2 0x00007e2b90a42520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #3 0x00007e2b90a969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #4 0x00007e2b90a42476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #5 0x00007e2b90a287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #6 0x0000000000720e07 (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x720e07)
 #7 0x000000000379ccad llvm::SelectionDAGISel::CannotYetSelect(llvm::SDNode*) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x379ccad)
 #8 0x00000000037a1c9a llvm::SelectionDAGISel::SelectCodeCommon(llvm::SDNode*, unsigned char const*, unsigned int) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x37a1c9a)
 #9 0x00000000016a2837 llvm::LoongArchDAGToDAGISel::Select(llvm::SDNode*) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x16a2837)
#10 0x0000000003799aee llvm::SelectionDAGISel::DoInstructionSelection() (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x3799aee)
#11 0x00000000037a7db6 llvm::SelectionDAGISel::CodeGenAndEmitDAG() (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x37a7db6)
#12 0x00000000037ab0bd llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x37ab0bd)
#13 0x00000000037acaff llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) (.part.0) SelectionDAGISel.cpp:0:0
#14 0x00000000029e6721 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (.part.0) MachineFunctionPass.cpp:0:0
#15 0x0000000002fad603 llvm::FPPassManager::runOnFunction(llvm::Function&) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x2fad603)
#16 0x0000000002fad841 llvm::FPPassManager::runOnModule(llvm::Module&) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x2fad841)
#17 0x0000000002fae0a5 llvm::legacy::PassManagerImpl::run(llvm::Module&) (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x2fae0a5)
#18 0x000000000083129c compileModule(char**, llvm::LLVMContext&) llc.cpp:0:0
#19 0x0000000000728536 main (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x728536)
#20 0x00007e2b90a29d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#21 0x00007e2b90a29e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#22 0x000000000082804e _start (/opt/compiler-explorer/clang-assertions-trunk/bin/llc+0x82804e)
Program terminated with signal: SIGSEGV
Compiler returned: 139
```

There is no error if the `-mattr` flag is omitted

Reproduction: https://llvm.godbolt.org/z/faenafnzh
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJy8mN9v47gRx_8a-mVgg6Jk_Xjwg2PH6QJJL0gWW_TJoChKZkORAkndJvfXF6Rkx_Kll0vP7WJ3LVGj73yGM-Ivaq1oFOcrtLxBy-2M9u6gzco1RlsbL2elrt5WKMXDXyl_bRHeIryueC0UhwOVNaAE-989rSpE8qGJLCkiGzjelIgU0CtFW155OwOIxBhQdjPIWUeNQ_F6uAP_yh4DirdQ06qCiWaQG-0Md6eHezy0omw7Xhyxx9vw_z-EOwBK8bx1RnSSo3grtVYNNeyQJvNevSj9U82lUP3rvFE9zFvqnEHxFpGbGpENIjeV1zzCXvhy_NUNTff3Px7g9unplycUr2FDldIOLJec-UjBkdj_1DEZ4uyidO_0vu7AkegYn7-M1yDSZDQaTKIUXHK0AX89KCGyYYdgudHd287o9ok34LDvtifeCOu4QfE6-CTL6F0BwE1ojsZnZt8U1L1iTmjlLU8ZDw8f72_Xz7dg-7IVDiiUfQOGd9o4cBoOznXWdxjZIbJrhDv05YLpFpFdqKjhZ94Z_S_fOWQnrO25RWQHVFUgFJN9xcEdODBD7QFKyl6coYwvBvfPjrIXqPq2O6UFLxAuHo1uDG2BmqZvuXIeAhDZ6c57YbrthORmzl87qQ03vk1S1cyptdz4SO3cmV69ILIrhQqcDObaS9Cu80K963q3sDB_zdM5te3cvilHX1G8FcpxCX-pzADFG6t7wziKb4ewIh_WU6-UUA101FpAJNuNeYFH3_BAFW18MBloBa2uesm91USMZGPXkY8E7z3q2rADbNd3cxTfbtd38Eid40bBN2Wd6QeHz6GcfUkM3o4VEvydDwvZWGvhs8ev-PgnLniRZjmEOojXKF7bNztcPBqhXMjsd59qRPJ3I0N_7rV1htMWkdSXt1DOjzGI5H8xv4jc4NcRC5HinTu64E6rksGzaBSVf6Oqkl4_HzGGZrtgna9IHP6dhMgolHFSFpgmZEnwCC5FicjuNU_3afJeHMMDtrB6kQa88MoELp5qFmlRM-jcwXBa7V-ElF9zEN6fOEguoZMshcaGOL8Kn2TpRHs51SZ5VsdASz96fEk5vDhRTs9zhjOCOc6uVSOD2sRdNimRrGCMVmelffpatuu7b89cDq3DzPBP7obHkzp_3v5dVxyR9TVre-CagOdTcBqxgn4KPrRudMU3um39GPAx-QZ6FVYZFbADNcC0su7yyZW_3yGESYzFeYxRSkkeZ2cxnsa87fruu_4g0P95YkamE7Qfc_BFRRWU808Ts9VnY_TZEJ1ft4o8ywQ2uqiirCrTz8tfV_yOq7Wqblvhtuu7a3MGjAknueAscfn5Zzq0rqW8oVawG6nZi52UxGkWHus7vW4UHnISRXwRBaN1_WkUple_qAfKDkLxI_Akit89O4ax6KhxCxxmtwvp309zni855yMFTzMSwX905JcuZ4gfsv0h1Ad6H3MtJ1w1rVIcn3HtHv2rx0XUl4muke0RapLt9JI6T6I_Qf0Qln_TDI9N1ybOk2hCnF0Qc0yXZ8SSN5S9jUu9d_Zvbfdeqv8Pbo814Z7MhTiPI1IwGH2cutNPZGH0D7PY2Sxy_-Nho1XYBQ6kUrKP67C4WJvkyziFlgp1vQWKlzyPjeCLlVZRFV9ceoZXJprRpSZPMOz3_rV92Nfvz4L60154MvVCplkhOU44DPrX6q9B9OT1uHl03LRCUccr-CncAYY1r99JPn-7e769-zGYb0bHYLjrjeKVt4ji4g_OIr4fuOEgLCgN3BhtQNRhlxvOJ8J-MMVQS9p4I90K53h1LvDEO6Or_n1TPtlo-6pcNLoqtXQLbRpEdr8hsqspV7RWvx1m1SquirigM76KsiiLoijKo9lhFaVlVNKacMYI4STFecFKFtU5KSJGYjYTK4JJgpcx9nWcRIuizCitMl5ERV0leYkSzFsq5CIwaNPMwpZ-VcR5kcwkLbm04ciJEMV_QniICEHL7cyswmFA2TcWJVgK6-y7ihNO8tXZTvp4-pPXUfjaaipkbzg4PR61DDnzHe_31SkOJwrDbYVSPOuNXP335xNDPL-uyL8DAAD___ZHzQg">