<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/132610>132610</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [Flang][OpenMP] Assertion `!teamsOp.getRegion().empty() && teamsOp.getRegion().getBlocks().size() == 1' failed.
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
      </td>
    </tr>

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

    <tr>
      <th>Reporter</th>
      <td>
          k-arrows
      </td>
    </tr>
</table>

<pre>
    Reproducer:
```f90
 integer :: n
  !$omp teams

    n = 2
    if (n >= 2) &
      error stop

  !$omp end teams
end
```

Stack dump:
```console
flang: /path_to_llvm_project/llvm-project/flang/lib/Optimizer/OpenMP/GenericLoopConversion.cpp:402: static mlir::omp::LoopOp (anonymous namespace)::ReductionsHoistingPattern::tryToFindNestedLoopWithReduction(mlir::omp::TeamsOp): Assertion `!teamsOp.getRegion().empty() && teamsOp.getRegion().getBlocks().size() == 1' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
 #0 0x00007f8afe01b0d7 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) 
 #1 0x00007f8afe018c6e llvm::sys::RunSignalHandlers() 
 #2 0x00007f8afe01b7a5 SignalHandler(int, siginfo_t*, void*) Signals.cpp:0:0
 #3 0x00007f8afd940520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x00007f8afd9949fc __pthread_kill_implementation ./nptl/pthread_kill.c:44:76
 #5 0x00007f8afd9949fc __pthread_kill_internal ./nptl/pthread_kill.c:78:10
 #6 0x00007f8afd9949fc pthread_kill ./nptl/pthread_kill.c:89:10
 #7 0x00007f8afd940476 gsignal ./signal/../sysdeps/posix/raise.c:27:6
 #8 0x00007f8afd9267f3 abort ./stdlib/abort.c:81:7
 #9 0x00007f8afd92671b _nl_load_domain ./intl/loadmsgcat.c:1177:9
#10 0x00007f8afd937e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
#11 0x00007f8af96c382d (anonymous namespace)::ReductionsHoistingPattern::tryToFindNestedLoopWithReduction(mlir::omp::TeamsOp) GenericLoopConversion.cpp:0:0
#12 0x00007f8af96c8e14 std::_Function_handler<std::optional<bool> (mlir::Operation*), std::enable_if<!std::is_invocable_v<(anonymous namespace)::GenericLoopConversionPass::runOnOperation()::'lambda'(mlir::omp::TeamsOp), mlir::Operation*>, void>::type mlir::ConversionTarget::addDynamicallyLegalOp<mlir::omp::TeamsOp, (anonymous namespace)::GenericLoopConversionPass::runOnOperation()::'lambda'(mlir::omp::TeamsOp)>((anonymous namespace)::GenericLoopConversionPass::runOnOperation()::'lambda'(mlir::omp::TeamsOp)&&)::'lambda'(mlir::Operation*)>::_M_invoke(std::_Any_data const&, mlir::Operation*&&) GenericLoopConversion.cpp:0:0
#13 0x00007f8af23f8b2d mlir::ConversionTarget::isLegal(mlir::Operation*) const 
#14 0x00007f8af240bd19 mlir::WalkResult llvm::function_ref<mlir::WalkResult (mlir::Operation*)>::callback_fn<mlir::OperationConverter::convertOperations(llvm::ArrayRef<mlir::Operation*>)::$_6>(long, mlir::Operation*) DialectConversion.cpp:0:0
#15 0x00007f8af240ad8c mlir::WalkResult mlir::detail::walk<mlir::ForwardDominanceIterator<false>>(mlir::Operation*, llvm::function_ref<mlir::WalkResult (mlir::Operation*)>, mlir::WalkOrder) 
#16 0x00007f8af240ac08 mlir::WalkResult mlir::detail::walk<mlir::ForwardDominanceIterator<false>>(mlir::Operation*, llvm::function_ref<mlir::WalkResult (mlir::Operation*)>, mlir::WalkOrder) 
#17 0x00007f8af23f4c09 mlir::OperationConverter::convertOperations(llvm::ArrayRef<mlir::Operation*>) 
#18 0x00007f8af23fb54e mlir::applyFullConversion(mlir::Operation*, mlir::ConversionTarget const&, mlir::FrozenRewritePatternSet const&, mlir::ConversionConfig) 
#19 0x00007f8af96c2480 (anonymous namespace)::GenericLoopConversionPass::runOnOperation() GenericLoopConversion.cpp:0:0
#20 0x00007f8afae93a57 mlir::detail::OpToOpPassAdaptor::run(mlir::Pass*, mlir::Operation*, mlir::AnalysisManager, bool, unsigned int) 
#21 0x00007f8afae942c1 mlir::detail::OpToOpPassAdaptor::runPipeline(mlir::OpPassManager&, mlir::Operation*, mlir::AnalysisManager, bool, unsigned int, mlir::PassInstrumentor*, mlir::PassInstrumentation::PipelineParentInfo const*) 
#22 0x00007f8afae9bdce auto void mlir::parallelForEach<__gnu_cxx::__normal_iterator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo*, std::vector<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo, std::allocator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo>>>, mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::$_15>(mlir::MLIRContext*, __gnu_cxx::__normal_iterator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo*, std::vector<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo, std::allocator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo>>>, __gnu_cxx::__normal_iterator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo*, std::vector<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo, std::allocator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo>>>, mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::$_15&&)::'lambda'(__gnu_cxx::__normal_iterator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo*, std::vector<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo, std::allocator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo>>>&&)::operator()<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo&>(__gnu_cxx::__normal_iterator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo*, std::vector<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo, std::allocator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo>>>&&) const Pass.cpp:0:0
#23 0x00007f8afae9cd82 std::_Function_handler<void (), llvm::LogicalResult mlir::failableParallelForEach<__gnu_cxx::__normal_iterator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo*, std::vector<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo, std::allocator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo>>>, void mlir::parallelForEach<__gnu_cxx::__normal_iterator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo*, std::vector<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo, std::allocator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo>>>, mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::$_15>(mlir::MLIRContext*, __gnu_cxx::__normal_iterator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo*, std::vector<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo, std::allocator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo>>>, __gnu_cxx::__normal_iterator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo*, std::vector<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo, std::allocator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo>>>, mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::$_15&&)::'lambda'(__gnu_cxx::__normal_iterator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo*, std::vector<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo, std::allocator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo>>>&&)>(mlir::MLIRContext*, __gnu_cxx::__normal_iterator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo*, std::vector<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo, std::allocator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo>>>, __gnu_cxx::__normal_iterator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo*, std::vector<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo, std::allocator<mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::OpPMInfo>>>, mlir::detail::OpToOpPassAdaptor::runOnOperationAsyncImpl(bool)::$_15&&)::'lambda'()>::_M_invoke(std::_Any_data const&) Pass.cpp:0:0
#24 0x00007f8afdf227a8 std::_Function_handler<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> (), std::__future_base::_Task_setter<std::unique_ptr<std::__future_base::_Result<void>, std::__future_base::_Result_base::_Deleter>, std::thread::_Invoker<std::tuple<std::function<void ()>>>, void>>::_M_invoke(std::_Any_data const&) 
#25 0x00007f8afdf22707 std::__future_base::_State_baseV2::_M_do_set(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*) 
#26 0x00007f8afd997ee8 __pthread_once_slow ./nptl/pthread_once.c:118:7
#27 0x00007f8afdf22ad1 std::__future_base::_Deferred_state<std::thread::_Invoker<std::tuple<std::function<void ()>>>, void>::_M_complete_async() 
#28 0x00007f8afae9cb6c std::_Function_handler<void (), std::shared_future<void> llvm::ThreadPoolInterface::asyncImpl<void>(std::function<void ()>, llvm::ThreadPoolTaskGroup*)::'lambda'()>::_M_invoke(std::_Any_data const&) 
#29 0x00007f8afdfb92d5 llvm::StdThreadPool::processTasks(llvm::ThreadPoolTaskGroup*) 
#30 0x00007f8afdfba967 void* llvm::thread::ThreadProxy<std::tuple<llvm::StdThreadPool::grow(int)::$_0>>(void*) ThreadPool.cpp:0:0
#31 0x00007f8afd992ac3 start_thread ./nptl/pthread_create.c:442:8
#32 0x00007f8afda24850 ./misc/../sysdeps/unix/sysv/linux/x86_64/clone3.S:83:0
flang-21: error: unable to execute command: Aborted (core dumped)
flang-21: error: flang frontend command failed due to signal (use -v to see invocation)
flang version 21.0.0git (https://github.com/llvm/llvm-project.git 417390d77d6f828a2f2341e0565784c677ef13ab)
Target: x86_64-unknown-linux-gnu
Thread model: posix
```
</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJzsW91P47gW_2vCizVV4qRN8sBDp9BdpJkLAnT3MXLsk-KLY-faDtD966_spG0SoDPM3fnQLhJIiT_O5-_Yx_EpMYZvJMBpMP8YzM9OSGvvlD69_0C0Vo_mpFRse3oNjVaspaCDeBmEy2ARdn9VHgbhEnFpYQMaud54iaRrQwGOApyoukEWSG3cNNeMkERBfIZw_8YrFODMtZ13zThHAV70vQiB1kojY1Wzo3AgDJLtiYNkQ8m6wTeW0HvE2rqZCE6VNEpAEC4rQeTGSR3gdUPsXWFVIcRDXTRa_QeoDfDavX44vHYz8FrwMsDry8bymv8J2j-D_HwV4PVvIEFz-kmpZqXkA2jDlZzRxomRhNixM5ZYTlEtuO7Mpjoh46Wbddk4qxCp5LZWrUGS1GAaQiHAeTfqGlhLLVfS_K64sVxuroi1oGXXbfX2Vq25ZP8CY4E5mn9we7efFeDsBda3zpiXTccELY0B7QYjZzQc2a53tgF7DZuOSIDzGdSN3XbP3nV4gV4bugH7USh6b_p3w_-E3cz4zAEgCnCKKsIFsFkQLq8-nS9vzpFpy5pbRFDZbpCGRmmLrEJ31jbGiY7XAV5vuL1ryxlVde-0577jxrRgArxGRDLEJRUtA2TvAFFNzB0qCb23mlBwvFGA4xCFT2EYhmmVkQrCqAxZijxtbzCzNd3DlebSerjdau-m7DBIk8dCGauB1N48KxcwXuWORzThkdEFvMTjupU3fCOJ-J1IJkCbneU6MngqakrmaDQhwJnnvEKGb7isVGEDvHTvD4oz_5j3M0yP1tD_dwziIQOWJ-Ech8jL0MfCU7YoFskHwWX79GEj266DzoyaLQL8MXxK8ByHDl0dwWRMME_yiqKiaOydBsKKey5EwetGQA3ShYuSaBbgtWyscNE6GDajLrKSIF6mi574_GuISxcxRBwlm2ZBvIx2Rli8RHY45yitLB_SSqcGTdIF2hjvAE-mewzweubftoZB49DbKMOfArzWhBvwhHEaxMud6tmYLl6kVYxI6YLG07Gs85dv6uSKnKL99PzZ9KhEhRSFUIQVTNWEd47g0mvpmmuzoaSjFUWpE8Y52YE7HFOLU8gXb0NNnEO-6FDjCI7CJV_QOMPsJ6-W6NiCvwshJzueyJ5BlCBjWUewWLfS8yvu-oCNV_tO1bgeIoJ4VSolgvgcjcS6bECTTlgXxz7Kd3NBklJAwasgXgU42rdzU3D5oKjvffCdR834oppXxPQLlG7lpRzIke0nBjgVpC4ZCXD6xa0Hr9ArasXn-8XKpQveddsGBsMPYt0SvQHbtRLGzraS1JwSIbafYEPEZRPEq2NyrL6EqR9jDKdy9ktI4nf2L0-d4nDnqOKzx9q92xsPiF_KbcGIJchlZLbfHl8j1gvw1dE22rBwXGUlZl_ECjceH8d06oRFPZfRLoaTsGRRPuDyBxH312BaYQd7erULdA3VCIeD0V9lVQdol7QUlRzR2Y_vlLTQt9Pudd9tRpnKUmuyvZ6I9CwC9whIikWHT6FcRvy643J0xokAao-6az4xJGEZfdmQh0YGlnDRPT8ScT-SfK30I9HsTNVcEknhwjqhlFtWKyIMeCueH7Hz6i922chEbt6lZi4ty3dYWkxNQMPsH2aCdBK0CQ3zl4D1PYC9kyGbyFDOk-EmQ5pGbNetEAc4H7Xg60vOK8veWqs_QV7Do-YW-kzl5tXRB6IrJSu-GSiST_INnGThd9jXvnZFxqNkkEAek3n6CpQvm1t12Ti-S0YaD9me_cjWXrCpmV93wFISsTXcfCaSbBzuVshnU3iFWuk_hbDB6cyJHE1ETjCN3izyFW9AcAkTmLihe0mObn3fpMNwkmN1IY3VrTtMKf2M6nhAx7nr6GW_IhqkvZCV2uFwOTATnpipZBQQaa3y6dqAT0M0EQLEWulzQu-CeFUUG9kW9OmpzwkKqXRNRMEPa9Vb7T1A6NJsJb2oG7ejd2bK9-b_7LTpLbHPSR6A_gimA45ECEV_hKbdYj9dhf86Ri4liObTDeXzp4vrlZIWnnafG949_jM8_m71v1mcHT2RvXv7x3t75A_V9IbuD9zfWfP-KPbu9p_m9v6zgCP8QuobTxIkyjJ8_NOfT5x69IzOYZ_UhlMinp0EK8IFKYXL1N5TrJ-OitV75vtruuU98_2nefzd6n-zOHvPfH8xb-_98b4A_nrOebf6P2sB_KZr1_y1g8u4SqfCOCXZV9YstJL_t4WisaPWoqha22ooSmKgb-rOMl3L0G9fGtu1nIEAfxN0PjgvHaVxS8x9YcDa_0_g_pTW-_ubpR5N7mqG-jEX3ncjaWzbCBg27K7lJkfG6Ulk1_BGVPQomD9DQZgeV_jGEts1_BvvuTLlrD7kOpD-F8CNM9fycKMyvOGYVn6lANmgoExJCoUR6vGlAjDX2RdHZX2llSOZTo1KWHRchzOoQGtghXHWHcHie8Km9x5VdeMsVhC3PB3KD50u2fT7Rrmgb_q-sR9r7ojTsFP-EGGDDyC3XtcrpcSFtKArQnv7kP2yOQjMF7E2UXn0feVA3i0Tv2nVNrsL7L9ute3NNi62q8ocs_lAlBvLDtJ0TY1WFIxxoo0vuV8Vu-c1LmZlVUnyRbor_RzwHCKpp6nV0_YlMB0VdKPV467kdLB7hfuag0HV6WHu8x1oXCDL8hwTGiNjibZFJ-tLIUc1EAt9YahbgLKe2uimkhGcZPPQE6i5oc9rLVvpSy3N1jz4ykTZPu2LFgO8pkJJiGc3jkHcy-wrxD_gKIiXXf26e2h9DR6yCsET0NYCoqquiWS-1LpU2oIHJFUafMk6sK7m8UVqvhFV2uXWku1I9YXTiLWeUV9JGuCsNYA-PPg2ANTV_HV3y3sOqL-1RziahbNww30tx9sqrGduVhKlcR6yNGWLKsMZwRWOkwjC-WKeZgldpClUUUzKjve-9Ar1daCtvJfqUQ7qQcMehahWDBy2UFf_OqjnP2GnMcvjnJzAaZQmOI2TNMEnd6c5hSyCBUnSjM6rLIxTHOKEhhSnuIxiesJPcYjnYYzjCM_zEM9CyuY5LADypCxznAVJCDXhYuYUnSm9OfFF5KdRjBdReCJICcLsfj6hT705ynZjgiQU3FhzmGe5Ff6HFmv_C4L5WTD_2P9kYH7286vtT1otTr-9or63x8Mp_l8AAAD__6Kly2s">