<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/68539>68539</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            clang crash: Assertion `LHS.getValueType() == VT && RHS.getValueType() == VT && "Cannot use select on differing types"' failed.
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          shao-hua-li
      </td>
    </tr>
</table>

<pre>
    clang at -O3 crashes.

Bisected to f82c55fa082711f520a7359393b483956b69bf08, which was committed by @jayfoad 

Compiler explorer: https://godbolt.org/z/eexKfTxjn

```console
% cat a.c
unsigned a;
int b, d, h, i, j, l, r;
struct m {
  long n;
  short o;
 int p;
} q;
static int *s = &q.p;
unsigned char t;
int v() {
 int c;
  if (d) {
    if (h) {
      c = j;
    } else {
 if (l)
      c = i << b;
    }
  }
  return c;
}
void w(struct m p) {}
static struct m x() {
  unsigned k;
  struct m m = {};
  w(m);
  int **u = &s;
  int **n[] = {u};
  n != 0;
  for (; m.o <= 2;) {
    int o;
    *s = 0;
    r = 0 || 8;
    for (; t <= 2; t++) {
      k = 0;
      for (; k <= 2; k++) {
        int e[] = {2, 5, 5, 7, 0, 0, 6, 5, 0};
        int f;
        for (; f < a;) {
          int g;
          if (e[f])
            break;
 f += 6;
        }
      }
      m.p = 0;
      for (; v() + r + 1 + *s + k - 4 + m.p < 1; m.p = m.p + 1)
        for (; o; o++)
 ;
    }
  }
  return m;
}
int main() { x(); }
%
% clang -w -O3 a.c
clang: /root/llvm-project/llvm/include/llvm/CodeGen/SelectionDAG.h:1237: llvm::SDValue llvm::SelectionDAG::getSelect(const llvm::SDLoc&, llvm::EVT, llvm::SDValue, llvm::SDValue, llvm::SDValue): Assertion `LHS.getValueType() == VT && RHS.getValueType() == VT && "Cannot use select on differing types"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: /opt/compiler-explorer/clang-assertions-trunk/bin/clang -gdwarf-4 -g -o /app/output.s -S --gcc-toolchain=/opt/compiler-explorer/gcc-9.2.0 -fcolor-diagnostics -fno-crash-diagnostics -w -O3 <source>
1.      <eof> parser at end of file
2.      Code generation
3.      Running pass 'Function Pass Manager' on module '<source>'.
4.      Running pass 'X86 DAG->DAG Instruction Selection' on function '@main'
 #0 0x00000000037217e8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x37217e8)
 #1 0x000000000371f4ac llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x371f4ac)
 #2 0x0000000003668058 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007f6776ecc420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #4 0x00007f677698f00b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4300b)
 #5 0x00007f677696e859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859)
 #6 0x00007f677696e729 (/lib/x86_64-linux-gnu/libc.so.6+0x22729)
 #7 0x00007f677697ffd6 (/lib/x86_64-linux-gnu/libc.so.6+0x33fd6)
 #8 0x0000000000dc2e1f llvm::SelectionDAG::getSelect(llvm::SDLoc const&, llvm::EVT, llvm::SDValue, llvm::SDValue, llvm::SDValue) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xdc2e1f)
 #9 0x000000000469dee9 (anonymous namespace)::DAGCombiner::visitSELECT(llvm::SDNode*) DAGCombiner.cpp:0:0
#10 0x00000000046f77f8 (anonymous namespace)::DAGCombiner::visit(llvm::SDNode*) DAGCombiner.cpp:0:0
#11 0x00000000046f8805 (anonymous namespace)::DAGCombiner::combine(llvm::SDNode*) DAGCombiner.cpp:0:0
#12 0x00000000046fa06c (anonymous namespace)::DAGCombiner::Run(llvm::CombineLevel) DAGCombiner.cpp:0:0
#13 0x00000000046fc64a llvm::SelectionDAG::Combine(llvm::CombineLevel, llvm::AAResults*, llvm::CodeGenOptLevel) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x46fc64a)
#14 0x0000000004825a38 llvm::SelectionDAGISel::CodeGenAndEmitDAG() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x4825a38)
#15 0x00000000048294b8 llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x48294b8)
#16 0x000000000482b1b2 llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) (.part.0) SelectionDAGISel.cpp:0:0
#17 0x000000000231874c (anonymous namespace)::X86DAGToDAGISel::runOnMachineFunction(llvm::MachineFunction&) X86ISelDAGToDAG.cpp:0:0
#18 0x0000000002afabd1 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (.part.0) MachineFunctionPass.cpp:0:0
#19 0x00000000030a5b19 llvm::FPPassManager::runOnFunction(llvm::Function&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x30a5b19)
#20 0x00000000030a5d51 llvm::FPPassManager::runOnModule(llvm::Module&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x30a5d51)
#21 0x00000000030a6572 llvm::legacy::PassManagerImpl::run(llvm::Module&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x30a6572)
#22 0x0000000003995ed2 (anonymous namespace)::EmitAssemblyHelper::EmitAssembly(clang::BackendAction, std::unique_ptr<llvm::raw_pwrite_stream, std::default_delete<llvm::raw_pwrite_stream>>) BackendUtil.cpp:0:0
#23 0x0000000003996379 clang::EmitBackendOutput(clang::DiagnosticsEngine&, clang::HeaderSearchOptions const&, clang::CodeGenOptions const&, clang::TargetOptions const&, clang::LangOptions const&, 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>>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x3996379)
#24 0x000000000498c19f clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x498c19f)
#25 0x0000000005e89ea9 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x5e89ea9)
#26 0x000000000498b388 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x498b388)
#27 0x00000000041f0b09 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x41f0b09)
#28 0x0000000004171fde clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x4171fde)
#29 0x00000000042cfcae clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x42cfcae)
#30 0x0000000000bef2d6 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xbef2d6)
#31 0x0000000000be6b9a ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#32 0x0000000003fce1a9 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
#33 0x0000000003668504 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x3668504)
#34 0x0000000003fce79f 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
#35 0x0000000003f96965 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x3f96965)
#36 0x0000000003f973cd 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+0x3f973cd)
#37 0x0000000003f9f2f5 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x3f9f2f5)
#38 0x0000000000bec77c clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xbec77c)
#39 0x0000000000ae6c91 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xae6c91)
#40 0x00007f6776970083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083)
#41 0x0000000000be667e _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xbe667e)
clang: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134
%
```
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzkWltz27iS_jXwC0oqErw_-IGWrCSzmU0q9knNmwoEQYkxCXAA0Jf99VsASImg5Ng5o5ndqpNKGKkBdH99QzcoYCnrHaP0GkQ3IFpf4V7tubiWe8wX-x4vmvqq4OXLNWkw20Gs4OJLAInAck_lEnhr4OX2eVNLShQtoeKwShGJogp7KUp8v4qQh5MgyoIsKMI0yKK4iLOi8lKAVvBpX5M9fMISEt62tdIsihcIQu8Hfqk4LuFUyoq3Xd1QAelz13BBBQhyuFeqkyDIAdoAtNnxsuCNWnKxA2jzPwBtKH3-r-r--QebcgKxZ_8SziRv6EBFESRYQbwkltAzY58SYhDcWFLNFCw09FI_9vpR68cP_Wj0QxzmSiV6omALQTJQIGw420F2mAKh3HOhID9StITu8BUka_jnhCNWNTFTAMolBMEaAhT_uTwuOGAmeyygcoA_ApQClE3waCqZoKkrCFBaupPgSN-f0CEkBsSPCQ8INWjaSDoVZBg0AGWni2sIghUIVrCYcxm_TD4KqnrBJqAPY4-8LuETQOnB7t2Id5wy2O8w4fnEIPBgv4epk8YFrTW5ZXkc11JbrdvEktZHAOX96CZ5dpjZ5BsZ9y5nBgHy9ZA3IVZcaGuC4Aa2S26tt4ZIzzhxHHOCS5t1DBzPIQtLgyBZgWQFU2dwIlBNxUEF0I35exIXD2dkOIweHEYPrzKyOlDXSkhnWnR4JPrhHR7xYcBzrXnkV51QJ9AqDc0m_Tk8lsPuhMOYJhprBaL1LNjtn0JQPAktveBGKxWfsJsE_Zmv7bJ7y8KHdEc32r3oBvrmaSMAaRcsYGg-WW4r6NuYsqzN_3rViSITIdw-Ru8N896fyO1pImvrtrhmx-QcE1XLOkwDKJrs26ZELZ5MiTps4IaqqwRAG8G5AmjTNI_tohP8ByXjV4A2NSNNX9IjYcVL-oEygDZ3tKFE1Zyt8w_LPQhyHwWJ5mlmBjkI8rv1d9z0dEqZLLKUHVWWCFCqq45y1n_mBCATtkfq7fd7lzCI-RVipoHmUlKhwUAQe58_3i13VJnx-5eOjkYO1trl3--hwRHDb--cBxBaYca4gr2kUBoVIWewrKuKiprtoHrpqAQIAZTACtcNLYfe4evn2_zuFsq-aGsFMSz6HRS00_VQ8Xlhr9W-L5aEt0cfzVxZS9lrQRuIWQkHj0K1p7ZlgQUmD0pgYmzVCdoJTqiUtISS98KS9UosJSc11r2I6BmURNSdGiDfKUweYNm3nUZmSN4SeNlXwXcCtxCLXd9SpuQQdLzTyMjQuCwOjQvamNBc4NE1cqFEzx4A2hQ68DdDPO_KJyyqRQgXO7jgmiPuOs23V12vlhIu7uBisSNkoThvyF5nTbD-qWA9OVuipQcXFeENF4uyxjvGpaqJhIuK8YWxl0u2iQWC1WCr4NZq72vtQbCivALBLeywkFToVpGyEvIKVvXYXSE9U6cV3FFGBdZa25FAj3zrGdPR0mGpN6dk0zOTQPCrJvyOGd5p-ImOrZaXfUP1LAcQSgYvhecY_pHGcJ1_WIDgdp1_gJ-YLepaxCFbB_7VKFtLCD27FyXj1oYCD3rP3vgnSJCf0HSSffJF2g9fRc2UCZl7G3fpcZLAT1sulaC4HTK_Zsru1ulfDhyAbrznAdhkU0aB7yL3qxCTc8hXDcWs776wu3rHcANQeuiLdAd7YZwGhoMTOTjjOPWiFK50WH6jhD9S8WKBfcSsbLS4dLCeM2fFmaLPakk6na6e-XcQEQwikipOkpgSEiIPbreCSsUF3Qo1aNjUBUCb5zTexuGiqVn_vNix3g50ai8oLpeSLz2jix-GyHM0CR0xWVp5XgEFrnV3_CZ_ojnHhnMYeF7hcI5czjFNowzigr8L-YQzQmmUOZzjOefk4O9380yQyzNxeSZVVca_xjMIqjJ2eKbTKPFKgqhfvbsIz8ovNEX57ynCl8sVq6NjhGxqhDDOSkqNQMw4e2l5LyHDLZWd2YAyC22df1jxtqiZOUODIH-sZa3ubj_fru5npvlvrtuiXGsxWXWaUnpz8VwoVZJU6b8H5S-A8Gcg0tSLfhkEsd_-Agw0g4G9mPwyjG89cyAMo5_pI23ehSKYoSBxiH-aIaszirtSpyGe59-o7BsljVWmI0P__KVTB7AXS4JBj0MWaEVDR9EURThIX1H00x1tHJA5K2_bWmkbjAemSyG1QByk0QxpFhZvI7XUvGlusKzJTcPJg3R8dGiXjtvYZfXQMB094pkehV-gN_UQPfvCfsdkXzM6Qnb0OBkbFVl2WChdZTM4Z30-9JMpPhT4aRK-mYB_pPE6_3DPL4H5jzTWPEZ-50E6FQzhChelD1_lrFvhCaazYH5quTP8zuNyikrg4ajwswmuzVe9dGzKfxnRhfpGC2salMib4y4j_x24fzcHCtepA-nymMvIdzD7M8xxlEwTqaE7TF6GA8UR_ae2O8bnP4NcA3OQu116lkW0RG-lmN5pcylpWzQvH2nTjX6Y0gFKxzc3IMhvMHmgrMyHIFpBqUo70rP6z55uOyVAsHKPVt2TqBXdjgesyaKSVrhv1LakDVX0jYXBrTlYZnAA8S9Vn99uUDCzRRwkGZxoofUbmHwxh3dXyfXxsH3LdqYCm050MuUjxSUVdxQLsv_SGW85Tetk6rH6_mzWPRY7qt6Y9Bmz3bkpk51eiZrtvtHKJY9hmM8YnrjzuOQTU6KX9SP9RqsVU19nfn2sht1vUzf07kUqahz0fxQRl8ssGyxOZrntTJYSP6vOGHHFmezbMYXsYfheYCYb83rlX6yehVl-dz8cii_eIliQjhZOqxPRNKPYyYmvWEia3927GO9oi4cgKzhvjv9fEO0AxkEbz2xeBGl6JqmGwLVJ_UxJr-gYyxduHi0EB6PT1IR-5RWeY9GN0N49ZNcU5MXhWekOvNSFl_hVSV0TWoGfmFSYEXreiq_rc-mYtQgdFdzjNCIVwY4KA9ijJo-c4FPgJ5raY-PloFtkU-jua0mvoBUqY0iIvx1-TJmc24TAL3rHDlbmZ-JhY8-H7dSloRV85HV5aQ0sPkcBf6ZAXGQYjgZf-fdmF5ieyFvcNN8pUXxoh85oMytWmsewAzpHpVLUj68comcvIytCfZwZk0z4jq-Mt8JY1YyOv1ndDu8UcNMUmDxsK6aRHmPFyh7iZuWveNtiVs6T96z3DjWMmxKNG6d6HSvzULUmRW-7Jc_Pvm-_FPpUqStcrTEZKzqTNWGrBK6VHIdn7HDT6DzgYjKup-TH7duEj7W5WQJQ0uC2KDFAydFUKB1fMP_Gi_P-COYvhyMvnL56OPMK-PA65Q5X1DSY73XdRSu9xerEfDgPrsSt9P9xwTE7sr4aBZFruCzO4uhVwxmv4ZOaOFrT2bpnC_WE15rjn0zNnRZmotuFQskq7IRSPLNIEpDyVy3yGy_k6-b4jRefa6leOwicbMeHCOhwrZ1vfqR5vwWHMPmb7ajN5NgxmdmxQtWrkbWefHZagzM9wWv2_wfteMnNzBrGsVw6K-AkSYhFOfYgI3KzieQnr41fK88X7Do0Jge00_F5mMYk8839k8tJtUynUkNv9nuY56UB3G6butB7LRZqO4Hw3l_dQi8NHCknHVWcUGj5X9Kmmu1B7uHSDRWCmzua9jJDNfTy5q6njk97GQQ-1WoP6XOtPV5S6AehhtZLChePUHEoKYX1pM3OZrdB7UUiqjNEL55fDhqvel6V10GZBRm-otd-nMWp56VherW_zrI0CaogjIusSNMkLMIgiQmJaBJ6YeDRq_oaeSjwPS9FfhB66RL5aVwiggMUJ2mFAhB6tMV1s9SBvORid2XuolzHaRRkVw0uaCPNHVuEBqshEK2vxLW5wVL0OwlCr6mlkkcOqlYNHW7emvsY_z9v8lz1orn-96_qGAv9bwAAAP__7y4q1A">