<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/69880>69880</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            clang: Assertion `SrcSubReg == PrevCopy->getOperand(1).getSubReg() && "Unexpected mismatching subreg!"' 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 on the following test case.

Bisected to 760e7d00d142ba85fcf48c00e0acc14a355da7c3, which was committed by @weiguozhi 

Compiler explorer: https://godbolt.org/z/Yz1M9hKv8

```console
% cat a.c
int a, b, c, d, j;
static int *e = &d, *h;
static int **f = &e;
int *g;
int *i;
long l;
void m() { int ***k[2] = {&f, &f}; }
int* n() {return i;}
void o() {
  int *p = &c;
  int q = 5;
  int r;
  for (; j;)
  s:;
    for (;;) {
      *p = q;
      **f = 0 >= b;
 if (a << **f) {
        i = &r;
        for (;;)
          ;
 }
      int *t = &q;
      h = t;
      if (c)
        goto s;
      if (l)
        g = n();
    }
}
int main() {}
% clang -O3 a.c
clang-18: /tmp/tmp85p3naqm/tmpa6gf87vx/llvm/lib/CodeGen/PeepholeOptimizer.cpp:1451: bool {anonymous}::PeepholeOptimizer::foldRedundantCopy(llvm::MachineInstr&, llvm::DenseMap<llvm::TargetInstrInfo::RegSubRegPair, llvm::MachineInstr*>&, llvm::SmallPtrSetImpl<llvm::MachineInstr*>&): Assertion `SrcSubReg == PrevCopy->getOperand(1).getSubReg() && "Unexpected mismatching subreg!"' 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: /zdata/shaoli/compilers/ccbuilder-compilers/clang-760e7d00d142ba85fcf48c00e0acc14a355da7c3/bin/clang-18 -cc1 -triple x86_64-unknown-linux-gnu -emit-obj -dumpdir a- -disable-free -clear-ast-before-backend -main-file-name reduced.c -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=none -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fdebug-compilation-dir=/zdata/shaoli/realsmith/watchdir/reduced/case_pMV4NNXz -fcoverage-compilation-dir=/zdata/shaoli/realsmith/watchdir/reduced/case_pMV4NNXz -resource-dir /zdata/shaoli/compilers/ccbuilder-compilers/clang-760e7d00d142ba85fcf48c00e0acc14a355da7c3/lib/clang/18 -internal-isystem /zdata/shaoli/compilers/ccbuilder-compilers/clang-760e7d00d142ba85fcf48c00e0acc14a355da7c3/lib/clang/18/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/11/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O3 -ferror-limit 19 -fgnuc-version=4.2.1 -fcolor-diagnostics -vectorize-loops -vectorize-slp -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/reduced-17f42f.o -x c reduced.c
1.      <eof> parser at end of file
2.      Code generation
3.      Running pass 'Function Pass Manager' on module 'reduced.c'.
4.      Running pass 'Peephole Optimizations' on function '@o'
 #0 0x00007f1154c42f2f llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-760e7d00d142ba85fcf48c00e0acc14a355da7c3/bin/../lib/libLLVM-18git.so+0x926f2f)
 #1 0x00007f1154c40494 SignalHandler(int) Signals.cpp:0:0
 #2 0x00007f1153f31090 (/lib/x86_64-linux-gnu/libc.so.6+0x43090)
 #3 0x00007f1153f3100b raise /build/glibc-BHL3KM/glibc-2.31/signal/../sysdeps/unix/sysv/linux/raise.c:51:1
 #4 0x00007f1153f10859 abort /build/glibc-BHL3KM/glibc-2.31/stdlib/abort.c:81:7
 #5 0x00007f1153f10729 get_sysdep_segment_value /build/glibc-BHL3KM/glibc-2.31/intl/loadmsgcat.c:509:8
 #6 0x00007f1153f10729 _nl_load_domain /build/glibc-BHL3KM/glibc-2.31/intl/loadmsgcat.c:970:34
 #7 0x00007f1153f21fd6 (/lib/x86_64-linux-gnu/libc.so.6+0x33fd6)
 #8 0x00007f1155327336 (anonymous namespace)::PeepholeOptimizer::foldRedundantCopy(llvm::MachineInstr&, llvm::DenseMap<llvm::TargetInstrInfo::RegSubRegPair, llvm::MachineInstr*, llvm::DenseMapInfo<llvm::TargetInstrInfo::RegSubRegPair, void>, llvm::detail::DenseMapPair<llvm::TargetInstrInfo::RegSubRegPair, llvm::MachineInstr*>>&, llvm::SmallPtrSetImpl<llvm::MachineInstr*>&) (.isra.0) PeepholeOptimizer.cpp:0:0
 #9 0x00007f1155327c4e (anonymous namespace)::PeepholeOptimizer::runOnMachineFunction(llvm::MachineFunction&) (.part.0) PeepholeOptimizer.cpp:0:0
#10 0x00007f11551ab0c1 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (.part.0) MachineFunctionPass.cpp:0:0
#11 0x00007f1154e0ac51 llvm::FPPassManager::runOnFunction(llvm::Function&) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-760e7d00d142ba85fcf48c00e0acc14a355da7c3/bin/../lib/libLLVM-18git.so+0xaeec51)
#12 0x00007f1154e0ae99 llvm::FPPassManager::runOnModule(llvm::Module&) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-760e7d00d142ba85fcf48c00e0acc14a355da7c3/bin/../lib/libLLVM-18git.so+0xaeee99)
#13 0x00007f1154e0b722 llvm::legacy::PassManagerImpl::run(llvm::Module&) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-760e7d00d142ba85fcf48c00e0acc14a355da7c3/bin/../lib/libLLVM-18git.so+0xaef722)
#14 0x00007f115b5732ca (anonymous namespace)::EmitAssemblyHelper::EmitAssembly(clang::BackendAction, std::unique_ptr<llvm::raw_pwrite_stream, std::default_delete<llvm::raw_pwrite_stream>>) BackendUtil.cpp:0:0
#15 0x00007f115b5737a9 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>>) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-760e7d00d142ba85fcf48c00e0acc14a355da7c3/bin/../lib/libclang-cpp.so.18git+0x20977a9)
#16 0x00007f115ba337d7 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-760e7d00d142ba85fcf48c00e0acc14a355da7c3/bin/../lib/libclang-cpp.so.18git+0x25577d7)
#17 0x00007f1159f4f3a9 clang::ParseAST(clang::Sema&, bool, bool) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-760e7d00d142ba85fcf48c00e0acc14a355da7c3/bin/../lib/libclang-cpp.so.18git+0xa733a9)
#18 0x00007f115ba329b8 clang::CodeGenAction::ExecuteAction() (/zdata/shaoli/compilers/ccbuilder-compilers/clang-760e7d00d142ba85fcf48c00e0acc14a355da7c3/bin/../lib/libclang-cpp.so.18git+0x25569b8)
#19 0x00007f115c6ccbb9 clang::FrontendAction::Execute() (/zdata/shaoli/compilers/ccbuilder-compilers/clang-760e7d00d142ba85fcf48c00e0acc14a355da7c3/bin/../lib/libclang-cpp.so.18git+0x31f0bb9)
#20 0x00007f115c64862e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-760e7d00d142ba85fcf48c00e0acc14a355da7c3/bin/../lib/libclang-cpp.so.18git+0x316c62e)
#21 0x00007f115c765766 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-760e7d00d142ba85fcf48c00e0acc14a355da7c3/bin/../lib/libclang-cpp.so.18git+0x3289766)
#22 0x0000564f16109aa6 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-760e7d00d142ba85fcf48c00e0acc14a355da7c3/bin/clang-18+0x15aa6)
#23 0x0000564f161013da ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#24 0x0000564f1610601c clang_main(int, char**, llvm::ToolContext const&) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-760e7d00d142ba85fcf48c00e0acc14a355da7c3/bin/clang-18+0x1201c)
#25 0x0000564f16100e55 main (/zdata/shaoli/compilers/ccbuilder-compilers/clang-760e7d00d142ba85fcf48c00e0acc14a355da7c3/bin/clang-18+0xce55)
#26 0x00007f1153f12083 __libc_start_main /build/glibc-BHL3KM/glibc-2.31/csu/../csu/libc-start.c:342:3
#27 0x0000564f16100e9e _start (/zdata/shaoli/compilers/ccbuilder-compilers/clang-760e7d00d142ba85fcf48c00e0acc14a355da7c3/bin/clang-18+0xce9e)
clang: error: unable to execute command: Aborted
clang: error: clang frontend command failed due to signal (use -v to see invocation)
clang version 18.0.0 (https://github.com/llvm/llvm-project.git 760e7d00d142ba85fcf48c00e0acc14a355da7c3)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /zdata/shaoli/compilers/ccbuilder-compilers/clang-760e7d00d142ba85fcf48c00e0acc14a355da7c3/bin
clang: note: diagnostic msg:
********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang: note: diagnostic msg: /tmp/reduced-55cf75.c
clang: note: diagnostic msg: /tmp/reduced-55cf75.sh
clang: note: diagnostic msg:

********************
%
```
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzUOtty27a2XwO_YKghQfH24AdZtprMTmqP7Xaf86QBwUUKLQiwACjb-fozAKkLZXkn6elu3IxDSQsL64Z1AwhqDG8kwCVKrlByfUF7u1H60myoCjY9DQS_KFX1crkUVDaYWhzcxphpajZgsJLYbgDXSgj1xGWDLRiLGTUwQ-E1ChfD84obYBYqbBXO0hCyKgyraE5Kmic1q-c5C0MIKWPRnMZJUtGMxYgs8dOGsw1-ogYz1bbcOhLlC0bz8Al406svG46P-SxV23EBGsNzJ5QGjeIF3ljbGRQvEFkhsmpUVSphZ0o3iKy-ILL63y_R52Lzr21-TAml4fDHlDRKwAglCWbUYjpjA4BLi6mTtHQP5h6Ve_yG4qsBw1hqOcMOEZEFYBRfY0RSj4XIYvMGIiKLeocLe5xxsDkF8D1AKNlgsf-5VbzCLSI5IgVG2dUReUQWv6PkiqDkemCUXSGS1oNcaY2yaxRfYfex44TIAssDLQ221xJ73jssz08dcAYo3rHtdiqxvYTD2B9-IDmB6qPftdLY0Y2vBuOSYjfi1_aAeIw6IB4L4v7tBfljMg1P7B5iFN-4L-UBideOLsUoXqJ4uUM_wwFjvtNUn_B4Ld50FOPDhL1ZR5qDEe2O9Kn4Gz9gT6CD0OwVo0ZZ5Wx3Blm8Rvakx8WfzNnLeOwpuKX8yFMOOC5-fB5xSWQfRR4URLmLVkRWtu2GZ550saR_tMMvmjZ1nm2fEVkJsXVAwUtEVktVwU8gEVndAXQbJeC2s7zlX0DPWNeheBHNk8jRLpUSTh4qlXxpVW-8ky9QvHg1cwDXSlT3UPWyotIuVffijON4-9HPlG24hI_SWI1I6iLnMHgN0sBn2qF4eQA-Ut2A9RM-yloNwHtoHvryHpo7yvWUyJTDwnnkKZ-HlgpxZ_UD2I9tJybs3pheOFssjAFtuZIYpeGDZoMIbpndSt9p2Dp9AxTfNGBvO9BUVojkESLFrAE7oO-W2FFNMSLkFwnP3ZDqW25aap0ADTZ9qR12hAhBJMM15QKqsUTcfbpZPNw4nJZbTHHZN1hDp7R15eIke3O76csZU-2RF4htG3Ra_QbMIrLixvRgEFlhKivMJRN9Bb5K-aKFS8p-t5oycHbsNHRaMTAGKmxUrwewm0mNUYxTp4ruJTZM886OIj9Yyn7HVd867xpA4QzfadVo2mKqm74Fac3oz18qaikiK1dSBUdkxcYy5aRkrOy5qEAHE6iPiG8vlavSxdtqF0g4YCzCgdW8E4Cf83SdzoNe_i7VkwwEl_1z0MgeB9ByG6jyNxw4XSquMQ1wUHFDSwFBrQFwwARQHVBjgxJqpSFwBgRZ4cAFeVBzAYGkLWANVc-gmjEctBqEYtS5V9CqCgTuOMNBx1kgYAsCk-EHN0HHAQdtrWkLQae4tC72rqWSgIO6pXYTgNZS4aCuu4Ap6ZbOovhaSRzUUgVa9bLisgkcLg5aV6-t7plVOqCCUwMGB3Uvn7isAuv0Mii-JjiwPhYD1vXOQEE6x4HtJXhAAxK0k7iCsm8a0G6IywbF101V4qD28HHFBjUr7uQ-t9oaqDAttxtEVk8uIhyqA3tzuVWjBtbd51_nP__8P19wUDO1BU0b-C_R1zA4uiP5d7nnkKn9NERWzkH9SksqAm5ejIX2R0niMsaYI87K1BtnTOfN4htRPYOGMURWY-TtI85xjBBZzWavH2dwX3ODZ_eFveY6op6h859nfz8LX7qDGrRWOhDc5eyowEHdyJ4FW9CGK4ni6_mMzCLvzELpoOK0kcpYzgwOtuCik3-BQCjVTQBGdDioaVVpwxscXK_XPy2X6w-LX2_W1_9e3K_Iern6uF48fEbxdYQDdWgXRncPoqyek3qmcPCM2SEnDUk6mu1arCWoGsU3uKPagHbbGpfSVI1dPhuQyYjs-oshI_hIHAbjcfC-ly4x4I4agxHJVr1kvqreOcBnKmkD2pU8JXGrql6AwzqIRbKxpMzfILjrTPDYmngZzEix3nFDJEPzULmPsXUkcYjD5zAMw6yOomTO5qQm9VHjYF7M2PtoLq2vaI9DWTxqcTR9WitjNdB27Dz8PqDwDezfWdl8iAyhJXj56dOvn4Mob7idGYXIVfhckLQm9aFvRSSOTvQP58UcP_BGUvGBykq4dclHdQawGfvF0P_fEyLHhOI6jsIiHA0wSHQmdAUv2cyoWeqlm8dhEU6Ei1_RDEusKTfOP1becC6LODLB1YdP8b8-73-SWexyiPEi70xjXkwFnTNwL_nzANh6OWTvfnrSM4bihW-Fo4Mk86kkUZgnBaala7--VRJbDXbwszyT3DE58sXklElGCtyAXQ9yrw00rmNab6nov9kCXFrhczOtWtMwOrBOQtff5gfe6TneaynWbuK6Uq6N-f-xLDLnMfH8wDOb8iRRXaXf5zJxXFfpxGXyY5pJTLI49jT3uxns2jDT-Rgu_lH7mrMcBkrfzWWreOV3Osc0K7CUiyl9P-Ev3p39RRs0t6wzbjSduayB39rXnuSp4tRB2Bz-pIPoXt7KUbpdSTvnI4exvdgd1fabxXZpelKnkoiWIYteW3nHydXVIxnPCvcfpTpD77xc0_rhKlNyLNfqzk3dVfjvluhdVU8KwJJon22c9uRUeyiKb9D-s-9xpq4ygt6r5lAUE83jE83LjJAjzQU0lL2M0XOwwRDbox3-SfrXGSET_ScNQZlkMWH0a2nkpuV2YQy0pXj5AKLb-cQxHJF82Hb5kavhFGExhsUSG1sNI73kf_Sw7uw0O7tWtHvS3MJ615AeTaqgpr2w6woEWPjKxDFRF3gU4hfLxfkckJzaIqMFPtLC6TcSue1t19upkteHbc-NbLiEsTocoXwAWoF-AKrZxiVKJQ32ZxivUceDzq9gDVXsK0ifqGzOoRyVLau5bO6hPql5ozMvTgi-Ws7DlI_S6t7wLdxDvZT27mRdt_WYz1dcwIPfc47l-0d4xI-Nz4EI6zrXB_o49UFKwiLL6DRLTbraksZxVmVnFmSppOnbXTgO-55HTaUZjpV-kfzEZRcPj0slLTzbd5Gx3rJIkmRZlU0sMum5i3pex9NYvXNb_cXD41TfB2jp6PylUuLw-U41p1kcn7hCfuIKpCjzM3ljjM0hbz0D6y3swjV_t-qSJEmLMp_oO-lzWcpYWU4WeqWdA--T0bHC71nVOKrDspwsLQmnqs7zlMB0aQfZ3A6CSgbnV_dt27zjEI-jlKUEJuaYtOQsS5MsTSfleFD8YJXt-BZiaoRXVnPl7L2ageRFlqYTM-x68ySd11EahQWlKWYsWo-vXQ-VbqE1fXFFPF6yDdW7Wr8YK-wUtts8_xhr7F8CO62jhNKpzvGJzlFcUbxb72X06HN2frLt_tUfLI_b7tcGOGl5HI2x9h01RQWuNN--sXkl8xOx0jBig0fuFsOfMA6m3l28-BamP9b8JIzYxPzJiZ4hJAkeT85-oKAMkmQi5-lhHwnzGK_XLr7WxlJt199z3MdMv4vT4asf9HT8wV88J-55YJ-9MlMBeGD8ow1VHFLpLhVi_xLHfeklLQVgqzAMIeUvXFFZ-asCpdIWqrfmDhc66rGw7CaO7_hx1Xuyw2m1s0FvAAdbDwPA_ChFH0uHxzdJOMpn4cwft3_fTYBZw-133DUbeQ-bJ6fVWy_NR7yNBlph_27bYXfK8OdhyBcVIaC65vpvvgAwXSCp3LZngQ_v3nBrmv2Fhf0tsD_zd3RTbry-sXh8XCw_4McPN3h1--nT7b8__vwTXn38dPOAH289-OqXn_D9zd3t_eNehrtz1y9y4_Lfm1cw9ggasL9kABWmdk_y6-q_fmeYJKzOksltpD9HwWy-cw3-qpUgycm1xYvqMq6KuKAXcBmlRVbkcZiSi81lXpWQxCQr5rQmISlyiOMqr0jMQsgJiS74JQlJHIWERHGSzclsXlEW1TmpQzaHLCrQPISWcjFz4TZTurnwV24u0yLPwwtBSxDGXyYlZHzNTlByfaEvfXiWfWPQPBTcWHOgYLkVcLk323u4nHTRa3H5528feWv8XwAAAP__GY4lqg">