<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/149022>149022</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Clang assertion failure at O2 "Assertion `IterCnt++ < 1000 && "Iterative simplification didn't converge!"' failed."
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          bi6c
      </td>
    </tr>
</table>

<pre>
    Compiler Explorer: https://godbolt.org/z/s1E95dza1
- generated by fuzzer

console:
```console
clang: /root/llvm-project/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp:248: bool iterativelySimplifyCFG(llvm::Function&, const llvm::TargetTransformInfo&, llvm::DomTreeUpdater*, const llvm::SimplifyCFGOptions&): Assertion `IterCnt++ < 1000 && "Iterative simplification didn't converge!"' 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 -fno-verbose-asm -c --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -O2 <source>
1.      <eof> parser at end of file
2.      Optimizer
3.      Running pass "function<eager-inv>(ee-instrument<>,lower-expect,simplifycfg<bonus-inst-threshold=1;no-forward-switch-cond;no-switch-range-to-icmp;no-switch-to-lookup;keep-loops;no-hoist-common-insts;no-hoist-loads-stores-with-cond-faulting;no-sink-common-insts;speculate-blocks;simplify-cond-branch;no-speculate-unpredictables>,sroa<modify-cfg>,early-cse<>)" on module "<source>"
4.      Running pass "simplifycfg<bonus-inst-threshold=1;no-forward-switch-cond;no-switch-range-to-icmp;no-switch-to-lookup;keep-loops;no-hoist-common-insts;no-hoist-loads-stores-with-cond-faulting;no-sink-common-insts;speculate-blocks;simplify-cond-branch;no-speculate-unpredictables>" on function "foo"
 #0 0x0000000003fb0ae8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x3fb0ae8)
 #1 0x0000000003fadf14 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x3fadf14)
 #2 0x0000000003ef26e8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007c0a64a42520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x00007c0a64a969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #5 0x00007c0a64a42476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #6 0x00007c0a64a287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #7 0x00007c0a64a2871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #8 0x00007c0a64a39e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #9 0x0000000003e8ee8a iterativelySimplifyCFG(llvm::Function&, llvm::TargetTransformInfo const&, llvm::DomTreeUpdater*, llvm::SimplifyCFGOptions const&) SimplifyCFGPass.cpp:0:0
#10 0x0000000003e90202 simplifyFunctionCFGImpl(llvm::Function&, llvm::TargetTransformInfo const&, llvm::DominatorTree*, llvm::SimplifyCFGOptions const&) SimplifyCFGPass.cpp:0:0
#11 0x0000000003e90c55 simplifyFunctionCFG(llvm::Function&, llvm::TargetTransformInfo const&, llvm::DominatorTree*, llvm::SimplifyCFGOptions const&) SimplifyCFGPass.cpp:0:0
#12 0x0000000003e90d9a llvm::SimplifyCFGPass::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x3e90d9a)
#13 0x0000000001b8022e llvm::detail::PassModel<llvm::Function, llvm::SimplifyCFGPass, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x1b8022e)
#14 0x0000000003930a21 llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x3930a21)
#15 0x00000000011f51ee llvm::detail::PassModel<llvm::Function, llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x11f51ee)
#16 0x0000000003930ef4 llvm::ModuleToFunctionPassAdaptor::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x3930ef4)
#17 0x00000000011f54be llvm::detail::PassModel<llvm::Module, llvm::ModuleToFunctionPassAdaptor, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x11f54be)
#18 0x000000000392eac1 llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x392eac1)
#19 0x00000000042660fb (anonymous namespace)::EmitAssemblyHelper::RunOptimizationPipeline(clang::BackendAction, std::unique_ptr<llvm::raw_pwrite_stream, std::default_delete<llvm::raw_pwrite_stream>>&, std::unique_ptr<llvm::ToolOutputFile, std::default_delete<llvm::ToolOutputFile>>&, clang::BackendConsumer*) BackendUtil.cpp:0:0
#20 0x00000000042697f1 clang::emitBackendOutput(clang::CompilerInstance&, clang::CodeGenOptions&, 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>>, clang::BackendConsumer*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x42697f1)
#21 0x0000000004965923 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x4965923)
#22 0x000000000665fb9c clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x665fb9c)
#23 0x0000000004965d28 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x4965d28)
#24 0x0000000004c5fa55 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x4c5fa55)
#25 0x0000000004bdc73e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x4bdc73e)
#26 0x0000000004d51891 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x4d51891)
#27 0x0000000000d93aef cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xd93aef)
#28 0x0000000000d8a6ca ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#29 0x00000000049cce79 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
#30 0x0000000003ef2b84 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x3ef2b84)
#31 0x00000000049cd48f 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
#32 0x000000000498f45d clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x498f45d)
#33 0x00000000049904ee 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+0x49904ee)
#34 0x0000000004999085 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x4999085)
#35 0x0000000000d8ff9f clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xd8ff9f)
#36 0x0000000000c44cb4 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xc44cb4)
#37 0x00007c0a64a29d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#38 0x00007c0a64a29e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#39 0x0000000000d8a175 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xd8a175)
clang: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134
```
code:
```c
unsigned int foo(unsigned int a, unsigned int *b, unsigned int c) {
  unsigned int d;
#define A(n) \
  d = a + b[n]; \
  if (d < a) \
    c++; \
  a = d;
#define B(n) \
  A(n##0) \
  A(n##1) A(n##2) A(n##3) A(n##4) A(n##5) A(n##6) A(n##7) A(n##8) A(n##9)
#define C(n) \
  B(n##0) \
  B(n##1) B(n##2) B(n##3) B(n##4) B(n##5) B(n##6) B(n##7) B(n##8) B(n##9)
#define D(n) \
  C(n##0) \
  C(n##1) C(n##2) C(n##3) C(n##4) C(n##5) C(n##6) C(n##7) C(n##8) C(n##9)
#define E(n) \
  D(n##0) \
  D(n##1) D(n##2) D(n##3) D(n##4) D(n##5) D(n##6) D(n##7) D(n##8) D(n##9)
  C(1) C(2) C(3) C(4) C(5) C(6) __builtin_unreachable ();
}
```
</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJzsWltz5CYW_jX4hZJLQpeWHvygVtvJpJKaqbGzr10IoW7WCLSAfJlfvwVSty5uO_ZsT2qT3SlP2UJw-L6Pw-GAwFqznaD0CsRrEG8ucGf2Ul2VLCEXpayerwrZtIxTBa-fWi4VVSDM4d6YVoMwB-gGoJudrErJzaVUO4BuvgF0o4PrLK6-4QD4uQd3VFCFDa1g-Qzr7ts3qoCfAz8nUmjJqTXk5yDx-59DqZ8TjsXO9gfQjZLSAHTD-UPjtUr-k5LDo_3FSoBu7hQWupaq0QDd3BLMsbJ_sKblrH4ubn76grW-JG0LwhxFqTVcSskhMxYee6D8eVIZoNRZD3MQ5jedIIZJAVACUAEtRAPH13dY7ag59v9J1HKoOdbZyOZOUfp7W2FDFUD5KUOT_j-3tkPt7GQWa641VbYMgsT_ZKgqhAFoDdAagrCAge_70NVOIEDo04EU1L1NRrBrXLFKALQytu8HqnYUoAAgBNAK1phxWl0CP__y63V-ew11VzbMQAzLbgcVbaUy0Mjl8DOz78pLIpvJgMyHiWndUTsqEIsKMkF4V1Fo9hQShfUelpjcG4UJtZq0irZKEqo1raCWneqLbUustSTMuZLqBNREsdZYvLcGk3tYdU3bO5N_Cfzsi5I7hRuI1a5rqDB6cCXZWkxkcGyPHhwb3TiH8_BBaO0Z1Yl7gG5KJg6voberHrGqvQh6O-hJaxG3rbXbmbYzlxp6tZDeA1Wl1NTDuoEegZ63I8QzUnKyx0yAcPMmEltZC9zqvTTQq4nkUnkVwzshtWFk6MOpNy_-jKw3DLKF18DPA6sFCAsqaxBewxYrTRXEBlJRQVnDmrnJhmw163QN6ydoaAu-dkIwsYMt1tq6VX2YCGFB8Y4qj4kH2w1KKfWY0EY5qUFYuNKCy8eemHOEYvDFZ1LvQFiUUnTatfLMXlG9l7wC4SYA4VpIr5bqEavK04_MkL1HpKj6F0OBwmJHPSM9RuywT94Y6XEp7ztbek9pa5-sw9oqe8m08YhsGilc17NyLnGlPW2kotp7ZKbv1qtxxw2zscj1wsT90oJuKek4NtQruST3rmjg2psoFRZkPxg4Vu5Eq2jFiMElp7qXTCuJQVg0snKNrVK2mGLFnz2i6UHbDCAEpYCNrDpO7eDMBh4h4OfRqTH8_yD84SA4YQ--7vxeyl5RCFDoQ__JP_wL69LHNJ0Ecf2s-z--KCaMC013fXCbrCgKP26lNoriZlgqmA3nGQQo_Y9jFEBr_2kAZh2lhx3MYeOqDqJTsAtOsejaz-KW7QTmAKWdcFlCBbm0xs8K0sEYQaIZSFqjhKawsHHuKyXygarnHtXPWFTc9pUOus3qFFIY-mSGxd53_3v74WB_RXycRDhCMfIHOn0W8ZQm2yTyOBPdk7cTXf-CXGp5mTjIrskIOJobzJKsJrC1UwlX23vG-cesu_aj9XgJN1olcKedBB-FHa2S0XAyN4zSVR1CXNoV_kNmXcPR7OqF2aD8sMGgHA2mc4NhRrPkYwZdk9FgNnewlNIUf0cK-Gby1-d170sB30r-JnYyeDqRPfi2nd_zuEQzH_nokP49H_AXNz99alr-A7gxgY1UluH5qQVLaiSOT1H7i9FCS1pVhk_btwaGlaMT72OZC8yfNdO_YWFTNRAWJxrZ1S45b0jvafQzzpIMpySDMvURohOYFTWY8WHFxFr_JivKT4N9TXwnzndxtz9_BVEH2UZRo5nnZKGPUTCB6YR8C-LfWq1Bj1GteOaCQR0H9Bwu-MNU_luPzqD_ODrJ0pdpPU1Mf3MbnDt5gGRVzyvcGqlOE-4bfIju0OTHuCKto5HsaumKUfkxVzywK94p0Xdo8Jon_TcJO0g3CpvOvQhRTN4TEU_J-fdRadBhVGmW_kYoSfzaJehYSPHcyE5DgRuqW7dfzXp01w0zuda0Kfnzz5S3dJh3XzsxHBi5o8UvrKWcCbvPPZzcgjBfY3JPRZUfA6I2Vf-mE-xfHd22Zq6F3Rm3j4oZuj3sjyeNKurOAbYV5dTQP2g4BNPkPd3eSck_uxO8G9b7w3v6XLSadvhSg0IK3TVD5p_BofR3w_jL1BD5i4HKVnUwtUkbZgYLPYC57Idz-09CGywIfQmqkBX9iYrpOfMsvTKKid1XWp-KNIfj6zeGeWzySRjVafZAv9K6EObLQviHekhsrYK3z9rQZlgC_3xPeceonW1qDmN6nJpotseJsiTOUPgWHlfYn4O4rQx3s_B3wRaukN_eDech544uA8iRwmw_kyRxXWZkSuELVprmt3dzgLe0wYP_lVLy8fcZoQ5gRqjhUu0KpSemx-DQfRx8oqQz9ODj6dm1rFA6Apxl-BGJaxzHU4A3yg7qccpNEZ4dW9_7iG2WT0dlRVYhhW9Fn5P6vU7m3H7aIxzxzzLOqIqDNJsF1wHpSONB9p_P_ijInjlE9MhG3LPk0a-yENMaEhJsG8zmSUiuFH620TssyB6rw7lEfghzszJUwAfJqnPD7_GN6NM5-hQnBMOD1EVw5-b8hMNtgzn_ByVGKndkdYrK8mRHSj4Eu9lRTKXYA1Unltl5PpQRQleZE2Ni9PAhYKucnu5tP8WOOSDBnJeY3G9rYWGOLtJ3PLhLERSyabColrP15LgdVzLplmg83waM6_Nx7To22G7J01MQ9A8l1ozYdc59O3ESzirbgq1RmBl9eL0whzm37m-3W8f3tko-RmrnOL3grglAK46bssIArUapUHr4gPCLLF8OxuLDCq1RmU43gqeO-I-Z6C2uKX-eafn2uJ33zMthPbp6uFjLSRWlNfxfdgur9WWLlbn0Xx9_NFctraO4elU1N174xdp3kHIWqBcNbYXZge_7quazJGVC7FwZgCM8OtEiRcn8iNKPyvGLLPXrWvwiy1-ZNq8cfr-Mv8exbzGzw-6-vb1fvun26IeJ6GQaRYwWImZ-Gr8GeDP5e5YCnFj7XxP_TxTxrNmnE2aULV6s1XWdDQHskGscYLvAkb_4NvLaSny-7MJhGhHPcjqfRBEpI2ixnq_L3ujY5fJrZ1ZlH_yY7JqMBtOlQRr5cLu1bbbaYGW2E0Lv7oJGky6yZRIWrGLYGz_n2FizfafHW3xUKXdi27sRrIeUH5LBw_vrZ_CRmT2kT8y6TUVhEEYWV6cp9B6gkVBTCtkkIbd9HG8pKmo6JaidYLbl9F6hu3BYvbhtCPz8eL2BCQPdTY90VoStZ89KAMrLF4XEufdqDfwczt9UIFz38le0ZoLCHKBUuOpx4apXEIQbiCFAa1iCeC1AvAHh-vie1VaEyt30w9OG0Ha7tj-T2thZe9HretnrACMEKPRfKbebj-kzWjyHi-do8RwvnpPF82rxnC6es6PnDiSKJYn1KyTWCxLrBYn1gsR6QWK9ILFekFgvSKwXJNZvkNgsSRSvkCgWJIoFiWJBoliQKBYkigWJYkGiWJAo3iBxvSSxeYXEZkFisyCxWZDYLEhsFiQ2CxKbBYnNgsTmBYle2KOiRymPGh7FO6rmetpuy45xw8S2E4pisselu3rX7yncbFttpuHloroKqyzM8AW9ClYxSqJk5fsX-ys_QfEqLAOMgygo4yzDURyXOIhSf-X7cXDBrpCPYn8VJH4SpMi_TAMahxGJEhwkiAYERD5tMOOXds29lGp34a7ZXgVR5iN0wXFJuXb3uhEaIjMC8eZCXbnbuWW30yDyOdNGjyYMM5xeFS5AH-O8i8ydohAb-BlBgNCfdxcZoYtO8avvv3I8yPFwhf4dAAD__1-SUSQ">