<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/155287>155287</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Attempt to use a SCEVCouldNotCompute object! UNREACHABLE executed at /root/llvm-project/llvm/lib/Analysis/ScalarEvolution.cpp:412!
        </td>
    </tr>

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

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

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

<pre>
    To reproduce run opt with the test below, -passes=loop-idiom.
```
; ModuleID = './reduced.ll'
source_filename = "./reduced.ll"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128-ni:1-p2:32:8:8:32-ni:2"
target triple = "x86_64-unknown-linux-gnu"

define i32 @wombat(ptr addrspace(1) %arg) gc "statepoint-example" {
bb:
  br label %bb2

bb1: ; preds = %bb2
  %phi = phi ptr addrspace(1) [ %getelementptr, %bb2 ]
  br label %bb7

bb2: ; preds = %bb2, %bb
  %phi3 = phi i64 [ 0, %bb ], [ %add5, %bb2 ]
  %phi4 = phi i64 [ 0, %bb ], [ %add, %bb2 ]
  %add = add i64 %phi4, 1
  %getelementptr = getelementptr i16, ptr addrspace(1) null, i64 %add
 %add5 = add i64 %phi3, 1
  br i1 false, label %bb2, label %bb1

bb6: ; preds = %bb7
  ret i32 0

bb7: ; preds = %bb10, %bb1
  %phi8 = phi i64 [ %phi3, %bb1 ], [ %add11, %bb10 ]
  %getelementptr9 = getelementptr i32, ptr addrspace(1) %arg, i64 %phi8
  store i32 0, ptr addrspace(1) %getelementptr9, align 4
  %icmp = icmp ult i64 %phi8, 1
  br i1 %icmp, label %bb10, label %bb6

bb10: ; preds = %bb7
  %add11 = add i64 %phi8, 1
  br label %bb7
}
```
Reproducer: https://godbolt.org/z/qrWxb665W
Stack dump:
```
0.      Program arguments: /opt/compiler-explorer/clang-assertions-trunk/bin/opt -o /app/output.s -S -passes=loop-idiom <source>
1.      Running pass "function(loop(loop-idiom))" on module "<source>"
2.      Running pass "loop(loop-idiom)" on function "wombat"
 #0 0x00000000056fda38 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x56fda38)
 #1 0x00000000056fa8e4 SignalHandler(int, siginfo_t*, void*) Signals.cpp:0:0
 #2 0x000072a056242520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #3 0x000072a0562969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #4 0x000072a056242476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #5 0x000072a0562287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #6 0x0000000005634fda (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x5634fda)
 #7 0x0000000004d415be llvm::SCEV::getType() const (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x4d415be)
 #8 0x0000000004d8c80e llvm::ScalarEvolution::getMinusSCEV(llvm::SCEV const*, llvm::SCEV const*, llvm::SCEV::NoWrapFlags, unsigned int) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x4d8c80e)
 #9 0x00000000049c63d8 llvm::SCEVExpander::tryToReuseLCSSAPhi(llvm::SCEVAddRecExpr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x49c63d8)
#10 0x00000000049cb858 llvm::SCEVExpander::visitAddRecExpr(llvm::SCEVAddRecExpr const*) (.part.0) ScalarEvolutionExpander.cpp:0:0
#11 0x00000000049c5455 llvm::SCEVVisitor<llvm::SCEVExpander, llvm::Value*>::visit(llvm::SCEV const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x49c5455)
#12 0x00000000049c60fd llvm::SCEVExpander::expand(llvm::SCEV const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x49c60fd)
#13 0x00000000049cb0f3 llvm::SCEVExpander::expandAddToGEP(llvm::SCEV const*, llvm::Value*, llvm::SCEV::NoWrapFlags) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x49cb0f3)
#14 0x00000000049cc095 llvm::SCEVExpander::visitAddRecExpr(llvm::SCEVAddRecExpr const*) (.part.0) ScalarEvolutionExpander.cpp:0:0
#15 0x00000000049c5455 llvm::SCEVVisitor<llvm::SCEVExpander, llvm::Value*>::visit(llvm::SCEV const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x49c5455)
#16 0x00000000049c60fd llvm::SCEVExpander::expand(llvm::SCEV const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x49c60fd)
#17 0x00000000049cc928 llvm::SCEVExpander::expandCodeFor(llvm::SCEV const*, llvm::Type*, llvm::ilist_iterator_w_bits<llvm::ilist_detail::node_options<llvm::Instruction, true, false, void, true, llvm::BasicBlock>, false, false>) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x49cc928)
#18 0x0000000004494e77 (anonymous namespace)::LoopIdiomRecognize::processLoopStridedStore(llvm::Value*, llvm::SCEV const*, llvm::MaybeAlign, llvm::Value*, llvm::Instruction*, llvm::SmallPtrSetImpl<llvm::Instruction*>&, llvm::SCEVAddRecExpr const*, llvm::SCEV const*, bool, bool) LoopIdiomRecognize.cpp:0:0
#19 0x0000000004498c11 (anonymous namespace)::LoopIdiomRecognize::processLoopStores(llvm::SmallVectorImpl<llvm::StoreInst*>&, llvm::SCEV const*, (anonymous namespace)::LoopIdiomRecognize::ForMemset) LoopIdiomRecognize.cpp:0:0
#20 0x00000000044997b4 (anonymous namespace)::LoopIdiomRecognize::runOnCountableLoop() LoopIdiomRecognize.cpp:0:0
#21 0x000000000449b0fd llvm::LoopIdiomRecognizePass::run(llvm::Loop&, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>&, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x449b0fd)
#22 0x0000000002e085be llvm::detail::PassModel<llvm::Loop, llvm::LoopIdiomRecognizePass, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&>::run(llvm::Loop&, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>&, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x2e085be)
#23 0x00000000044c0406 std::optional<llvm::PreservedAnalyses> llvm::PassManager<llvm::Loop, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&>::runSinglePass<llvm::Loop, std::unique_ptr<llvm::detail::PassConcept<llvm::Loop, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&>, std::default_delete<llvm::detail::PassConcept<llvm::Loop, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&>>>>(llvm::Loop&, std::unique_ptr<llvm::detail::PassConcept<llvm::Loop, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&>, std::default_delete<llvm::detail::PassConcept<llvm::Loop, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&>>>&, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>&, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&, llvm::PassInstrumentation&) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x44c0406)
#24 0x00000000044c05ef llvm::PassManager<llvm::Loop, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&>::runWithoutLoopNestPasses(llvm::Loop&, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>&, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x44c05ef)
#25 0x00000000044c1d54 llvm::PassManager<llvm::Loop, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&>::run(llvm::Loop&, llvm::AnalysisManager<llvm::Loop, llvm::LoopStandardAnalysisResults&>&, llvm::LoopStandardAnalysisResults&, llvm::LPMUpdater&) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x44c1d54)
#26 0x00000000044c2860 llvm::FunctionToLoopPassAdaptor::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x44c2860)
#27 0x0000000000ed957e llvm::detail::PassModel<llvm::Function, llvm::FunctionToLoopPassAdaptor, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0xed957e)
#28 0x00000000054eb6c1 llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x54eb6c1)
#29 0x0000000000ed969e 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/opt+0xed969e)
#30 0x00000000054ebd0a llvm::ModuleToFunctionPassAdaptor::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x54ebd0a)
#31 0x000000000096d56e 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/opt+0x96d56e)
#32 0x00000000054e9771 llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x54e9771)
#33 0x000000000097780a llvm::runPassPipeline(llvm::StringRef, llvm::Module&, llvm::TargetMachine*, llvm::TargetLibraryInfoImpl*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::StringRef, llvm::ArrayRef<llvm::PassPlugin>, llvm::ArrayRef<std::function<void (llvm::PassBuilder&)>>, llvm::opt_tool::OutputKind, llvm::opt_tool::VerifierKind, bool, bool, bool, bool, bool, bool, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x97780a)
#34 0x000000000096b8d7 optMain (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x96b8d7)
#35 0x000072a056229d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#36 0x000072a056229e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#37 0x00000000009629f5 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/opt+0x9629f5)
Program terminated with signal: SIGSEGV
Compiler returned: 139
```
</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJzsW19z4ygS_zTkhbJLQv8f8qA48e7UTWZTcTbz6EICO9xg0ALKn_30VyDJshQ768x673Zzk3JiCTXdv_510yCJYK3ZWlB6DqILEF2e4do8SHV-h80LFvhS1oXRZ4UkL-d3EipaKUnqkkJVCygrA5-YeYDmgUJDtYEF5fIJoBmcVFhrqkFwyaWsJowwuZkCLwex1368HAQX8FqSmtNPlxAElxCgZArQXFFrgUw5BygBXq5lrUq6XDFOBd7QVhSNRRHwcoPVmhpIsMEcv8jadMJ0sgFBTicVSjwQ5AFyf-ypPzy1R3Ho_kzY9sBHKQhyH6WTVeq1R8I1xV33OJwsXDOzzZMKdRfS9jdAzTU0gGoUq_jWp-c0XsbhpBbfhHwSE85E_TxZi7rpAryc0BUTFLIAQRB6T3JTYANQWhkFMSFKV7ikAKU-QBkEKMJqbY_WpVWuDTa0kkyYCX3Gm4pTgBAEyQXw8qIAgdUPYaEgxwXltntRtGaLwtIEbcQqRYlu8bYC0B5WD8y12u_9cKILK7emhnK6ocJURtlUadRAEF3usZ909tFB-52KHSDBFgmLQ2fY24o5Q_akgYMJifagaPSE79KzXw0mxGmx305Lo9kK-53MgBMnPWxhfmzl99Iqapv8s063xeHlnWd7LAe95cJqhivMNbWNg7APz_0uDPGBMCROoaLGpabXiScHxP2eR3-H7_QV3zuYG-nXtPt-f9XbZX7AYbaP1gAdpLUbPLMd6lKnWRupaOvmG72H1q0k5mwtYNjBY-WmcqDcQc3NwNIoSK38OCzeqCHeDlfvzUB1zO3Jj6Hp8VBMLkdF_LabEZQ1-GBMpW0lQXOA5mtJCsnNVFoi578DNP9NfX0u4jj6Crx8YXD5DZJ6UzWlZ1erNwVedqPkWuENxGpdWx61cwnNZWUAmpdyUzFO1YQ-V1wqqmwbx2I9sTOPMkwKPTGqFt8AmhdMNB3hRFoVuKrseW2q2kw1nCz2TlgQBLNm8gHBFfBy36K6rYVgYg2tvK2qq1qU1hhAqe3ZfjUKAMrcB0Ep4MZNdbbLQK2r7Gif5v3qnK7OqBXrJgHUjPvAg96z1_1E8YrgIIWcP9oJEAS5ftHNwY1iwrgg3KkmdXshhZ-WUhtF8QYgV3uYME1ip38yAgBdeM8tLOtQA9ofgcYpDeGCrQXmP2NBuFWeOgwzqNmaiZVcGoBye_4oGXGHWdtDT8vKJpXnfhsDqDWQIOxFMQpRhLzWG84KgObt1Lsz5doL5VTLaewwuy494mCoMIuzVQkr86AoJstvjPP3aXf9e-3hGG6YxHCtnXvvhR0mca84GipGabIKIC6kMu9T6zr2auNh_IJwRfDpksWp640lu8ZCEvpRQXcyfDG7um-O1tTcvVTU4chgKYU2pwLVmu1BpUNQaZl6A1Al5lhdPUpeu2rR4btmotYO8e74sw0N3jbHj77UHH2RXxWu5hyvtRWphVvjkxOP4tbLnoNswEFWxgFJR_iunissiJstQJAb9XInb2mt6efZYpHfPLBXNOSE3NLy6rlSO16fzoUGZOOCrUPeyIUijd524ZFpZnqQ78A_rbAyU8_VrWF2dBZGdczi80f4ojCKRvjuLSKpQDA7gHuQNPeY19SCCq52HHorG09JvoXfk4_G-eOtyJvkU3f23wJr4fRgg3GmeKvgCLA5IXfyp6ubY8f7Nj7HDPVTemv96b0NR96WXjbOu__puIg-8riI_0njIhlnSoberqAN2JkkdC5f58mBYdHM66NGxpk2S2aowkaq5dOyYPauYTaWINRgxpsWIQldysq5OBD9JLRRdbu2n0GjaneXvL1dbpad_YW-5wXWrLzgsvzmFvg7fZoD23hK_i3DPf_DhUiYhTRJrDEspHjZyFpDgTe0vV3NGsSfpaw-2VuMW1rKtWC_06a9UrKkWtvLC6MYoWRh734HQTpcoA6E7hq_FDS3N8PHVLpBGMZGNpjzG6MW1HzaVPxw-Nwobm5kjqhCb_pRSMn77wy-pm5PdcpGMUlLe-99gphIRfVwyFhK7mlppHpFiRP_1LpygJCBr9-JcC7VNd1oao7lB3kjfrKkCL_XuqrFL2Ima2Fwwenn5ib6aCT-CEkxLLWvddxgrbeGB6FoTI84zgXmL5rpayzwmg4no6bDbGRuYbAgWJGu5y3VNTfaat4Twz_oMZS9uf61ItjYchOfsiQ1tG1LEhqs6xD10uEN2245tnReS0L5EczsCcRfy_VpiO4WFD_ypc2XNiP6fBkurcPSC70YakMaGM1kjYcZcqOopuqRtk5QDYKrHegurY6i8O-fNAsm1rytO3vAbXmqBfutpsvKDJ0Yj7aZFCWtzD-Wll2XCV3hmtsFHqeGfmi3t58DJeRHGvwfpcE_aNaYjapys07fUGFws1Y_7UrEzR39zBKOZ5aIrj7oNPGVmQdZG6vrC9Xmpnm_9WPB0aZFRFd9WkSjtPBJFH7QtPiRAW0G2Bj3GRCPMgClsbeDY96-cL2TFr3Nh5zgyj1N3MfrfPtS-B3cbju1nJ3SWetO7-zgEZ1HSRYl77sf6_2bHUXSd3FwKGn_XuQ27PXcDh6_RSEt4tI_opTsZ_RjUdWy0XOVjfMwzk6Rh38Zxx84Ng3529CMdpGEtCAe3n2G6zaz3MkOzx9WxKbDu3xtu_wVWUg83Ls6eOTnZTGJ4vdlYefb7EiCvoOBQ0n096G14a1nFY0SKEuSY-rgPi4_CkUtCz1HwTDzkiQdDDJVu7S5YRXlTAzfuiyMYmJ9axexr9PulbN3brPxNS4fnJ7xuzR39TMrFFYvn8RKujcHr6Sk5L-4HXNzxvco-VOXD7iTK4VfbOvgUZ_lhNdrJl7X5F5--zBgu0EvmD1KRuCARqvromacdAvMfZVeVmZppGxrQOPFv5ggb0ndU8VWjKpObvja6L3fpxulLsf6DAxHta9ISQJlZa4xE6erDFZrb3O8BS0j2Tu34rkuvcJ4rJCGHlwubZ-lNliZ5aZ352gTNNwxkYx4Qtkqgo3y09FklTYmu62vhqoNE9hQ0vyjRbMBEAQ5XHz6aXH10z3w8llrEipqaiWoTXvoB9nultozch6QLMjwGT33kyj2oyCJ0rOHcz8oUBZ4frpK0iAsPeL5RRTRCMf-KkNedsbOkYciL0UR8lDmp9MyJkVa0ATjMqJREoDQoxvM-NSOhKlU6zOmdU3P_ShCaXLmNhBr988lCAn6BN1VgBCILs_Uue00Keq1BqHHmTa6V2OY4fQ8N4ZuKgONhLWmEMPF7Op-JmtOvkhjXa8NhbL4Ny0NQD789cvtVT77Ob_4fAXpMy1rSx22MZorKW2EnMVKyaaHO91mRTcnADQf7Txp3xSGPgLIP6sVPx9tdWbmoS6mpdzs6Bxaco5b1S0zj-foPwEAAP__SqvPcg">