<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/102934>102934</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [LoopVectorize] Assertion `WideningDecision != CM_Unknown && "Widening decision should be ready at this moment"' failed.
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          patrick-rivos
      </td>
    </tr>
</table>

<pre>
    Reduced LLVM IR:
```llvm ir
; ModuleID = 'reduced.bc'
target datalayout = "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128"
target triple = "riscv64-unknown-linux-gnu"

define i32 @main(i64 %indvars.iv.i) #0 {
entry:
  br label %for.body6.i

for.body6.i: ; preds = %for.inc34.i, %entry
  %indvars.iv.i1 = phi i64 [ 0, %entry ], [ %indvars.iv.next.i, %for.inc34.i ]
  br i1 false, label %for.body6.i.for.inc34.i_crit_edge, label %for.cond7.preheader.i

for.body6.i.for.inc34.i_crit_edge: ; preds = %for.body6.i
  br label %for.inc34.i

for.cond7.preheader.i:                            ; preds = %for.body6.i
  %arrayidx30.i = getelementptr [0 x i16], ptr null, i64 0, i64 %indvars.iv.i
  store i16 0, ptr %arrayidx30.i, align 2
  br label %for.inc34.i

for.body19.1.i:                                   ; preds = %for.body19.1.i
  store i16 0, ptr %arrayidx30.i, align 2
  br label %for.body19.1.i

for.inc34.i:                                      ; preds = %for.cond7.preheader.i, %for.body6.i.for.inc34.i_crit_edge
 %indvars.iv.next.i = add i64 %indvars.iv.i1, 1
  %exitcond.not.i = icmp eq i64 %indvars.iv.next.i, 0
  br i1 %exitcond.not.i, label %q.exit, label %for.body6.i

q.exit:                                           ; preds = %for.inc34.i
  ret i32 0
}

attributes #0 = { "target-features"="+64bit,+a,+c,+d,+f,+m,+relax,+v,+zicsr,+zifencei,+zmmul,+zve32f,+zve32x,+zve64d,+zve64f,+zve64x,+zvl128b,+zvl256b,+zvl32b,+zvl64b,-b,-e,-experimental-smmpm,-experimental-smnpm,-experimental-ssnpm,-experimental-sspm,-experimental-ssqosid,-experimental-supm,-experimental-zacas,-experimental-zalasr,-experimental-zicfilp,-experimental-zicfiss,-h,-shcounterenw,-shgatpa,-shtvala,-shvsatpa,-shvstvala,-shvstvecd,-smaia,-smcdeleg,-smcsrind,-smepmp,-smstateen,-ssaia,-ssccfg,-ssccptr,-sscofpmf,-sscounterenw,-sscsrind,-ssstateen,-ssstrict,-sstc,-sstvala,-sstvecd,-ssu64xl,-svade,-svadu,-svbare,-svinval,-svnapot,-svpbmt,-xcvalu,-xcvbi,-xcvbitmanip,-xcvelw,-xcvmac,-xcvmem,-xcvsimd,-xsfcease,-xsfvcp,-xsfvfnrclipxfqf,-xsfvfwmaccqqq,-xsfvqmaccdod,-xsfvqmaccqoq,-xsifivecdiscarddlone,-xsifivecflushdlone,-xtheadba,-xtheadbb,-xtheadbs,-xtheadcmo,-xtheadcondmov,-xtheadfmemidx,-xtheadmac,-xtheadmemidx,-xtheadmempair,-xtheadsync,-xtheadvdot,-xventanacondops,-xwchc,-za128rs,-za64rs,-zaamo,-zabha,-zalrsc,-zama16b,-zawrs,-zba,-zbb,-zbc,-zbkb,-zbkc,-zbkx,-zbs,-zca,-zcb,-zcd,-zce,-zcf,-zcmop,-zcmp,-zcmt,-zdinx,-zfa,-zfbfmin,-zfh,-zfhmin,-zfinx,-zhinx,-zhinxmin,-zic64b,-zicbom,-zicbop,-zicboz,-ziccamoa,-ziccif,-zicclsm,-ziccrse,-zicntr,-zicond,-zihintntl,-zihintpause,-zihpm,-zimop,-zk,-zkn,-zknd,-zkne,-zknh,-zkr,-zks,-zksed,-zksh,-zkt,-ztso,-zvbb,-zvbc,-zvfbfmin,-zvfbfwma,-zvfh,-zvfhmin,-zvkb,-zvkg,-zvkn,-zvknc,-zvkned,-zvkng,-zvknha,-zvknhb,-zvks,-zvksc,-zvksed,-zvksg,-zvksh,-zvkt,-zvl1024b,-zvl16384b,-zvl2048b,-zvl32768b,-zvl4096b,-zvl512b,-zvl65536b,-zvl8192b" }
```

Backtrace:
```
> /scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt -passes="loop-vectorize" -S reduced.ll
opt: /scratch/tc-testing/tc-compiler-fuzz-trunk/llvm/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:3631: llvm::LoopVectorizationCostModel::collectLoopUniforms(llvm::ElementCount)::<lambda(llvm::Instruction*, llvm::ElementCount)>: Assertion `WideningDecision != CM_Unknown && "Widening decision should be ready at this moment"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.      Program arguments: /scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt -passes=loop-vectorize -S reduced.ll
1.      Running pass "function(loop-vectorize<no-interleave-forced-only;no-vectorize-forced-only;>)" on module "reduced.ll"
2.      Running pass "loop-vectorize<no-interleave-forced-only;no-vectorize-forced-only;>" on function "main"
 #0 0x000059f80448a570 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x2f4f570)
 #1 0x000059f80448798f llvm::sys::RunSignalHandlers() (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x2f4c98f)
 #2 0x000059f804487ae5 SignalHandler(int) Signals.cpp:0:0
 #3 0x0000795355842520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x00007953558969fc __pthread_kill_implementation ./nptl/pthread_kill.c:44:76
 #5 0x00007953558969fc __pthread_kill_internal ./nptl/pthread_kill.c:78:10
 #6 0x00007953558969fc pthread_kill ./nptl/pthread_kill.c:89:10
 #7 0x0000795355842476 gsignal ./signal/../sysdeps/posix/raise.c:27:6
 #8 0x00007953558287f3 abort ./stdlib/abort.c:81:7
 #9 0x000079535582871b _nl_load_domain ./intl/loadmsgcat.c:1177:9
#10 0x0000795355839e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
#11 0x000059f80347d610 llvm::LoopVectorizationCostModel::collectLoopUniforms(llvm::ElementCount) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x1f42610)
#12 0x000059f80348fa77 llvm::LoopVectorizationPlanner::plan(llvm::ElementCount, unsigned int) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x1f54a77)
#13 0x000059f803491b83 llvm::LoopVectorizePass::processLoop(llvm::Loop*) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x1f56b83)
#14 0x000059f803494de1 llvm::LoopVectorizePass::runImpl(llvm::Function&, llvm::ScalarEvolution&, llvm::LoopInfo&, llvm::TargetTransformInfo&, llvm::DominatorTree&, llvm::BlockFrequencyInfo*, llvm::TargetLibraryInfo*, llvm::DemandedBits&, llvm::AssumptionCache&, llvm::LoopAccessInfoManager&, llvm::OptimizationRemarkEmitter&, llvm::ProfileSummaryInfo*) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x1f59de1)
#15 0x000059f803495497 llvm::LoopVectorizePass::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x1f5a497)
#16 0x000059f8022ff336 llvm::detail::PassModel<llvm::Function, llvm::LoopVectorizePass, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0xdc4336)
#17 0x000059f8042a17ff llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x2d667ff)
#18 0x000059f8023024c6 llvm::detail::PassModel<llvm::Function, llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0xdc74c6)
#19 0x000059f8042a057b llvm::ModuleToFunctionPassAdaptor::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x2d6557b)
#20 0x000059f8022fe7c6 llvm::detail::PassModel<llvm::Module, llvm::ModuleToFunctionPassAdaptor, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0xdc37c6)
#21 0x000059f80429e5dd llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x2d635dd)
#22 0x000059f801b38c36 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) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x5fdc36)
#23 0x000059f801b2a881 optMain (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x5ef881)
#24 0x0000795355829d90 __libc_start_call_main ./csu/../sysdeps/nptl/libc_start_call_main.h:58:16
#25 0x0000795355829e40 call_init ./csu/../csu/libc-start.c:128:20
#26 0x0000795355829e40 __libc_start_main ./csu/../csu/libc-start.c:379:5
#27 0x000059f801b206c5 _start (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x5e56c5)
zsh: IOT instruction (core dumped) /scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt
```

Found via fuzzer.
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzkWl-T26iy_zSaF8ouCf31wzx4ZuK6qbupTSU5ex9dCJDNHQQaQBqPP_0t_siWPJ5skrs7p05tKiN-NN1Nd9MgQEZas52g9DbK76L84Qb1Zi_VbYeMYvhxodgg9U0tycvtF0p6TAn47bc_PoGPX6J0HcUPUbyOitj_53xoAVOBmt6BT5L0nH58AFH6ACJYKq9hWeMIlp7NILWjBhBkEEcvsjeBF9JFG6VruuiidF1k7rFgJ5DAKkrXCawWIoWe9tXSIJypNYp1nI4qFdN4KLJFLx6FfBYLzkR_WOxEfxLzT0IbJihgKQRRFreIiQhWrMhABHMmyICUXrJhySK4AhFMYxCVd16SCqNeToEBoFaAo5pyK9lItbRxLJZs2tmUnK6BDVunKNHBaCfGBE4z29-9pfhOQg8XJiVOrNsz4OzN70A8lQJR_uDq-d2FpKAHc-ph0qeTOHvDEtAgrqllvObZciK6xYqZLSW719xYClIuO0X3FBGq3ozIG-reitMsvK-jP4bxoq_XxqRr8J1_P9J1BHOkFHph5JDGNorpA9hRQzltqTCdUXYIYnAALCnCmFii6Dm32A5ePILLrAtdaCMVtfKe0-mc92rJiLOdAPAnQ2K9SVbL5E9j8WchCUr-SpMv1Z6tHp35IZPfsvp1NpznxPez0tt7bVo5_YiQa8OZWP3JJG_ogRlrxFLIUZThtgP06Yr4edrG81n6StFsDj4tbeNbk3ga18D5oyF9O66zTANAUeMW2GB2VD5Me0XGKFb3huqwwFo9pV2zoF_ZFw1FpldU26U7fbBPeFdktXMqgnfIF9gXxBeNL1pfKMrRwcPBF0eGtRphQwWmLNTatucBDjSFzQQfTrjIyAQ3E3zi4Qms6lMF5sW5ksIzLjKLF-5B3ePQUcXs0oH4Qrdt116himtUfZ16lfgkNSOv6f0V5iPCSF-hcuQieEFmuGG8u07XTs3ePvQey14Yqqh49vUdMh3y0AyIBzjoM3nQswYzUOxc0C1intpiQjndBawVE4GBdm3nkTbIUCpcRY9yGuNmN6LOqABl07XNiGfW6olyPVOp7V7KeGxwKE9mT4zWfZEduIMDInQEvQc1UoHExIACm0Cd9KqHrm4dOuAB8T6gmp2AaZFgXahS_hxQi_CIaBuQZq2z6KAbTJF731s84G5EjVCYs-7QPDUn0nOLMH56ehoJT7ZOJJnVn2RoZw2zjjONkSKES0Gn9Ib3en-mGrsc12iC6wnWZ4xbOalIQVo5nAlNS1tGDmfC6LyvXDbStkNMnQn6RUzYB-IjfxhsPgtke5Odt-UZ7x3nESWwUtrDIhsR8lYeUb1HHnClg0CLErcuLI7oOfB7x4_e52PtGevHUH0c6wdfehnsZbBn8gl2xNQXjS9a2QUwls6hI2HC62q8kqZuWiY83IfiRBh591MwtjIcFrMjw7VsT6g7oWNAGLUSjZg1I-J6FMLK5-GRYeGn45HZkHu0Z8IIw8-VDvUj_74LOkZ_H_1ThIKEkobSu_jo-3jUoaCBTYdmHyqj_UgOYXCGMDrDJGYWP7co4P1YnprDQA6Pu1COdIFHEDofHsWJJ2SORaO8HstRTp_k9CgXzB-C_QNPYhiGaOBJkVanCoyzasQpLItTJYtXxYjzBI6wyPP0RK-SlW2A4PxqH8-J0zf9HcKPRiFMXx8nx3PkBxDBjcYKGbyP4MbghaHaMBsIW8Gy7RinatH0x-PCqF48RnBT94yTxQ4PJ2xPp_7IZ0k29BvZGbDokNZU-00El7JbDBQbqdiRWusXX8F4auXcWyQ7tx_6BaOsCZOC1RHcfFNI6EaqVkdw88e5681vUnan-hJ39iCcFmli-3Ya0nWUrqdcyDAp7qU2nySh3LdjyTnFxrL9S7DQT3WW_-BPJPf2VRbBlSdG6T1HbU3QjPWj0Eb12HYSwbXbPL6t5oM1c601VZYfREX8P4xQwcTugWKmHQ0mdl93_2n7L38gBxEsIljYXd7IDMjIrfey5wTUFCiKyAtABpg906CVtmO3ASxBgxinZOnH6fNvH9ZfPwDd1y0zAIG63wFFO6kMMBLsjem0NR5uIrjZMbPv6yWW7XyYFp2S_0vtu3vDtO7tfnMDkCCACcx7QoHZU4AV0ntQj5kcuv9qEH4EpG-7U2rHS79B_qzkTqEWILXrrfX6F_PpF5J8nuHX0jsJRn7phRsBK2qHpOlFGPvqYpqk90IumN0KcYoGumikwpQspOAvUXon5Jn1osmmCVzZaSYFaN1lkbunOVs0XszAN4z6Sy1xZoxuWu3-6geeTnZpDOJDHMdxvmqqOMsqlJfxZBboF-3BZ8WEcQnwza1t02mk0PNWaqMoal2-3wPm5gyIYPU35kAE7-IDbLImL2Mb9JNPyYVP5apqrvn0pRdf2U4g_l9IEE7tzqR6P7PxqmpmZsNLsxHNwczACFYhsp6swyIau7-TojQoKld5mudVBnMYB6f8Cn2oim2RTW8LbQNearksnHlOZGZcNte5KlYNBtttZ_Z28do-Ms63rO38oumWbbCM4EZ0dgOzmbItcZSusyxK12Vx1p__iH47DQTi39VcumvUSTSKa5qnYt9VV60u1JWXwc3KAuy0Gw-nycMIbpau9qIJtTvoTSc1s4mgENPU6YZllK4nMajmqmFVNilAtV3enSpD_PA5krfOvjvLs4bVKw1JDbaCb7lEZEuknf5OF3Mby40lt3qHkVeXJKU1KQy7nUnxXGG6oqvi51LJiZxSyeqcTc80K0mRxH_f-_89ZnPSZLBI4pmXcO5l1aCy_J6XnzkSgirf2nEkvuPUPeiF-8ZB3nGlTZo8Q2U5czKdO7lK6ip9w0n6Gemw7nZKYqq1bZ056Qnr9_OnqKt05k924U9GaPLn_qhefGw7PvNlc9pbFPN95VeMOFIfBsn7q-22j4-ika8avrlrwtPm-irPg2yZQEaqb4rSV613XOLHjaJPPRX4xStYX-vkN1YrpK5zPNAWCULJHTP6VQ9rrfu2c5MW4f1rC6xza2wH3-r-hATa2bfaBdfvnWFtmBZfaIvU44eWGXOF87OSDeP0a9-2U3vfK39WhCaz_Mkv8ifPVm9N-nn-_FjurAXiL5rpMXDp_RUhu-8r3i8GKFvN14RiGgMImyZNi4kPhBrEwlJuQxBW9muevEqdeex-KTTuGPcfHXOCszSdv1HL2c4RoqRsphteF-bvmf8PjSQkRVE2zSyU1Sx70xhm-K_I3r9tCP6hQ0dwmeH5JFhdTII4L-uJC_6XG9_kaK4dkTVBnZHqejC8wE-FIoi8cw7neVlPIwHjixWYlj-Zw6Pr9z8Yv18I0Fsp-J8RdYLTcp5-cH7pAFc0J-QHFoBrof4nRBCSIs0JmYVwdmRK6rTCs52D6l3SfWYd5UzMr6C-GsXE7gttriXtG1vpTwjvnZ4_2wP7zf0ll5T89950vdkwfkXJ_6v5DXfWSqEXS50OnosJ73dMvH4fnPm1IZ52uvRM7wfJCJiF0eq6s0MX9tqra28Z2ZmtkTKsIN6L__afid_k-oMq1jCqRr7atvx0-S6ZmTcEz_dXMJ0nJkRVlQDZmU-IiXcxiTZVNTtpwIv7OLgiqxhst5zVeKsNUmaLEefb04UP1v3rK6lw6XVNaLmP0nXu7tKKc6_5Za80i4GTYYKZy448tNoXTru_Y3K_c4TxWWlxTenMlWteXFWelitr9ll3eTFycYFz4LW-z8DlBc5PA3fUNqrg4-_fADt_erKGYKmo-7JCiU_zv8-ut79cbmQvCBgYAlYzVcsbcpuSVbpCN_Q2KWGaVQmE2c3-NqY4STCFdQPpCsN0tWqSJs4ISTDGMSE37BbGMIurBCZFVsbpsi4bWpdpXVaroqjqJspi2iLGl9bKpVS7G_c16jaJ4SrNbtyPuLT7BS-Egj4D1xpBGOUPN-rWuVb3Ox1lMWfa6LMawwx3P_2dHRij_OHf9u3uplf89tc_zoWIDLfw_wIAAP__0Of0pQ">