<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/113526>113526</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            clang crashes at -O{s,2,3} on x86_64-linux-gnu: Assertion `(BestFactor.Width == LegacyVF.Width || planContainsAdditionalSimplifications(getPlanFor(BestFactor.Width), CostCtx, OrigLoop)) && " VPlan cost model and legacy cost model disagreed"' failed 
        </td>
    </tr>

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

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

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

<pre>
    It appears to be a recent regression as it doesn't reproduce with 19.1.0 and earlier.

Compiler Explorer: https://godbolt.org/z/jPaW9fnKj

```
[531] % clangtk -v
clang version 20.0.0git (https://github.com/llvm/llvm-project.git a9050525954cbe11d45b415e2248d9e25e004bfe)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /local/home/suz/suz-local/software/local/clang-trunk/bin
Build config: +assertions
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/11
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/12
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/12
Candidate multilib: .;@m64
Selected multilib: .;@m64
Found CUDA installation: /usr/local/cuda, version 11.8
[532] %
[532] % clangtk -O3 small.c
clang-20: /local/suz-local/software/clangbuild/llvm-project/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:7519: llvm::VectorizationFactor llvm::LoopVectorizationPlanner::computeBestVF(): Assertion `(BestFactor.Width == LegacyVF.Width || planContainsAdditionalSimplifications(getPlanFor(BestFactor.Width), CostCtx, OrigLoop)) && " VPlan cost model and legacy cost model disagreed"' 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: /local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20 -cc1 -triple x86_64-unknown-linux-gnu -emit-obj -dumpdir a- -disable-free -clear-ast-before-backend -main-file-name small.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=/local/suz-local/software/emitesting/bugs/20241024-clangtk-m64-Os-build-062114/delta -fcoverage-compilation-dir=/local/suz-local/software/emitesting/bugs/20241024-clangtk-m64-Os-build-062114/delta -resource-dir /local/home/suz/suz-local/software/local/clang-trunk/lib/clang/20 -I /usr/local/include -I /local/suz-local/software/local/include -internal-isystem /local/home/suz/suz-local/software/local/clang-trunk/lib/clang/20/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/12/../../../../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 -fskip-odr-check-in-gmf -fcolor-diagnostics -vectorize-loops -vectorize-slp -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/small-22743c.o -x c small.c
1. <eof> parser at end of file
2.      Optimizer
3.      Running pass "function<eager-inv>(float2int,lower-constant-intrinsics,chr,loop(loop-rotate<header-duplication;no-prepare-for-lto>,loop-deletion),loop-distribute,inject-tli-mappings,loop-vectorize<no-interleave-forced-only;no-vectorize-forced-only;>,infer-alignment,loop-load-elim,instcombine<max-iterations=1;no-verify-fixpoint>,simplifycfg<bonus-inst-threshold=1;forward-switch-cond;switch-range-to-icmp;switch-to-lookup;no-keep-loops;hoist-common-insts;no-hoist-loads-stores-with-cond-faulting;sink-common-insts;speculate-blocks;simplify-cond-branch;no-speculate-unpredictables>,slp-vectorizer,vector-combine,instcombine<max-iterations=1;no-verify-fixpoint>,loop-unroll<O3>,transform-warning,sroa<preserve-cfg>,infer-alignment,instcombine<max-iterations=1;no-verify-fixpoint>,loop-mssa(licm<allowspeculation>),alignment-from-assumptions,loop-sink,instsimplify,div-rem-pairs,tailcallelim,simplifycfg<bonus-inst-threshold=1;no-forward-switch-cond;switch-range-to-icmp;no-switch-to-lookup;keep-loops;no-hoist-common-insts;hoist-loads-stores-with-cond-faulting;no-sink-common-insts;speculate-blocks;simplify-cond-branch;speculate-unpredictables>)" on module "small.c"
4.      Running pass "loop-vectorize<no-interleave-forced-only;no-vectorize-forced-only;>" on function "main"
 #0 0x000056385e381f80 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x43e3f80)
 #1 0x000056385e37f38f llvm::sys::RunSignalHandlers() (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x43e138f)
 #2 0x000056385e37f4e5 SignalHandler(int) Signals.cpp:0:0
 #3 0x00007fe699585520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x00007fe6995d9a7c pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x96a7c)
 #5 0x00007fe699585476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #6 0x00007fe69956b7f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #7 0x00007fe69956b71b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #8 0x00007fe69957ce96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #9 0x000056385fd39986 llvm::LoopVectorizationPlanner::computeBestVF() (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x5d9b986)
#10 0x000056385fd50d8c llvm::LoopVectorizePass::processLoop(llvm::Loop*) (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x5db2d8c)
#11 0x000056385fd53ea1 llvm::LoopVectorizePass::runImpl(llvm::Function&) (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x5db5ea1)
#12 0x000056385fd54517 llvm::LoopVectorizePass::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x5db6517)
#13 0x000056385f8a7d86 llvm::detail::PassModel<llvm::Function, llvm::LoopVectorizePass, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x5909d86)
#14 0x000056385dd0d52f llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x3d6f52f)
#15 0x000056385b779146 llvm::detail::PassModel<llvm::Function, llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x17db146)
#16 0x000056385dd0b8bb llvm::ModuleToFunctionPassAdaptor::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x3d6d8bb)
#17 0x000056385b777be6 llvm::detail::PassModel<llvm::Module, llvm::ModuleToFunctionPassAdaptor, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x17d9be6)
#18 0x000056385dd0c41d llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x3d6e41d)
#19 0x000056385e6253b6 (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 0x000056385e628d53 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>>, clang::BackendConsumer*) (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x468ad53)
#21 0x000056385eceb3f5 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x4d4d3f5)
#22 0x0000563860a56ffc clang::ParseAST(clang::Sema&, bool, bool) (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x6ab8ffc)
#23 0x000056385efcbdd9 clang::FrontendAction::Execute() (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x502ddd9)
#24 0x000056385ef45205 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x4fa7205)
#25 0x000056385f0aa403 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x510c403)
#26 0x000056385b330b57 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x1392b57)
#27 0x000056385b3275ea ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#28 0x000056385b32b96f clang_main(int, char**, llvm::ToolContext const&) (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x138d96f)
#29 0x000056385b21ef2b main (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x1280f2b)
#30 0x00007fe69956cd90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#31 0x00007fe69956ce40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#32 0x000056385b326d15 _start (/local/home/suz/suz-local/software/local/clang-trunk/bin/clang-20+0x1388d15)
clangtk: error: unable to execute command: Aborted
clangtk: error: clang frontend command failed due to signal (use -v to see invocation)
clang version 20.0.0git (https://github.com/llvm/llvm-project.git a9050525954cbe11d45b415e2248d9e25e004bfe)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /local/home/suz/suz-local/software/local/clang-trunk/bin
Build config: +assertions
clangtk: note: diagnostic msg:
********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clangtk: note: diagnostic msg: /tmp/small-ed84bf.c
clangtk: note: diagnostic msg: /tmp/small-ed84bf.sh
clangtk: note: diagnostic msg:

********************
[533] %
[533] % cat small.c
int a, b, c;
int main() {
  for (; a; a++) {
    c &= 1;
    c |= b == 1;
  }
  return 0;
}
```
</pre>
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