[VPlan] Assertion `VF.Width == BestVF && "VPlan cost model and legacy cost model disagreed"' failed.

[patrick-rivos]

Tested using d082f1f

C Testcase:

int a;
extern int b[];
signed char c;
int d[1];
void e() {
  for (short f = 2; f < c; f += 3) {
    a = ({ d[f - 1]; }) ? d[f] : 0;
    b[f] = 0;
  }
}

Command:

/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/clang -march=rv64gcv_zvl256b -O3 red.c -o /dev/null

Testcase:

; 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 void @e(i8 %0, i64 %indvars.iv) #0 {
entry:
  %1 = zext i8 %0 to i64
  br label %for.body

for.cond.for.cond.cleanup_crit_edge:              ; preds = %cond.end
  ret void

for.body:                                         ; preds = %cond.end, %entry
  %indvars.iv1 = phi i64 [ 0, %entry ], [ %indvars.iv.next, %cond.end ]
  %sub = add i64 0, 0
  %arrayidx = getelementptr [1 x i32], ptr null, i64 0, i64 %sub
  %2 = load i32, ptr %arrayidx, align 4
  %tobool.not = icmp eq i32 %2, 0
  br i1 %tobool.not, label %cond.end, label %cond.true

cond.true:                                        ; preds = %for.body
  %arrayidx5 = getelementptr [1 x i32], ptr null, i64 0, i64 %indvars.iv
  %3 = load i32, ptr %arrayidx5, align 4
  br label %cond.end

cond.end:                                         ; preds = %cond.true, %for.body
  %arrayidx7 = getelementptr [0 x i32], ptr null, i64 0, i64 %indvars.iv1
  store i32 0, ptr %arrayidx7, align 4
  %indvars.iv.next = add i64 %indvars.iv1, 3
  %cmp = icmp ult i64 %indvars.iv1, %1
  br i1 %cmp, label %for.body, label %for.cond.for.cond.cleanup_crit_edge
}

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" }

Command/backtrace:

> /scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt -passes loop-vectorize reduced.ll -S
opt: /scratch/tc-testing/tc-compiler-fuzz-trunk/llvm/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:10037: bool llvm::LoopVectorizePass::processLoop(llvm::Loop*): Assertion `VF.Width == BestVF && "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.
Stack dump:
0.      Program arguments: /scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt -passes loop-vectorize reduced.ll -S
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 "e"
 #0 0x000063e889a673c0 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x2ff63c0)
 #1 0x000063e889a647df llvm::sys::RunSignalHandlers() (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x2ff37df)
 #2 0x000063e889a64935 SignalHandler(int) Signals.cpp:0:0
 #3 0x00007a5322242520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x00007a53222969fc __pthread_kill_implementation ./nptl/pthread_kill.c:44:76
 #5 0x00007a53222969fc __pthread_kill_internal ./nptl/pthread_kill.c:78:10
 #6 0x00007a53222969fc pthread_kill ./nptl/pthread_kill.c:89:10
 #7 0x00007a5322242476 gsignal ./signal/../sysdeps/posix/raise.c:27:6
 #8 0x00007a53222287f3 abort ./stdlib/abort.c:81:7
 #9 0x00007a532222871b _nl_load_domain ./intl/loadmsgcat.c:1177:9
#10 0x00007a5322239e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
#11 0x000063e888a5ba9a llvm::LoopVectorizePass::processLoop(llvm::Loop*) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x1feaa9a)
#12 0x000063e888a5df51 llvm::LoopVectorizePass::runImpl(llvm::Function&) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x1fecf51)
#13 0x000063e888a5e5c7 llvm::LoopVectorizePass::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x1fed5c7)
#14 0x000063e8878c6096 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+0xe55096)
#15 0x000063e88987deef 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+0x2e0ceef)
#16 0x000063e8878c91d6 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+0xe581d6)
#17 0x000063e88987cc6b llvm::ModuleToFunctionPassAdaptor::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x2e0bc6b)
#18 0x000063e8878c54c6 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+0xe544c6)
#19 0x000063e88987accd 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+0x2e09ccd)
#20 0x000063e8870f3eb6 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+0x682eb6)
#21 0x000063e8870e5c41 optMain (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x674c41)
#22 0x00007a5322229d90 __libc_start_call_main ./csu/../sysdeps/nptl/libc_start_call_main.h:58:16
#23 0x00007a5322229e40 call_init ./csu/../csu/libc-start.c:128:20
#24 0x00007a5322229e40 __libc_start_main ./csu/../csu/libc-start.c:379:5
#25 0x000063e8870dbff5 _start (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x66aff5)
zsh: IOT instruction (core dumped)  /scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt

Godbolt: https://godbolt.org/z/v1nbzWqMb

Found via fuzzer.

cc @fhahn

[patrick-rivos]

Linking some meta-discussion about the assert here: #100591

[zhendongsu]

Some additional reproducers on x86_64-linux-gnu in case they are of help:

[519] % clangtk -v
clang version 20.0.0git (https://github.com/llvm/llvm-project.git 410f751144e8b2e9574f03e0d0fb8560fe3cb797)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /local/suz-local/software/local/clang-trunk/bin
Build config: +assertions
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/10
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/11
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/9
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/11
Candidate multilib: .;@m64
Selected multilib: .;@m64
[520] % 
[520] % clangtk -Os small.c
clang-20: /local/suz-local/software/clangbuild/llvm-project/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:7288: llvm::VectorizationFactor llvm::LoopVectorizationPlanner::computeBestVF(): Assertion `BestFactor.Width == LegacyVF.Width && " 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/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/WAIT/20240822-clangtk-m64-Os-Wall-Wextra-pipe-fPIC-build-182745/delta -fcoverage-compilation-dir=/local/suz-local/software/emitesting/bugs/WAIT/20240822-clangtk-m64-Os-Wall-Wextra-pipe-fPIC-build-182745/delta -resource-dir /local/suz-local/software/local/clang-trunk/lib/clang/20 -I /usr/local/include -I /local/suz-local/software/local/include -internal-isystem /local/suz-local/software/local/clang-trunk/lib/clang/20/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 -Os -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-e51115.o -x c small.c
1.	<eof> parser at end of file
2.	Optimizer
3.	Running pass "function<eager-inv>(float2int,lower-constant-intrinsics,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-use-loop-info;no-verify-fixpoint>,simplifycfg<bonus-inst-threshold=1;forward-switch-cond;switch-range-to-icmp;switch-to-lookup;no-keep-loops;hoist-common-insts;sink-common-insts;speculate-blocks;simplify-cond-branch;no-speculate-unpredictables>,slp-vectorizer,vector-combine,instcombine<max-iterations=1;no-use-loop-info;no-verify-fixpoint>,loop-unroll<O2>,transform-warning,sroa<preserve-cfg>,infer-alignment,instcombine<max-iterations=1;no-use-loop-info;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;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 0x00005559685ec3ef llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x42ea3ef)
 #1 0x00005559685e9934 SignalHandler(int) Signals.cpp:0:0
 #2 0x00007f0380f76420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #3 0x00007f03809ad00b raise /build/glibc-LcI20x/glibc-2.31/signal/../sysdeps/unix/sysv/linux/raise.c:51:1
 #4 0x00007f038098c859 abort /build/glibc-LcI20x/glibc-2.31/stdlib/abort.c:81:7
 #5 0x00007f038098c729 get_sysdep_segment_value /build/glibc-LcI20x/glibc-2.31/intl/loadmsgcat.c:509:8
 #6 0x00007f038098c729 _nl_load_domain /build/glibc-LcI20x/glibc-2.31/intl/loadmsgcat.c:970:34
 #7 0x00007f038099dfd6 (/lib/x86_64-linux-gnu/libc.so.6+0x33fd6)
 #8 0x0000555969ef4948 llvm::LoopVectorizationPlanner::computeBestVF() (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x5bf2948)
 #9 0x0000555969f0f9ea llvm::LoopVectorizePass::processLoop(llvm::Loop*) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x5c0d9ea)
#10 0x0000555969f12691 llvm::LoopVectorizePass::runImpl(llvm::Function&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x5c10691)
#11 0x0000555969f12d43 llvm::LoopVectorizePass::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x5c10d43)
#12 0x0000555969a9d326 llvm::detail::PassModel<llvm::Function, llvm::LoopVectorizePass, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x579b326)
#13 0x0000555967f872a1 llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x3c852a1)
#14 0x0000555965ae2ae6 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/suz-local/software/local/clang-trunk/bin/clang-20+0x17e0ae6)
#15 0x0000555967f85bed llvm::ModuleToFunctionPassAdaptor::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x3c83bed)
#16 0x0000555965ae19e6 llvm::detail::PassModel<llvm::Module, llvm::ModuleToFunctionPassAdaptor, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x17df9e6)
#17 0x0000555967f83cf1 llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x3c81cf1)
#18 0x00005559688a0c29 (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
#19 0x00005559688a3d83 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/suz-local/software/local/clang-trunk/bin/clang-20+0x45a1d83)
#20 0x0000555968f440fa clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x4c420fa)
#21 0x000055596ad8938c clang::ParseAST(clang::Sema&, bool, bool) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x6a8738c)
#22 0x0000555968f44598 clang::CodeGenAction::ExecuteAction() (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x4c42598)
#23 0x00005559691dec59 clang::FrontendAction::Execute() (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x4edcc59)
#24 0x00005559691603be clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x4e5e3be)
#25 0x00005559692cb886 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x4fc9886)
#26 0x00005559656b5dd5 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x13b3dd5)
#27 0x00005559656aee7a ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#28 0x00005559656b284e clang_main(int, char**, llvm::ToolContext const&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x13b084e)
#29 0x00005559655a31bb main (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x12a11bb)
#30 0x00007f038098e083 __libc_start_main /build/glibc-LcI20x/glibc-2.31/csu/../csu/libc-start.c:342:3
#31 0x00005559656ae90e _start (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x13ac90e)
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 410f751144e8b2e9574f03e0d0fb8560fe3cb797)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /local/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-1b0f28.c
clangtk: note: diagnostic msg: /tmp/small-1b0f28.sh
clangtk: note: diagnostic msg: 

********************
[521] % 
[521] % cat small.c
char a;
int b, *c = &b, d[3], e;
int main() {
  int f, g[3] = {0,0,0};
  g[e] = *c = 0;
  for (; *c < 3; (*c)++) {
    f = a ? b % a : 0;
    g[2] &= d[*c] & f;
  }
  return 0;
}

[537] % clangtk -O3 small.c
clang-20: /local/suz-local/software/clangbuild/llvm-project/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:7288: llvm::VectorizationFactor llvm::LoopVectorizationPlanner::computeBestVF(): Assertion `BestFactor.Width == LegacyVF.Width && " 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/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/WAIT/20240814-clangtk-m64-O3-build-085604/delta -fcoverage-compilation-dir=/local/suz-local/software/emitesting/bugs/WAIT/20240814-clangtk-m64-O3-build-085604/delta -resource-dir /local/suz-local/software/local/clang-trunk/lib/clang/20 -I /usr/local/include -I /local/suz-local/software/local/include -internal-isystem /local/suz-local/software/local/clang-trunk/lib/clang/20/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 -fskip-odr-check-in-gmf -fcolor-diagnostics -vectorize-loops -vectorize-slp -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/small-83d1cf.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-use-loop-info;no-verify-fixpoint>,simplifycfg<bonus-inst-threshold=1;forward-switch-cond;switch-range-to-icmp;switch-to-lookup;no-keep-loops;hoist-common-insts;sink-common-insts;speculate-blocks;simplify-cond-branch;no-speculate-unpredictables>,slp-vectorizer,vector-combine,instcombine<max-iterations=1;no-use-loop-info;no-verify-fixpoint>,loop-unroll<O3>,transform-warning,sroa<preserve-cfg>,infer-alignment,instcombine<max-iterations=1;no-use-loop-info;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;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 0x0000558427a123ef llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x42ea3ef)
 #1 0x0000558427a0f934 SignalHandler(int) Signals.cpp:0:0
 #2 0x00007fa32f70a420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #3 0x00007fa32f14100b raise /build/glibc-LcI20x/glibc-2.31/signal/../sysdeps/unix/sysv/linux/raise.c:51:1
 #4 0x00007fa32f120859 abort /build/glibc-LcI20x/glibc-2.31/stdlib/abort.c:81:7
 #5 0x00007fa32f120729 get_sysdep_segment_value /build/glibc-LcI20x/glibc-2.31/intl/loadmsgcat.c:509:8
 #6 0x00007fa32f120729 _nl_load_domain /build/glibc-LcI20x/glibc-2.31/intl/loadmsgcat.c:970:34
 #7 0x00007fa32f131fd6 (/lib/x86_64-linux-gnu/libc.so.6+0x33fd6)
 #8 0x000055842931a948 llvm::LoopVectorizationPlanner::computeBestVF() (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x5bf2948)
 #9 0x00005584293359ea llvm::LoopVectorizePass::processLoop(llvm::Loop*) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x5c0d9ea)
#10 0x0000558429338691 llvm::LoopVectorizePass::runImpl(llvm::Function&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x5c10691)
#11 0x0000558429338d43 llvm::LoopVectorizePass::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x5c10d43)
#12 0x0000558428ec3326 llvm::detail::PassModel<llvm::Function, llvm::LoopVectorizePass, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x579b326)
#13 0x00005584273ad2a1 llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x3c852a1)
#14 0x0000558424f08ae6 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/suz-local/software/local/clang-trunk/bin/clang-20+0x17e0ae6)
#15 0x00005584273abbed llvm::ModuleToFunctionPassAdaptor::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x3c83bed)
#16 0x0000558424f079e6 llvm::detail::PassModel<llvm::Module, llvm::ModuleToFunctionPassAdaptor, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x17df9e6)
#17 0x00005584273a9cf1 llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x3c81cf1)
#18 0x0000558427cc6c29 (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
#19 0x0000558427cc9d83 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/suz-local/software/local/clang-trunk/bin/clang-20+0x45a1d83)
#20 0x000055842836a0fa clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x4c420fa)
#21 0x000055842a1af38c clang::ParseAST(clang::Sema&, bool, bool) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x6a8738c)
#22 0x000055842836a598 clang::CodeGenAction::ExecuteAction() (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x4c42598)
#23 0x0000558428604c59 clang::FrontendAction::Execute() (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x4edcc59)
#24 0x00005584285863be clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x4e5e3be)
#25 0x00005584286f1886 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x4fc9886)
#26 0x0000558424adbdd5 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x13b3dd5)
#27 0x0000558424ad4e7a ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#28 0x0000558424ad884e clang_main(int, char**, llvm::ToolContext const&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x13b084e)
#29 0x00005584249c91bb main (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x12a11bb)
#30 0x00007fa32f122083 __libc_start_main /build/glibc-LcI20x/glibc-2.31/csu/../csu/libc-start.c:342:3
#31 0x0000558424ad490e _start (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x13ac90e)
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 410f751144e8b2e9574f03e0d0fb8560fe3cb797)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /local/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-aeee73.c
clangtk: note: diagnostic msg: /tmp/small-aeee73.sh
clangtk: note: diagnostic msg: 

********************
[538] % 
[538] % cat small.c
int a[1], *d, e, f[1];
static int b, c, *volatile g = &c;
void h(int i) { b = b >> 1 ^ a[b ^ i & 1]; }
void j(long i) {
  b = b >> 1 ^ b;
  b = b >> 1 ^ a[b ^ 1];
  h(i >> 1);
  h(i >> 3);
  h(i >> 2);
  h(i >> 4);
  h(i >> 5);
}
static void m() {
  int l;
  while (e) {
    c = 0;
    for (; c < 5; c++) {
      l = 0;
      for (; l < 7; l++)
        if (*d)
          j(f[c * l]);
    }
  }
}
int main() {
  if (e) {
    m();
    g;
  }
  return 0;
}

[fhahn]

@zhendongsu thanks for the report, it was the same issue as the test case @sjoerdmeijer shared at #100591, which was a different underlying issue to the one for this issue.

Both should be fixed now, please let me know if you find any other instances of this triggering.

[zhendongsu]

Hi @fhahn, here is another related instance that still triggers:

[512] % clangtk -v
clang version 20.0.0git (https://github.com/llvm/llvm-project.git f22b1da8791edd557ce34c87190e329df2e1c892)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /local/suz-local/software/local/clang-trunk/bin
Build config: +assertions
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/10
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/11
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/9
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/11
Candidate multilib: .;@m64
Selected multilib: .;@m64
[513] % 
[513] % clangtk -Os small.c
clang-20: /local/suz-local/software/clangbuild/llvm-project/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:7359: llvm::VectorizationFactor llvm::LoopVectorizationPlanner::computeBestVF(): Assertion `(BestFactor.Width == LegacyVF.Width || planContainsAdditionalSimplifications(getPlanFor(BestFactor.Width), BestFactor.Width, CostCtx, OrigLoop, CM)) && " 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/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/20240825-clangtk-m64-Os-Wall-Wextra-pipe-fPIC-build-043108/delta -fcoverage-compilation-dir=/local/suz-local/software/emitesting/bugs/20240825-clangtk-m64-Os-Wall-Wextra-pipe-fPIC-build-043108/delta -resource-dir /local/suz-local/software/local/clang-trunk/lib/clang/20 -I /usr/local/include -I /local/suz-local/software/local/include -internal-isystem /local/suz-local/software/local/clang-trunk/lib/clang/20/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 -Os -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-d7ba19.o -x c small.c
1.	<eof> parser at end of file
2.	Optimizer
3.	Running pass "function<eager-inv>(float2int,lower-constant-intrinsics,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-use-loop-info;no-verify-fixpoint>,simplifycfg<bonus-inst-threshold=1;forward-switch-cond;switch-range-to-icmp;switch-to-lookup;no-keep-loops;hoist-common-insts;sink-common-insts;speculate-blocks;simplify-cond-branch;no-speculate-unpredictables>,slp-vectorizer,vector-combine,instcombine<max-iterations=1;no-use-loop-info;no-verify-fixpoint>,loop-unroll<O2>,transform-warning,sroa<preserve-cfg>,infer-alignment,instcombine<max-iterations=1;no-use-loop-info;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;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 0x0000564ef7a4babf llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x42ddabf)
 #1 0x0000564ef7a49004 SignalHandler(int) Signals.cpp:0:0
 #2 0x00007f89634f9420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #3 0x00007f8962f3000b raise /build/glibc-LcI20x/glibc-2.31/signal/../sysdeps/unix/sysv/linux/raise.c:51:1
 #4 0x00007f8962f0f859 abort /build/glibc-LcI20x/glibc-2.31/stdlib/abort.c:81:7
 #5 0x00007f8962f0f729 get_sysdep_segment_value /build/glibc-LcI20x/glibc-2.31/intl/loadmsgcat.c:509:8
 #6 0x00007f8962f0f729 _nl_load_domain /build/glibc-LcI20x/glibc-2.31/intl/loadmsgcat.c:970:34
 #7 0x00007f8962f20fd6 (/lib/x86_64-linux-gnu/libc.so.6+0x33fd6)
 #8 0x0000564ef9358b42 llvm::LoopVectorizationPlanner::computeBestVF() (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x5beab42)
 #9 0x0000564ef937504a llvm::LoopVectorizePass::processLoop(llvm::Loop*) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x5c0704a)
#10 0x0000564ef9377c81 llvm::LoopVectorizePass::runImpl(llvm::Function&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x5c09c81)
#11 0x0000564ef9378333 llvm::LoopVectorizePass::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x5c0a333)
#12 0x0000564ef8f026e6 llvm::detail::PassModel<llvm::Function, llvm::LoopVectorizePass, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x57946e6)
#13 0x0000564ef73e68d1 llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x3c788d1)
#14 0x0000564ef4f4ff46 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/suz-local/software/local/clang-trunk/bin/clang-20+0x17e1f46)
#15 0x0000564ef73e521d llvm::ModuleToFunctionPassAdaptor::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x3c7721d)
#16 0x0000564ef4f4ee46 llvm::detail::PassModel<llvm::Module, llvm::ModuleToFunctionPassAdaptor, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x17e0e46)
#17 0x0000564ef73e3321 llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x3c75321)
#18 0x0000564ef7d04bb1 (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
#19 0x0000564ef7d07d73 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/suz-local/software/local/clang-trunk/bin/clang-20+0x4599d73)
#20 0x0000564ef83a840c clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x4c3a40c)
#21 0x0000564efa1f004c clang::ParseAST(clang::Sema&, bool, bool) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x6a8204c)
#22 0x0000564ef83a8828 clang::CodeGenAction::ExecuteAction() (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x4c3a828)
#23 0x0000564ef8643cb9 clang::FrontendAction::Execute() (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x4ed5cb9)
#24 0x0000564ef85c543e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x4e5743e)
#25 0x0000564ef8730876 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x4fc2876)
#26 0x0000564ef4b21e55 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x13b3e55)
#27 0x0000564ef4b1aefa ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#28 0x0000564ef4b1e8ce clang_main(int, char**, llvm::ToolContext const&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x13b08ce)
#29 0x0000564ef4a0f1bb main (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x12a11bb)
#30 0x00007f8962f11083 __libc_start_main /build/glibc-LcI20x/glibc-2.31/csu/../csu/libc-start.c:342:3
#31 0x0000564ef4b1a98e _start (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x13ac98e)
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 f22b1da8791edd557ce34c87190e329df2e1c892)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /local/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-6fc973.c
clangtk: note: diagnostic msg: /tmp/small-6fc973.sh
clangtk: note: diagnostic msg: 

********************
[514] % 
[514] % cat small.c
int a, d;
static int b = 1, c;
void e() {
  while (a)
    b--;
}
int main() {
  for (d = 0; d < 3; d++)
    if (a)
      for (c = 0; c < 2; c++)
        if (b)
          break;
  return 0;
}

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

[zhendongsu]

Hi @fhahn, another reproducer that triggers at -O{s,2,3}:

[520] % clangtk -v
clang version 20.0.0git (https://github.com/llvm/llvm-project.git 7e6b1504c7cf6976ac8e9012c4513ffa258bd8eb)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /local/suz-local/software/local/clang-trunk/bin
Build config: +assertions
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/10
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/11
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/9
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/11
Candidate multilib: .;@m64
Selected multilib: .;@m64
[521] % 
[521] % clangtk -O3 small.c
clang-20: /local/suz-local/software/clangbuild/llvm-project/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:7359: llvm::VectorizationFactor llvm::LoopVectorizationPlanner::computeBestVF(): Assertion `(BestFactor.Width == LegacyVF.Width || planContainsAdditionalSimplifications(getPlanFor(BestFactor.Width), BestFactor.Width, CostCtx, OrigLoop, CM)) && " 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/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/20240826-clangtk-m64-Os-build-191303/delta -fcoverage-compilation-dir=/local/suz-local/software/emitesting/bugs/20240826-clangtk-m64-Os-build-191303/delta -resource-dir /local/suz-local/software/local/clang-trunk/lib/clang/20 -I /usr/local/include -I /local/suz-local/software/local/include -internal-isystem /local/suz-local/software/local/clang-trunk/lib/clang/20/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 -fskip-odr-check-in-gmf -fcolor-diagnostics -vectorize-loops -vectorize-slp -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/small-bd6e8d.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-use-loop-info;no-verify-fixpoint>,simplifycfg<bonus-inst-threshold=1;forward-switch-cond;switch-range-to-icmp;switch-to-lookup;no-keep-loops;hoist-common-insts;sink-common-insts;speculate-blocks;simplify-cond-branch;no-speculate-unpredictables>,slp-vectorizer,vector-combine,instcombine<max-iterations=1;no-use-loop-info;no-verify-fixpoint>,loop-unroll<O3>,transform-warning,sroa<preserve-cfg>,infer-alignment,instcombine<max-iterations=1;no-use-loop-info;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;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 0x0000561e24237f5f llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x42f4f5f)
 #1 0x0000561e242354a4 SignalHandler(int) Signals.cpp:0:0
 #2 0x00007f7461dc8420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #3 0x00007f74617ff00b raise /build/glibc-LcI20x/glibc-2.31/signal/../sysdeps/unix/sysv/linux/raise.c:51:1
 #4 0x00007f74617de859 abort /build/glibc-LcI20x/glibc-2.31/stdlib/abort.c:81:7
 #5 0x00007f74617de729 get_sysdep_segment_value /build/glibc-LcI20x/glibc-2.31/intl/loadmsgcat.c:509:8
 #6 0x00007f74617de729 _nl_load_domain /build/glibc-LcI20x/glibc-2.31/intl/loadmsgcat.c:970:34
 #7 0x00007f74617effd6 (/lib/x86_64-linux-gnu/libc.so.6+0x33fd6)
 #8 0x0000561e25b45232 llvm::LoopVectorizationPlanner::computeBestVF() (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x5c02232)
 #9 0x0000561e25b616ca llvm::LoopVectorizePass::processLoop(llvm::Loop*) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x5c1e6ca)
#10 0x0000561e25b64301 llvm::LoopVectorizePass::runImpl(llvm::Function&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x5c21301)
#11 0x0000561e25b649b3 llvm::LoopVectorizePass::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x5c219b3)
#12 0x0000561e256ef0a6 llvm::detail::PassModel<llvm::Function, llvm::LoopVectorizePass, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x57ac0a6)
#13 0x0000561e23bd2da1 llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x3c8fda1)
#14 0x0000561e21724f86 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/suz-local/software/local/clang-trunk/bin/clang-20+0x17e1f86)
#15 0x0000561e23bd16ed llvm::ModuleToFunctionPassAdaptor::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x3c8e6ed)
#16 0x0000561e21723e86 llvm::detail::PassModel<llvm::Module, llvm::ModuleToFunctionPassAdaptor, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x17e0e86)
#17 0x0000561e23bcf7f1 llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x3c8c7f1)
#18 0x0000561e244f0f41 (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
#19 0x0000561e244f4103 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/suz-local/software/local/clang-trunk/bin/clang-20+0x45b1103)
#20 0x0000561e24b9480c clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x4c5180c)
#21 0x0000561e269dcc5c clang::ParseAST(clang::Sema&, bool, bool) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x6a99c5c)
#22 0x0000561e24b94c28 clang::CodeGenAction::ExecuteAction() (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x4c51c28)
#23 0x0000561e24e30189 clang::FrontendAction::Execute() (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x4eed189)
#24 0x0000561e24db162e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x4e6e62e)
#25 0x0000561e24f1cde6 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x4fd9de6)
#26 0x0000561e212f6ed5 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x13b3ed5)
#27 0x0000561e212eff7a ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#28 0x0000561e212f394e clang_main(int, char**, llvm::ToolContext const&) (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x13b094e)
#29 0x0000561e211e41eb main (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x12a11eb)
#30 0x00007f74617e0083 __libc_start_main /build/glibc-LcI20x/glibc-2.31/csu/../csu/libc-start.c:342:3
#31 0x0000561e212efa0e _start (/local/suz-local/software/local/clang-trunk/bin/clang-20+0x13aca0e)
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 7e6b1504c7cf6976ac8e9012c4513ffa258bd8eb)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /local/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-796071.c
clangtk: note: diagnostic msg: /tmp/small-796071.sh
clangtk: note: diagnostic msg: 

********************
[522] % 
[522] % cat small.c
char a;
static char b, *c = &b, **d = &c;
int e;
unsigned f;
char g(int h) { return a << h; }
int main() {
  char ***i[2] = {&d, &d};
  int *j;
  for (; f < 3; f++) {
    j = &e;
    *j = g(**d);
  }
  return 0;
}

Compiler Explorer: https://godbolt.org/z/7Y5PzTx4P