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

[patrick-rivos]

I have a few finds by the fuzzer that affect LLVM (tested using a1d77ca).
I think they're all duplicates but I'm attaching them all in a .zip so it can be confirmed.

Testcase:

target datalayout = "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128"
target triple = "riscv64-unknown-linux-gnu"

define void @e(i64 %0) #0 {
entry:
  br label %for.body

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

for.body:                                         ; preds = %for.body, %entry
  %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
  %arrayidx = getelementptr i16, ptr null, i64 %indvars.iv
  %1 = load i16, ptr %arrayidx, align 2
  %arrayidx5 = getelementptr [0 x i8], ptr null, i64 0, i64 %indvars.iv
  store i8 0, ptr %arrayidx5, align 1
  %indvars.iv.next = add nsw i64 %indvars.iv, 4
  %cmp = icmp ult i64 %indvars.iv, %0
  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,+zvl32b,+zvl64b,-b,-e,-experimental-smmpm,-experimental-smnpm,-experimental-ssnpm,-experimental-sspm,-experimental-ssqosid,-experimental-supm,-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,-zacas,-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,-zvl256b,-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:10444: bool llvm::LoopVectorizePass::processLoop(llvm::Loop*): Assertion `VF.Width == 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.
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 0x000055b365fe4a60 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x2f0ea60)
 #1 0x000055b365fe1e7f llvm::sys::RunSignalHandlers() (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x2f0be7f)
 #2 0x000055b365fe1fd5 SignalHandler(int) Signals.cpp:0:0
 #3 0x00007612a3042520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x00007612a30969fc __pthread_kill_implementation ./nptl/pthread_kill.c:44:76
 #5 0x00007612a30969fc __pthread_kill_internal ./nptl/pthread_kill.c:78:10
 #6 0x00007612a30969fc pthread_kill ./nptl/pthread_kill.c:89:10
 #7 0x00007612a3042476 gsignal ./signal/../sysdeps/posix/raise.c:27:6
 #8 0x00007612a30287f3 abort ./stdlib/abort.c:81:7
 #9 0x00007612a302871b _nl_load_domain ./intl/loadmsgcat.c:1177:9
#10 0x00007612a3039e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
#11 0x000055b365005ba8 llvm::LoopVectorizePass::processLoop(llvm::Loop*) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x1f2fba8)
#12 0x000055b365008761 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+0x1f32761)
#13 0x000055b365008ee0 llvm::LoopVectorizePass::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x1f32ee0)
#14 0x000055b363e81296 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+0xdab296)
#15 0x000055b365dfd4be 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+0x2d274be)
#16 0x000055b363e84426 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+0xdae426)
#17 0x000055b365dfc24b llvm::ModuleToFunctionPassAdaptor::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x2d2624b)
#18 0x000055b363e80776 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+0xdaa776)
#19 0x000055b365dfa39d 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+0x2d2439d)
#20 0x000055b3636cbdc6 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+0x5f5dc6)
#21 0x000055b3636bda11 optMain (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x5e7a11)
#22 0x00007612a3029d90 __libc_start_call_main ./csu/../sysdeps/nptl/libc_start_call_main.h:58:16
#23 0x00007612a3029e40 call_init ./csu/../csu/libc-start.c:128:20
#24 0x00007612a3029e40 __libc_start_main ./csu/../csu/libc-start.c:379:5
#25 0x000055b3636b3855 _start (/scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt+0x5dd855)
zsh: IOT instruction  /scratch/tc-testing/tc-compiler-fuzz-trunk/build-gcv/build-llvm-linux/bin/opt

Godbolt: https://godbolt.org/z/a7KPnMh94

Zip with all finds reduced:
finds.zip

Related: #92555 @fhahn

Found via fuzzer.

[JonPsson1]

I'm seeing this as well with a multitude of hits with csmith. One reduced test case:

clang -O3 -march=z16 crash0.i -o a.out -w -mllvm -disable-licm-promotion -mllvm -force-target-instruction-cost=1 -mllvm -unroll-count=4
LoopVectorize.cpp:10071: bool llvm::LoopVectorizePass::processLoop(llvm::Loop*): Assertion `VF.Width == Width && "VPlan cost model and legacy cost model disagreed"' failed.
#9 0x0000000004749e30 llvm::LoopVectorizePass::processLoop()

tc_lv.i.tar.gz

[fhahn]

Thanks @patrick-rivos, it looks like all test cases had dead instructions, which would be considered by the legacy cost model but not the VPlan-based one (because VPlan-based DCE would clean them up before). Should be fixed now.

@JonPsson1's case was a different issue and should also be fixed.