llvm crash on loop-vectorize: Assertion `OldResSizeInBits > NewResSizeInBits && "Nothing to shrink?"' failed.

[shao-hua-li]

llvm crashes on the following IR.

Bisected to 822c749, which was committed by @fhahn

Compiler explorer: https://godbolt.org/z/rWj9dhvPo

target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

define void @i(i64 %0) {
entry:
  %conv = sext i16 1 to i32
  br label %for.body

for.body:                                         ; preds = %for.body, %entry
  %1 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
  %tobool.not.i = icmp eq i64 %0, 0
  %..i = select i1 %tobool.not.i, i32 0, i32 0
  %cmp = icmp eq i32 %..i, 0
  %conv1 = zext i1 %tobool.not.i to i32
  %or = or i32 %conv1, %conv
  %cmp2 = icmp slt i32 %or, 7
  %conv4 = zext i1 %cmp2 to i64
  store i64 %conv4, ptr null, align 8
  %inc = add i32 %1, 1
  %tobool.not = icmp eq i32 %inc, 0
  br i1 %tobool.not, label %for.cond.for.end_crit_edge, label %for.body

for.cond.for.end_crit_edge:                       ; preds = %for.body
  ret void
}

% opt -passes=loop-vectorize reduced.ll
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.	Program arguments: /zdata/shaoli/compilers/ccbuilder-compilers/clang-822c749aec69ace75bd3923a4c850e2fd2e34fb1/bin/opt -disable-output -passes=loop-vectorize reduced.ll
 #0 0x00007f5302fedeff llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-822c749aec69ace75bd3923a4c850e2fd2e34fb1/bin/../lib/libLLVM-18git.so+0x902eff)
 #1 0x00007f5302feb654 SignalHandler(int) Signals.cpp:0:0
 #2 0x00007f5302300090 (/lib/x86_64-linux-gnu/libc.so.6+0x43090)
 #3 0x00007f5304a458f0 llvm::InnerLoopVectorizer::truncateToMinimalBitwidths(llvm::VPTransformState&) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-822c749aec69ace75bd3923a4c850e2fd2e34fb1/bin/../lib/libLLVM-18git.so+0x235a8f0)
 #4 0x00007f5304a49d95 llvm::InnerLoopVectorizer::fixVectorizedLoop(llvm::VPTransformState&, llvm::VPlan&) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-822c749aec69ace75bd3923a4c850e2fd2e34fb1/bin/../lib/libLLVM-18git.so+0x235ed95)
 #5 0x00007f5304a4abb1 llvm::LoopVectorizationPlanner::executePlan(llvm::ElementCount, unsigned int, llvm::VPlan&, llvm::InnerLoopVectorizer&, llvm::DominatorTree*, bool, llvm::DenseMap<llvm::SCEV const*, llvm::Value*, llvm::DenseMapInfo<llvm::SCEV const*, void>, llvm::detail::DenseMapPair<llvm::SCEV const*, llvm::Value*>>*) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-822c749aec69ace75bd3923a4c850e2fd2e34fb1/bin/../lib/libLLVM-18git.so+0x235fbb1)
 #6 0x00007f5304a4d564 llvm::LoopVectorizePass::processLoop(llvm::Loop*) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-822c749aec69ace75bd3923a4c850e2fd2e34fb1/bin/../lib/libLLVM-18git.so+0x2362564)
 #7 0x00007f5304a4fbdd 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*) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-822c749aec69ace75bd3923a4c850e2fd2e34fb1/bin/../lib/libLLVM-18git.so+0x2364bdd)
 #8 0x00007f5304a50e20 llvm::LoopVectorizePass::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-822c749aec69ace75bd3923a4c850e2fd2e34fb1/bin/../lib/libLLVM-18git.so+0x2365e20)
 #9 0x00007f5305e0d916 llvm::detail::PassModel<llvm::Function, llvm::LoopVectorizePass, llvm::PreservedAnalyses, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-822c749aec69ace75bd3923a4c850e2fd2e34fb1/bin/../lib/libLLVM-18git.so+0x3722916)
#10 0x00007f53031fd3fd llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-822c749aec69ace75bd3923a4c850e2fd2e34fb1/bin/../lib/libLLVM-18git.so+0xb123fd)
#11 0x00007f5305e069f6 llvm::detail::PassModel<llvm::Function, llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>, llvm::PreservedAnalyses, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-822c749aec69ace75bd3923a4c850e2fd2e34fb1/bin/../lib/libLLVM-18git.so+0x371b9f6)
#12 0x00007f53031fbc8d llvm::ModuleToFunctionPassAdaptor::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-822c749aec69ace75bd3923a4c850e2fd2e34fb1/bin/../lib/libLLVM-18git.so+0xb10c8d)
#13 0x00007f5305e0d696 llvm::detail::PassModel<llvm::Module, llvm::ModuleToFunctionPassAdaptor, llvm::PreservedAnalyses, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-822c749aec69ace75bd3923a4c850e2fd2e34fb1/bin/../lib/libLLVM-18git.so+0x3722696)
#14 0x00007f53031f9c0d llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-822c749aec69ace75bd3923a4c850e2fd2e34fb1/bin/../lib/libLLVM-18git.so+0xb0ec0d)
#15 0x0000555c5281fcb5 llvm::runPassPipeline(llvm::StringRef, llvm::Module&, llvm::TargetMachine*, llvm::TargetLibraryInfoImpl*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::StringRef, llvm::ArrayRef<llvm::PassPlugin>, llvm::opt_tool::OutputKind, llvm::opt_tool::VerifierKind, bool, bool, bool, bool, bool, bool, bool) (/zdata/shaoli/compilers/ccbuilder-compilers/clang-822c749aec69ace75bd3923a4c850e2fd2e34fb1/bin/opt+0x25cb5)
#16 0x0000555c52813876 main (/zdata/shaoli/compilers/ccbuilder-compilers/clang-822c749aec69ace75bd3923a4c850e2fd2e34fb1/bin/opt+0x19876)
#17 0x00007f53022e1083 __libc_start_main /build/glibc-wuryBv/glibc-2.31/csu/../csu/libc-start.c:342:3
#18 0x0000555c5281451e _start (/zdata/shaoli/compilers/ccbuilder-compilers/clang-822c749aec69ace75bd3923a4c850e2fd2e34fb1/bin/opt+0x1a51e)
[1]    1975861 segmentation fault   -disable-output -passes=loop-vectorize reduced.ll

This IR is reduced from

long a, b;
int c, d, f;
static long *e = &b;
static short g = 5;
int h() {
  if (a)
    return 0;
  return 5;
}
void i() {
  int j;
  long **k = &e;
  for (; d; d++) {
    j = h();
    *e = 6 >= (g | (j + c == 0));
  }
  j =  &k || 1;
  short *l[6];
  l[f] = &g;
}
int main() {}