[NFC] Use single quotes for single char output during `printPipline`

[arsenm]

LGTM

llvm/include/llvm/Analysis/CGSCCPassManager.h

PreservedAnalyses run(LazyCallGraph::SCC &C, CGSCCAnalysisManager &AM,
                         LazyCallGraph &CG, CGSCCUpdateResult &) {
     (void)AM.template getResult<AnalysisT>(C, CG);
     return PreservedAnalyses::all();
   }
   void printPipeline(raw_ostream &OS,
                      function_ref<StringRef(StringRef)> MapClassName2PassName) {
     auto ClassName = AnalysisT::name();
     auto PassName = MapClassName2PassName(ClassName);
-    OS << "require<" << PassName << ">";
+    OS << "require<" << PassName << '>';
   }
 };
 
 /// A proxy from a \c CGSCCAnalysisManager to a \c Module.
 using CGSCCAnalysisManagerModuleProxy =
     InnerAnalysisManagerProxy<CGSCCAnalysisManager, Module>;
 
 /// We need a specialized result for the \c CGSCCAnalysisManagerModuleProxy so
public:
 
   /// Runs the CGSCC pass across every SCC in the module.
   PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
 
   void printPipeline(raw_ostream &OS,
                      function_ref<StringRef(StringRef)> MapClassName2PassName) {
     OS << "cgscc(";
     Pass->printPipeline(OS, MapClassName2PassName);
-    OS << ")";
+    OS << ')';
   }
 
   static bool isRequired() { return true; }
 
 private:
   std::unique_ptr<PassConceptT> Pass;
 };
 
public:
   PreservedAnalyses run(LazyCallGraph::SCC &C, CGSCCAnalysisManager &AM,
                         LazyCallGraph &CG, CGSCCUpdateResult &UR);
 
   void printPipeline(raw_ostream &OS,
                      function_ref<StringRef(StringRef)> MapClassName2PassName) {
     OS << "function";
     if (EagerlyInvalidate)
       OS << "<eager-inv>";
-    OS << "(";
+    OS << '(';
     Pass->printPipeline(OS, MapClassName2PassName);
-    OS << ")";
+    OS << ')';
   }
 
   static bool isRequired() { return true; }
 
 private:
   std::unique_ptr<PassConceptT> Pass;
   bool EagerlyInvalidate;
   bool NoRerun;
public:
   /// whenever an indirect call is refined.
   PreservedAnalyses run(LazyCallGraph::SCC &InitialC, CGSCCAnalysisManager &AM,
                         LazyCallGraph &CG, CGSCCUpdateResult &UR);
 
   void printPipeline(raw_ostream &OS,
                      function_ref<StringRef(StringRef)> MapClassName2PassName) {
     OS << "devirt<" << MaxIterations << ">(";
     Pass->printPipeline(OS, MapClassName2PassName);
-    OS << ")";
+    OS << ')';
   }
 
 private:
   std::unique_ptr<PassConceptT> Pass;
   int MaxIterations;
 };
 
 /// A function to deduce a function pass type and wrap it in the

llvm/include/llvm/IR/PassManager.h

public:
   }
 
   void printPipeline(raw_ostream &OS,
                      function_ref<StringRef(StringRef)> MapClassName2PassName) {
     for (unsigned Idx = 0, Size = Passes.size(); Idx != Size; ++Idx) {
       auto *P = Passes[Idx].get();
       P->printPipeline(OS, MapClassName2PassName);
       if (Idx + 1 < Size)
-        OS << ",";
+        OS << ',';
     }
   }
 
   /// Run all of the passes in this manager over the given unit of IR.
   /// ExtraArgs are passed to each pass.
   PreservedAnalyses run(IRUnitT &IR, AnalysisManagerT &AM,
                         ExtraArgTs... ExtraArgs) {
     PreservedAnalyses PA = PreservedAnalyses::all();
(void)AM.template getResult<AnalysisT>(Arg,
                                            std::forward<ExtraArgTs>(Args)...);
 
     return PreservedAnalyses::all();
   }
   void printPipeline(raw_ostream &OS,
                      function_ref<StringRef(StringRef)> MapClassName2PassName) {
     auto ClassName = AnalysisT::name();
     auto PassName = MapClassName2PassName(ClassName);
-    OS << "require<" << PassName << ">";
+    OS << "require<" << PassName << '>';
   }
   static bool isRequired() { return true; }
 };
 
 /// A no-op pass template which simply forces a specific analysis result
 /// to be invalidated.
 template <typename AnalysisT>
 struct InvalidateAnalysisPass
PreservedAnalyses run(IRUnitT &Arg, AnalysisManagerT &AM, ExtraArgTs &&...) {
     auto PA = PreservedAnalyses::all();
     PA.abandon<AnalysisT>();
     return PA;
   }
   void printPipeline(raw_ostream &OS,
                      function_ref<StringRef(StringRef)> MapClassName2PassName) {
     auto ClassName = AnalysisT::name();
     auto PassName = MapClassName2PassName(ClassName);
-    OS << "invalidate<" << PassName << ">";
+    OS << "invalidate<" << PassName << '>';
   }
 };
 
 /// A utility pass that does nothing, but preserves no analyses.
 ///
 /// Because this preserves no analyses, any analysis passes queried after this
 /// pass runs will recompute fresh results.
 struct InvalidateAllAnalysesPass : PassInfoMixin<InvalidateAllAnalysesPass> {
PreservedAnalyses run(IRUnitT &IR, AnalysisManagerT &AM, Ts &&... Args) {
     }
     return PA;
   }
 
   void printPipeline(raw_ostream &OS,
                      function_ref<StringRef(StringRef)> MapClassName2PassName) {
     OS << "repeat<" << Count << ">(";
     P.printPipeline(OS, MapClassName2PassName);
-    OS << ")";
+    OS << ')';
   }
 
 private:
   int Count;
   PassT P;
 };
 
 template <typename PassT>
 RepeatedPass<PassT> createRepeatedPass(int Count, PassT &&P) {
   return RepeatedPass<PassT>(Count, std::forward<PassT>(P));
 }
 
 } // end namespace llvm
 
 #endif // LLVM_IR_PASSMANAGER_H

llvm/include/llvm/Transforms/Scalar/LoopPassManager.h

PreservedAnalyses run(Loop &L, LoopAnalysisManager &AM,
                         LoopStandardAnalysisResults &AR, LPMUpdater &) {
     (void)AM.template getResult<AnalysisT>(L, AR);
     return PreservedAnalyses::all();
   }
   void printPipeline(raw_ostream &OS,
                      function_ref<StringRef(StringRef)> MapClassName2PassName) {
     auto ClassName = AnalysisT::name();
     auto PassName = MapClassName2PassName(ClassName);
-    OS << "require<" << PassName << ">";
+    OS << "require<" << PassName << '>';
   }
 };
 
 /// An alias template to easily name a require analysis loop pass.
 template <typename AnalysisT>
 using RequireAnalysisLoopPass =
     RequireAnalysisPass<AnalysisT, Loop, LoopAnalysisManager,
                         LoopStandardAnalysisResults &, LPMUpdater &>;

llvm/lib/Analysis/StackLifetime.cpp

PreservedAnalyses StackLifetimePrinterPass::run(Function &F,
   SL.print(OS);
   return PreservedAnalyses::all();
 }
 
 void StackLifetimePrinterPass::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   static_cast<PassInfoMixin<StackLifetimePrinterPass> *>(this)->printPipeline(
       OS, MapClassName2PassName);
-  OS << "<";
+  OS << '<';
   switch (Type) {
   case StackLifetime::LivenessType::May:
     OS << "may";
     break;
   case StackLifetime::LivenessType::Must:
     OS << "must";
     break;
   }
-  OS << ">";
+  OS << '>';
 }

llvm/lib/IR/PassManager.cpp

 }
 } // namespace llvm
 
 void ModuleToFunctionPassAdaptor::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   OS << "function";
   if (EagerlyInvalidate)
     OS << "<eager-inv>";
-  OS << "(";
+  OS << '(';
   Pass->printPipeline(OS, MapClassName2PassName);
-  OS << ")";
+  OS << ')';
 }
 
 PreservedAnalyses ModuleToFunctionPassAdaptor::run(Module &M,
                                                    ModuleAnalysisManager &AM) {
   FunctionAnalysisManager &FAM =
       AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
 
   // Request PassInstrumentation from analysis manager, will use it to run

llvm/lib/Transforms/Coroutines/CoroConditionalWrapper.cpp

if (!coro::declaresAnyIntrinsic(M))
     return PreservedAnalyses::all();
 
   return PM.run(M, AM);
 }
 
 void CoroConditionalWrapper::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   OS << "coro-cond";
-  OS << "(";
+  OS << '(';
   PM.printPipeline(OS, MapClassName2PassName);
-  OS << ")";
+  OS << ')';
 }

llvm/lib/Transforms/IPO/Inliner.cpp

 
 void ModuleInlinerWrapperPass::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   // Print some info about passes added to the wrapper. This is however
   // incomplete as InlineAdvisorAnalysis part isn't included (which also depends
   // on Params and Mode).
   if (!MPM.isEmpty()) {
     MPM.printPipeline(OS, MapClassName2PassName);
-    OS << ",";
+    OS << ',';
   }
   OS << "cgscc(";
   if (MaxDevirtIterations != 0)
     OS << "devirt<" << MaxDevirtIterations << ">(";
   PM.printPipeline(OS, MapClassName2PassName);
   if (MaxDevirtIterations != 0)
-    OS << ")";
-  OS << ")";
+    OS << ')';
+  OS << ')';
 }

llvm/lib/Transforms/IPO/LoopExtractor.cpp

PreservedAnalyses LoopExtractorPass::run(Module &M, ModuleAnalysisManager &AM) {
   PA.preserve<LoopAnalysis>();
   return PA;
 }
 
 void LoopExtractorPass::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   static_cast<PassInfoMixin<LoopExtractorPass> *>(this)->printPipeline(
       OS, MapClassName2PassName);
-  OS << "<";
+  OS << '<';
   if (NumLoops == 1)
     OS << "single";
-  OS << ">";
+  OS << '>';
 }

llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp

 };
 
 } // end anonymous namespace
 
 void AddressSanitizerPass::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   static_cast<PassInfoMixin<AddressSanitizerPass> *>(this)->printPipeline(
       OS, MapClassName2PassName);
-  OS << "<";
+  OS << '<';
   if (Options.CompileKernel)
     OS << "kernel";
-  OS << ">";
+  OS << '>';
 }
 
 AddressSanitizerPass::AddressSanitizerPass(
     const AddressSanitizerOptions &Options, bool UseGlobalGC,
     bool UseOdrIndicator, AsanDtorKind DestructorKind,
     AsanCtorKind ConstructorKind)
     : Options(Options), UseGlobalGC(UseGlobalGC),
       UseOdrIndicator(UseOdrIndicator), DestructorKind(DestructorKind),

llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp

PreservedAnalyses HWAddressSanitizerPass::run(Module &M,
   // make changes that require GlobalsAA to be invalidated.
   PA.abandon<GlobalsAA>();
   return PA;
 }
 void HWAddressSanitizerPass::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   static_cast<PassInfoMixin<HWAddressSanitizerPass> *>(this)->printPipeline(
       OS, MapClassName2PassName);
-  OS << "<";
+  OS << '<';
   if (Options.CompileKernel)
     OS << "kernel;";
   if (Options.Recover)
     OS << "recover";
-  OS << ">";
+  OS << '>';
 }
 
 void HWAddressSanitizer::createHwasanCtorComdat() {
   std::tie(HwasanCtorFunction, std::ignore) =
       getOrCreateSanitizerCtorAndInitFunctions(
           M, kHwasanModuleCtorName, kHwasanInitName,
           /*InitArgTypes=*/{},
           /*InitArgs=*/{},

llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp

PreservedAnalyses MemorySanitizerPass::run(Module &M,
   PA.abandon<GlobalsAA>();
   return PA;
 }
 
 void MemorySanitizerPass::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   static_cast<PassInfoMixin<MemorySanitizerPass> *>(this)->printPipeline(
       OS, MapClassName2PassName);
-  OS << "<";
+  OS << '<';
   if (Options.Recover)
     OS << "recover;";
   if (Options.Kernel)
     OS << "kernel;";
   if (Options.EagerChecks)
     OS << "eager-checks;";
   OS << "track-origins=" << Options.TrackOrigins;
-  OS << ">";
+  OS << '>';
 }
 
 /// Create a non-const global initialized with the given string.
 ///
 /// Creates a writable global for Str so that we can pass it to the
 /// run-time lib. Runtime uses first 4 bytes of the string to store the
 /// frame ID, so the string needs to be mutable.
 static GlobalVariable *createPrivateConstGlobalForString(Module &M,

llvm/lib/Transforms/Scalar/EarlyCSE.cpp

if (UseMemorySSA)
     PA.preserve<MemorySSAAnalysis>();
   return PA;
 }
 
 void EarlyCSEPass::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   static_cast<PassInfoMixin<EarlyCSEPass> *>(this)->printPipeline(
       OS, MapClassName2PassName);
-  OS << "<";
+  OS << '<';
   if (UseMemorySSA)
     OS << "memssa";
-  OS << ">";
+  OS << '>';
 }
 
 namespace {
 
 /// A simple and fast domtree-based CSE pass.
 ///
 /// This pass does a simple depth-first walk over the dominator tree,
 /// eliminating trivially redundant instructions and using instsimplify to

llvm/lib/Transforms/Scalar/GVN.cpp

PreservedAnalyses GVNPass::run(Function &F, FunctionAnalysisManager &AM) {
   return PA;
 }
 
 void GVNPass::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   static_cast<PassInfoMixin<GVNPass> *>(this)->printPipeline(
       OS, MapClassName2PassName);
 
-  OS << "<";
+  OS << '<';
   if (Options.AllowPRE != std::nullopt)
     OS << (*Options.AllowPRE ? "" : "no-") << "pre;";
   if (Options.AllowLoadPRE != std::nullopt)
     OS << (*Options.AllowLoadPRE ? "" : "no-") << "load-pre;";
   if (Options.AllowLoadPRESplitBackedge != std::nullopt)
     OS << (*Options.AllowLoadPRESplitBackedge ? "" : "no-")
        << "split-backedge-load-pre;";
   if (Options.AllowMemDep != std::nullopt)
     OS << (*Options.AllowMemDep ? "" : "no-") << "memdep";
-  OS << ">";
+  OS << '>';
 }
 
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
 LLVM_DUMP_METHOD void GVNPass::dump(DenseMap<uint32_t, Value *> &d) const {
   errs() << "{\n";
   for (auto &I : d) {
     errs() << I.first << "\n";
     I.second->dump();

llvm/lib/Transforms/Scalar/LICM.cpp

PreservedAnalyses LICMPass::run(Loop &L, LoopAnalysisManager &AM,
   return PA;
 }
 
 void LICMPass::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   static_cast<PassInfoMixin<LICMPass> *>(this)->printPipeline(
       OS, MapClassName2PassName);
 
-  OS << "<";
+  OS << '<';
   OS << (Opts.AllowSpeculation ? "" : "no-") << "allowspeculation";
-  OS << ">";
+  OS << '>';
 }
 
 PreservedAnalyses LNICMPass::run(LoopNest &LN, LoopAnalysisManager &AM,
                                  LoopStandardAnalysisResults &AR,
                                  LPMUpdater &) {
   if (!AR.MSSA)
     report_fatal_error("LNICM requires MemorySSA (loop-mssa)",
                        /*GenCrashDiag*/false);
PreservedAnalyses LNICMPass::run(LoopNest &LN, LoopAnalysisManager &AM,
   return PA;
 }
 
 void LNICMPass::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   static_cast<PassInfoMixin<LNICMPass> *>(this)->printPipeline(
       OS, MapClassName2PassName);
 
-  OS << "<";
+  OS << '<';
   OS << (Opts.AllowSpeculation ? "" : "no-") << "allowspeculation";
-  OS << ">";
+  OS << '>';
 }
 
 char LegacyLICMPass::ID = 0;
 INITIALIZE_PASS_BEGIN(LegacyLICMPass, "licm", "Loop Invariant Code Motion",
                       false, false)
 INITIALIZE_PASS_DEPENDENCY(LoopPass)
 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)

llvm/lib/Transforms/Scalar/LoopPassManager.cpp

for (unsigned Idx = 0, Size = IsLoopNestPass.size(); Idx != Size; ++Idx) {
     if (IsLoopNestPass[Idx]) {
       auto *P = LoopNestPasses[IdxLNP++].get();
       P->printPipeline(OS, MapClassName2PassName);
     } else {
       auto *P = LoopPasses[IdxLP++].get();
       P->printPipeline(OS, MapClassName2PassName);
     }
     if (Idx + 1 < Size)
-      OS << ",";
+      OS << ',';
   }
 }
 
 // Run both loop passes and loop-nest passes on top-level loop \p L.
 PreservedAnalyses
 LoopPassManager::runWithLoopNestPasses(Loop &L, LoopAnalysisManager &AM,
                                        LoopStandardAnalysisResults &AR,
                                        LPMUpdater &U) {
LoopPassManager::runWithoutLoopNestPasses(Loop &L, LoopAnalysisManager &AM,
   return PA;
 }
 } // namespace llvm
 
 void FunctionToLoopPassAdaptor::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   OS << (UseMemorySSA ? "loop-mssa(" : "loop(");
   Pass->printPipeline(OS, MapClassName2PassName);
-  OS << ")";
+  OS << ')';
 }
 PreservedAnalyses FunctionToLoopPassAdaptor::run(Function &F,
                                                  FunctionAnalysisManager &AM) {
   // Before we even compute any loop analyses, first run a miniature function
   // pass pipeline to put loops into their canonical form. Note that we can
   // directly build up function analyses after this as the function pass
   // manager handles all the invalidation at that layer.
   PassInstrumentation PI = AM.getResult<PassInstrumentationAnalysis>(F);

llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp

#endif
 
   return getLoopPassPreservedAnalyses();
 }
 
 void LoopUnrollPass::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   static_cast<PassInfoMixin<LoopUnrollPass> *>(this)->printPipeline(
       OS, MapClassName2PassName);
-  OS << "<";
+  OS << '<';
   if (UnrollOpts.AllowPartial != std::nullopt)
     OS << (*UnrollOpts.AllowPartial ? "" : "no-") << "partial;";
   if (UnrollOpts.AllowPeeling != std::nullopt)
     OS << (*UnrollOpts.AllowPeeling ? "" : "no-") << "peeling;";
   if (UnrollOpts.AllowRuntime != std::nullopt)
     OS << (*UnrollOpts.AllowRuntime ? "" : "no-") << "runtime;";
   if (UnrollOpts.AllowUpperBound != std::nullopt)
     OS << (*UnrollOpts.AllowUpperBound ? "" : "no-") << "upperbound;";
   if (UnrollOpts.AllowProfileBasedPeeling != std::nullopt)
     OS << (*UnrollOpts.AllowProfileBasedPeeling ? "" : "no-")
        << "profile-peeling;";
   if (UnrollOpts.FullUnrollMaxCount != std::nullopt)
-    OS << "full-unroll-max=" << UnrollOpts.FullUnrollMaxCount << ";";
-  OS << "O" << UnrollOpts.OptLevel;
-  OS << ">";
+    OS << "full-unroll-max=" << UnrollOpts.FullUnrollMaxCount << ';';
+  OS << 'O' << UnrollOpts.OptLevel;
+  OS << '>';
 }

llvm/lib/Transforms/Scalar/LowerMatrixIntrinsics.cpp

PreservedAnalyses LowerMatrixIntrinsicsPass::run(Function &F,
   }
   return PreservedAnalyses::all();
 }
 
 void LowerMatrixIntrinsicsPass::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   static_cast<PassInfoMixin<LowerMatrixIntrinsicsPass> *>(this)->printPipeline(
       OS, MapClassName2PassName);
-  OS << "<";
+  OS << '<';
   if (Minimal)
     OS << "minimal";
-  OS << ">";
+  OS << '>';
 }
 
 namespace {
 
 class LowerMatrixIntrinsicsLegacyPass : public FunctionPass {
 public:
   static char ID;
 

llvm/lib/Transforms/Scalar/MergedLoadStoreMotion.cpp

if (!Options.SplitFooterBB)
     PA.preserveSet<CFGAnalyses>();
   return PA;
 }
 
 void MergedLoadStoreMotionPass::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   static_cast<PassInfoMixin<MergedLoadStoreMotionPass> *>(this)->printPipeline(
       OS, MapClassName2PassName);
-  OS << "<";
+  OS << '<';
   OS << (Options.SplitFooterBB ? "" : "no-") << "split-footer-bb";
-  OS << ">";
+  OS << '>';
 }

llvm/lib/Transforms/Scalar/SeparateConstOffsetFromGEP.cpp

void SeparateConstOffsetFromGEP::swapGEPOperand(GetElementPtrInst *First,
   } else
     First->setIsInBounds(true);
 }
 
 void SeparateConstOffsetFromGEPPass::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   static_cast<PassInfoMixin<SeparateConstOffsetFromGEPPass> *>(this)
       ->printPipeline(OS, MapClassName2PassName);
-  OS << "<";
+  OS << '<';
   if (LowerGEP)
     OS << "lower-gep";
-  OS << ">";
+  OS << '>';
 }
 
 PreservedAnalyses
 SeparateConstOffsetFromGEPPass::run(Function &F, FunctionAnalysisManager &AM) {
   auto *DT = &AM.getResult<DominatorTreeAnalysis>(F);
   auto *SE = &AM.getResult<ScalarEvolutionAnalysis>(F);
   auto *LI = &AM.getResult<LoopAnalysis>(F);
   auto *TLI = &AM.getResult<TargetLibraryAnalysis>(F);

llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp

PreservedAnalyses SimpleLoopUnswitchPass::run(Loop &L, LoopAnalysisManager &AM,
   return PA;
 }
 
 void SimpleLoopUnswitchPass::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   static_cast<PassInfoMixin<SimpleLoopUnswitchPass> *>(this)->printPipeline(
       OS, MapClassName2PassName);
 
-  OS << "<";
+  OS << '<';
   OS << (NonTrivial ? "" : "no-") << "nontrivial;";
   OS << (Trivial ? "" : "no-") << "trivial";
-  OS << ">";
+  OS << '>';
 }
 
 namespace {
 
 class SimpleLoopUnswitchLegacyPass : public LoopPass {
   bool NonTrivial;
 
 public:

llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp

SimplifyCFGPass::SimplifyCFGPass(const SimplifyCFGOptions &Opts)
     : Options(Opts) {
   applyCommandLineOverridesToOptions(Options);
 }
 
 void SimplifyCFGPass::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   static_cast<PassInfoMixin<SimplifyCFGPass> *>(this)->printPipeline(
       OS, MapClassName2PassName);
-  OS << "<";
-  OS << "bonus-inst-threshold=" << Options.BonusInstThreshold << ";";
+  OS << '<';
+  OS << "bonus-inst-threshold=" << Options.BonusInstThreshold << ';';
   OS << (Options.ForwardSwitchCondToPhi ? "" : "no-") << "forward-switch-cond;";
   OS << (Options.ConvertSwitchRangeToICmp ? "" : "no-")
      << "switch-range-to-icmp;";
   OS << (Options.ConvertSwitchToLookupTable ? "" : "no-")
      << "switch-to-lookup;";
   OS << (Options.NeedCanonicalLoop ? "" : "no-") << "keep-loops;";
   OS << (Options.HoistCommonInsts ? "" : "no-") << "hoist-common-insts;";
   OS << (Options.SinkCommonInsts ? "" : "no-") << "sink-common-insts";
-  OS << ">";
+  OS << '>';
 }
 
 PreservedAnalyses SimplifyCFGPass::run(Function &F,
                                        FunctionAnalysisManager &AM) {
   auto &TTI = AM.getResult<TargetIRAnalysis>(F);
   Options.AC = &AM.getResult<AssumptionAnalysis>(F);
   DominatorTree *DT = nullptr;
   if (RequireAndPreserveDomTree)

llvm/lib/Transforms/Utils/EntryExitInstrumenter.cpp

llvm::EntryExitInstrumenterPass::run(Function &F, FunctionAnalysisManager &AM) {
   PA.preserveSet<CFGAnalyses>();
   return PA;
 }
 
 void llvm::EntryExitInstrumenterPass::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   static_cast<PassInfoMixin<llvm::EntryExitInstrumenterPass> *>(this)
       ->printPipeline(OS, MapClassName2PassName);
-  OS << "<";
+  OS << '<';
   if (PostInlining)
     OS << "post-inline";
-  OS << ">";
+  OS << '>';
 }

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

     return PA;
 }
 
 void LoopVectorizePass::printPipeline(
     raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
   static_cast<PassInfoMixin<LoopVectorizePass> *>(this)->printPipeline(
       OS, MapClassName2PassName);
 
-  OS << "<";
+  OS << '<';
   OS << (InterleaveOnlyWhenForced ? "" : "no-") << "interleave-forced-only;";
   OS << (VectorizeOnlyWhenForced ? "" : "no-") << "vectorize-forced-only;";
-  OS << ">";
+  OS << '>';
 }