[NFC] Rename BBSectionsPrepare -> BasicBlockSections.

[snehasish]

Summary

Rename the BBSectionsPrepare pass as suggested by the review comment in
https://reviews.llvm.org/D85368.

[tmsriram]

IMO, I think this naming is very clear as this pass exists to carve basic block sections.

llvm/include/llvm/CodeGen/Passes.h

namespace llvm {
   /// createUnreachableBlockEliminationPass - The LLVM code generator does not
   /// work well with unreachable basic blocks (what live ranges make sense for a
   /// block that cannot be reached?).  As such, a code generator should either
   /// not instruction select unreachable blocks, or run this pass as its
   /// last LLVM modifying pass to clean up blocks that are not reachable from
   /// the entry block.
   FunctionPass *createUnreachableBlockEliminationPass();
 
-  /// createBBSectionsPrepare Pass - This pass assigns sections to machine basic
-  /// blocks and is enabled with -fbasic-block-sections.
-  /// Buf is a memory buffer that contains the list of functions and basic
-  /// block ids to selectively enable basic block sections.
-  MachineFunctionPass *createBBSectionsPreparePass(const MemoryBuffer *Buf);
+  /// createBasicBlockSections Pass - This pass assigns sections to machine
+  /// basic blocks and is enabled with -fbasic-block-sections. Buf is a memory
+  /// buffer that contains the list of functions and basic block ids to
+  /// selectively enable basic block sections.
+  MachineFunctionPass *createBasicBlockSectionsPass(const MemoryBuffer *Buf);
 
   /// MachineFunctionPrinter pass - This pass prints out the machine function to
   /// the given stream as a debugging tool.
   MachineFunctionPass *
   createMachineFunctionPrinterPass(raw_ostream &OS,
                                    const std::string &Banner ="");
 
   /// MIRPrinting pass - this pass prints out the LLVM IR into the given stream

llvm/include/llvm/InitializePasses.h

 void initializeAssumeSimplifyPassLegacyPassPass(PassRegistry &);
 void initializeAssumeBuilderPassLegacyPassPass(PassRegistry &);
 void initializeOpenMPOptLegacyPassPass(PassRegistry &);
 void initializeArgPromotionPass(PassRegistry&);
 void initializeAssumptionCacheTrackerPass(PassRegistry&);
 void initializeAtomicExpandPass(PassRegistry&);
 void initializeAttributorLegacyPassPass(PassRegistry&);
 void initializeAttributorCGSCCLegacyPassPass(PassRegistry &);
-void initializeBBSectionsPreparePass(PassRegistry &);
+void initializeBasicBlockSectionsPass(PassRegistry &);
 void initializeBDCELegacyPassPass(PassRegistry&);
 void initializeBarrierNoopPass(PassRegistry&);
 void initializeBasicAAWrapperPassPass(PassRegistry&);
 void initializeBlockExtractorPass(PassRegistry &);
 void initializeBlockFrequencyInfoWrapperPassPass(PassRegistry&);
 void initializeBoundsCheckingLegacyPassPass(PassRegistry&);
 void initializeBranchFolderPassPass(PassRegistry&);
 void initializeBranchProbabilityInfoWrapperPassPass(PassRegistry&);

llvm/lib/CodeGen/BasicBlockSections.cpp

-//===-- BBSectionsPrepare.cpp ---=========---------------------------------===//
+//===-- BasicBlockSections.cpp ---=========--------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
-// BBSectionsPrepare implementation.
+// BasicBlockSections implementation.
 //
 // The purpose of this pass is to assign sections to basic blocks when
 // -fbasic-block-sections= option is used. Further, with profile information
 // only the subset of basic blocks with profiles are placed in separate sections
 // and the rest are grouped in a cold section. The exception handling blocks are
 // treated specially to ensure they are all in one seciton.
 //
 // Basic Block Sections
struct BBClusterInfo {
   // Cluster ID this basic block belongs to.
   unsigned ClusterID;
   // Position of basic block within the cluster.
   unsigned PositionInCluster;
 };
 
 using ProgramBBClusterInfoMapTy = StringMap<SmallVector<BBClusterInfo, 4>>;
 
-class BBSectionsPrepare : public MachineFunctionPass {
+class BasicBlockSections : public MachineFunctionPass {
 public:
   static char ID;
 
   // This contains the basic-block-sections profile.
   const MemoryBuffer *MBuf = nullptr;
 
   // This encapsulates the BB cluster information for the whole program.
   //
   // For every function name, it contains the cluster information for (all or
   // some of) its basic blocks. The cluster information for every basic block
   // includes its cluster ID along with the position of the basic block in that
   // cluster.
   ProgramBBClusterInfoMapTy ProgramBBClusterInfo;
 
   // Some functions have alias names. We use this map to find the main alias
   // name for which we have mapping in ProgramBBClusterInfo.
   StringMap<StringRef> FuncAliasMap;
 
-  BBSectionsPrepare(const MemoryBuffer *Buf)
+  BasicBlockSections(const MemoryBuffer *Buf)
       : MachineFunctionPass(ID), MBuf(Buf) {
-    initializeBBSectionsPreparePass(*PassRegistry::getPassRegistry());
+    initializeBasicBlockSectionsPass(*PassRegistry::getPassRegistry());
   };
 
-  BBSectionsPrepare() : MachineFunctionPass(ID) {
-    initializeBBSectionsPreparePass(*PassRegistry::getPassRegistry());
+  BasicBlockSections() : MachineFunctionPass(ID) {
+    initializeBasicBlockSectionsPass(*PassRegistry::getPassRegistry());
   }
 
   StringRef getPassName() const override {
     return "Basic Block Sections Analysis";
   }
 
   void getAnalysisUsage(AnalysisUsage &AU) const override;
 
   /// Read profiles of basic blocks if available here.
   bool doInitialization(Module &M) override;
 
   /// Identify basic blocks that need separate sections and prepare to emit them
   /// accordingly.
   bool runOnMachineFunction(MachineFunction &MF) override;
 };
 
 } // end anonymous namespace
 
-char BBSectionsPrepare::ID = 0;
-INITIALIZE_PASS(BBSectionsPrepare, "bbsections-prepare",
+char BasicBlockSections::ID = 0;
+INITIALIZE_PASS(BasicBlockSections, "bbsections-prepare",
                 "Prepares for basic block sections, by splitting functions "
                 "into clusters of basic blocks.",
                 false, false)
 
 // This function updates and optimizes the branching instructions of every basic
 // block in a given function to account for changes in the layout.
 static void updateBranches(
     MachineFunction &MF,
static bool assignSectionsAndSortBasicBlocks(
   // After reordering basic blocks, we must update basic block branches to
   // insert explicit fallthrough branches when required and optimize branches
   // when possible.
   updateBranches(MF, PreLayoutFallThroughs);
 
   return true;
 }
 
-bool BBSectionsPrepare::runOnMachineFunction(MachineFunction &MF) {
+bool BasicBlockSections::runOnMachineFunction(MachineFunction &MF) {
   auto BBSectionsType = MF.getTarget().getBBSectionsType();
   assert(BBSectionsType != BasicBlockSection::None &&
          "BB Sections not enabled!");
   // Renumber blocks before sorting them for basic block sections.  This is
   // useful during sorting, basic blocks in the same section will retain the
   // default order.  This renumbering should also be done for basic block
   // labels to match the profiles with the correct blocks.
   MF.RenumberBlocks();
if (S.consume_front("!")) {
       FI = ProgramBBClusterInfo.try_emplace(Aliases.front()).first;
       CurrentCluster = 0;
       FuncBBIDs.clear();
     }
   }
   return Error::success();
 }
 
-bool BBSectionsPrepare::doInitialization(Module &M) {
+bool BasicBlockSections::doInitialization(Module &M) {
   if (!MBuf)
     return false;
   if (auto Err = getBBClusterInfo(MBuf, ProgramBBClusterInfo, FuncAliasMap))
     report_fatal_error(std::move(Err));
   return false;
 }
 
-void BBSectionsPrepare::getAnalysisUsage(AnalysisUsage &AU) const {
+void BasicBlockSections::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.setPreservesAll();
   MachineFunctionPass::getAnalysisUsage(AU);
 }
 
 MachineFunctionPass *
-llvm::createBBSectionsPreparePass(const MemoryBuffer *Buf) {
-  return new BBSectionsPrepare(Buf);
+llvm::createBasicBlockSectionsPass(const MemoryBuffer *Buf) {
+  return new BasicBlockSections(Buf);
 }

llvm/lib/CodeGen/CMakeLists.txt

 add_llvm_component_library(LLVMCodeGen
   AggressiveAntiDepBreaker.cpp
   AllocationOrder.cpp
   Analysis.cpp
   AtomicExpandPass.cpp
   BasicTargetTransformInfo.cpp
   BranchFolding.cpp
   BranchRelaxation.cpp
   BreakFalseDeps.cpp
   BuiltinGCs.cpp
-  BBSectionsPrepare.cpp
+  BasicBlockSections.cpp
   CalcSpillWeights.cpp
   CallingConvLower.cpp
   CFGuardLongjmp.cpp
   CFIInstrInserter.cpp
   CodeGen.cpp
   CodeGenPrepare.cpp
   CommandFlags.cpp
   CriticalAntiDepBreaker.cpp

llvm/lib/CodeGen/CodeGen.cpp

 #include "llvm/InitializePasses.h"
 #include "llvm/PassRegistry.h"
 
 using namespace llvm;
 
 /// initializeCodeGen - Initialize all passes linked into the CodeGen library.
 void llvm::initializeCodeGen(PassRegistry &Registry) {
   initializeAtomicExpandPass(Registry);
-  initializeBBSectionsPreparePass(Registry);
+  initializeBasicBlockSectionsPass(Registry);
   initializeBranchFolderPassPass(Registry);
   initializeBranchRelaxationPass(Registry);
   initializeCFGuardLongjmpPass(Registry);
   initializeCFIInstrInserterPass(Registry);
   initializeCodeGenPreparePass(Registry);
   initializeDeadMachineInstructionElimPass(Registry);
   initializeDebugifyMachineModulePass(Registry);
   initializeDetectDeadLanesPass(Registry);

llvm/lib/CodeGen/TargetPassConfig.cpp

if (TM->Options.EnableMachineOutliner && getOptLevel() != CodeGenOpt::None &&
     bool RunOnAllFunctions = (EnableMachineOutliner == AlwaysOutline);
     bool AddOutliner = RunOnAllFunctions ||
                        TM->Options.SupportsDefaultOutlining;
     if (AddOutliner)
       addPass(createMachineOutlinerPass(RunOnAllFunctions));
   }
 
   if (TM->getBBSectionsType() != llvm::BasicBlockSection::None)
-    addPass(llvm::createBBSectionsPreparePass(TM->getBBSectionsFuncListBuf()));
+    addPass(llvm::createBasicBlockSectionsPass(TM->getBBSectionsFuncListBuf()));
 
   // Add passes that directly emit MI after all other MI passes.
   addPreEmitPass2();
 
   AddingMachinePasses = false;
 }
 
 /// Add passes that optimize machine instructions in SSA form.

llvm/utils/gn/secondary/llvm/lib/CodeGen/BUILD.gn

deps = [
     "//llvm/lib/Transforms/Scalar",
     "//llvm/lib/Transforms/Utils",
   ]
   sources = [
     "AggressiveAntiDepBreaker.cpp",
     "AllocationOrder.cpp",
     "Analysis.cpp",
     "AtomicExpandPass.cpp",
-    "BBSectionsPrepare.cpp",
+    "BasicBlockSections.cpp",
     "BasicTargetTransformInfo.cpp",
     "BranchFolding.cpp",
     "BranchRelaxation.cpp",
     "BreakFalseDeps.cpp",
     "BuiltinGCs.cpp",
     "CFGuardLongjmp.cpp",
     "CFIInstrInserter.cpp",
     "CalcSpillWeights.cpp",