[NFC] Move hot cold splitting class to header file

[hiraditya]

Summary

This is to facilitate unittests

[tejohnson]

lgtm

llvm/include/llvm/Transforms/IPO/HotColdSplitting.h

 #ifndef LLVM_TRANSFORMS_IPO_HOTCOLDSPLITTING_H
 #define LLVM_TRANSFORMS_IPO_HOTCOLDSPLITTING_H
 
 #include "llvm/IR/PassManager.h"
 
 namespace llvm {
 
 class Module;
+class ProfileSummaryInfo;
+class BlockFrequencyInfo;
+class TargetTransformInfo;
+class OptimizationRemarkEmitter;
+class AssumptionCache;
+class DominatorTree;
+
+/// A sequence of basic blocks.
+///
+/// A 0-sized SmallVector is slightly cheaper to move than a std::vector.
+using BlockSequence = SmallVector<BasicBlock *, 0>;
+
+class HotColdSplitting {
+public:
+  HotColdSplitting(ProfileSummaryInfo *ProfSI,
+                   function_ref<BlockFrequencyInfo *(Function &)> GBFI,
+                   function_ref<TargetTransformInfo &(Function &)> GTTI,
+                   std::function<OptimizationRemarkEmitter &(Function &)> *GORE,
+                   function_ref<AssumptionCache *(Function &)> LAC)
+      : PSI(ProfSI), GetBFI(GBFI), GetTTI(GTTI), GetORE(GORE), LookupAC(LAC) {}
+  bool run(Module &M);
+
+private:
+  bool isFunctionCold(const Function &F) const;
+  bool shouldOutlineFrom(const Function &F) const;
+  bool outlineColdRegions(Function &F, bool HasProfileSummary);
+  Function *extractColdRegion(const BlockSequence &Region, DominatorTree &DT,
+                              BlockFrequencyInfo *BFI, TargetTransformInfo &TTI,
+                              OptimizationRemarkEmitter &ORE,
+                              AssumptionCache *AC, unsigned Count);
+  ProfileSummaryInfo *PSI;
+  function_ref<BlockFrequencyInfo *(Function &)> GetBFI;
+  function_ref<TargetTransformInfo &(Function &)> GetTTI;
+  std::function<OptimizationRemarkEmitter &(Function &)> *GetORE;
+  function_ref<AssumptionCache *(Function &)> LookupAC;
+};
 
 /// Pass to outline cold regions.
 class HotColdSplittingPass : public PassInfoMixin<HotColdSplittingPass> {
 public:
   PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
 };
 
 } // end namespace llvm
 
 #endif // LLVM_TRANSFORMS_IPO_HOTCOLDSPLITTING_H
 

llvm/lib/Transforms/IPO/HotColdSplitting.cpp

static cl::opt<bool> EnableStaticAnalyis("hot-cold-static-analysis",
                               cl::init(true), cl::Hidden);
 
 static cl::opt<int>
     SplittingThreshold("hotcoldsplit-threshold", cl::init(2), cl::Hidden,
                        cl::desc("Base penalty for splitting cold code (as a "
                                 "multiple of TCC_Basic)"));
 
 namespace {
-
-/// A sequence of basic blocks.
-///
-/// A 0-sized SmallVector is slightly cheaper to move than a std::vector.
-using BlockSequence = SmallVector<BasicBlock *, 0>;
-
 // Same as blockEndsInUnreachable in CodeGen/BranchFolding.cpp. Do not modify
 // this function unless you modify the MBB version as well.
 //
 /// A no successor, non-return block probably ends in unreachable and is cold.
 /// Also consider a block that ends in an indirect branch to be a return block,
 /// since many targets use plain indirect branches to return.
 bool blockEndsInUnreachable(const BasicBlock &BB) {
   if (!succ_empty(&BB))
if (UpdateEntryCount) {
     // section when function sections are enabled.
     F.setEntryCount(0);
     Changed = true;
   }
 
   return Changed;
 }
 
-class HotColdSplitting {
-public:
-  HotColdSplitting(ProfileSummaryInfo *ProfSI,
-                   function_ref<BlockFrequencyInfo *(Function &)> GBFI,
-                   function_ref<TargetTransformInfo &(Function &)> GTTI,
-                   std::function<OptimizationRemarkEmitter &(Function &)> *GORE,
-                   function_ref<AssumptionCache *(Function &)> LAC)
-      : PSI(ProfSI), GetBFI(GBFI), GetTTI(GTTI), GetORE(GORE), LookupAC(LAC) {}
-  bool run(Module &M);
-
-private:
-  bool isFunctionCold(const Function &F) const;
-  bool shouldOutlineFrom(const Function &F) const;
-  bool outlineColdRegions(Function &F, bool HasProfileSummary);
-  Function *extractColdRegion(const BlockSequence &Region, DominatorTree &DT,
-                              BlockFrequencyInfo *BFI, TargetTransformInfo &TTI,
-                              OptimizationRemarkEmitter &ORE,
-                              AssumptionCache *AC, unsigned Count);
-  ProfileSummaryInfo *PSI;
-  function_ref<BlockFrequencyInfo *(Function &)> GetBFI;
-  function_ref<TargetTransformInfo &(Function &)> GetTTI;
-  std::function<OptimizationRemarkEmitter &(Function &)> *GetORE;
-  function_ref<AssumptionCache *(Function &)> LookupAC;
-};
-
 class HotColdSplittingLegacyPass : public ModulePass {
 public:
   static char ID;
   HotColdSplittingLegacyPass() : ModulePass(ID) {
     initializeHotColdSplittingLegacyPassPass(*PassRegistry::getPassRegistry());
   }
 
   void getAnalysisUsage(AnalysisUsage &AU) const override {