Create a wrapper pass for BlockFrequencyInfo so that block frequency analysis can be done without requiring a pass.

[congh]

Summary

There are already several wrapper passes in LLVM such as LoopInfoWrapperPass and DominatorTreeWrapperPass. The benefit of a wrapper pass is to decouple the analysis from the function pass. This patch creates a wrapper pass for BlockFrequencyInfo. This is useful when we want to do block frequency analysis conditionally (e.g. only in PGO mode) but don't want to add one more pass dependence.

[congh]

Update the patch according to dexonsmith's comments.

[congh]

Split the chang on doFunction() to another commit.

llvm/trunk/include/llvm/Analysis/BlockFrequencyInfo.h

 
 #include "llvm/Pass.h"
 #include "llvm/Support/BlockFrequency.h"
 #include <climits>
 
 namespace llvm {
 
 class BranchProbabilityInfo;
+class LoopInfo;
 template <class BlockT> class BlockFrequencyInfoImpl;
 
 /// BlockFrequencyInfo pass uses BlockFrequencyInfoImpl implementation to
 /// estimate IR basic block frequencies.
-class BlockFrequencyInfo : public FunctionPass {
+class BlockFrequencyInfo {
   typedef BlockFrequencyInfoImpl<BasicBlock> ImplType;
   std::unique_ptr<ImplType> BFI;
 
 public:
-  static char ID;
-
-  BlockFrequencyInfo();
-
-  ~BlockFrequencyInfo() override;
-
-  void getAnalysisUsage(AnalysisUsage &AU) const override;
-
-  bool runOnFunction(Function &F) override;
-  void releaseMemory() override;
-  void print(raw_ostream &O, const Module *M) const override;
   const Function *getFunction() const;
   void view() const;
 
   /// getblockFreq - Return block frequency. Return 0 if we don't have the
   /// information. Please note that initial frequency is equal to ENTRY_FREQ. It
   /// means that we should not rely on the value itself, but only on the
   /// comparison to the other block frequencies. We do this to avoid using of
   /// floating points.
   BlockFrequency getBlockFreq(const BasicBlock *BB) const;
 
+  /// calculate - compute block frequency info for the given function.
+  void calculate(const Function &F, const BranchProbabilityInfo &BPI,
+                 const LoopInfo &LI);
+
   // Print the block frequency Freq to OS using the current functions entry
   // frequency to convert freq into a relative decimal form.
   raw_ostream &printBlockFreq(raw_ostream &OS, const BlockFrequency Freq) const;
 
   // Convenience method that attempts to look up the frequency associated with
   // BB and print it to OS.
   raw_ostream &printBlockFreq(raw_ostream &OS, const BasicBlock *BB) const;
 
   uint64_t getEntryFreq() const;
+  void releaseMemory();
+  void print(raw_ostream &OS) const;
+};
 
+/// \brief Legacy analysis pass which computes \c BlockFrequencyInfo.
+class BlockFrequencyInfoWrapperPass : public FunctionPass {
+  BlockFrequencyInfo BFI;
+
+public:
+  static char ID;
+
+  BlockFrequencyInfoWrapperPass();
+  ~BlockFrequencyInfoWrapperPass() override;
+
+  BlockFrequencyInfo &getBFI() { return BFI; }
+  const BlockFrequencyInfo &getBFI() const { return BFI; }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override;
+
+  bool runOnFunction(Function &F) override;
+  void releaseMemory() override;
+  void print(raw_ostream &OS, const Module *M) const override;
 };
 
 }
 
 #endif

llvm/trunk/include/llvm/InitializePasses.h

 void initializeArgPromotionPass(PassRegistry&);
 void initializeAtomicExpandPass(PassRegistry&);
 void initializeSampleProfileLoaderPass(PassRegistry&);
 void initializeAlignmentFromAssumptionsPass(PassRegistry&);
 void initializeBarrierNoopPass(PassRegistry&);
 void initializeBasicAliasAnalysisPass(PassRegistry&);
 void initializeCallGraphWrapperPassPass(PassRegistry &);
 void initializeBlockExtractorPassPass(PassRegistry&);
-void initializeBlockFrequencyInfoPass(PassRegistry&);
+void initializeBlockFrequencyInfoWrapperPassPass(PassRegistry&);
 void initializeBoundsCheckingPass(PassRegistry&);
 void initializeBranchFolderPassPass(PassRegistry&);
 void initializeBranchProbabilityInfoPass(PassRegistry&);
 void initializeBreakCriticalEdgesPass(PassRegistry&);
 void initializeCallGraphPrinterPass(PassRegistry&);
 void initializeCallGraphViewerPass(PassRegistry&);
 void initializeCFGOnlyPrinterPass(PassRegistry&);
 void initializeCFGOnlyViewerPass(PassRegistry&);

llvm/trunk/lib/Analysis/Analysis.cpp

 void llvm::initializeAnalysis(PassRegistry &Registry) {
   initializeAliasAnalysisAnalysisGroup(Registry);
   initializeAliasAnalysisCounterPass(Registry);
   initializeAAEvalPass(Registry);
   initializeAliasDebuggerPass(Registry);
   initializeAliasSetPrinterPass(Registry);
   initializeNoAAPass(Registry);
   initializeBasicAliasAnalysisPass(Registry);
-  initializeBlockFrequencyInfoPass(Registry);
+  initializeBlockFrequencyInfoWrapperPassPass(Registry);
   initializeBranchProbabilityInfoPass(Registry);
   initializeCostModelAnalysisPass(Registry);
   initializeCFGViewerPass(Registry);
   initializeCFGPrinterPass(Registry);
   initializeCFGOnlyViewerPass(Registry);
   initializeCFGOnlyPrinterPass(Registry);
   initializeCFLAliasAnalysisPass(Registry);
   initializeDependenceAnalysisPass(Registry);

llvm/trunk/lib/Analysis/BlockFrequencyInfo.cpp

std::string getNodeLabel(const BasicBlock *Node,
 
     return Result;
   }
 };
 
 } // end namespace llvm
 #endif
 
-INITIALIZE_PASS_BEGIN(BlockFrequencyInfo, "block-freq",
-                      "Block Frequency Analysis", true, true)
-INITIALIZE_PASS_DEPENDENCY(BranchProbabilityInfo)
-INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
-INITIALIZE_PASS_END(BlockFrequencyInfo, "block-freq",
-                    "Block Frequency Analysis", true, true)
-
-char BlockFrequencyInfo::ID = 0;
-
-
-BlockFrequencyInfo::BlockFrequencyInfo() : FunctionPass(ID) {
-  initializeBlockFrequencyInfoPass(*PassRegistry::getPassRegistry());
-}
-
-BlockFrequencyInfo::~BlockFrequencyInfo() {}
-
-void BlockFrequencyInfo::getAnalysisUsage(AnalysisUsage &AU) const {
-  AU.addRequired<BranchProbabilityInfo>();
-  AU.addRequired<LoopInfoWrapperPass>();
-  AU.setPreservesAll();
-}
-
-bool BlockFrequencyInfo::runOnFunction(Function &F) {
-  BranchProbabilityInfo &BPI = getAnalysis<BranchProbabilityInfo>();
-  LoopInfo &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
+void BlockFrequencyInfo::calculate(const Function &F,
+                                   const BranchProbabilityInfo &BPI,
+                                   const LoopInfo &LI) {
   if (!BFI)
     BFI.reset(new ImplType);
   BFI->doFunction(&F, &BPI, &LI);
 #ifndef NDEBUG
   if (ViewBlockFreqPropagationDAG != GVDT_None)
     view();
 #endif
-  return false;
-}
-
-void BlockFrequencyInfo::releaseMemory() { BFI.reset(); }
-
-void BlockFrequencyInfo::print(raw_ostream &O, const Module *) const {
-  if (BFI) BFI->print(O);
 }
 
 BlockFrequency BlockFrequencyInfo::getBlockFreq(const BasicBlock *BB) const {
   return BFI ? BFI->getBlockFreq(BB) : 0;
 }
 
 /// Pop up a ghostview window with the current block frequency propagation
 /// rendered using dot.

 BlockFrequencyInfo::printBlockFreq(raw_ostream &OS,
                                    const BasicBlock *BB) const {
   return BFI ? BFI->printBlockFreq(OS, BB) : OS;
 }
 
 uint64_t BlockFrequencyInfo::getEntryFreq() const {
   return BFI ? BFI->getEntryFreq() : 0;
 }
+
+void BlockFrequencyInfo::releaseMemory() { BFI.reset(); }
+
+void BlockFrequencyInfo::print(raw_ostream &OS) const {
+  if (BFI)
+    BFI->print(OS);
+}
+
+
+INITIALIZE_PASS_BEGIN(BlockFrequencyInfoWrapperPass, "block-freq",
+                      "Block Frequency Analysis", true, true)
+INITIALIZE_PASS_DEPENDENCY(BranchProbabilityInfo)
+INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
+INITIALIZE_PASS_END(BlockFrequencyInfoWrapperPass, "block-freq",
+                    "Block Frequency Analysis", true, true)
+
+char BlockFrequencyInfoWrapperPass::ID = 0;
+
+
+BlockFrequencyInfoWrapperPass::BlockFrequencyInfoWrapperPass()
+    : FunctionPass(ID) {
+  initializeBlockFrequencyInfoWrapperPassPass(*PassRegistry::getPassRegistry());
+}
+
+BlockFrequencyInfoWrapperPass::~BlockFrequencyInfoWrapperPass() {}
+
+void BlockFrequencyInfoWrapperPass::print(raw_ostream &OS,
+                                          const Module *) const {
+  BFI.print(OS);
+}
+
+void BlockFrequencyInfoWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.addRequired<BranchProbabilityInfo>();
+  AU.addRequired<LoopInfoWrapperPass>();
+  AU.setPreservesAll();
+}
+
+void BlockFrequencyInfoWrapperPass::releaseMemory() { BFI.releaseMemory(); }
+
+bool BlockFrequencyInfoWrapperPass::runOnFunction(Function &F) {
+  BranchProbabilityInfo &BPI = getAnalysis<BranchProbabilityInfo>();
+  LoopInfo &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
+  BFI.calculate(F, BPI, LI);
+  return false;
+}

llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp

struct LoopVectorize : public FunctionPass {
 
   BlockFrequency ColdEntryFreq;
 
   bool runOnFunction(Function &F) override {
     SE = &getAnalysis<ScalarEvolution>();
     LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
     TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
     DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
-    BFI = &getAnalysis<BlockFrequencyInfo>();
+    BFI = &getAnalysis<BlockFrequencyInfoWrapperPass>().getBFI();
     auto *TLIP = getAnalysisIfAvailable<TargetLibraryInfoWrapperPass>();
     TLI = TLIP ? &TLIP->getTLI() : nullptr;
     AA = &getAnalysis<AliasAnalysis>();
     AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
     LAA = &getAnalysis<LoopAccessAnalysis>();
 
     // Compute some weights outside of the loop over the loops. Compute this
     // using a BranchProbability to re-use its scaling math.
#endif /* NDEBUG */
     DEBUG(verifyFunction(*L->getHeader()->getParent()));
     return true;
   }
 
   void getAnalysisUsage(AnalysisUsage &AU) const override {
     AU.addRequired<AssumptionCacheTracker>();
     AU.addRequiredID(LoopSimplifyID);
     AU.addRequiredID(LCSSAID);
-    AU.addRequired<BlockFrequencyInfo>();
+    AU.addRequired<BlockFrequencyInfoWrapperPass>();
     AU.addRequired<DominatorTreeWrapperPass>();
     AU.addRequired<LoopInfoWrapperPass>();
     AU.addRequired<ScalarEvolution>();
     AU.addRequired<TargetTransformInfoWrapperPass>();
     AU.addRequired<AliasAnalysis>();
     AU.addRequired<LoopAccessAnalysis>();
     AU.addPreserved<LoopInfoWrapperPass>();
     AU.addPreserved<DominatorTreeWrapperPass>();

 }
 
 char LoopVectorize::ID = 0;
 static const char lv_name[] = "Loop Vectorization";
 INITIALIZE_PASS_BEGIN(LoopVectorize, LV_NAME, lv_name, false, false)
 INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
 INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
 INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
-INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfo)
+INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
 INITIALIZE_PASS_DEPENDENCY(LCSSA)
 INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
 INITIALIZE_PASS_DEPENDENCY(LoopAccessAnalysis)
 INITIALIZE_PASS_END(LoopVectorize, LV_NAME, lv_name, false, false)