2 files changed, 69 insertions, 0 deletions
diff --git a/llvm/include/llvm/Analysis/BranchProbabilityInfo.h b/llvm/include/llvm/Analysis/BranchProbabilityInfo.h
new file mode 100644
index 00000000000..bf2a6a765f6
--- /dev/null
+++ b/llvm/include/llvm/Analysis/BranchProbabilityInfo.h
@@ -0,0 +1,68 @@
+//===--- BranchProbabilityInfo.h - Branch Probability Analysis --*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass is used to evaluate branch probabilties.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_BRANCHPROBABILITYINFO_H
+#define LLVM_ANALYSIS_BRANCHPROBABILITYINFO_H
+
+#include "llvm/InitializePasses.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Support/Debug.h"
+
+namespace llvm {
+
+class BranchProbabilityInfo : public FunctionPass {
+
+  // Default weight value. Used when we don't have information about the edge.
+  static const unsigned int DEFAULT_WEIGHT = 16;
+
+  typedef std::pair<BasicBlock *, BasicBlock *> Edge;
+
+  DenseMap<Edge, unsigned> Weights;
+
+public:
+  static char ID;
+
+  BranchProbabilityInfo() : FunctionPass(ID) {
+    initializeBranchProbabilityInfoPass(*PassRegistry::getPassRegistry());
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const {
+    AU.addRequired<LoopInfo>();
+    AU.setPreservesAll();
+  }
+
+  bool runOnFunction(Function &F);
+
+  // Returned value is between 1 and UINT_MAX. Look at BranchProbabilityInfo.cpp
+  // for details.
+  unsigned getEdgeWeight(BasicBlock *Src, BasicBlock *Dst) const;
+
+  // Look at BranchProbabilityInfo.cpp for details. Use it with caution!
+  void setEdgeWeight(BasicBlock *Src, BasicBlock *Dst, unsigned Weight);
+
+  // A 'Hot' edge is an edge which probability is >= 80%.
+  bool isEdgeHot(BasicBlock *Src, BasicBlock *Dst) const;
+
+  // Return a hot successor for the block BB or null if there isn't one.
+  BasicBlock *getHotSucc(BasicBlock *BB) const;
+
+  // Print value between 0 (0% probability) and 1 (100% probability),
+  // however the value is never equal to 0, and can be 1 only iff SRC block
+  // has only one successor.
+  raw_ostream &printEdgeProbability(raw_ostream &OS, BasicBlock *Src,
+                                   BasicBlock *Dst) const;
+};
+
+}
+
+#endif
diff --git a/llvm/include/llvm/InitializePasses.h b/llvm/include/llvm/InitializePasses.h
index cca0194a60e..372eaba74a7 100644
--- a/llvm/include/llvm/InitializePasses.h
+++ b/llvm/include/llvm/InitializePasses.h
@@ -66,6 +66,7 @@ void initializeBasicAliasAnalysisPass(PassRegistry&);
 void initializeBasicCallGraphPass(PassRegistry&);
 void initializeBlockExtractorPassPass(PassRegistry&);
 void initializeBlockPlacementPass(PassRegistry&);
+void initializeBranchProbabilityInfoPass(PassRegistry&);
 void initializeBreakCriticalEdgesPass(PassRegistry&);
 void initializeCFGOnlyPrinterPass(PassRegistry&);
 void initializeCFGOnlyViewerPass(PassRegistry&);