Missing files for the BlockFrequency analysis added.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133767 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 336 insertions, 0 deletions

diff --git a/include/llvm/Analysis/BlockFrequencyImpl.h b/include/llvm/Analysis/BlockFrequencyImpl.h
new file mode 100644
index 0000000000..7447e80a31
--- /dev/null
+++ b/include/llvm/Analysis/BlockFrequencyImpl.h
@@ -0,0 +1,336 @@
+//===---- BlockFrequencyImpl.h - Machine Block Frequency Implementation ---===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Shared implementation of BlockFrequency for IR and Machine Instructions.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_BLOCKFREQUENCYIMPL_H
+#define LLVM_ANALYSIS_BLOCKFREQUENCYIMPL_H
+
+#include "llvm/BasicBlock.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/PostOrderIterator.h"
+#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/Support/BranchProbability.h"
+#include "llvm/Support/Debug.h"
+#include <vector>
+#include <sstream>
+#include <string>
+
+namespace llvm {
+
+
+class BlockFrequency;
+/// BlockFrequencyImpl implements block frequency algorithm for IR and
+/// Machine Instructions. Algorithm starts with value 1024 (START_FREQ)
+/// for the entry block and then propagates frequencies using branch weights
+/// from (Machine)BranchProbabilityInfo. LoopInfo is not required because
+/// algorithm can find "backedges" by itself.
+template<class BlockT, class FunctionT, class BlockProbInfoT>
+class BlockFrequencyImpl {
+
+  DenseMap<BlockT *, uint32_t> Freqs;
+
+  BlockProbInfoT *BPI;
+
+  FunctionT *Fn;
+
+  typedef GraphTraits< Inverse<BlockT *> > GT;
+
+  static const uint32_t START_FREQ = 1024;
+
+  std::string getBlockName(BasicBlock *BB) const {
+    return BB->getNameStr();
+  }
+
+  std::string getBlockName(MachineBasicBlock *MBB) const {
+    std::stringstream ss;
+    ss << "BB#" << MBB->getNumber();
+    const BasicBlock *BB = MBB->getBasicBlock();
+
+    if (BB)
+      ss << " derived from LLVM BB " << BB->getNameStr();
+
+    return ss.str();
+  }
+
+  void setBlockFreq(BlockT *BB, uint32_t Freq) {
+    Freqs[BB] = Freq;
+    DEBUG(dbgs() << "Frequency(" << getBlockName(BB) << ") = " << Freq << "\n");
+  }
+
+  /// getEdgeFreq - Return edge frequency based on SRC frequency and Src -> Dst
+  /// edge probability.
+  uint32_t getEdgeFreq(BlockT *Src, BlockT *Dst) const {
+    BranchProbability Prob = BPI->getEdgeProbability(Src, Dst);
+    uint64_t N = Prob.getNumerator();
+    uint64_t D = Prob.getDenominator();
+    uint64_t Res = (N * getBlockFreq(Src)) / D;
+
+    assert(Res <= UINT32_MAX);
+    return (uint32_t) Res;
+  }
+
+  /// incBlockFreq - Increase BB block frequency by FREQ.
+  ///
+  void incBlockFreq(BlockT *BB, uint32_t Freq) {
+    Freqs[BB] += Freq;
+    DEBUG(dbgs() << "Frequency(" << getBlockName(BB) << ") += " << Freq
+                 << " --> " << Freqs[BB] << "\n");
+  }
+
+  /// divBlockFreq - Divide BB block frequency by PROB. If Prob = 0 do nothing.
+  ///
+  void divBlockFreq(BlockT *BB, BranchProbability Prob) {
+    uint64_t N = Prob.getNumerator();
+    assert(N && "Illegal division by zero!");
+    uint64_t D = Prob.getDenominator();
+    uint64_t Freq = (Freqs[BB] * D) / N;
+
+    // Should we assert it?
+    if (Freq > UINT32_MAX)
+      Freq = UINT32_MAX;
+
+    Freqs[BB] = (uint32_t) Freq;
+    DEBUG(dbgs() << "Frequency(" << getBlockName(BB) << ") /= (" << Prob
+                 << ") --> " << Freqs[BB] << "\n");
+  }
+
+  // All blocks in postorder.
+  std::vector<BlockT *> POT;
+
+  // Map Block -> Position in reverse-postorder list.
+  DenseMap<BlockT *, unsigned> RPO;
+
+  // Cycle Probability for each bloch.
+  DenseMap<BlockT *, uint32_t> CycleProb;
+
+  // (reverse-)postorder traversal iterators.
+  typedef typename std::vector<BlockT *>::iterator pot_iterator;
+  typedef typename std::vector<BlockT *>::reverse_iterator rpot_iterator;
+
+  pot_iterator pot_begin() { return POT.begin(); }
+  pot_iterator pot_end() { return POT.end(); }
+
+  rpot_iterator rpot_begin() { return POT.rbegin(); }
+  rpot_iterator rpot_end() { return POT.rend(); }
+
+  rpot_iterator rpot_at(BlockT *BB) {
+    rpot_iterator I = rpot_begin();
+    unsigned idx = RPO[BB];
+    assert(idx);
+    std::advance(I, idx - 1);
+
+    assert(*I == BB);
+    return I;
+  }
+
+
+  /// isReachable - Returns if BB block is reachable from the entry.
+  ///
+  bool isReachable(BlockT *BB) {
+    return RPO.count(BB);
+  }
+
+  /// isBackedge - Return if edge Src -> Dst is a backedge.
+  ///
+  bool isBackedge(BlockT *Src, BlockT *Dst) {
+    assert(isReachable(Src));
+    assert(isReachable(Dst));
+
+    unsigned a = RPO[Src];
+    unsigned b = RPO[Dst];
+
+    return a > b;
+  }
+
+  /// getSingleBlockPred - return single BB block predecessor or NULL if
+  /// BB has none or more predecessors.
+  BlockT *getSingleBlockPred(BlockT *BB) {
+    typename GT::ChildIteratorType
+      PI = GraphTraits< Inverse<BlockT *> >::child_begin(BB),
+      PE = GraphTraits< Inverse<BlockT *> >::child_end(BB);
+
+    if (PI == PE)
+      return 0;
+
+    BlockT *Pred = *PI;
+
+    ++PI;
+    if (PI != PE)
+      return 0;
+
+    return Pred;
+  }
+
+  void doBlock(BlockT *BB, BlockT *LoopHead,
+               SmallPtrSet<BlockT *, 8> &BlocksInLoop) {
+
+    DEBUG(dbgs() << "doBlock(" << getBlockName(BB) << ")\n");
+    setBlockFreq(BB, 0);
+
+    if (BB == LoopHead) {
+      setBlockFreq(BB, START_FREQ);
+      return;
+    }
+
+    if(BlockT *Pred = getSingleBlockPred(BB)) {
+      if (BlocksInLoop.count(Pred))
+        setBlockFreq(BB, getEdgeFreq(Pred, BB));
+      // TODO: else? irreducible, ignore it for now.
+      return;
+    }
+
+    bool isInLoop = false;
+    bool isLoopHead = false;
+
+    for (typename GT::ChildIteratorType
+         PI = GraphTraits< Inverse<BlockT *> >::child_begin(BB),
+         PE = GraphTraits< Inverse<BlockT *> >::child_end(BB);
+         PI != PE; ++PI) {
+      BlockT *Pred = *PI;
+
+      if (isReachable(Pred) && isBackedge(Pred, BB)) {
+        isLoopHead = true;
+      } else if (BlocksInLoop.count(Pred)) {
+        incBlockFreq(BB, getEdgeFreq(Pred, BB));
+        isInLoop = true;
+      }
+      // TODO: else? irreducible.
+    }
+
+    if (!isInLoop)
+      return;
+
+    if (!isLoopHead)
+      return;
+
+    assert(START_FREQ >= CycleProb[BB]);
+    divBlockFreq(BB, BranchProbability(START_FREQ - CycleProb[BB], START_FREQ));
+  }
+
+  /// doLoop - Propagate block frequency down throught the loop.
+  void doLoop(BlockT *Head, BlockT *Tail) {
+    DEBUG(dbgs() << "doLoop(" << getBlockName(Head) << ", "
+                 << getBlockName(Tail) << ")\n");
+
+    SmallPtrSet<BlockT *, 8> BlocksInLoop;
+
+    for (rpot_iterator I = rpot_at(Head), E = rpot_end(); I != E; ++I) {
+      BlockT *BB = *I;
+      doBlock(BB, Head, BlocksInLoop);
+
+      BlocksInLoop.insert(BB);
+    }
+
+    // Compute loop's cyclic probability using backedges probabilities.
+    for (typename GT::ChildIteratorType
+         PI = GraphTraits< Inverse<BlockT *> >::child_begin(Head),
+         PE = GraphTraits< Inverse<BlockT *> >::child_end(Head);
+         PI != PE; ++PI) {
+      BlockT *Pred = *PI;
+      assert(Pred);
+      if (isReachable(Pred) && isBackedge(Pred, Head)) {
+        BranchProbability Prob = BPI->getBackEdgeProbability(Pred, Head);
+        uint64_t N = Prob.getNumerator();
+        uint64_t D = Prob.getDenominator();
+        uint64_t Res = (N * START_FREQ) / D;
+
+        // CycleProb[Head] += getEdgeFreq(Pred, Head);
+        assert(Res <= UINT32_MAX);
+        CycleProb[Head] += (uint32_t) Res;
+      }
+    }
+  }
+
+
+  friend class BlockFrequency;
+
+  void doFunction(FunctionT *fn, BlockProbInfoT *bpi) {
+    Fn = fn;
+    BPI = bpi;
+
+    // Clear everything.
+    RPO.clear();
+    POT.clear();
+    CycleProb.clear();
+    Freqs.clear();
+
+    BlockT *EntryBlock = fn->begin();
+
+    copy(po_begin(EntryBlock), po_end(EntryBlock), back_inserter(POT));
+
+    unsigned RPOidx = 0;
+    for (rpot_iterator I = rpot_begin(), E = rpot_end(); I != E; ++I) {
+      BlockT *BB = *I;
+      RPO[BB] = ++RPOidx;
+      DEBUG(dbgs() << "RPO[" << getBlockName(BB) << "] = " << RPO[BB] << "\n");
+    }
+
+    // Travel over all blocks in postorder.
+    for (pot_iterator I = pot_begin(), E = pot_end(); I != E; ++I) {
+      BlockT *BB = *I;
+      BlockT *LastTail = 0;
+      DEBUG(dbgs() << "POT: " << getBlockName(BB) << "\n");
+
+      for (typename GT::ChildIteratorType
+           PI = GraphTraits< Inverse<BlockT *> >::child_begin(BB),
+           PE = GraphTraits< Inverse<BlockT *> >::child_end(BB);
+           PI != PE; ++PI) {
+
+        BlockT *Pred = *PI;
+        if (isReachable(Pred) && isBackedge(Pred, BB)
+            && (!LastTail || RPO[Pred] > RPO[LastTail]))
+          LastTail = Pred;
+      }
+
+      if (LastTail)
+        doLoop(BB, LastTail);
+    }
+
+    // At the end assume the whole function as a loop, and travel over it once
+    // again.
+    doLoop(*(rpot_begin()), *(pot_begin()));
+  }
+
+public:
+  /// getBlockFreq - Return block frequency. Never return 0, value must be
+  /// positive.
+  uint32_t getBlockFreq(BlockT *BB) const {
+    typename DenseMap<BlockT *, uint32_t>::const_iterator I = Freqs.find(BB);
+    if (I != Freqs.end())
+      return I->second ? I->second : 1;
+    return 1;
+  }
+
+  void print(raw_ostream &OS) const {
+    OS << "\n\n---- Block Freqs ----\n";
+    for (typename FunctionT::iterator I = Fn->begin(), E = Fn->end(); I != E;) {
+      BlockT *BB = I++;
+      OS << " " << getBlockName(BB) << " = " << getBlockFreq(BB) << "\n";
+
+      for (typename GraphTraits<BlockT *>::ChildIteratorType
+           SI = GraphTraits<BlockT *>::child_begin(BB),
+           SE = GraphTraits<BlockT *>::child_end(BB); SI != SE; ++SI) {
+        BlockT *Succ = *SI;
+        OS << "  " << getBlockName(BB) << " -> " << getBlockName(Succ)
+           << " = " << getEdgeFreq(BB, Succ) << "\n";
+      }
+    }
+  }
+
+  void dump() const {
+    print(dbgs());
+  }
+};
+
+}
+
+#endif