Merge "Update prebuilt Clang to r353983." into p9.0HEADp9.0-backupp9.0

1 files changed, 252 insertions, 0 deletions

diff --git a/clang-r353983/include/llvm/Analysis/BranchProbabilityInfo.h b/clang-r353983/include/llvm/Analysis/BranchProbabilityInfo.h
new file mode 100644
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+++ b/clang-r353983/include/llvm/Analysis/BranchProbabilityInfo.h
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+//===- BranchProbabilityInfo.h - Branch Probability Analysis ----*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass is used to evaluate branch probabilties.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_BRANCHPROBABILITYINFO_H
+#define LLVM_ANALYSIS_BRANCHPROBABILITYINFO_H
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/DenseMapInfo.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/IR/ValueHandle.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/BranchProbability.h"
+#include "llvm/Support/Casting.h"
+#include <algorithm>
+#include <cassert>
+#include <cstdint>
+#include <utility>
+
+namespace llvm {
+
+class Function;
+class LoopInfo;
+class raw_ostream;
+class TargetLibraryInfo;
+class Value;
+
+/// Analysis providing branch probability information.
+///
+/// This is a function analysis which provides information on the relative
+/// probabilities of each "edge" in the function's CFG where such an edge is
+/// defined by a pair (PredBlock and an index in the successors). The
+/// probability of an edge from one block is always relative to the
+/// probabilities of other edges from the block. The probabilites of all edges
+/// from a block sum to exactly one (100%).
+/// We use a pair (PredBlock and an index in the successors) to uniquely
+/// identify an edge, since we can have multiple edges from Src to Dst.
+/// As an example, we can have a switch which jumps to Dst with value 0 and
+/// value 10.
+class BranchProbabilityInfo {
+public:
+  BranchProbabilityInfo() = default;
+
+  BranchProbabilityInfo(const Function &F, const LoopInfo &LI,
+                        const TargetLibraryInfo *TLI = nullptr) {
+    calculate(F, LI, TLI);
+  }
+
+  BranchProbabilityInfo(BranchProbabilityInfo &&Arg)
+      : Probs(std::move(Arg.Probs)), LastF(Arg.LastF),
+        PostDominatedByUnreachable(std::move(Arg.PostDominatedByUnreachable)),
+        PostDominatedByColdCall(std::move(Arg.PostDominatedByColdCall)) {}
+
+  BranchProbabilityInfo(const BranchProbabilityInfo &) = delete;
+  BranchProbabilityInfo &operator=(const BranchProbabilityInfo &) = delete;
+
+  BranchProbabilityInfo &operator=(BranchProbabilityInfo &&RHS) {
+    releaseMemory();
+    Probs = std::move(RHS.Probs);
+    PostDominatedByColdCall = std::move(RHS.PostDominatedByColdCall);
+    PostDominatedByUnreachable = std::move(RHS.PostDominatedByUnreachable);
+    return *this;
+  }
+
+  void releaseMemory();
+
+  void print(raw_ostream &OS) const;
+
+  /// Get an edge's probability, relative to other out-edges of the Src.
+  ///
+  /// This routine provides access to the fractional probability between zero
+  /// (0%) and one (100%) of this edge executing, relative to other edges
+  /// leaving the 'Src' block. The returned probability is never zero, and can
+  /// only be one if the source block has only one successor.
+  BranchProbability getEdgeProbability(const BasicBlock *Src,
+                                       unsigned IndexInSuccessors) const;
+
+  /// Get the probability of going from Src to Dst.
+  ///
+  /// It returns the sum of all probabilities for edges from Src to Dst.
+  BranchProbability getEdgeProbability(const BasicBlock *Src,
+                                       const BasicBlock *Dst) const;
+
+  BranchProbability getEdgeProbability(const BasicBlock *Src,
+                                       succ_const_iterator Dst) const;
+
+  /// Test if an edge is hot relative to other out-edges of the Src.
+  ///
+  /// Check whether this edge out of the source block is 'hot'. We define hot
+  /// as having a relative probability >= 80%.
+  bool isEdgeHot(const BasicBlock *Src, const BasicBlock *Dst) const;
+
+  /// Retrieve the hot successor of a block if one exists.
+  ///
+  /// Given a basic block, look through its successors and if one exists for
+  /// which \see isEdgeHot would return true, return that successor block.
+  const BasicBlock *getHotSucc(const BasicBlock *BB) const;
+
+  /// Print an edge's probability.
+  ///
+  /// Retrieves an edge's probability similarly to \see getEdgeProbability, but
+  /// then prints that probability to the provided stream. That stream is then
+  /// returned.
+  raw_ostream &printEdgeProbability(raw_ostream &OS, const BasicBlock *Src,
+                                    const BasicBlock *Dst) const;
+
+  /// Set the raw edge probability for the given edge.
+  ///
+  /// This allows a pass to explicitly set the edge probability for an edge. It
+  /// can be used when updating the CFG to update and preserve the branch
+  /// probability information. Read the implementation of how these edge
+  /// probabilities are calculated carefully before using!
+  void setEdgeProbability(const BasicBlock *Src, unsigned IndexInSuccessors,
+                          BranchProbability Prob);
+
+  static BranchProbability getBranchProbStackProtector(bool IsLikely) {
+    static const BranchProbability LikelyProb((1u << 20) - 1, 1u << 20);
+    return IsLikely ? LikelyProb : LikelyProb.getCompl();
+  }
+
+  void calculate(const Function &F, const LoopInfo &LI,
+                 const TargetLibraryInfo *TLI = nullptr);
+
+  /// Forget analysis results for the given basic block.
+  void eraseBlock(const BasicBlock *BB);
+
+  // Use to track SCCs for handling irreducible loops.
+  using SccMap = DenseMap<const BasicBlock *, int>;
+  using SccHeaderMap = DenseMap<const BasicBlock *, bool>;
+  using SccHeaderMaps = std::vector<SccHeaderMap>;
+  struct SccInfo {
+    SccMap SccNums;
+    SccHeaderMaps SccHeaders;
+  };
+
+private:
+  // We need to store CallbackVH's in order to correctly handle basic block
+  // removal.
+  class BasicBlockCallbackVH final : public CallbackVH {
+    BranchProbabilityInfo *BPI;
+
+    void deleted() override {
+      assert(BPI != nullptr);
+      BPI->eraseBlock(cast<BasicBlock>(getValPtr()));
+      BPI->Handles.erase(*this);
+    }
+
+  public:
+    BasicBlockCallbackVH(const Value *V, BranchProbabilityInfo *BPI = nullptr)
+        : CallbackVH(const_cast<Value *>(V)), BPI(BPI) {}
+  };
+
+  DenseSet<BasicBlockCallbackVH, DenseMapInfo<Value*>> Handles;
+
+  // Since we allow duplicate edges from one basic block to another, we use
+  // a pair (PredBlock and an index in the successors) to specify an edge.
+  using Edge = std::pair<const BasicBlock *, unsigned>;
+
+  // Default weight value. Used when we don't have information about the edge.
+  // TODO: DEFAULT_WEIGHT makes sense during static predication, when none of
+  // the successors have a weight yet. But it doesn't make sense when providing
+  // weight to an edge that may have siblings with non-zero weights. This can
+  // be handled various ways, but it's probably fine for an edge with unknown
+  // weight to just "inherit" the non-zero weight of an adjacent successor.
+  static const uint32_t DEFAULT_WEIGHT = 16;
+
+  DenseMap<Edge, BranchProbability> Probs;
+
+  /// Track the last function we run over for printing.
+  const Function *LastF;
+
+  /// Track the set of blocks directly succeeded by a returning block.
+  SmallPtrSet<const BasicBlock *, 16> PostDominatedByUnreachable;
+
+  /// Track the set of blocks that always lead to a cold call.
+  SmallPtrSet<const BasicBlock *, 16> PostDominatedByColdCall;
+
+  void updatePostDominatedByUnreachable(const BasicBlock *BB);
+  void updatePostDominatedByColdCall(const BasicBlock *BB);
+  bool calcUnreachableHeuristics(const BasicBlock *BB);
+  bool calcMetadataWeights(const BasicBlock *BB);
+  bool calcColdCallHeuristics(const BasicBlock *BB);
+  bool calcPointerHeuristics(const BasicBlock *BB);
+  bool calcLoopBranchHeuristics(const BasicBlock *BB, const LoopInfo &LI,
+                                SccInfo &SccI);
+  bool calcZeroHeuristics(const BasicBlock *BB, const TargetLibraryInfo *TLI);
+  bool calcFloatingPointHeuristics(const BasicBlock *BB);
+  bool calcInvokeHeuristics(const BasicBlock *BB);
+};
+
+/// Analysis pass which computes \c BranchProbabilityInfo.
+class BranchProbabilityAnalysis
+    : public AnalysisInfoMixin<BranchProbabilityAnalysis> {
+  friend AnalysisInfoMixin<BranchProbabilityAnalysis>;
+
+  static AnalysisKey Key;
+
+public:
+  /// Provide the result type for this analysis pass.
+  using Result = BranchProbabilityInfo;
+
+  /// Run the analysis pass over a function and produce BPI.
+  BranchProbabilityInfo run(Function &F, FunctionAnalysisManager &AM);
+};
+
+/// Printer pass for the \c BranchProbabilityAnalysis results.
+class BranchProbabilityPrinterPass
+    : public PassInfoMixin<BranchProbabilityPrinterPass> {
+  raw_ostream &OS;
+
+public:
+  explicit BranchProbabilityPrinterPass(raw_ostream &OS) : OS(OS) {}
+
+  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
+};
+
+/// Legacy analysis pass which computes \c BranchProbabilityInfo.
+class BranchProbabilityInfoWrapperPass : public FunctionPass {
+  BranchProbabilityInfo BPI;
+
+public:
+  static char ID;
+
+  BranchProbabilityInfoWrapperPass() : FunctionPass(ID) {
+    initializeBranchProbabilityInfoWrapperPassPass(
+        *PassRegistry::getPassRegistry());
+  }
+
+  BranchProbabilityInfo &getBPI() { return BPI; }
+  const BranchProbabilityInfo &getBPI() const { return BPI; }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override;
+  bool runOnFunction(Function &F) override;
+  void releaseMemory() override;
+  void print(raw_ostream &OS, const Module *M = nullptr) const override;
+};
+
+} // end namespace llvm
+
+#endif // LLVM_ANALYSIS_BRANCHPROBABILITYINFO_H