Subversion Repositories QNX 8.QNX8 LLVM/Clang compiler suite

//===- LazyValueInfo.h - Value constraint 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 file defines the interface for lazy computation of value constraint

// information.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_ANALYSIS_LAZYVALUEINFO_H

#define LLVM_ANALYSIS_LAZYVALUEINFO_H

#include "llvm/IR/PassManager.h"

#include "llvm/Pass.h"

namespace llvm {

  class AssumptionCache;

  class Constant;

  class ConstantRange;

  class DataLayout;

  class DominatorTree;

  class Instruction;

  class TargetLibraryInfo;

  class Value;

/// This pass computes, caches, and vends lazy value constraint information.

class LazyValueInfo {

  friend class LazyValueInfoWrapperPass;

  AssumptionCache *AC = nullptr;

  const DataLayout *DL = nullptr;

  class TargetLibraryInfo *TLI = nullptr;

  void *PImpl = nullptr;

  LazyValueInfo(const LazyValueInfo&) = delete;

  void operator=(const LazyValueInfo&) = delete;

public:

  ~LazyValueInfo();

  LazyValueInfo() = default;

  LazyValueInfo(AssumptionCache *AC_, const DataLayout *DL_,

                TargetLibraryInfo *TLI_)

      : AC(AC_), DL(DL_), TLI(TLI_) {}

  LazyValueInfo(LazyValueInfo &&Arg)

      : AC(Arg.AC), DL(Arg.DL), TLI(Arg.TLI), PImpl(Arg.PImpl) {

    Arg.PImpl = nullptr;

  }

  LazyValueInfo &operator=(LazyValueInfo &&Arg) {

    releaseMemory();

    AC = Arg.AC;

    DL = Arg.DL;

    TLI = Arg.TLI;

    PImpl = Arg.PImpl;

    Arg.PImpl = nullptr;

    return *this;

  }

  /// This is used to return true/false/dunno results.

  enum Tristate {

    Unknown = -1, False = 0, True = 1

  };

  // Public query interface.

  /// Determine whether the specified value comparison with a constant is known

  /// to be true or false on the specified CFG edge.

  /// Pred is a CmpInst predicate.

  Tristate getPredicateOnEdge(unsigned Pred, Value *V, Constant *C,

                              BasicBlock *FromBB, BasicBlock *ToBB,

                              Instruction *CxtI = nullptr);

  /// Determine whether the specified value comparison with a constant is known

  /// to be true or false at the specified instruction.

  /// \p Pred is a CmpInst predicate. If \p UseBlockValue is true, the block

  /// value is also taken into account.

  Tristate getPredicateAt(unsigned Pred, Value *V, Constant *C,

                          Instruction *CxtI, bool UseBlockValue);

  /// Determine whether the specified value comparison is known to be true

  /// or false at the specified instruction. While this takes two Value's,

  /// it still requires that one of them is a constant.

  /// \p Pred is a CmpInst predicate.

  /// If \p UseBlockValue is true, the block value is also taken into account.

  Tristate getPredicateAt(unsigned Pred, Value *LHS, Value *RHS,

                          Instruction *CxtI, bool UseBlockValue);

  /// Determine whether the specified value is known to be a constant at the

  /// specified instruction. Return null if not.

  Constant *getConstant(Value *V, Instruction *CxtI);

  /// Return the ConstantRange constraint that is known to hold for the

  /// specified value at the specified instruction. This may only be called

  /// on integer-typed Values.

  ConstantRange getConstantRange(Value *V, Instruction *CxtI,

                                 bool UndefAllowed = true);

  /// Return the ConstantRange constraint that is known to hold for the value

  /// at a specific use-site.

  ConstantRange getConstantRangeAtUse(const Use &U, bool UndefAllowed = true);

  /// Determine whether the specified value is known to be a

  /// constant on the specified edge.  Return null if not.

  Constant *getConstantOnEdge(Value *V, BasicBlock *FromBB, BasicBlock *ToBB,

                              Instruction *CxtI = nullptr);

  /// Return the ConstantRage constraint that is known to hold for the

  /// specified value on the specified edge. This may be only be called

  /// on integer-typed Values.

  ConstantRange getConstantRangeOnEdge(Value *V, BasicBlock *FromBB,

                                       BasicBlock *ToBB,

                                       Instruction *CxtI = nullptr);

  /// Inform the analysis cache that we have threaded an edge from

  /// PredBB to OldSucc to be from PredBB to NewSucc instead.

  void threadEdge(BasicBlock *PredBB, BasicBlock *OldSucc, BasicBlock *NewSucc);

  /// Inform the analysis cache that we have erased a block.

  void eraseBlock(BasicBlock *BB);

  /// Complete flush all previously computed values

  void clear(const Module *M);

  /// Print the \LazyValueInfo Analysis.

  /// We pass in the DTree that is required for identifying which basic blocks

  /// we can solve/print for, in the LVIPrinter.

  void printLVI(Function &F, DominatorTree &DTree, raw_ostream &OS);

  // For old PM pass. Delete once LazyValueInfoWrapperPass is gone.

  void releaseMemory();

  /// Handle invalidation events in the new pass manager.

  bool invalidate(Function &F, const PreservedAnalyses &PA,

                  FunctionAnalysisManager::Invalidator &Inv);

};

/// Analysis to compute lazy value information.

class LazyValueAnalysis : public AnalysisInfoMixin<LazyValueAnalysis> {

public:

  typedef LazyValueInfo Result;

  Result run(Function &F, FunctionAnalysisManager &FAM);

private:

  static AnalysisKey Key;

  friend struct AnalysisInfoMixin<LazyValueAnalysis>;

};

/// Wrapper around LazyValueInfo.

class LazyValueInfoWrapperPass : public FunctionPass {

  LazyValueInfoWrapperPass(const LazyValueInfoWrapperPass&) = delete;

  void operator=(const LazyValueInfoWrapperPass&) = delete;

public:

  static char ID;

  LazyValueInfoWrapperPass();

  ~LazyValueInfoWrapperPass() override {

    assert(!Info.PImpl && "releaseMemory not called");

  }

  LazyValueInfo &getLVI();

  void getAnalysisUsage(AnalysisUsage &AU) const override;

  void releaseMemory() override;

  bool runOnFunction(Function &F) override;

private:

  LazyValueInfo Info;

};

}  // end namespace llvm

#endif