//=- FunctionPropertiesAnalysis.h - Function Properties 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 FunctionPropertiesInfo and FunctionPropertiesAnalysis
// classes used to extract function properties.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_ANALYSIS_FUNCTIONPROPERTIESANALYSIS_H
#define LLVM_ANALYSIS_FUNCTIONPROPERTIESANALYSIS_H

#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/iterator_range.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/PassManager.h"

namespace llvm {
class DominatorTree;
class Function;
class LoopInfo;

class FunctionPropertiesInfo {
  friend class FunctionPropertiesUpdater;
  void updateForBB(const BasicBlock &BB, int64_t Direction);
  void updateAggregateStats(const Function &F, const LoopInfo &LI);
  void reIncludeBB(const BasicBlock &BB);

public:
  static FunctionPropertiesInfo
  getFunctionPropertiesInfo(const Function &F, const DominatorTree &DT,
                            const LoopInfo &LI);

  static FunctionPropertiesInfo
  getFunctionPropertiesInfo(Function &F, FunctionAnalysisManager &FAM);

  bool operator==(const FunctionPropertiesInfo &FPI) const {
    return std::memcmp(this, &FPI, sizeof(FunctionPropertiesInfo)) == 0;
  }

  bool operator!=(const FunctionPropertiesInfo &FPI) const {
    return !(*this == FPI);
  }

  void print(raw_ostream &OS) const;

  /// Number of basic blocks
  int64_t BasicBlockCount = 0;

  /// Number of blocks reached from a conditional instruction, or that are
  /// 'cases' of a SwitchInstr.
  // FIXME: We may want to replace this with a more meaningful metric, like
  // number of conditionally executed blocks:
  // 'if (a) s();' would be counted here as 2 blocks, just like
  // 'if (a) s(); else s2(); s3();' would.
  int64_t BlocksReachedFromConditionalInstruction = 0;

  /// Number of uses of this function, plus 1 if the function is callable
  /// outside the module.
  int64_t Uses = 0;

  /// Number of direct calls made from this function to other functions
  /// defined in this module.
  int64_t DirectCallsToDefinedFunctions = 0;

  // Load Instruction Count
  int64_t LoadInstCount = 0;

  // Store Instruction Count
  int64_t StoreInstCount = 0;

  // Maximum Loop Depth in the Function
  int64_t MaxLoopDepth = 0;

  // Number of Top Level Loops in the Function
  int64_t TopLevelLoopCount = 0;

  // All non-debug instructions
  int64_t TotalInstructionCount = 0;
};

// Analysis pass
class FunctionPropertiesAnalysis
    : public AnalysisInfoMixin<FunctionPropertiesAnalysis> {

public:
  static AnalysisKey Key;

  using Result = const FunctionPropertiesInfo;

  FunctionPropertiesInfo run(Function &F, FunctionAnalysisManager &FAM);
};

/// Printer pass for the FunctionPropertiesAnalysis results.
class FunctionPropertiesPrinterPass
    : public PassInfoMixin<FunctionPropertiesPrinterPass> {
  raw_ostream &OS;

public:
  explicit FunctionPropertiesPrinterPass(raw_ostream &OS) : OS(OS) {}

  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
};

/// Correctly update FunctionPropertiesInfo post-inlining. A
/// FunctionPropertiesUpdater keeps the state necessary for tracking the changes
/// llvm::InlineFunction makes. The idea is that inlining will at most modify
/// a few BBs of the Caller (maybe the entry BB and definitely the callsite BB)
/// and potentially affect exception handling BBs in the case of invoke
/// inlining.
class FunctionPropertiesUpdater {
public:
  FunctionPropertiesUpdater(FunctionPropertiesInfo &FPI, CallBase &CB);

  void finish(FunctionAnalysisManager &FAM) const;
  bool finishAndTest(FunctionAnalysisManager &FAM) const {
    finish(FAM);
    return isUpdateValid(Caller, FPI, FAM);
  }

private:
  FunctionPropertiesInfo &FPI;
  BasicBlock &CallSiteBB;
  Function &Caller;

  static bool isUpdateValid(Function &F, const FunctionPropertiesInfo &FPI,
                            FunctionAnalysisManager &FAM);

  DenseSet<const BasicBlock *> Successors;
};
} // namespace llvm
#endif // LLVM_ANALYSIS_FUNCTIONPROPERTIESANALYSIS_H