//===- StackSafetyAnalysis.h - Stack memory safety 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
//
//===----------------------------------------------------------------------===//
//
// Stack Safety Analysis detects allocas and arguments with safe access.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_ANALYSIS_STACKSAFETYANALYSIS_H
#define LLVM_ANALYSIS_STACKSAFETYANALYSIS_H

#include "llvm/IR/ModuleSummaryIndex.h"
#include "llvm/IR/PassManager.h"
#include "llvm/Pass.h"

namespace llvm {

class AllocaInst;
class ScalarEvolution;

/// Interface to access stack safety analysis results for single function.
class StackSafetyInfo {
public:
  struct InfoTy;

private:
  Function *F = nullptr;
  std::function<ScalarEvolution &()> GetSE;
  mutable std::unique_ptr<InfoTy> Info;

public:
  LLVM_ABI StackSafetyInfo();
  LLVM_ABI StackSafetyInfo(Function *F,
                           std::function<ScalarEvolution &()> GetSE);
  LLVM_ABI StackSafetyInfo(StackSafetyInfo &&);
  LLVM_ABI StackSafetyInfo &operator=(StackSafetyInfo &&);
  LLVM_ABI ~StackSafetyInfo();

  LLVM_ABI const InfoTy &getInfo() const;

  // TODO: Add useful for client methods.
  LLVM_ABI void print(raw_ostream &O) const;

  /// Parameters use for a FunctionSummary.
  /// Function collects access information of all pointer parameters.
  /// Information includes a range of direct access of parameters by the
  /// functions and all call sites accepting the parameter.
  /// StackSafety assumes that missing parameter information means possibility
  /// of access to the parameter with any offset, so we can correctly link
  /// code without StackSafety information, e.g. non-ThinLTO.
  LLVM_ABI std::vector<FunctionSummary::ParamAccess>
  getParamAccesses(ModuleSummaryIndex &Index) const;
};

class StackSafetyGlobalInfo {
public:
  struct InfoTy;

private:
  Module *M = nullptr;
  std::function<const StackSafetyInfo &(Function &F)> GetSSI;
  const ModuleSummaryIndex *Index = nullptr;
  mutable std::unique_ptr<InfoTy> Info;
  const InfoTy &getInfo() const;

public:
  LLVM_ABI StackSafetyGlobalInfo();
  LLVM_ABI StackSafetyGlobalInfo(
      Module *M, std::function<const StackSafetyInfo &(Function &F)> GetSSI,
      const ModuleSummaryIndex *Index);
  LLVM_ABI StackSafetyGlobalInfo(StackSafetyGlobalInfo &&);
  LLVM_ABI StackSafetyGlobalInfo &operator=(StackSafetyGlobalInfo &&);
  LLVM_ABI ~StackSafetyGlobalInfo();

  // Whether we can prove that all accesses to this Alloca are in-range and
  // during its lifetime.
  LLVM_ABI bool isSafe(const AllocaInst &AI) const;

  // Returns true if the instruction can be proven to do only two types of
  // memory accesses:
  //  (1) live stack locations in-bounds or
  //  (2) non-stack locations.
  LLVM_ABI bool stackAccessIsSafe(const Instruction &I) const;
  LLVM_ABI void print(raw_ostream &O) const;
  LLVM_ABI void dump() const;
};

/// StackSafetyInfo wrapper for the new pass manager.
class StackSafetyAnalysis : public AnalysisInfoMixin<StackSafetyAnalysis> {
  friend AnalysisInfoMixin<StackSafetyAnalysis>;
  static AnalysisKey Key;

public:
  using Result = StackSafetyInfo;
  LLVM_ABI StackSafetyInfo run(Function &F, FunctionAnalysisManager &AM);
};

/// Printer pass for the \c StackSafetyAnalysis results.
class StackSafetyPrinterPass
    : public RequiredPassInfoMixin<StackSafetyPrinterPass> {
  raw_ostream &OS;

public:
  explicit StackSafetyPrinterPass(raw_ostream &OS) : OS(OS) {}
  LLVM_ABI PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
};

/// StackSafetyInfo wrapper for the legacy pass manager
class LLVM_ABI StackSafetyInfoWrapperPass : public FunctionPass {
  StackSafetyInfo SSI;

public:
  static char ID;
  StackSafetyInfoWrapperPass();

  const StackSafetyInfo &getResult() const { return SSI; }

  void print(raw_ostream &O, const Module *M) const override;
  void getAnalysisUsage(AnalysisUsage &AU) const override;

  bool runOnFunction(Function &F) override;
};

/// This pass performs the global (interprocedural) stack safety analysis (new
/// pass manager).
class StackSafetyGlobalAnalysis
    : public AnalysisInfoMixin<StackSafetyGlobalAnalysis> {
  friend AnalysisInfoMixin<StackSafetyGlobalAnalysis>;
  static AnalysisKey Key;

public:
  using Result = StackSafetyGlobalInfo;
  LLVM_ABI Result run(Module &M, ModuleAnalysisManager &AM);
};

/// Printer pass for the \c StackSafetyGlobalAnalysis results.
class StackSafetyGlobalPrinterPass
    : public RequiredPassInfoMixin<StackSafetyGlobalPrinterPass> {
  raw_ostream &OS;

public:
  explicit StackSafetyGlobalPrinterPass(raw_ostream &OS) : OS(OS) {}
  LLVM_ABI PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
};

/// This pass performs the global (interprocedural) stack safety analysis
/// (legacy pass manager).
class LLVM_ABI StackSafetyGlobalInfoWrapperPass : public ModulePass {
  StackSafetyGlobalInfo SSGI;

public:
  static char ID;

  StackSafetyGlobalInfoWrapperPass();
  ~StackSafetyGlobalInfoWrapperPass() override;

  const StackSafetyGlobalInfo &getResult() const { return SSGI; }

  void print(raw_ostream &O, const Module *M) const override;
  void getAnalysisUsage(AnalysisUsage &AU) const override;

  bool runOnModule(Module &M) override;
};

LLVM_ABI bool needsParamAccessSummary(const Module &M);

LLVM_ABI void generateParamAccessSummary(ModuleSummaryIndex &Index);

} // end namespace llvm

#endif // LLVM_ANALYSIS_STACKSAFETYANALYSIS_H