revng-revng/include/revng/BasicAnalyses/GeneratedCodeBasicInfo.h

#pragma once

//
// This file is distributed under the MIT License. See LICENSE.md for details.
//

#include <cstdint>
#include <map>
#include <utility>

#include "llvm/ADT/Any.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/GlobalObject.h"
#include "llvm/IR/PassManager.h"
#include "llvm/Pass.h"
#include "llvm/Support/Casting.h"

#include "revng/ADT/Concepts.h"
#include "revng/Lift/Lift.h"
#include "revng/Model/Architecture.h"
#include "revng/Model/Binary.h"
#include "revng/Model/LoadModelPass.h"
#include "revng/Support/BlockType.h"
#include "revng/Support/FunctionTags.h"
#include "revng/Support/IRHelpers.h"
#include "revng/Support/ProgramCounterHandler.h"

// Forward declarations
namespace llvm {
class BasicBlock;
class GlobalVariable;
class Instruction;
class MDNode;
} // namespace llvm

/// Pass to collect basic information about the generated code
///
/// This pass provides useful information for other passes by extracting them
/// from the generated IR, and possibly caching them.
///
/// It provides details about the input architecture such as the size of its
/// delay slot, the name of the program counter register and so on. It also
/// provides information about the generated basic blocks, distinguishing
/// between basic blocks generated due to translation and dispatcher-related
/// basic blocks.
class GeneratedCodeBasicInfo {
public:
  GeneratedCodeBasicInfo(const model::Binary &Binary) :
    Binary(&Binary),
    PC(nullptr),
    SP(nullptr),
    RA(nullptr),
    Dispatcher(nullptr),
    DispatcherFail(nullptr),
    AnyPC(nullptr),
    UnexpectedPC(nullptr),
    PCRegSize(0),
    RootFunction(nullptr),
    PCH(),
    RootParsed(false) {}

  void run(llvm::Module &M);

  /// Handle the invalidation of this information, so that it does not get
  /// invalidated by other passes.
  bool invalidate(llvm::Module &,
                  const llvm::PreservedAnalyses &,
                  llvm::ModuleAnalysisManager::Invalidator &) {
    return false;
  }

  bool invalidate(llvm::Function &,
                  const llvm::PreservedAnalyses &,
                  llvm::FunctionAnalysisManager::Invalidator &) {
    return false;
  }

  static uint32_t getJTReasons(llvm::BasicBlock *BB) {
    return getJTReasons(BB->getTerminator());
  }

  static uint32_t getJTReasons(llvm::Instruction *T) {
    using namespace llvm;

    revng_assert(T->isTerminator());

    uint32_t Result = 0;

    MDNode *Node = T->getMetadata(JTReasonMDName);
    auto *Tuple = cast_or_null<MDTuple>(Node);
    revng_assert(Tuple != nullptr);

    for (Metadata *ReasonMD : Tuple->operands()) {
      StringRef Text = cast<MDString>(ReasonMD)->getString();
      Result |= static_cast<uint32_t>(JTReason::fromName(Text));
    }

    return Result;
  }

  KillReason::Values getKillReason(llvm::BasicBlock *BB) const {
    return getKillReason(BB->getTerminator());
  }

  KillReason::Values getKillReason(llvm::Instruction *T) const {
    using namespace llvm;

    revng_assert(T->isTerminator());

    auto *NoReturnMD = T->getMetadata("noreturn");
    if (auto *NoreturnTuple = dyn_cast_or_null<MDTuple>(NoReturnMD)) {
      QuickMetadata QMD(getContext(T));
      return KillReason::fromName(QMD.extract<StringRef>(NoreturnTuple, 0));
    }

    return KillReason::NonKiller;
  }

  bool isKiller(llvm::BasicBlock *BB) const {
    return isKiller(BB->getTerminator());
  }

  bool isKiller(llvm::Instruction *T) const {
    revng_assert(T->isTerminator());
    return getKillReason(T) != KillReason::NonKiller;
  }

  /// Return the CSV representing the stack pointer
  llvm::GlobalVariable *spReg() const { return SP; }
  /// Return the CSV representing the return address register
  llvm::GlobalVariable *raReg() const { return RA; }

  /// Check if \p GV is the stack pointer CSV
  bool isSPReg(const llvm::GlobalVariable *GV) const {
    revng_assert(SP != nullptr);
    return GV == SP;
  }

  bool isSPReg(const llvm::Value *V) const {
    if (auto *GV = llvm::dyn_cast<const llvm::GlobalVariable>(V))
      return isSPReg(GV);
    return false;
  }

  // TODO: this method should probably be deprecated
  /// Return the CSV representing the program counter
  llvm::GlobalVariable *pcReg() const { return PC; }

  // TODO: this method should probably be deprecated
  /// Check if \p GV is the program counter CSV
  bool isPCReg(const llvm::GlobalVariable *GV) const {
    revng_assert(PC != nullptr);
    return GV == PC;
  }

  // TODO: this method should probably be deprecated
  bool isServiceRegister(const llvm::Value *V) const {
    auto *GV = llvm::dyn_cast<llvm::GlobalVariable>(V);
    return GV != nullptr and (isPCReg(GV) or isSPReg(GV));
  }

  const ProgramCounterHandler *programCounterHandler() {
    if (not PCH) {
      llvm::Module *M = RootFunction->getParent();
      using namespace model::Architecture;
      auto Architecture = toLLVMArchitecture(Binary->Architecture());
      PCH = ProgramCounterHandler::fromModule(Architecture, M);
    }

    return PCH.get();
  }

  template<typename T>
  ProgramCounterHandler::DispatcherInfo
  buildDispatcher(T &Targets,
                  llvm::IRBuilder<> &Builder,
                  llvm::BasicBlock *Default = nullptr) {
    parseRoot();

    ProgramCounterHandler::DispatcherTargets TargetsPairs;
    TargetsPairs.reserve(Targets.size());
    for (MetaAddress MA : Targets)
      TargetsPairs.push_back({ MA, getBlockAt(MA) });

    if (Default == nullptr)
      Default = UnexpectedPC;

    auto IBDHB = BlockType::IndirectBranchDispatcherHelperBlock;
    return programCounterHandler()->buildDispatcher(TargetsPairs,
                                                    Builder,
                                                    Default,
                                                    { IBDHB });
  }

  /// Return the basic block associated to \p PC
  ///
  /// Returns nullptr if the PC doesn't have a basic block (yet)
  llvm::BasicBlock *getBlockAt(MetaAddress PC) {
    parseRoot();

    auto It = JumpTargets.find(PC);
    if (It == JumpTargets.end())
      return nullptr;

    return It->second;
  }

  bool isJump(llvm::BasicBlock *BB) { return isJump(BB->getTerminator()); }

  /// Return true if \p T represents a jump in the input assembly
  ///
  /// Return true if \p T targets include only dispatcher-related basic blocks
  /// and jump targets.
  bool isJump(llvm::Instruction *T) {
    parseRoot();
    revng_assert(T->getParent()->getParent() == RootFunction);
    revng_assert(T != nullptr);
    revng_assert(T->isTerminator());

    for (llvm::BasicBlock *Successor : successors(T)) {
      if (not(Successor->empty() or Successor == Dispatcher
              or Successor == DispatcherFail or Successor == AnyPC
              or Successor == UnexpectedPC or isJumpTarget(Successor)))
        return false;
    }

    return true;
  }

  /// Return true if \p BB is the result of translating some code
  ///
  /// Return false if \p BB is a dispatcher-related basic block.
  static bool isTranslated(const llvm::BasicBlock *BB) {
    BlockType::Values Type = getType(BB);
    return (Type == BlockType::TranslatedBlock
            or Type == BlockType::JumpTargetBlock);
  }

  /// Return the program counter of the next (i.e., fallthrough) instruction
  /// of \p TheInstruction
  MetaAddress getNextPC(llvm::Instruction *TheInstruction) const {
    auto Pair = getPC(TheInstruction);
    return Pair.first + Pair.second;
  }

  llvm::BasicBlock *getCallReturnBlock(llvm::BasicBlock *BB) const {
    using namespace llvm;
    CallInst *FunctionCallMarker = getMarker(BB, "function_call");
    revng_assert(FunctionCallMarker != nullptr);
    auto *FallthroughBA = cast<BlockAddress>(FunctionCallMarker->getOperand(1));
    return FallthroughBA->getBasicBlock();
  }

  auto getBlocksGeneratedByPC(MetaAddress PC) {
    using namespace llvm;
    BasicBlock *Entry = getBlockAt(PC);
    revng_assert(isJumpTarget(Entry));
    std::set<BasicBlock *> Result;

    llvm::df_iterator_default_set<BasicBlock *> Visited;
    for (BasicBlock *BB : llvm::depth_first_ext(Entry, Visited)) {
      Result.insert(BB);

      for (BasicBlock *Successor : successors(BB)) {
        const auto IBDHB = BlockType::IndirectBranchDispatcherHelperBlock;
        if (isJumpTarget(Successor)
            or (not isTranslated(Successor) and getType(Successor) != IBDHB)) {
          Visited.insert(Successor);
        }
      }
    }

    return Result;
  }

  llvm::BasicBlock *anyPC() {
    parseRoot();
    return AnyPC;
  }

  llvm::BasicBlock *unexpectedPC() {
    parseRoot();
    return UnexpectedPC;
  }

  llvm::BasicBlock *dispatcher() {
    parseRoot();
    return Dispatcher;
  }

  const llvm::ArrayRef<llvm::GlobalVariable *> csvs() const { return CSVs; }

  const std::vector<llvm::GlobalVariable *> &abiRegisters() const {
    return ABIRegisters;
  }

  bool isABIRegister(llvm::GlobalVariable *CSV) const {
    return ABIRegistersSet.contains(CSV);
  }

  MetaAddress fromPC(uint64_t PC) const {
    using namespace model::Architecture;
    auto Architecture = toLLVMArchitecture(Binary->Architecture());
    return MetaAddress::fromPC(Architecture, PC);
  }

  llvm::Function *root() {
    parseRoot();
    return RootFunction;
  }

  llvm::SmallVector<std::pair<llvm::BasicBlock *, bool>, 4>
  blocksByPCRange(MetaAddress Start, MetaAddress End);

private:
  void parseRoot();

private:
  const model::Binary *Binary;
  llvm::GlobalVariable *PC;
  llvm::GlobalVariable *SP;
  llvm::GlobalVariable *RA;
  llvm::BasicBlock *Dispatcher;
  llvm::BasicBlock *DispatcherFail;
  llvm::BasicBlock *AnyPC;
  llvm::BasicBlock *UnexpectedPC;
  std::map<MetaAddress, llvm::BasicBlock *> JumpTargets;
  unsigned PCRegSize;
  llvm::Function *RootFunction;
  std::vector<llvm::GlobalVariable *> CSVs;
  std::vector<llvm::GlobalVariable *> ABIRegisters;
  std::set<llvm::GlobalVariable *> ABIRegistersSet;
  llvm::Function *NewPC;
  std::unique_ptr<ProgramCounterHandler> PCH;
  using PCToBlockMap = std::multimap<MetaAddress, llvm::BasicBlock *>;
  bool RootParsed = false;
};

template<>
struct BlackListTrait<const GeneratedCodeBasicInfo &, llvm::BasicBlock *>
  : BlackListTraitBase<const GeneratedCodeBasicInfo &> {
  using BlackListTraitBase<const GeneratedCodeBasicInfo &>::BlackListTraitBase;
  bool isBlacklisted(llvm::BasicBlock *Value) const {
    return !this->Obj.isTranslated(Value);
  }
};

/// An analysis pass that computes a \c GCBI result. The result of
/// this analysis is invalidated each time the analysis is called.
class GeneratedCodeBasicInfoAnalysis
  : public llvm::AnalysisInfoMixin<GeneratedCodeBasicInfoAnalysis> {
  friend llvm::AnalysisInfoMixin<GeneratedCodeBasicInfoAnalysis>;
  static llvm::AnalysisKey Key;

public:
  using Result = GeneratedCodeBasicInfo;
  /// \note If a MPM is used, then make sure to register the
  /// analysis manually and use a proxy.
  Result run(llvm::Module &M, llvm::ModuleAnalysisManager &);
  Result run(llvm::Function &F, llvm::FunctionAnalysisManager &);
};

/// Legacy pass manager pass to access GCBI.
class GeneratedCodeBasicInfoWrapperPass : public llvm::ModulePass {
  std::unique_ptr<GeneratedCodeBasicInfo> GCBI;

public:
  static char ID;

  GeneratedCodeBasicInfoWrapperPass() : llvm::ModulePass(ID) {}

  GeneratedCodeBasicInfo &getGCBI() { return *GCBI; }

  bool runOnModule(llvm::Module &M) override;
  void releaseMemory() override;
  void getAnalysisUsage(llvm::AnalysisUsage &AU) const override {
    AU.setPreservesAll();
    AU.addRequired<LoadModelWrapperPass>();
  }
};