Method DecodeInstructionsAtEntry

FEXCore/Source/Interface/Core/Frontend.cpp:1304–1489

}

void Decoder::DecodeInstructionsAtEntry(FEXCore::Core::InternalThreadState *Thread, const uint8_t* _InstStream, uint64_t PC, uint64_t MaxInst) {
  FEXCORE_PROFILE_SCOPED("DecodeInstructions");
  BlockInfo.TotalInstructionCount = 0;
  BlockInfo.Blocks.clear();
  VisitedBlocks.clear();
  // Reset internal state management
  DecodedSize = 0;
  MaxCondBranchForward = 0;
  MaxCondBranchBackwards = ~0ULL;
  DecodedBuffer = PoolObject.ReownOrClaimBuffer();

  // Decode operating mode from thread's CS segment.
  const auto CSSegment = Core::CPUState::GetSegmentFromIndex(Thread->CurrentFrame->State, Thread->CurrentFrame->State.cs_idx);
  BlockInfo.Is64BitMode = CSSegment->L == 1;
  LOGMAN_THROW_A_FMT(BlockInfo.Is64BitMode == CTX->Config.Is64BitMode, "Expected operating mode to not change at runtime!");

  // XXX: Load symbol data
  SymbolAvailable = false;
  EntryPoint = PC;
  BlockInfo.EntryPoints = {PC};
  InstStream = _InstStream;

  uint64_t TotalInstructions {};

  // If we don't have symbols available then we become a bit optimistic about multiblock ranges
  if (!SymbolAvailable) {
    // If we don't have a symbol available then assume all branches are valid for multiblock
    SymbolMaxAddress = SectionMaxAddress;
    SymbolMinAddress = EntryPoint;
  }

  DecodedMinAddress = EntryPoint;
  DecodedMaxAddress = EntryPoint;

  // Entry is a jump target
  BlocksToDecode = {PC};

  uint64_t CurrentCodePage = PC & FEXCore::Utils::FEX_PAGE_MASK;

  BlockInfo.CodePages = {CurrentCodePage};

  if (MaxInst == 0) {
    MaxInst = CTX->Config.MaxInstPerBlock;
  }

  bool EntryBlock {true};
  bool FinalInstruction {false};

  while (!FinalInstruction && !BlocksToDecode.empty()) {
    auto BlockDecodeIt = BlocksToDecode.begin();
    uint64_t RIPToDecode = *BlockDecodeIt;
    BlocksToDecode.erase(BlockDecodeIt);
    VisitedBlocks.emplace(RIPToDecode);

    auto BlockSuccIt = std::lower_bound(BlockInfo.Blocks.begin(), BlockInfo.Blocks.end(), RIPToDecode,
                                        [](const auto& a, uint64_t Address) { return a.Entry < Address; });

    LOGMAN_THROW_A_FMT(BlockSuccIt == BlockInfo.Blocks.end() || BlockSuccIt->Entry != RIPToDecode, "unexpected");