Method CheckLegacySegmentWrite

FEXCore/Source/Interface/Core/OpcodeDispatcher.cpp:4079–4115

}

void OpDispatchBuilder::CheckLegacySegmentWrite(Ref NewNode, uint32_t SegmentReg) {
#ifndef FEX_DISABLE_TELEMETRY
  if (SegmentReg == FEXCore::X86Tables::DecodeFlags::FLAG_FS_PREFIX || SegmentReg == FEXCore::X86Tables::DecodeFlags::FLAG_GS_PREFIX) {
    // FS and GS segments aren't considered legacy.
    return;
  }

  if (CTX->Config.DisableTelemetry()) {
    // Telemetry disabled at runtime.
    return;
  }

  FEXCore::Telemetry::TelemetryType TelemIndex {};
  switch (SegmentReg) {
  case FEXCore::X86Tables::DecodeFlags::FLAG_ES_PREFIX:
    TelemIndex = FEXCore::Telemetry::TelemetryType::TYPE_WRITES_32BIT_SEGMENT_ES;
    SegmentsNeedReadCheck |= FEXCore::X86Tables::DecodeFlags::FLAG_ES_PREFIX;
    break;
  case FEXCore::X86Tables::DecodeFlags::FLAG_CS_PREFIX:
    TelemIndex = FEXCore::Telemetry::TelemetryType::TYPE_WRITES_32BIT_SEGMENT_CS;
    SegmentsNeedReadCheck |= FEXCore::X86Tables::DecodeFlags::FLAG_CS_PREFIX;
    break;
  case FEXCore::X86Tables::DecodeFlags::FLAG_SS_PREFIX:
    TelemIndex = FEXCore::Telemetry::TelemetryType::TYPE_WRITES_32BIT_SEGMENT_SS;
    SegmentsNeedReadCheck |= FEXCore::X86Tables::DecodeFlags::FLAG_SS_PREFIX;
    break;
  case FEXCore::X86Tables::DecodeFlags::FLAG_DS_PREFIX:
    TelemIndex = FEXCore::Telemetry::TelemetryType::TYPE_WRITES_32BIT_SEGMENT_DS;
    SegmentsNeedReadCheck |= FEXCore::X86Tables::DecodeFlags::FLAG_DS_PREFIX;
    break;
  default: FEX_UNREACHABLE;
  }

  // Will set the telemetry value if NewNode is != 0
  _TelemetrySetValue(NewNode, TelemIndex);
#endif
}

void OpDispatchBuilder::UpdatePrefixFromSegment(Ref Segment, uint32_t SegmentReg) {
  // Use BFE to extract the selector index in bits [15,3] of the segment register.