Commit 90a94c02 authored by Vedant Kumar's avatar Vedant Kumar
Browse files

[lldb/LibCxx] Have ExtractLibcxxStringInfo return an Optional result, NFC 

Differential Revision: https://reviews.llvm.org/D74018
parent 7aabad13

lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp

+54 −49
Original line number Diff line number Diff line
@@ -468,22 +468,20 @@ enum LibcxxStringLayoutMode { 
  eLibcxxStringLayoutModeInvalid = 0xffff

};



// this function abstracts away the layout and mode details of a libc++ string

// and returns the address of the data and the size ready for callers to

// consume

static bool ExtractLibcxxStringInfo(ValueObject &valobj,

                                    ValueObjectSP &location_sp,

                                    uint64_t &size) {

/// Determine the size in bytes of \p valobj (a libc++ std::string object) and

/// extract its data payload. Return the size + payload pair.

static llvm::Optional<std::pair<uint64_t, ValueObjectSP>>

ExtractLibcxxStringInfo(ValueObject &valobj) {

  ValueObjectSP D(valobj.GetChildAtIndexPath({0, 0, 0, 0}));

  if (!D)

    return false;

    return {};



  ValueObjectSP layout_decider(

    D->GetChildAtIndexPath(llvm::ArrayRef<size_t>({0, 0})));



  // this child should exist

  if (!layout_decider)

    return false;

    return {};



  ConstString g_data_name("__data_");

  ConstString g_size_name("__size_");
@@ -497,13 +495,13 @@ static bool ExtractLibcxxStringInfo(ValueObject &valobj, 
  if (layout == eLibcxxStringLayoutModeDSC) {

    ValueObjectSP size_mode(D->GetChildAtIndexPath({1, 1, 0}));

    if (!size_mode)

      return false;

      return {};



    if (size_mode->GetName() != g_size_name) {

      // we are hitting the padding structure, move along

      size_mode = D->GetChildAtIndexPath({1, 1, 1});

      if (!size_mode)

        return false;

        return {};

    }



    size_mode_value = (size_mode->GetValueAsUnsigned(0));
@@ -511,7 +509,7 @@ static bool ExtractLibcxxStringInfo(ValueObject &valobj, 
  } else {

    ValueObjectSP size_mode(D->GetChildAtIndexPath({1, 0, 0}));

    if (!size_mode)

      return false;

      return {};



    size_mode_value = (size_mode->GetValueAsUnsigned(0));

    short_mode = ((size_mode_value & 1) == 0);
@@ -520,10 +518,10 @@ static bool ExtractLibcxxStringInfo(ValueObject &valobj, 
  if (short_mode) {

    ValueObjectSP s(D->GetChildAtIndex(1, true));

    if (!s)

      return false;

    location_sp = s->GetChildAtIndex(

      return {};

    ValueObjectSP location_sp = s->GetChildAtIndex(

        (layout == eLibcxxStringLayoutModeDSC) ? 0 : 1, true);

    size = (layout == eLibcxxStringLayoutModeDSC)

    const uint64_t size = (layout == eLibcxxStringLayoutModeDSC)

                              ? size_mode_value

                              : ((size_mode_value >> 1) % 256);
@@ -534,16 +532,17 @@ static bool ExtractLibcxxStringInfo(ValueObject &valobj, 
    const llvm::Optional<uint64_t> max_bytes =

        location_sp->GetCompilerType().GetByteSize(

            exe_ctx.GetBestExecutionContextScope());

    if (!max_bytes || size > *max_bytes)

      return false;

    if (!max_bytes || size > *max_bytes || !location_sp)

      return {};



    return std::make_pair(size, location_sp);

  }



    return (location_sp.get() != nullptr);

  } else {

  ValueObjectSP l(D->GetChildAtIndex(0, true));

  if (!l)

      return false;

    return {};

  // we can use the layout_decider object as the data pointer

    location_sp = (layout == eLibcxxStringLayoutModeDSC)

  ValueObjectSP location_sp = (layout == eLibcxxStringLayoutModeDSC)

                                  ? layout_decider

                                  : l->GetChildAtIndex(2, true);

  ValueObjectSP size_vo(l->GetChildAtIndex(1, true));
@@ -551,22 +550,26 @@ static bool ExtractLibcxxStringInfo(ValueObject &valobj, 
      (layout == eLibcxxStringLayoutModeDSC) ? 2 : 0;

  ValueObjectSP capacity_vo(l->GetChildAtIndex(capacity_index, true));

  if (!size_vo || !location_sp || !capacity_vo)

      return false;

    size = size_vo->GetValueAsUnsigned(LLDB_INVALID_OFFSET);

    const uint64_t cap = capacity_vo->GetValueAsUnsigned(LLDB_INVALID_OFFSET);

    if (size == LLDB_INVALID_OFFSET || cap == LLDB_INVALID_OFFSET || cap < size)

      return false;

    return true;

  }

    return {};

  const uint64_t size = size_vo->GetValueAsUnsigned(LLDB_INVALID_OFFSET);

  const uint64_t capacity =

      capacity_vo->GetValueAsUnsigned(LLDB_INVALID_OFFSET);

  if (size == LLDB_INVALID_OFFSET || capacity == LLDB_INVALID_OFFSET ||

      capacity < size)

    return {};

  return std::make_pair(size, location_sp);

}



bool lldb_private::formatters::LibcxxWStringSummaryProvider(

    ValueObject &valobj, Stream &stream,

    const TypeSummaryOptions &summary_options) {

  uint64_t size = 0;

  ValueObjectSP location_sp;

  if (!ExtractLibcxxStringInfo(valobj, location_sp, size))

  auto string_info = ExtractLibcxxStringInfo(valobj);

  if (!string_info)

    return false;

  uint64_t size;

  ValueObjectSP location_sp;

  std::tie(size, location_sp) = *string_info;



  if (size == 0) {

    stream.Printf("L\"\"");

    return true;
@@ -574,10 +577,8 @@ bool lldb_private::formatters::LibcxxWStringSummaryProvider( 
  if (!location_sp)

    return false;



  DataExtractor extractor;



  StringPrinter::ReadBufferAndDumpToStreamOptions options(valobj);



  if (summary_options.GetCapping() == TypeSummaryCapping::eTypeSummaryCapped) {

    const auto max_size = valobj.GetTargetSP()->GetMaximumSizeOfStringSummary();

    if (size > max_size) {
@@ -585,6 +586,8 @@ bool lldb_private::formatters::LibcxxWStringSummaryProvider( 
      options.SetIsTruncated(true);

    }

  }



  DataExtractor extractor;

  const size_t bytes_read = location_sp->GetPointeeData(extractor, 0, size);

  if (bytes_read < size)

    return false;
@@ -632,10 +635,13 @@ template <StringPrinter::StringElementType element_type> 
bool LibcxxStringSummaryProvider(ValueObject &valobj, Stream &stream,

                                 const TypeSummaryOptions &summary_options,

                                 std::string prefix_token) {

  uint64_t size = 0;

  ValueObjectSP location_sp;

  if (!ExtractLibcxxStringInfo(valobj, location_sp, size))

  auto string_info = ExtractLibcxxStringInfo(valobj);

  if (!string_info)

    return false;

  uint64_t size;

  ValueObjectSP location_sp;

  std::tie(size, location_sp) = *string_info;



  if (size == 0) {

    stream.Printf("\"\"");

    return true;
@@ -646,7 +652,6 @@ bool LibcxxStringSummaryProvider(ValueObject &valobj, Stream &stream, 


  StringPrinter::ReadBufferAndDumpToStreamOptions options(valobj);



  DataExtractor extractor;

  if (summary_options.GetCapping() == TypeSummaryCapping::eTypeSummaryCapped) {

    const auto max_size = valobj.GetTargetSP()->GetMaximumSizeOfStringSummary();

    if (size > max_size) {
@@ -654,18 +659,18 @@ bool LibcxxStringSummaryProvider(ValueObject &valobj, Stream &stream, 
      options.SetIsTruncated(true);

    }

  }



  DataExtractor extractor;

  const size_t bytes_read = location_sp->GetPointeeData(extractor, 0, size);

  if (bytes_read < size)

    return false;



  options.SetData(extractor);

  options.SetStream(&stream);



  if (prefix_token.empty())

    options.SetPrefixToken(nullptr);

  else

    options.SetPrefixToken(prefix_token);



  options.SetQuote('"');

  options.SetSourceSize(size);

  options.SetBinaryZeroIsTerminator(false);