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

Differential Revision: https://reviews.llvm.org/D74018
This commit is contained in:
Vedant Kumar 2020-02-05 09:46:51 -08:00
parent 7aabad1312
commit 90a94c02fb
1 changed files with 54 additions and 49 deletions
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103
lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp
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@ -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);
@ -520,12 +518,12 @@ 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)
? size_mode_value
: ((size_mode_value >> 1) % 256);
const uint64_t size = (layout == eLibcxxStringLayoutModeDSC)
? size_mode_value
: ((size_mode_value >> 1) % 256);
// When the small-string optimization takes place, the data must fit in the
// inline string buffer (23 bytes on x86_64/Darwin). If it doesn't, it's
@ -534,39 +532,44 @@ 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 (location_sp.get() != nullptr);
} else {
ValueObjectSP l(D->GetChildAtIndex(0, true));
if (!l)
return false;
// we can use the layout_decider object as the data pointer
location_sp = (layout == eLibcxxStringLayoutModeDSC)
? layout_decider
: l->GetChildAtIndex(2, true);
ValueObjectSP size_vo(l->GetChildAtIndex(1, true));
const unsigned capacity_index =
(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 std::make_pair(size, location_sp);
}
ValueObjectSP l(D->GetChildAtIndex(0, true));
if (!l)
return {};
// we can use the layout_decider object as the data pointer
ValueObjectSP location_sp = (layout == eLibcxxStringLayoutModeDSC)
? layout_decider
: l->GetChildAtIndex(2, true);
ValueObjectSP size_vo(l->GetChildAtIndex(1, true));
const unsigned capacity_index =
(layout == eLibcxxStringLayoutModeDSC) ? 2 : 0;
ValueObjectSP capacity_vo(l->GetChildAtIndex(capacity_index, true));
if (!size_vo || !location_sp || !capacity_vo)
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);