1 //===-- LibCxx.cpp --------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "LibCxx.h"
10 
11 #include "lldb/Core/Debugger.h"
12 #include "lldb/Core/FormatEntity.h"
13 #include "lldb/Core/ValueObject.h"
14 #include "lldb/Core/ValueObjectConstResult.h"
15 #include "lldb/DataFormatters/FormattersHelpers.h"
16 #include "lldb/DataFormatters/StringPrinter.h"
17 #include "lldb/DataFormatters/TypeSummary.h"
18 #include "lldb/DataFormatters/VectorIterator.h"
19 #include "lldb/Target/ProcessStructReader.h"
20 #include "lldb/Target/SectionLoadList.h"
21 #include "lldb/Target/Target.h"
22 #include "lldb/Utility/ConstString.h"
23 #include "lldb/Utility/DataBufferHeap.h"
24 #include "lldb/Utility/Endian.h"
25 #include "lldb/Utility/Status.h"
26 #include "lldb/Utility/Stream.h"
27 
28 #include "Plugins/LanguageRuntime/CPlusPlus/CPPLanguageRuntime.h"
29 #include "Plugins/TypeSystem/Clang/TypeSystemClang.h"
30 #include <tuple>
31 
32 using namespace lldb;
33 using namespace lldb_private;
34 using namespace lldb_private::formatters;
35 
36 bool lldb_private::formatters::LibcxxOptionalSummaryProvider(
37     ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
38   ValueObjectSP valobj_sp(valobj.GetNonSyntheticValue());
39   if (!valobj_sp)
40     return false;
41 
42   // An optional either contains a value or not, the member __engaged_ is
43   // a bool flag, it is true if the optional has a value and false otherwise.
44   ValueObjectSP engaged_sp(
45       valobj_sp->GetChildMemberWithName(ConstString("__engaged_"), true));
46 
47   if (!engaged_sp)
48     return false;
49 
50   llvm::StringRef engaged_as_cstring(
51       engaged_sp->GetValueAsUnsigned(0) == 1 ? "true" : "false");
52 
53   stream.Printf(" Has Value=%s ", engaged_as_cstring.data());
54 
55   return true;
56 }
57 
58 bool lldb_private::formatters::LibcxxFunctionSummaryProvider(
59     ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
60 
61   ValueObjectSP valobj_sp(valobj.GetNonSyntheticValue());
62 
63   if (!valobj_sp)
64     return false;
65 
66   ExecutionContext exe_ctx(valobj_sp->GetExecutionContextRef());
67   Process *process = exe_ctx.GetProcessPtr();
68 
69   if (process == nullptr)
70     return false;
71 
72   CPPLanguageRuntime *cpp_runtime = CPPLanguageRuntime::Get(*process);
73 
74   if (!cpp_runtime)
75     return false;
76 
77   CPPLanguageRuntime::LibCppStdFunctionCallableInfo callable_info =
78       cpp_runtime->FindLibCppStdFunctionCallableInfo(valobj_sp);
79 
80   switch (callable_info.callable_case) {
81   case CPPLanguageRuntime::LibCppStdFunctionCallableCase::Invalid:
82     stream.Printf(" __f_ = %" PRIu64, callable_info.member_f_pointer_value);
83     return false;
84     break;
85   case CPPLanguageRuntime::LibCppStdFunctionCallableCase::Lambda:
86     stream.Printf(
87         " Lambda in File %s at Line %u",
88         callable_info.callable_line_entry.file.GetFilename().GetCString(),
89         callable_info.callable_line_entry.line);
90     break;
91   case CPPLanguageRuntime::LibCppStdFunctionCallableCase::CallableObject:
92     stream.Printf(
93         " Function in File %s at Line %u",
94         callable_info.callable_line_entry.file.GetFilename().GetCString(),
95         callable_info.callable_line_entry.line);
96     break;
97   case CPPLanguageRuntime::LibCppStdFunctionCallableCase::FreeOrMemberFunction:
98     stream.Printf(" Function = %s ",
99                   callable_info.callable_symbol.GetName().GetCString());
100     break;
101   }
102 
103   return true;
104 }
105 
106 bool lldb_private::formatters::LibcxxSmartPointerSummaryProvider(
107     ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
108   ValueObjectSP valobj_sp(valobj.GetNonSyntheticValue());
109   if (!valobj_sp)
110     return false;
111   ValueObjectSP ptr_sp(
112       valobj_sp->GetChildMemberWithName(ConstString("__ptr_"), true));
113   ValueObjectSP count_sp(valobj_sp->GetChildAtNamePath(
114       {ConstString("__cntrl_"), ConstString("__shared_owners_")}));
115   ValueObjectSP weakcount_sp(valobj_sp->GetChildAtNamePath(
116       {ConstString("__cntrl_"), ConstString("__shared_weak_owners_")}));
117 
118   if (!ptr_sp)
119     return false;
120 
121   if (ptr_sp->GetValueAsUnsigned(0) == 0) {
122     stream.Printf("nullptr");
123     return true;
124   } else {
125     bool print_pointee = false;
126     Status error;
127     ValueObjectSP pointee_sp = ptr_sp->Dereference(error);
128     if (pointee_sp && error.Success()) {
129       if (pointee_sp->DumpPrintableRepresentation(
130               stream, ValueObject::eValueObjectRepresentationStyleSummary,
131               lldb::eFormatInvalid,
132               ValueObject::PrintableRepresentationSpecialCases::eDisable,
133               false))
134         print_pointee = true;
135     }
136     if (!print_pointee)
137       stream.Printf("ptr = 0x%" PRIx64, ptr_sp->GetValueAsUnsigned(0));
138   }
139 
140   if (count_sp)
141     stream.Printf(" strong=%" PRIu64, 1 + count_sp->GetValueAsUnsigned(0));
142 
143   if (weakcount_sp)
144     stream.Printf(" weak=%" PRIu64, 1 + weakcount_sp->GetValueAsUnsigned(0));
145 
146   return true;
147 }
148 
149 bool lldb_private::formatters::LibcxxUniquePointerSummaryProvider(
150     ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
151   ValueObjectSP valobj_sp(valobj.GetNonSyntheticValue());
152   if (!valobj_sp)
153     return false;
154 
155   ValueObjectSP ptr_sp(
156       valobj_sp->GetChildMemberWithName(ConstString("__ptr_"), true));
157   if (!ptr_sp)
158     return false;
159 
160   ptr_sp = GetValueOfLibCXXCompressedPair(*ptr_sp);
161   if (!ptr_sp)
162     return false;
163 
164   if (ptr_sp->GetValueAsUnsigned(0) == 0) {
165     stream.Printf("nullptr");
166     return true;
167   } else {
168     bool print_pointee = false;
169     Status error;
170     ValueObjectSP pointee_sp = ptr_sp->Dereference(error);
171     if (pointee_sp && error.Success()) {
172       if (pointee_sp->DumpPrintableRepresentation(
173               stream, ValueObject::eValueObjectRepresentationStyleSummary,
174               lldb::eFormatInvalid,
175               ValueObject::PrintableRepresentationSpecialCases::eDisable,
176               false))
177         print_pointee = true;
178     }
179     if (!print_pointee)
180       stream.Printf("ptr = 0x%" PRIx64, ptr_sp->GetValueAsUnsigned(0));
181   }
182 
183   return true;
184 }
185 
186 /*
187  (lldb) fr var ibeg --raw --ptr-depth 1
188  (std::__1::__map_iterator<std::__1::__tree_iterator<std::__1::pair<int,
189  std::__1::basic_string<char, std::__1::char_traits<char>,
190  std::__1::allocator<char> > >, std::__1::__tree_node<std::__1::pair<int,
191  std::__1::basic_string<char, std::__1::char_traits<char>,
192  std::__1::allocator<char> > >, void *> *, long> >) ibeg = {
193  __i_ = {
194  __ptr_ = 0x0000000100103870 {
195  std::__1::__tree_node_base<void *> = {
196  std::__1::__tree_end_node<std::__1::__tree_node_base<void *> *> = {
197  __left_ = 0x0000000000000000
198  }
199  __right_ = 0x0000000000000000
200  __parent_ = 0x00000001001038b0
201  __is_black_ = true
202  }
203  __value_ = {
204  first = 0
205  second = { std::string }
206  */
207 
208 lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::
209     LibCxxMapIteratorSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)
210     : SyntheticChildrenFrontEnd(*valobj_sp), m_pair_ptr(), m_pair_sp() {
211   if (valobj_sp)
212     Update();
213 }
214 
215 bool lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::Update() {
216   m_pair_sp.reset();
217   m_pair_ptr = nullptr;
218 
219   ValueObjectSP valobj_sp = m_backend.GetSP();
220   if (!valobj_sp)
221     return false;
222 
223   TargetSP target_sp(valobj_sp->GetTargetSP());
224 
225   if (!target_sp)
226     return false;
227 
228   if (!valobj_sp)
229     return false;
230 
231   static ConstString g_i_("__i_");
232 
233   // this must be a ValueObject* because it is a child of the ValueObject we
234   // are producing children for it if were a ValueObjectSP, we would end up
235   // with a loop (iterator -> synthetic -> child -> parent == iterator) and
236   // that would in turn leak memory by never allowing the ValueObjects to die
237   // and free their memory
238   m_pair_ptr = valobj_sp
239                    ->GetValueForExpressionPath(
240                        ".__i_.__ptr_->__value_", nullptr, nullptr,
241                        ValueObject::GetValueForExpressionPathOptions()
242                            .DontCheckDotVsArrowSyntax()
243                            .SetSyntheticChildrenTraversal(
244                                ValueObject::GetValueForExpressionPathOptions::
245                                    SyntheticChildrenTraversal::None),
246                        nullptr)
247                    .get();
248 
249   if (!m_pair_ptr) {
250     m_pair_ptr = valobj_sp
251                      ->GetValueForExpressionPath(
252                          ".__i_.__ptr_", nullptr, nullptr,
253                          ValueObject::GetValueForExpressionPathOptions()
254                              .DontCheckDotVsArrowSyntax()
255                              .SetSyntheticChildrenTraversal(
256                                  ValueObject::GetValueForExpressionPathOptions::
257                                      SyntheticChildrenTraversal::None),
258                          nullptr)
259                      .get();
260     if (m_pair_ptr) {
261       auto __i_(valobj_sp->GetChildMemberWithName(g_i_, true));
262       if (!__i_) {
263         m_pair_ptr = nullptr;
264         return false;
265       }
266       CompilerType pair_type(
267           __i_->GetCompilerType().GetTypeTemplateArgument(0));
268       std::string name;
269       uint64_t bit_offset_ptr;
270       uint32_t bitfield_bit_size_ptr;
271       bool is_bitfield_ptr;
272       pair_type = pair_type.GetFieldAtIndex(
273           0, name, &bit_offset_ptr, &bitfield_bit_size_ptr, &is_bitfield_ptr);
274       if (!pair_type) {
275         m_pair_ptr = nullptr;
276         return false;
277       }
278 
279       auto addr(m_pair_ptr->GetValueAsUnsigned(LLDB_INVALID_ADDRESS));
280       m_pair_ptr = nullptr;
281       if (addr && addr != LLDB_INVALID_ADDRESS) {
282         TypeSystemClang *ast_ctx =
283             llvm::dyn_cast_or_null<TypeSystemClang>(pair_type.GetTypeSystem());
284         if (!ast_ctx)
285           return false;
286         CompilerType tree_node_type = ast_ctx->CreateStructForIdentifier(
287             ConstString(),
288             {{"ptr0",
289               ast_ctx->GetBasicType(lldb::eBasicTypeVoid).GetPointerType()},
290              {"ptr1",
291               ast_ctx->GetBasicType(lldb::eBasicTypeVoid).GetPointerType()},
292              {"ptr2",
293               ast_ctx->GetBasicType(lldb::eBasicTypeVoid).GetPointerType()},
294              {"cw", ast_ctx->GetBasicType(lldb::eBasicTypeBool)},
295              {"payload", pair_type}});
296         llvm::Optional<uint64_t> size = tree_node_type.GetByteSize(nullptr);
297         if (!size)
298           return false;
299         WritableDataBufferSP buffer_sp(new DataBufferHeap(*size, 0));
300         ProcessSP process_sp(target_sp->GetProcessSP());
301         Status error;
302         process_sp->ReadMemory(addr, buffer_sp->GetBytes(),
303                                buffer_sp->GetByteSize(), error);
304         if (error.Fail())
305           return false;
306         DataExtractor extractor(buffer_sp, process_sp->GetByteOrder(),
307                                 process_sp->GetAddressByteSize());
308         auto pair_sp = CreateValueObjectFromData(
309             "pair", extractor, valobj_sp->GetExecutionContextRef(),
310             tree_node_type);
311         if (pair_sp)
312           m_pair_sp = pair_sp->GetChildAtIndex(4, true);
313       }
314     }
315   }
316 
317   return false;
318 }
319 
320 size_t lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::
321     CalculateNumChildren() {
322   return 2;
323 }
324 
325 lldb::ValueObjectSP
326 lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::GetChildAtIndex(
327     size_t idx) {
328   if (m_pair_ptr)
329     return m_pair_ptr->GetChildAtIndex(idx, true);
330   if (m_pair_sp)
331     return m_pair_sp->GetChildAtIndex(idx, true);
332   return lldb::ValueObjectSP();
333 }
334 
335 bool lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::
336     MightHaveChildren() {
337   return true;
338 }
339 
340 size_t lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::
341     GetIndexOfChildWithName(ConstString name) {
342   if (name == "first")
343     return 0;
344   if (name == "second")
345     return 1;
346   return UINT32_MAX;
347 }
348 
349 lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd::
350     ~LibCxxMapIteratorSyntheticFrontEnd() {
351   // this will be deleted when its parent dies (since it's a child object)
352   // delete m_pair_ptr;
353 }
354 
355 SyntheticChildrenFrontEnd *
356 lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEndCreator(
357     CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
358   return (valobj_sp ? new LibCxxMapIteratorSyntheticFrontEnd(valobj_sp)
359                     : nullptr);
360 }
361 
362 /*
363  (lldb) fr var ibeg --raw --ptr-depth 1 -T
364  (std::__1::__wrap_iter<int *>) ibeg = {
365  (std::__1::__wrap_iter<int *>::iterator_type) __i = 0x00000001001037a0 {
366  (int) *__i = 1
367  }
368  }
369 */
370 
371 SyntheticChildrenFrontEnd *
372 lldb_private::formatters::LibCxxVectorIteratorSyntheticFrontEndCreator(
373     CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
374   static ConstString g_item_name;
375   if (!g_item_name)
376     g_item_name.SetCString("__i");
377   return (valobj_sp
378               ? new VectorIteratorSyntheticFrontEnd(valobj_sp, g_item_name)
379               : nullptr);
380 }
381 
382 lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEnd::
383     LibcxxSharedPtrSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)
384     : SyntheticChildrenFrontEnd(*valobj_sp), m_cntrl(nullptr) {
385   if (valobj_sp)
386     Update();
387 }
388 
389 size_t lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEnd::
390     CalculateNumChildren() {
391   return (m_cntrl ? 1 : 0);
392 }
393 
394 lldb::ValueObjectSP
395 lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEnd::GetChildAtIndex(
396     size_t idx) {
397   if (!m_cntrl)
398     return lldb::ValueObjectSP();
399 
400   ValueObjectSP valobj_sp = m_backend.GetSP();
401   if (!valobj_sp)
402     return lldb::ValueObjectSP();
403 
404   if (idx == 0)
405     return valobj_sp->GetChildMemberWithName(ConstString("__ptr_"), true);
406 
407   if (idx == 1) {
408     if (auto ptr_sp =
409             valobj_sp->GetChildMemberWithName(ConstString("__ptr_"), true)) {
410       Status status;
411       auto value_sp = ptr_sp->Dereference(status);
412       if (status.Success()) {
413         auto value_type_sp =
414             valobj_sp->GetCompilerType().GetTypeTemplateArgument(0);
415         return value_sp->Cast(value_type_sp);
416       }
417     }
418   }
419 
420   return lldb::ValueObjectSP();
421 }
422 
423 bool lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEnd::Update() {
424   m_cntrl = nullptr;
425 
426   ValueObjectSP valobj_sp = m_backend.GetSP();
427   if (!valobj_sp)
428     return false;
429 
430   TargetSP target_sp(valobj_sp->GetTargetSP());
431   if (!target_sp)
432     return false;
433 
434   lldb::ValueObjectSP cntrl_sp(
435       valobj_sp->GetChildMemberWithName(ConstString("__cntrl_"), true));
436 
437   m_cntrl = cntrl_sp.get(); // need to store the raw pointer to avoid a circular
438                             // dependency
439   return false;
440 }
441 
442 bool lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEnd::
443     MightHaveChildren() {
444   return true;
445 }
446 
447 size_t lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEnd::
448     GetIndexOfChildWithName(ConstString name) {
449   if (name == "__ptr_")
450     return 0;
451   if (name == "$$dereference$$")
452     return 1;
453   return UINT32_MAX;
454 }
455 
456 lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEnd::
457     ~LibcxxSharedPtrSyntheticFrontEnd() = default;
458 
459 SyntheticChildrenFrontEnd *
460 lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEndCreator(
461     CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
462   return (valobj_sp ? new LibcxxSharedPtrSyntheticFrontEnd(valobj_sp)
463                     : nullptr);
464 }
465 
466 lldb_private::formatters::LibcxxUniquePtrSyntheticFrontEnd::
467     LibcxxUniquePtrSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)
468     : SyntheticChildrenFrontEnd(*valobj_sp) {
469   if (valobj_sp)
470     Update();
471 }
472 
473 lldb_private::formatters::LibcxxUniquePtrSyntheticFrontEnd::
474     ~LibcxxUniquePtrSyntheticFrontEnd() = default;
475 
476 SyntheticChildrenFrontEnd *
477 lldb_private::formatters::LibcxxUniquePtrSyntheticFrontEndCreator(
478     CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
479   return (valobj_sp ? new LibcxxUniquePtrSyntheticFrontEnd(valobj_sp)
480                     : nullptr);
481 }
482 
483 size_t lldb_private::formatters::LibcxxUniquePtrSyntheticFrontEnd::
484     CalculateNumChildren() {
485   return (m_value_ptr_sp ? 1 : 0);
486 }
487 
488 lldb::ValueObjectSP
489 lldb_private::formatters::LibcxxUniquePtrSyntheticFrontEnd::GetChildAtIndex(
490     size_t idx) {
491   if (!m_value_ptr_sp)
492     return lldb::ValueObjectSP();
493 
494   if (idx == 0)
495     return m_value_ptr_sp;
496 
497   if (idx == 1) {
498     Status status;
499     auto value_sp = m_value_ptr_sp->Dereference(status);
500     if (status.Success()) {
501       return value_sp;
502     }
503   }
504 
505   return lldb::ValueObjectSP();
506 }
507 
508 bool lldb_private::formatters::LibcxxUniquePtrSyntheticFrontEnd::Update() {
509   ValueObjectSP valobj_sp = m_backend.GetSP();
510   if (!valobj_sp)
511     return false;
512 
513   ValueObjectSP ptr_sp(
514       valobj_sp->GetChildMemberWithName(ConstString("__ptr_"), true));
515   if (!ptr_sp)
516     return false;
517 
518   m_value_ptr_sp = GetValueOfLibCXXCompressedPair(*ptr_sp);
519 
520   return false;
521 }
522 
523 bool lldb_private::formatters::LibcxxUniquePtrSyntheticFrontEnd::
524     MightHaveChildren() {
525   return true;
526 }
527 
528 size_t lldb_private::formatters::LibcxxUniquePtrSyntheticFrontEnd::
529     GetIndexOfChildWithName(ConstString name) {
530   if (name == "__value_")
531     return 0;
532   if (name == "$$dereference$$")
533     return 1;
534   return UINT32_MAX;
535 }
536 
537 bool lldb_private::formatters::LibcxxContainerSummaryProvider(
538     ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
539   if (valobj.IsPointerType()) {
540     uint64_t value = valobj.GetValueAsUnsigned(0);
541     if (!value)
542       return false;
543     stream.Printf("0x%016" PRIx64 " ", value);
544   }
545   return FormatEntity::FormatStringRef("size=${svar%#}", stream, nullptr,
546                                        nullptr, nullptr, &valobj, false, false);
547 }
548 
549 /// The field layout in a libc++ string (cap, side, data or data, size, cap).
550 enum LibcxxStringLayoutMode {
551   eLibcxxStringLayoutModeCSD = 0,
552   eLibcxxStringLayoutModeDSC = 1,
553   eLibcxxStringLayoutModeInvalid = 0xffff
554 };
555 
556 /// Determine the size in bytes of \p valobj (a libc++ std::string object) and
557 /// extract its data payload. Return the size + payload pair.
558 // TODO: Support big-endian architectures.
559 static llvm::Optional<std::pair<uint64_t, ValueObjectSP>>
560 ExtractLibcxxStringInfo(ValueObject &valobj) {
561   ValueObjectSP dataval_sp(valobj.GetChildAtIndexPath({0, 0, 0, 0}));
562   if (!dataval_sp)
563     return {};
564   if (!dataval_sp->GetError().Success())
565     return {};
566 
567   ValueObjectSP layout_decider(
568       dataval_sp->GetChildAtIndexPath(llvm::ArrayRef<size_t>({0, 0})));
569 
570   // this child should exist
571   if (!layout_decider)
572     return {};
573 
574   ConstString g_data_name("__data_");
575   ConstString g_size_name("__size_");
576   bool short_mode = false; // this means the string is in short-mode and the
577                            // data is stored inline
578   bool using_bitmasks = true; // Whether the class uses bitmasks for the mode
579                               // flag (pre-D123580).
580   uint64_t size;
581   LibcxxStringLayoutMode layout = (layout_decider->GetName() == g_data_name)
582                                       ? eLibcxxStringLayoutModeDSC
583                                       : eLibcxxStringLayoutModeCSD;
584   uint64_t size_mode_value = 0;
585 
586   ValueObjectSP short_sp(dataval_sp->GetChildAtIndex(1, true));
587   if (!short_sp)
588     return {};
589 
590   ValueObjectSP short_fields_sp;
591   ValueObjectSP is_long =
592       short_sp->GetChildMemberWithName(ConstString("__is_long_"), true);
593   if (is_long) {
594     short_fields_sp = short_sp;
595   } else {
596     // After D128285, we need to access the `__is_long_` and `__size_` fields
597     // from a packed anonymous struct
598     short_fields_sp = short_sp->GetChildAtIndex(0, true);
599     is_long = short_sp->GetChildMemberWithName(ConstString("__is_long_"), true);
600   }
601 
602   if (is_long) {
603     using_bitmasks = false;
604     short_mode = !is_long->GetValueAsUnsigned(/*fail_value=*/0);
605     if (ValueObjectSP size_member =
606             dataval_sp->GetChildAtNamePath({ConstString("__s"), ConstString("__size_")}))
607       size = size_member->GetValueAsUnsigned(/*fail_value=*/0);
608     else
609       return {};
610   } else if (layout == eLibcxxStringLayoutModeDSC) {
611     llvm::SmallVector<size_t, 3> size_mode_locations[] = {
612         {1, 2}, // Post-c3d0205ee771 layout. This was in use for only a brief
613                 // period, so we can delete it if it becomes a burden.
614         {1, 1, 0},
615         {1, 1, 1},
616     };
617     ValueObjectSP size_mode;
618     for (llvm::ArrayRef<size_t> loc : size_mode_locations) {
619       size_mode = dataval_sp->GetChildAtIndexPath(loc);
620       if (size_mode && size_mode->GetName() == g_size_name)
621         break;
622     }
623 
624     if (!size_mode)
625       return {};
626 
627     size_mode_value = (size_mode->GetValueAsUnsigned(0));
628     short_mode = ((size_mode_value & 0x80) == 0);
629   } else {
630     ValueObjectSP size_mode(dataval_sp->GetChildAtIndexPath({1, 0, 0}));
631     if (!size_mode)
632       return {};
633 
634     size_mode_value = (size_mode->GetValueAsUnsigned(0));
635     short_mode = ((size_mode_value & 1) == 0);
636   }
637 
638   if (short_mode) {
639     ValueObjectSP location_sp =
640         short_sp->GetChildMemberWithName(g_data_name, true);
641     if (using_bitmasks)
642       size = (layout == eLibcxxStringLayoutModeDSC)
643                  ? size_mode_value
644                  : ((size_mode_value >> 1) % 256);
645 
646     // When the small-string optimization takes place, the data must fit in the
647     // inline string buffer (23 bytes on x86_64/Darwin). If it doesn't, it's
648     // likely that the string isn't initialized and we're reading garbage.
649     ExecutionContext exe_ctx(location_sp->GetExecutionContextRef());
650     const llvm::Optional<uint64_t> max_bytes =
651         location_sp->GetCompilerType().GetByteSize(
652             exe_ctx.GetBestExecutionContextScope());
653     if (!max_bytes || size > *max_bytes || !location_sp)
654       return {};
655 
656     return std::make_pair(size, location_sp);
657   }
658 
659   ValueObjectSP l(dataval_sp->GetChildAtIndex(0, true));
660   if (!l)
661     return {};
662 
663   // we can use the layout_decider object as the data pointer
664   ValueObjectSP location_sp =
665       l->GetChildMemberWithName(ConstString("__data_"), /*can_create=*/true);
666   ValueObjectSP size_vo =
667       l->GetChildMemberWithName(ConstString("__size_"), /*can_create=*/true);
668   ValueObjectSP capacity_vo =
669       l->GetChildMemberWithName(ConstString("__cap_"), /*can_create=*/true);
670   if (!capacity_vo) {
671     // After D128285, we need to access the `__cap_` field from a packed
672     // anonymous struct
673     if (ValueObjectSP packed_fields_sp = l->GetChildAtIndex(0, true)) {
674       ValueObjectSP capacity_vo = packed_fields_sp->GetChildMemberWithName(
675           ConstString("__cap_"), /*can_create=*/true);
676     }
677   }
678   if (!size_vo || !location_sp || !capacity_vo)
679     return {};
680   size = size_vo->GetValueAsUnsigned(LLDB_INVALID_OFFSET);
681   uint64_t capacity = capacity_vo->GetValueAsUnsigned(LLDB_INVALID_OFFSET);
682   if (!using_bitmasks && layout == eLibcxxStringLayoutModeCSD)
683     capacity *= 2;
684   if (size == LLDB_INVALID_OFFSET || capacity == LLDB_INVALID_OFFSET ||
685       capacity < size)
686     return {};
687   return std::make_pair(size, location_sp);
688 }
689 
690 static bool
691 LibcxxWStringSummaryProvider(ValueObject &valobj, Stream &stream,
692                              const TypeSummaryOptions &summary_options,
693                              ValueObjectSP location_sp, size_t size) {
694   if (size == 0) {
695     stream.Printf("L\"\"");
696     return true;
697   }
698   if (!location_sp)
699     return false;
700 
701   StringPrinter::ReadBufferAndDumpToStreamOptions options(valobj);
702   if (summary_options.GetCapping() == TypeSummaryCapping::eTypeSummaryCapped) {
703     const auto max_size = valobj.GetTargetSP()->GetMaximumSizeOfStringSummary();
704     if (size > max_size) {
705       size = max_size;
706       options.SetIsTruncated(true);
707     }
708   }
709 
710   DataExtractor extractor;
711   const size_t bytes_read = location_sp->GetPointeeData(extractor, 0, size);
712   if (bytes_read < size)
713     return false;
714 
715   // std::wstring::size() is measured in 'characters', not bytes
716   TypeSystemClang *ast_context =
717       ScratchTypeSystemClang::GetForTarget(*valobj.GetTargetSP());
718   if (!ast_context)
719     return false;
720 
721   auto wchar_t_size =
722       ast_context->GetBasicType(lldb::eBasicTypeWChar).GetByteSize(nullptr);
723   if (!wchar_t_size)
724     return false;
725 
726   options.SetData(std::move(extractor));
727   options.SetStream(&stream);
728   options.SetPrefixToken("L");
729   options.SetQuote('"');
730   options.SetSourceSize(size);
731   options.SetBinaryZeroIsTerminator(false);
732 
733   switch (*wchar_t_size) {
734   case 1:
735     return StringPrinter::ReadBufferAndDumpToStream<
736         lldb_private::formatters::StringPrinter::StringElementType::UTF8>(
737         options);
738     break;
739 
740   case 2:
741     return StringPrinter::ReadBufferAndDumpToStream<
742         lldb_private::formatters::StringPrinter::StringElementType::UTF16>(
743         options);
744     break;
745 
746   case 4:
747     return StringPrinter::ReadBufferAndDumpToStream<
748         lldb_private::formatters::StringPrinter::StringElementType::UTF32>(
749         options);
750   }
751   return false;
752 }
753 
754 bool lldb_private::formatters::LibcxxWStringSummaryProvider(
755     ValueObject &valobj, Stream &stream,
756     const TypeSummaryOptions &summary_options) {
757   auto string_info = ExtractLibcxxStringInfo(valobj);
758   if (!string_info)
759     return false;
760   uint64_t size;
761   ValueObjectSP location_sp;
762   std::tie(size, location_sp) = *string_info;
763 
764   return ::LibcxxWStringSummaryProvider(valobj, stream, summary_options,
765                                         location_sp, size);
766 }
767 
768 template <StringPrinter::StringElementType element_type>
769 static bool
770 LibcxxStringSummaryProvider(ValueObject &valobj, Stream &stream,
771                             const TypeSummaryOptions &summary_options,
772                             std::string prefix_token, ValueObjectSP location_sp,
773                             uint64_t size) {
774 
775   if (size == 0) {
776     stream.Printf("\"\"");
777     return true;
778   }
779 
780   if (!location_sp)
781     return false;
782 
783   StringPrinter::ReadBufferAndDumpToStreamOptions options(valobj);
784 
785   if (summary_options.GetCapping() == TypeSummaryCapping::eTypeSummaryCapped) {
786     const auto max_size = valobj.GetTargetSP()->GetMaximumSizeOfStringSummary();
787     if (size > max_size) {
788       size = max_size;
789       options.SetIsTruncated(true);
790     }
791   }
792 
793   {
794     DataExtractor extractor;
795     const size_t bytes_read = location_sp->GetPointeeData(extractor, 0, size);
796     if (bytes_read < size)
797       return false;
798 
799     options.SetData(std::move(extractor));
800   }
801   options.SetStream(&stream);
802   if (prefix_token.empty())
803     options.SetPrefixToken(nullptr);
804   else
805     options.SetPrefixToken(prefix_token);
806   options.SetQuote('"');
807   options.SetSourceSize(size);
808   options.SetBinaryZeroIsTerminator(false);
809   return StringPrinter::ReadBufferAndDumpToStream<element_type>(options);
810 }
811 
812 template <StringPrinter::StringElementType element_type>
813 static bool
814 LibcxxStringSummaryProvider(ValueObject &valobj, Stream &stream,
815                             const TypeSummaryOptions &summary_options,
816                             std::string prefix_token) {
817   auto string_info = ExtractLibcxxStringInfo(valobj);
818   if (!string_info)
819     return false;
820   uint64_t size;
821   ValueObjectSP location_sp;
822   std::tie(size, location_sp) = *string_info;
823 
824   return LibcxxStringSummaryProvider<element_type>(
825       valobj, stream, summary_options, prefix_token, location_sp, size);
826 }
827 template <StringPrinter::StringElementType element_type>
828 static bool formatStringImpl(ValueObject &valobj, Stream &stream,
829                              const TypeSummaryOptions &summary_options,
830                              std::string prefix_token) {
831   StreamString scratch_stream;
832   const bool success = LibcxxStringSummaryProvider<element_type>(
833       valobj, scratch_stream, summary_options, prefix_token);
834   if (success)
835     stream << scratch_stream.GetData();
836   else
837     stream << "Summary Unavailable";
838   return true;
839 }
840 
841 bool lldb_private::formatters::LibcxxStringSummaryProviderASCII(
842     ValueObject &valobj, Stream &stream,
843     const TypeSummaryOptions &summary_options) {
844   return formatStringImpl<StringPrinter::StringElementType::ASCII>(
845       valobj, stream, summary_options, "");
846 }
847 
848 bool lldb_private::formatters::LibcxxStringSummaryProviderUTF16(
849     ValueObject &valobj, Stream &stream,
850     const TypeSummaryOptions &summary_options) {
851   return formatStringImpl<StringPrinter::StringElementType::UTF16>(
852       valobj, stream, summary_options, "u");
853 }
854 
855 bool lldb_private::formatters::LibcxxStringSummaryProviderUTF32(
856     ValueObject &valobj, Stream &stream,
857     const TypeSummaryOptions &summary_options) {
858   return formatStringImpl<StringPrinter::StringElementType::UTF32>(
859       valobj, stream, summary_options, "U");
860 }
861 
862 static std::tuple<bool, ValueObjectSP, size_t>
863 LibcxxExtractStringViewData(ValueObject& valobj) {
864   ConstString g_data_name("__data");
865   ConstString g_size_name("__size");
866   auto dataobj = valobj.GetChildMemberWithName(g_data_name, true);
867   auto sizeobj = valobj.GetChildMemberWithName(g_size_name, true);
868 
869   if (!dataobj || !sizeobj)
870     return std::make_tuple<bool,ValueObjectSP,size_t>(false, {}, {});
871 
872   if (!dataobj->GetError().Success() || !sizeobj->GetError().Success())
873     return std::make_tuple<bool,ValueObjectSP,size_t>(false, {}, {});
874 
875   bool success{false};
876   uint64_t size = sizeobj->GetValueAsUnsigned(0, &success);
877   if (!success)
878     return std::make_tuple<bool,ValueObjectSP,size_t>(false, {}, {});
879 
880   return std::make_tuple(true,dataobj,size);
881 }
882 
883 template <StringPrinter::StringElementType element_type>
884 static bool formatStringViewImpl(ValueObject &valobj, Stream &stream,
885                                  const TypeSummaryOptions &summary_options,
886                                  std::string prefix_token) {
887 
888   bool success;
889   ValueObjectSP dataobj;
890   size_t size;
891   std::tie(success, dataobj, size) = LibcxxExtractStringViewData(valobj);
892 
893   if (!success) {
894     stream << "Summary Unavailable";
895     return true;
896   }
897 
898   return LibcxxStringSummaryProvider<element_type>(
899       valobj, stream, summary_options, prefix_token, dataobj, size);
900 }
901 
902 bool lldb_private::formatters::LibcxxStringViewSummaryProviderASCII(
903     ValueObject &valobj, Stream &stream,
904     const TypeSummaryOptions &summary_options) {
905   return formatStringViewImpl<StringPrinter::StringElementType::ASCII>(
906       valobj, stream, summary_options, "");
907 }
908 
909 bool lldb_private::formatters::LibcxxStringViewSummaryProviderUTF16(
910     ValueObject &valobj, Stream &stream,
911     const TypeSummaryOptions &summary_options) {
912   return formatStringViewImpl<StringPrinter::StringElementType::UTF16>(
913       valobj, stream, summary_options, "u");
914 }
915 
916 bool lldb_private::formatters::LibcxxStringViewSummaryProviderUTF32(
917     ValueObject &valobj, Stream &stream,
918     const TypeSummaryOptions &summary_options) {
919   return formatStringViewImpl<StringPrinter::StringElementType::UTF32>(
920       valobj, stream, summary_options, "U");
921 }
922 
923 bool lldb_private::formatters::LibcxxWStringViewSummaryProvider(
924     ValueObject &valobj, Stream &stream,
925     const TypeSummaryOptions &summary_options) {
926 
927   bool success;
928   ValueObjectSP dataobj;
929   size_t size;
930   std::tie( success, dataobj, size ) = LibcxxExtractStringViewData(valobj);
931 
932   if (!success) {
933     stream << "Summary Unavailable";
934     return true;
935   }
936 
937 
938   return ::LibcxxWStringSummaryProvider(valobj, stream, summary_options,
939                                         dataobj, size);
940 }
941