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   if (ValueObjectSP is_long = dataval_sp->GetChildAtNamePath(
587           {ConstString("__s"), ConstString("__is_long_")})) {
588     using_bitmasks = false;
589     short_mode = !is_long->GetValueAsUnsigned(/*fail_value=*/0);
590     if (ValueObjectSP size_member =
591             dataval_sp->GetChildAtNamePath({ConstString("__s"), ConstString("__size_")}))
592       size = size_member->GetValueAsUnsigned(/*fail_value=*/0);
593     else
594       return {};
595   } else if (layout == eLibcxxStringLayoutModeDSC) {
596     llvm::SmallVector<size_t, 3> size_mode_locations[] = {
597         {1, 2}, // Post-c3d0205ee771 layout. This was in use for only a brief
598                 // period, so we can delete it if it becomes a burden.
599         {1, 1, 0},
600         {1, 1, 1},
601     };
602     ValueObjectSP size_mode;
603     for (llvm::ArrayRef<size_t> loc : size_mode_locations) {
604       size_mode = dataval_sp->GetChildAtIndexPath(loc);
605       if (size_mode && size_mode->GetName() == g_size_name)
606         break;
607     }
608 
609     if (!size_mode)
610       return {};
611 
612     size_mode_value = (size_mode->GetValueAsUnsigned(0));
613     short_mode = ((size_mode_value & 0x80) == 0);
614   } else {
615     ValueObjectSP size_mode(dataval_sp->GetChildAtIndexPath({1, 0, 0}));
616     if (!size_mode)
617       return {};
618 
619     size_mode_value = (size_mode->GetValueAsUnsigned(0));
620     short_mode = ((size_mode_value & 1) == 0);
621   }
622 
623   if (short_mode) {
624     ValueObjectSP short_sp(dataval_sp->GetChildAtIndex(1, true));
625     if (!short_sp)
626       return {};
627     ValueObjectSP location_sp = short_sp->GetChildAtIndex(
628         (layout == eLibcxxStringLayoutModeDSC) ? 0 : 1, true);
629     // After D125496, there is a flat layout.
630     if (location_sp->GetName() == g_size_name)
631       location_sp = short_sp->GetChildAtIndex(3, true);
632     if (using_bitmasks)
633       size = (layout == eLibcxxStringLayoutModeDSC)
634                  ? size_mode_value
635                  : ((size_mode_value >> 1) % 256);
636 
637     // When the small-string optimization takes place, the data must fit in the
638     // inline string buffer (23 bytes on x86_64/Darwin). If it doesn't, it's
639     // likely that the string isn't initialized and we're reading garbage.
640     ExecutionContext exe_ctx(location_sp->GetExecutionContextRef());
641     const llvm::Optional<uint64_t> max_bytes =
642         location_sp->GetCompilerType().GetByteSize(
643             exe_ctx.GetBestExecutionContextScope());
644     if (!max_bytes || size > *max_bytes || !location_sp)
645       return {};
646 
647     return std::make_pair(size, location_sp);
648   }
649 
650   ValueObjectSP l(dataval_sp->GetChildAtIndex(0, true));
651   if (!l)
652     return {};
653   // we can use the layout_decider object as the data pointer
654   ValueObjectSP location_sp =
655       l->GetChildMemberWithName(ConstString("__data_"), /*can_create=*/true);
656   ValueObjectSP size_vo =
657       l->GetChildMemberWithName(ConstString("__size_"), /*can_create=*/true);
658   ValueObjectSP capacity_vo =
659       l->GetChildMemberWithName(ConstString("__cap_"), /*can_create=*/true);
660   if (!size_vo || !location_sp || !capacity_vo)
661     return {};
662   size = size_vo->GetValueAsUnsigned(LLDB_INVALID_OFFSET);
663   uint64_t capacity = capacity_vo->GetValueAsUnsigned(LLDB_INVALID_OFFSET);
664   if (!using_bitmasks && layout == eLibcxxStringLayoutModeCSD)
665     capacity *= 2;
666   if (size == LLDB_INVALID_OFFSET || capacity == LLDB_INVALID_OFFSET ||
667       capacity < size)
668     return {};
669   return std::make_pair(size, location_sp);
670 }
671 
672 static bool
673 LibcxxWStringSummaryProvider(ValueObject &valobj, Stream &stream,
674                              const TypeSummaryOptions &summary_options,
675                              ValueObjectSP location_sp, size_t size) {
676   if (size == 0) {
677     stream.Printf("L\"\"");
678     return true;
679   }
680   if (!location_sp)
681     return false;
682 
683   StringPrinter::ReadBufferAndDumpToStreamOptions options(valobj);
684   if (summary_options.GetCapping() == TypeSummaryCapping::eTypeSummaryCapped) {
685     const auto max_size = valobj.GetTargetSP()->GetMaximumSizeOfStringSummary();
686     if (size > max_size) {
687       size = max_size;
688       options.SetIsTruncated(true);
689     }
690   }
691 
692   DataExtractor extractor;
693   const size_t bytes_read = location_sp->GetPointeeData(extractor, 0, size);
694   if (bytes_read < size)
695     return false;
696 
697   // std::wstring::size() is measured in 'characters', not bytes
698   TypeSystemClang *ast_context =
699       ScratchTypeSystemClang::GetForTarget(*valobj.GetTargetSP());
700   if (!ast_context)
701     return false;
702 
703   auto wchar_t_size =
704       ast_context->GetBasicType(lldb::eBasicTypeWChar).GetByteSize(nullptr);
705   if (!wchar_t_size)
706     return false;
707 
708   options.SetData(std::move(extractor));
709   options.SetStream(&stream);
710   options.SetPrefixToken("L");
711   options.SetQuote('"');
712   options.SetSourceSize(size);
713   options.SetBinaryZeroIsTerminator(false);
714 
715   switch (*wchar_t_size) {
716   case 1:
717     return StringPrinter::ReadBufferAndDumpToStream<
718         lldb_private::formatters::StringPrinter::StringElementType::UTF8>(
719         options);
720     break;
721 
722   case 2:
723     return StringPrinter::ReadBufferAndDumpToStream<
724         lldb_private::formatters::StringPrinter::StringElementType::UTF16>(
725         options);
726     break;
727 
728   case 4:
729     return StringPrinter::ReadBufferAndDumpToStream<
730         lldb_private::formatters::StringPrinter::StringElementType::UTF32>(
731         options);
732   }
733   return false;
734 }
735 
736 bool lldb_private::formatters::LibcxxWStringSummaryProvider(
737     ValueObject &valobj, Stream &stream,
738     const TypeSummaryOptions &summary_options) {
739   auto string_info = ExtractLibcxxStringInfo(valobj);
740   if (!string_info)
741     return false;
742   uint64_t size;
743   ValueObjectSP location_sp;
744   std::tie(size, location_sp) = *string_info;
745 
746   return ::LibcxxWStringSummaryProvider(valobj, stream, summary_options,
747                                         location_sp, size);
748 }
749 
750 template <StringPrinter::StringElementType element_type>
751 static bool
752 LibcxxStringSummaryProvider(ValueObject &valobj, Stream &stream,
753                             const TypeSummaryOptions &summary_options,
754                             std::string prefix_token, ValueObjectSP location_sp,
755                             uint64_t size) {
756 
757   if (size == 0) {
758     stream.Printf("\"\"");
759     return true;
760   }
761 
762   if (!location_sp)
763     return false;
764 
765   StringPrinter::ReadBufferAndDumpToStreamOptions options(valobj);
766 
767   if (summary_options.GetCapping() == TypeSummaryCapping::eTypeSummaryCapped) {
768     const auto max_size = valobj.GetTargetSP()->GetMaximumSizeOfStringSummary();
769     if (size > max_size) {
770       size = max_size;
771       options.SetIsTruncated(true);
772     }
773   }
774 
775   {
776     DataExtractor extractor;
777     const size_t bytes_read = location_sp->GetPointeeData(extractor, 0, size);
778     if (bytes_read < size)
779       return false;
780 
781     options.SetData(std::move(extractor));
782   }
783   options.SetStream(&stream);
784   if (prefix_token.empty())
785     options.SetPrefixToken(nullptr);
786   else
787     options.SetPrefixToken(prefix_token);
788   options.SetQuote('"');
789   options.SetSourceSize(size);
790   options.SetBinaryZeroIsTerminator(false);
791   return StringPrinter::ReadBufferAndDumpToStream<element_type>(options);
792 }
793 
794 template <StringPrinter::StringElementType element_type>
795 static bool
796 LibcxxStringSummaryProvider(ValueObject &valobj, Stream &stream,
797                             const TypeSummaryOptions &summary_options,
798                             std::string prefix_token) {
799   auto string_info = ExtractLibcxxStringInfo(valobj);
800   if (!string_info)
801     return false;
802   uint64_t size;
803   ValueObjectSP location_sp;
804   std::tie(size, location_sp) = *string_info;
805 
806   return LibcxxStringSummaryProvider<element_type>(
807       valobj, stream, summary_options, prefix_token, location_sp, size);
808 }
809 template <StringPrinter::StringElementType element_type>
810 static bool formatStringImpl(ValueObject &valobj, Stream &stream,
811                              const TypeSummaryOptions &summary_options,
812                              std::string prefix_token) {
813   StreamString scratch_stream;
814   const bool success = LibcxxStringSummaryProvider<element_type>(
815       valobj, scratch_stream, summary_options, prefix_token);
816   if (success)
817     stream << scratch_stream.GetData();
818   else
819     stream << "Summary Unavailable";
820   return true;
821 }
822 
823 bool lldb_private::formatters::LibcxxStringSummaryProviderASCII(
824     ValueObject &valobj, Stream &stream,
825     const TypeSummaryOptions &summary_options) {
826   return formatStringImpl<StringPrinter::StringElementType::ASCII>(
827       valobj, stream, summary_options, "");
828 }
829 
830 bool lldb_private::formatters::LibcxxStringSummaryProviderUTF16(
831     ValueObject &valobj, Stream &stream,
832     const TypeSummaryOptions &summary_options) {
833   return formatStringImpl<StringPrinter::StringElementType::UTF16>(
834       valobj, stream, summary_options, "u");
835 }
836 
837 bool lldb_private::formatters::LibcxxStringSummaryProviderUTF32(
838     ValueObject &valobj, Stream &stream,
839     const TypeSummaryOptions &summary_options) {
840   return formatStringImpl<StringPrinter::StringElementType::UTF32>(
841       valobj, stream, summary_options, "U");
842 }
843 
844 static std::tuple<bool, ValueObjectSP, size_t>
845 LibcxxExtractStringViewData(ValueObject& valobj) {
846   ConstString g_data_name("__data");
847   ConstString g_size_name("__size");
848   auto dataobj = valobj.GetChildMemberWithName(g_data_name, true);
849   auto sizeobj = valobj.GetChildMemberWithName(g_size_name, true);
850 
851   if (!dataobj || !sizeobj)
852     return std::make_tuple<bool,ValueObjectSP,size_t>(false, {}, {});
853 
854   if (!dataobj->GetError().Success() || !sizeobj->GetError().Success())
855     return std::make_tuple<bool,ValueObjectSP,size_t>(false, {}, {});
856 
857   bool success{false};
858   uint64_t size = sizeobj->GetValueAsUnsigned(0, &success);
859   if (!success)
860     return std::make_tuple<bool,ValueObjectSP,size_t>(false, {}, {});
861 
862   return std::make_tuple(true,dataobj,size);
863 }
864 
865 template <StringPrinter::StringElementType element_type>
866 static bool formatStringViewImpl(ValueObject &valobj, Stream &stream,
867                                  const TypeSummaryOptions &summary_options,
868                                  std::string prefix_token) {
869 
870   bool success;
871   ValueObjectSP dataobj;
872   size_t size;
873   std::tie(success, dataobj, size) = LibcxxExtractStringViewData(valobj);
874 
875   if (!success) {
876     stream << "Summary Unavailable";
877     return true;
878   }
879 
880   return LibcxxStringSummaryProvider<element_type>(
881       valobj, stream, summary_options, prefix_token, dataobj, size);
882 }
883 
884 bool lldb_private::formatters::LibcxxStringViewSummaryProviderASCII(
885     ValueObject &valobj, Stream &stream,
886     const TypeSummaryOptions &summary_options) {
887   return formatStringViewImpl<StringPrinter::StringElementType::ASCII>(
888       valobj, stream, summary_options, "");
889 }
890 
891 bool lldb_private::formatters::LibcxxStringViewSummaryProviderUTF16(
892     ValueObject &valobj, Stream &stream,
893     const TypeSummaryOptions &summary_options) {
894   return formatStringViewImpl<StringPrinter::StringElementType::UTF16>(
895       valobj, stream, summary_options, "u");
896 }
897 
898 bool lldb_private::formatters::LibcxxStringViewSummaryProviderUTF32(
899     ValueObject &valobj, Stream &stream,
900     const TypeSummaryOptions &summary_options) {
901   return formatStringViewImpl<StringPrinter::StringElementType::UTF32>(
902       valobj, stream, summary_options, "U");
903 }
904 
905 bool lldb_private::formatters::LibcxxWStringViewSummaryProvider(
906     ValueObject &valobj, Stream &stream,
907     const TypeSummaryOptions &summary_options) {
908 
909   bool success;
910   ValueObjectSP dataobj;
911   size_t size;
912   std::tie( success, dataobj, size ) = LibcxxExtractStringViewData(valobj);
913 
914   if (!success) {
915     stream << "Summary Unavailable";
916     return true;
917   }
918 
919 
920   return ::LibcxxWStringSummaryProvider(valobj, stream, summary_options,
921                                         dataobj, size);
922 }
923