1 //===-- IRInterpreter.cpp ---------------------------------------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "lldb/Core/DataEncoder.h"
11 #include "lldb/Core/Log.h"
12 #include "lldb/Core/ValueObjectConstResult.h"
13 #include "lldb/Expression/ClangExpressionDeclMap.h"
14 #include "lldb/Expression/IRForTarget.h"
15 #include "lldb/Expression/IRInterpreter.h"
16 
17 #include "llvm/Constants.h"
18 #include "llvm/Function.h"
19 #include "llvm/Instructions.h"
20 #include "llvm/Module.h"
21 #include "llvm/Support/raw_ostream.h"
22 #include "llvm/Target/TargetData.h"
23 
24 #include <map>
25 
26 using namespace llvm;
27 
28 IRInterpreter::IRInterpreter(lldb_private::ClangExpressionDeclMap &decl_map,
29                                            lldb_private::Stream *error_stream) :
30     m_decl_map(decl_map),
31     m_error_stream(error_stream)
32 {
33 
34 }
35 
36 IRInterpreter::~IRInterpreter()
37 {
38 
39 }
40 
41 static std::string
42 PrintValue(const Value *value, bool truncate = false)
43 {
44     std::string s;
45     raw_string_ostream rso(s);
46     value->print(rso);
47     rso.flush();
48     if (truncate)
49         s.resize(s.length() - 1);
50 
51     size_t offset;
52     while ((offset = s.find('\n')) != s.npos)
53         s.erase(offset, 1);
54     while (s[0] == ' ' || s[0] == '\t')
55         s.erase(0, 1);
56 
57     return s;
58 }
59 
60 static std::string
61 PrintType(const Type *type, bool truncate = false)
62 {
63     std::string s;
64     raw_string_ostream rso(s);
65     type->print(rso);
66     rso.flush();
67     if (truncate)
68         s.resize(s.length() - 1);
69     return s;
70 }
71 
72 typedef lldb::SharedPtr <lldb_private::DataEncoder>::Type DataEncoderSP;
73 typedef lldb::SharedPtr <lldb_private::DataExtractor>::Type DataExtractorSP;
74 
75 class Memory
76 {
77 public:
78     typedef uint32_t                    index_t;
79 
80     struct Allocation
81     {
82         // m_virtual_address is always the address of the variable in the virtual memory
83         // space provided by Memory.
84         //
85         // m_origin is always non-NULL and describes the source of the data (possibly
86         // m_data if this allocation is the authoritative source).
87         //
88         // Possible value configurations:
89         //
90         // Allocation type  getValueType()          getContextType()            m_origin->GetScalar()       m_data
91         // =========================================================================================================================
92         // FileAddress      eValueTypeFileAddress   eContextTypeInvalid         A location in a binary      NULL
93         //                                                                      image
94         //
95         // LoadAddress      eValueTypeLoadAddress   eContextTypeInvalid         A location in the target's  NULL
96         //                                                                      virtual memory
97         //
98         // Alloca           eValueTypeHostAddress   eContextTypeInvalid         == m_data->GetBytes()       Deleted at end of
99         //                                                                                                  execution
100         //
101         // PersistentVar    eValueTypeHostAddress   eContextTypeClangType       A persistent variable's     NULL
102         //                                                                      location in LLDB's memory
103         //
104         // Register         [ignored]               eContextTypeRegister        [ignored]                   Flushed to the register
105         //                                                                                                  at the end of execution
106 
107         lldb::addr_t        m_virtual_address;
108         size_t              m_extent;
109         lldb_private::Value m_origin;
110         lldb::DataBufferSP  m_data;
111 
112         Allocation (lldb::addr_t virtual_address,
113                     size_t extent,
114                     lldb::DataBufferSP data) :
115             m_virtual_address(virtual_address),
116             m_extent(extent),
117             m_data(data)
118         {
119         }
120 
121         Allocation (const Allocation &allocation) :
122             m_virtual_address(allocation.m_virtual_address),
123             m_extent(allocation.m_extent),
124             m_origin(allocation.m_origin),
125             m_data(allocation.m_data)
126         {
127         }
128     };
129 
130     typedef lldb::SharedPtr <Allocation>::Type  AllocationSP;
131 
132     struct Region
133     {
134         AllocationSP m_allocation;
135         uint64_t m_base;
136         uint64_t m_extent;
137 
138         Region () :
139             m_allocation(),
140             m_base(0),
141             m_extent(0)
142         {
143         }
144 
145         Region (AllocationSP allocation, uint64_t base, uint64_t extent) :
146             m_allocation(allocation),
147             m_base(base),
148             m_extent(extent)
149         {
150         }
151 
152         Region (const Region &region) :
153             m_allocation(region.m_allocation),
154             m_base(region.m_base),
155             m_extent(region.m_extent)
156         {
157         }
158 
159         bool IsValid ()
160         {
161             return m_allocation != NULL;
162         }
163 
164         bool IsInvalid ()
165         {
166             return m_allocation == NULL;
167         }
168     };
169 
170     typedef std::vector <AllocationSP>          MemoryMap;
171 
172 private:
173     lldb::addr_t        m_addr_base;
174     lldb::addr_t        m_addr_max;
175     MemoryMap           m_memory;
176     lldb::ByteOrder     m_byte_order;
177     lldb::addr_t        m_addr_byte_size;
178     TargetData         &m_target_data;
179 
180     lldb_private::ClangExpressionDeclMap   &m_decl_map;
181 
182     MemoryMap::iterator LookupInternal (lldb::addr_t addr)
183     {
184         for (MemoryMap::iterator i = m_memory.begin(), e = m_memory.end();
185              i != e;
186              ++i)
187         {
188             if ((*i)->m_virtual_address <= addr &&
189                 (*i)->m_virtual_address + (*i)->m_extent > addr)
190                 return i;
191         }
192 
193         return m_memory.end();
194     }
195 
196 public:
197     Memory (TargetData &target_data,
198             lldb_private::ClangExpressionDeclMap &decl_map,
199             lldb::addr_t alloc_start,
200             lldb::addr_t alloc_max) :
201         m_addr_base(alloc_start),
202         m_addr_max(alloc_max),
203         m_target_data(target_data),
204         m_decl_map(decl_map)
205     {
206         m_byte_order = (target_data.isLittleEndian() ? lldb::eByteOrderLittle : lldb::eByteOrderBig);
207         m_addr_byte_size = (target_data.getPointerSize());
208     }
209 
210     Region Malloc (size_t size, size_t align)
211     {
212         lldb::DataBufferSP data(new lldb_private::DataBufferHeap(size, 0));
213 
214         if (data)
215         {
216             index_t index = m_memory.size();
217 
218             const size_t mask = (align - 1);
219 
220             m_addr_base += mask;
221             m_addr_base &= ~mask;
222 
223             if (m_addr_base + size < m_addr_base ||
224                 m_addr_base + size > m_addr_max)
225                 return Region();
226 
227             uint64_t base = m_addr_base;
228 
229             m_memory.push_back(AllocationSP(new Allocation(base, size, data)));
230 
231             m_addr_base += size;
232 
233             AllocationSP alloc = m_memory[index];
234 
235             alloc->m_origin.GetScalar() = (unsigned long long)data->GetBytes();
236             alloc->m_origin.SetContext(lldb_private::Value::eContextTypeInvalid, NULL);
237             alloc->m_origin.SetValueType(lldb_private::Value::eValueTypeHostAddress);
238 
239             return Region(alloc, base, size);
240         }
241 
242         return Region();
243     }
244 
245     Region Malloc (Type *type)
246     {
247         return Malloc (m_target_data.getTypeAllocSize(type),
248                        m_target_data.getPrefTypeAlignment(type));
249     }
250 
251     Region Place (Type *type, lldb::addr_t base, lldb_private::Value &value)
252     {
253         index_t index = m_memory.size();
254         size_t size = m_target_data.getTypeAllocSize(type);
255 
256         m_memory.push_back(AllocationSP(new Allocation(base, size, lldb::DataBufferSP())));
257 
258         AllocationSP alloc = m_memory[index];
259 
260         alloc->m_origin = value;
261 
262         return Region(alloc, base, size);
263     }
264 
265     void Free (lldb::addr_t addr)
266     {
267         MemoryMap::iterator i = LookupInternal (addr);
268 
269         if (i != m_memory.end())
270             m_memory.erase(i);
271     }
272 
273     Region Lookup (lldb::addr_t addr, Type *type)
274     {
275         MemoryMap::iterator i = LookupInternal(addr);
276 
277         if (i == m_memory.end())
278             return Region();
279 
280         size_t size = m_target_data.getTypeStoreSize(type);
281 
282         return Region(*i, addr, size);
283     }
284 
285     DataEncoderSP GetEncoder (Region region)
286     {
287         if (region.m_allocation->m_origin.GetValueType() != lldb_private::Value::eValueTypeHostAddress)
288             return DataEncoderSP();
289 
290         lldb::DataBufferSP buffer = region.m_allocation->m_data;
291 
292         if (!buffer)
293             return DataEncoderSP();
294 
295         size_t base_offset = (size_t)(region.m_base - region.m_allocation->m_virtual_address);
296 
297         return DataEncoderSP(new lldb_private::DataEncoder(buffer->GetBytes() + base_offset, region.m_extent, m_byte_order, m_addr_byte_size));
298     }
299 
300     DataExtractorSP GetExtractor (Region region)
301     {
302         if (region.m_allocation->m_origin.GetValueType() != lldb_private::Value::eValueTypeHostAddress)
303             return DataExtractorSP();
304 
305         lldb::DataBufferSP buffer = region.m_allocation->m_data;
306         size_t base_offset = (size_t)(region.m_base - region.m_allocation->m_virtual_address);
307 
308         if (buffer)
309             return DataExtractorSP(new lldb_private::DataExtractor(buffer->GetBytes() + base_offset, region.m_extent, m_byte_order, m_addr_byte_size));
310         else
311             return DataExtractorSP(new lldb_private::DataExtractor((uint8_t*)region.m_allocation->m_origin.GetScalar().ULongLong() + base_offset, region.m_extent, m_byte_order, m_addr_byte_size));
312     }
313 
314     lldb_private::Value GetAccessTarget(lldb::addr_t addr)
315     {
316         MemoryMap::iterator i = LookupInternal(addr);
317 
318         if (i == m_memory.end())
319             return lldb_private::Value();
320 
321         lldb_private::Value target = (*i)->m_origin;
322 
323         if (target.GetContextType() == lldb_private::Value::eContextTypeRegisterInfo)
324         {
325             target.SetContext(lldb_private::Value::eContextTypeInvalid, NULL);
326             target.SetValueType(lldb_private::Value::eValueTypeHostAddress);
327             target.GetScalar() = (unsigned long long)(*i)->m_data->GetBytes();
328         }
329 
330         target.GetScalar() += (addr - (*i)->m_virtual_address);
331 
332         return target;
333     }
334 
335     bool Write (lldb::addr_t addr, const uint8_t *data, size_t length)
336     {
337         lldb_private::Value target = GetAccessTarget(addr);
338 
339         return m_decl_map.WriteTarget(target, data, length);
340     }
341 
342     bool Read (uint8_t *data, lldb::addr_t addr, size_t length)
343     {
344         lldb_private::Value target = GetAccessTarget(addr);
345 
346         return m_decl_map.ReadTarget(data, target, length);
347     }
348 
349     std::string PrintData (lldb::addr_t addr, size_t length)
350     {
351         lldb_private::Value target = GetAccessTarget(addr);
352 
353         lldb_private::DataBufferHeap buf(length, 0);
354 
355         if (!m_decl_map.ReadTarget(buf.GetBytes(), target, length))
356             return std::string("<couldn't read data>");
357 
358         lldb_private::StreamString ss;
359 
360         for (size_t i = 0; i < length; i++)
361         {
362             if ((!(i & 0xf)) && i)
363                 ss.Printf("%02hhx - ", buf.GetBytes()[i]);
364             else
365                 ss.Printf("%02hhx ", buf.GetBytes()[i]);
366         }
367 
368         return ss.GetString();
369     }
370 
371     std::string SummarizeRegion (Region &region)
372     {
373         lldb_private::StreamString ss;
374 
375         lldb_private::Value base = GetAccessTarget(region.m_base);
376 
377         ss.Printf("%llx [%s - %s %llx]",
378                   region.m_base,
379                   lldb_private::Value::GetValueTypeAsCString(base.GetValueType()),
380                   lldb_private::Value::GetContextTypeAsCString(base.GetContextType()),
381                   base.GetScalar().ULongLong());
382 
383         ss.Printf(" %s", PrintData(region.m_base, region.m_extent).c_str());
384 
385         return ss.GetString();
386     }
387 };
388 
389 class InterpreterStackFrame
390 {
391 public:
392     typedef std::map <const Value*, Memory::Region> ValueMap;
393 
394     ValueMap                                m_values;
395     Memory                                 &m_memory;
396     TargetData                             &m_target_data;
397     lldb_private::ClangExpressionDeclMap   &m_decl_map;
398     const BasicBlock                       *m_bb;
399     BasicBlock::const_iterator              m_ii;
400     BasicBlock::const_iterator              m_ie;
401 
402     lldb::ByteOrder                         m_byte_order;
403     size_t                                  m_addr_byte_size;
404 
405     InterpreterStackFrame (TargetData &target_data,
406                            Memory &memory,
407                            lldb_private::ClangExpressionDeclMap &decl_map) :
408         m_target_data (target_data),
409         m_memory (memory),
410         m_decl_map (decl_map)
411     {
412         m_byte_order = (target_data.isLittleEndian() ? lldb::eByteOrderLittle : lldb::eByteOrderBig);
413         m_addr_byte_size = (target_data.getPointerSize());
414     }
415 
416     void Jump (const BasicBlock *bb)
417     {
418         m_bb = bb;
419         m_ii = m_bb->begin();
420         m_ie = m_bb->end();
421     }
422 
423     bool Cache (Memory::AllocationSP allocation, Type *type)
424     {
425         if (allocation->m_origin.GetContextType() != lldb_private::Value::eContextTypeRegisterInfo)
426             return false;
427 
428         return m_decl_map.ReadTarget(allocation->m_data->GetBytes(), allocation->m_origin, allocation->m_data->GetByteSize());
429     }
430 
431     std::string SummarizeValue (const Value *value)
432     {
433         lldb_private::StreamString ss;
434 
435         ss.Printf("%s", PrintValue(value).c_str());
436 
437         ValueMap::iterator i = m_values.find(value);
438 
439         if (i != m_values.end())
440         {
441             Memory::Region region = i->second;
442 
443             ss.Printf(" %s", m_memory.SummarizeRegion(region).c_str());
444         }
445 
446         return ss.GetString();
447     }
448 
449     bool AssignToMatchType (lldb_private::Scalar &scalar, uint64_t u64value, Type *type)
450     {
451         size_t type_size = m_target_data.getTypeStoreSize(type);
452 
453         switch (type_size)
454         {
455         case 1:
456             scalar = (uint8_t)u64value;
457             break;
458         case 2:
459             scalar = (uint16_t)u64value;
460             break;
461         case 4:
462             scalar = (uint32_t)u64value;
463             break;
464         case 8:
465             scalar = (uint64_t)u64value;
466             break;
467         default:
468             return false;
469         }
470 
471         return true;
472     }
473 
474     bool EvaluateValue (lldb_private::Scalar &scalar, const Value *value, Module &module)
475     {
476         const Constant *constant = dyn_cast<Constant>(value);
477 
478         if (constant)
479         {
480             if (const ConstantInt *constant_int = dyn_cast<ConstantInt>(constant))
481             {
482                 return AssignToMatchType(scalar, constant_int->getLimitedValue(), value->getType());
483             }
484         }
485         else
486         {
487             Memory::Region region = ResolveValue(value, module);
488             DataExtractorSP value_extractor = m_memory.GetExtractor(region);
489 
490             if (!value_extractor)
491                 return false;
492 
493             size_t value_size = m_target_data.getTypeStoreSize(value->getType());
494 
495             uint32_t offset = 0;
496             uint64_t u64value = value_extractor->GetMaxU64(&offset, value_size);
497 
498             return AssignToMatchType(scalar, u64value, value->getType());
499         }
500 
501         return false;
502     }
503 
504     bool AssignValue (const Value *value, lldb_private::Scalar &scalar, Module &module)
505     {
506         Memory::Region region = ResolveValue (value, module);
507 
508         lldb_private::Scalar cast_scalar;
509 
510         if (!AssignToMatchType(cast_scalar, scalar.GetRawBits64(0), value->getType()))
511             return false;
512 
513         lldb_private::DataBufferHeap buf(cast_scalar.GetByteSize(), 0);
514 
515         lldb_private::Error err;
516 
517         if (!cast_scalar.GetAsMemoryData(buf.GetBytes(), buf.GetByteSize(), m_byte_order, err))
518             return false;
519 
520         DataEncoderSP region_encoder = m_memory.GetEncoder(region);
521 
522         memcpy(region_encoder->GetDataStart(), buf.GetBytes(), buf.GetByteSize());
523 
524         return true;
525     }
526 
527     bool ResolveConstant (Memory::Region &region, const Constant *constant)
528     {
529         size_t constant_size = m_target_data.getTypeStoreSize(constant->getType());
530 
531         if (const ConstantInt *constant_int = dyn_cast<ConstantInt>(constant))
532         {
533             const uint64_t *raw_data = constant_int->getValue().getRawData();
534             return m_memory.Write(region.m_base, (const uint8_t*)raw_data, constant_size);
535         }
536         if (const ConstantFP *constant_fp = dyn_cast<ConstantFP>(constant))
537         {
538             const uint64_t *raw_data = constant_fp->getValueAPF().bitcastToAPInt().getRawData();
539             return m_memory.Write(region.m_base, (const uint8_t*)raw_data, constant_size);
540         }
541 
542         return false;
543     }
544 
545     Memory::Region ResolveValue (const Value *value, Module &module)
546     {
547         ValueMap::iterator i = m_values.find(value);
548 
549         if (i != m_values.end())
550             return i->second;
551 
552         const GlobalValue *global_value = dyn_cast<GlobalValue>(value);
553 
554         // Attempt to resolve the value using the program's data.
555         // If it is, the values to be created are:
556         //
557         // data_region - a region of memory in which the variable's data resides.
558         // ref_region - a region of memory in which its address (i.e., &var) resides.
559         //   In the JIT case, this region would be a member of the struct passed in.
560         // pointer_region - a region of memory in which the address of the pointer
561         //   resides.  This is an IR-level variable.
562         do
563         {
564             if (!global_value)
565                 break;
566 
567             lldb::LogSP log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_EXPRESSIONS));
568 
569             clang::NamedDecl *decl = IRForTarget::DeclForGlobal(global_value, &module);
570 
571             if (!decl)
572                 break;
573 
574             lldb_private::Value resolved_value = m_decl_map.LookupDecl(decl);
575 
576             if (resolved_value.GetScalar().GetType() != lldb_private::Scalar::e_void)
577             {
578                 if (resolved_value.GetContextType() == lldb_private::Value::eContextTypeRegisterInfo)
579                 {
580                     Memory::Region data_region = m_memory.Malloc(value->getType());
581                     data_region.m_allocation->m_origin = resolved_value;
582                     Memory::Region ref_region = m_memory.Malloc(value->getType());
583                     Memory::Region pointer_region = m_memory.Malloc(value->getType());
584 
585                     if (!Cache(data_region.m_allocation, value->getType()))
586                         return Memory::Region();
587 
588                     if (ref_region.IsInvalid())
589                         return Memory::Region();
590 
591                     if (pointer_region.IsInvalid())
592                         return Memory::Region();
593 
594                     DataEncoderSP ref_encoder = m_memory.GetEncoder(ref_region);
595 
596                     if (ref_encoder->PutAddress(0, data_region.m_base) == UINT32_MAX)
597                         return Memory::Region();
598 
599                     DataEncoderSP pointer_encoder = m_memory.GetEncoder(pointer_region);
600 
601                     if (pointer_encoder->PutAddress(0, ref_region.m_base) == UINT32_MAX)
602                         return Memory::Region();
603 
604                     m_values[value] = pointer_region;
605                     return pointer_region;
606                 }
607                 else if (isa<clang::FunctionDecl>(decl))
608                 {
609                     if (log)
610                         log->Printf("The interpreter does not handle function pointers at the moment");
611 
612                     return Memory::Region();
613                 }
614                 else
615                 {
616                     Memory::Region data_region = m_memory.Place(value->getType(), resolved_value.GetScalar().ULongLong(), resolved_value);
617                     Memory::Region ref_region = m_memory.Malloc(value->getType());
618                     Memory::Region pointer_region = m_memory.Malloc(value->getType());
619 
620                     if (ref_region.IsInvalid())
621                         return Memory::Region();
622 
623                     if (pointer_region.IsInvalid())
624                         return Memory::Region();
625 
626                     DataEncoderSP ref_encoder = m_memory.GetEncoder(ref_region);
627 
628                     if (ref_encoder->PutAddress(0, data_region.m_base) == UINT32_MAX)
629                         return Memory::Region();
630 
631                     DataEncoderSP pointer_encoder = m_memory.GetEncoder(pointer_region);
632 
633                     if (pointer_encoder->PutAddress(0, ref_region.m_base) == UINT32_MAX)
634                         return Memory::Region();
635 
636                     m_values[value] = pointer_region;
637 
638                     if (log)
639                     {
640                         log->Printf("Made an allocation for %s", PrintValue(global_value).c_str());
641                         log->Printf("  Data contents  : %s", m_memory.PrintData(data_region.m_base, data_region.m_extent).c_str());
642                         log->Printf("  Data region    : %llx", (unsigned long long)data_region.m_base);
643                         log->Printf("  Ref region     : %llx", (unsigned long long)ref_region.m_base);
644                         log->Printf("  Pointer region : %llx", (unsigned long long)pointer_region.m_base);
645                     }
646 
647                     return pointer_region;
648                 }
649             }
650         }
651         while(0);
652 
653         // Fall back and allocate space [allocation type Alloca]
654 
655         Type *type = value->getType();
656 
657         lldb::ValueSP backing_value(new lldb_private::Value);
658 
659         Memory::Region data_region = m_memory.Malloc(type);
660         data_region.m_allocation->m_origin.GetScalar() = (unsigned long long)data_region.m_allocation->m_data->GetBytes();
661         data_region.m_allocation->m_origin.SetContext(lldb_private::Value::eContextTypeInvalid, NULL);
662         data_region.m_allocation->m_origin.SetValueType(lldb_private::Value::eValueTypeHostAddress);
663 
664         const Constant *constant = dyn_cast<Constant>(value);
665 
666         do
667         {
668             if (!constant)
669                 break;
670 
671             if (!ResolveConstant (data_region, constant))
672                 return Memory::Region();
673         }
674         while(0);
675 
676         m_values[value] = data_region;
677         return data_region;
678     }
679 
680     bool ConstructResult (lldb::ClangExpressionVariableSP &result,
681                           const GlobalValue *result_value,
682                           const lldb_private::ConstString &result_name,
683                           lldb_private::TypeFromParser result_type,
684                           Module &module)
685     {
686         // The result_value resolves to P, a pointer to a region R containing the result data.
687         // If the result variable is a reference, the region R contains a pointer to the result R_final in the original process.
688 
689         if (!result_value)
690             return true; // There was no slot for a result – the expression doesn't return one.
691 
692         ValueMap::iterator i = m_values.find(result_value);
693 
694         if (i == m_values.end())
695             return false; // There was a slot for the result, but we didn't write into it.
696 
697         Memory::Region P = i->second;
698         DataExtractorSP P_extractor = m_memory.GetExtractor(P);
699 
700         if (!P_extractor)
701             return false;
702 
703         Type *pointer_ty = result_value->getType();
704         PointerType *pointer_ptr_ty = dyn_cast<PointerType>(pointer_ty);
705         if (!pointer_ptr_ty)
706             return false;
707         Type *R_ty = pointer_ptr_ty->getElementType();
708 
709         uint32_t offset = 0;
710         lldb::addr_t pointer = P_extractor->GetAddress(&offset);
711 
712         Memory::Region R = m_memory.Lookup(pointer, R_ty);
713 
714         if (R.m_allocation->m_origin.GetValueType() != lldb_private::Value::eValueTypeHostAddress ||
715             !R.m_allocation->m_data)
716             return false;
717 
718         lldb_private::Value base;
719 
720         if (m_decl_map.ResultIsReference(result_name))
721         {
722             PointerType *R_ptr_ty = dyn_cast<PointerType>(R_ty);
723             if (!R_ptr_ty)
724                 return false;
725             Type *R_final_ty = R_ptr_ty->getElementType();
726 
727             DataExtractorSP R_extractor = m_memory.GetExtractor(R);
728 
729             if (!R_extractor)
730                 return false;
731 
732             offset = 0;
733             lldb::addr_t R_pointer = R_extractor->GetAddress(&offset);
734 
735             Memory::Region R_final = m_memory.Lookup(R_pointer, R_final_ty);
736 
737             if (!R_final.m_allocation)
738                 return false;
739 
740             base = R_final.m_allocation->m_origin;
741             base.GetScalar() += (R_final.m_base - R_final.m_allocation->m_virtual_address);
742         }
743         else
744         {
745             base.SetContext(lldb_private::Value::eContextTypeInvalid, NULL);
746             base.SetValueType(lldb_private::Value::eValueTypeHostAddress);
747             base.GetScalar() = (unsigned long long)R.m_allocation->m_data->GetBytes() + (R.m_base - R.m_allocation->m_virtual_address);
748         }
749 
750         return m_decl_map.CompleteResultVariable (result, base, result_name, result_type);
751     }
752 };
753 
754 bool
755 IRInterpreter::maybeRunOnFunction (lldb::ClangExpressionVariableSP &result,
756                                    const lldb_private::ConstString &result_name,
757                                    lldb_private::TypeFromParser result_type,
758                                    Function &llvm_function,
759                                    Module &llvm_module)
760 {
761     if (supportsFunction (llvm_function))
762         return runOnFunction(result,
763                              result_name,
764                              result_type,
765                              llvm_function,
766                              llvm_module);
767     else
768         return false;
769 }
770 
771 bool
772 IRInterpreter::supportsFunction (Function &llvm_function)
773 {
774     lldb::LogSP log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_EXPRESSIONS));
775 
776     for (Function::iterator bbi = llvm_function.begin(), bbe = llvm_function.end();
777          bbi != bbe;
778          ++bbi)
779     {
780         for (BasicBlock::iterator ii = bbi->begin(), ie = bbi->end();
781              ii != ie;
782              ++ii)
783         {
784             switch (ii->getOpcode())
785             {
786             default:
787                 {
788                     if (log)
789                         log->Printf("Unsupported instruction: %s", PrintValue(ii).c_str());
790                     return false;
791                 }
792             case Instruction::Add:
793             case Instruction::Alloca:
794             case Instruction::BitCast:
795             case Instruction::Br:
796             case Instruction::GetElementPtr:
797                 break;
798             case Instruction::ICmp:
799                 {
800                     ICmpInst *icmp_inst = dyn_cast<ICmpInst>(ii);
801 
802                     if (!icmp_inst)
803                         return false;
804 
805                     switch (icmp_inst->getPredicate())
806                     {
807                     default:
808                         {
809                             if (log)
810                                 log->Printf("Unsupported ICmp predicate: %s", PrintValue(ii).c_str());
811                             return false;
812                         }
813                     case CmpInst::ICMP_EQ:
814                     case CmpInst::ICMP_NE:
815                     case CmpInst::ICMP_UGT:
816                     case CmpInst::ICMP_UGE:
817                     case CmpInst::ICMP_ULT:
818                     case CmpInst::ICMP_ULE:
819                     case CmpInst::ICMP_SGT:
820                     case CmpInst::ICMP_SGE:
821                     case CmpInst::ICMP_SLT:
822                     case CmpInst::ICMP_SLE:
823                         break;
824                     }
825                 }
826                 break;
827             case Instruction::Load:
828             case Instruction::Mul:
829             case Instruction::Ret:
830             case Instruction::SDiv:
831             case Instruction::Store:
832             case Instruction::Sub:
833             case Instruction::UDiv:
834                 break;
835             }
836         }
837     }
838 
839     return true;
840 }
841 
842 bool
843 IRInterpreter::runOnFunction (lldb::ClangExpressionVariableSP &result,
844                               const lldb_private::ConstString &result_name,
845                               lldb_private::TypeFromParser result_type,
846                               Function &llvm_function,
847                               Module &llvm_module)
848 {
849     lldb::LogSP log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_EXPRESSIONS));
850 
851     lldb_private::ClangExpressionDeclMap::TargetInfo target_info = m_decl_map.GetTargetInfo();
852 
853     if (!target_info.IsValid())
854         return false;
855 
856     lldb::addr_t alloc_min;
857     lldb::addr_t alloc_max;
858 
859     switch (target_info.address_byte_size)
860     {
861     default:
862         return false;
863     case 4:
864         alloc_min = 0x00001000llu;
865         alloc_max = 0x0000ffffllu;
866         break;
867     case 8:
868         alloc_min = 0x0000000000001000llu;
869         alloc_max = 0x000000000000ffffllu;
870         break;
871     }
872 
873     TargetData target_data(&llvm_module);
874     if (target_data.getPointerSize() != target_info.address_byte_size)
875         return false;
876     if (target_data.isLittleEndian() != (target_info.byte_order == lldb::eByteOrderLittle))
877         return false;
878 
879     Memory memory(target_data, m_decl_map, alloc_min, alloc_max);
880     InterpreterStackFrame frame(target_data, memory, m_decl_map);
881 
882     uint32_t num_insts = 0;
883 
884     frame.Jump(llvm_function.begin());
885 
886     while (frame.m_ii != frame.m_ie && (++num_insts < 4096))
887     {
888         const Instruction *inst = frame.m_ii;
889 
890         if (log)
891             log->Printf("Interpreting %s", PrintValue(inst).c_str());
892 
893         switch (inst->getOpcode())
894         {
895         default:
896             break;
897         case Instruction::Add:
898         case Instruction::Sub:
899         case Instruction::Mul:
900         case Instruction::SDiv:
901         case Instruction::UDiv:
902             {
903                 const BinaryOperator *bin_op = dyn_cast<BinaryOperator>(inst);
904 
905                 if (!bin_op)
906                 {
907                     if (log)
908                         log->Printf("getOpcode() returns %s, but instruction is not a BinaryOperator", inst->getOpcodeName());
909 
910                     return false;
911                 }
912 
913                 Value *lhs = inst->getOperand(0);
914                 Value *rhs = inst->getOperand(1);
915 
916                 lldb_private::Scalar L;
917                 lldb_private::Scalar R;
918 
919                 if (!frame.EvaluateValue(L, lhs, llvm_module))
920                 {
921                     if (log)
922                         log->Printf("Couldn't evaluate %s", PrintValue(lhs).c_str());
923 
924                     return false;
925                 }
926 
927                 if (!frame.EvaluateValue(R, rhs, llvm_module))
928                 {
929                     if (log)
930                         log->Printf("Couldn't evaluate %s", PrintValue(rhs).c_str());
931 
932                     return false;
933                 }
934 
935                 lldb_private::Scalar result;
936 
937                 switch (inst->getOpcode())
938                 {
939                 default:
940                     break;
941                 case Instruction::Add:
942                     result = L + R;
943                     break;
944                 case Instruction::Mul:
945                     result = L * R;
946                     break;
947                 case Instruction::Sub:
948                     result = L - R;
949                     break;
950                 case Instruction::SDiv:
951                     result = L / R;
952                     break;
953                 case Instruction::UDiv:
954                     result = L.GetRawBits64(0) / R.GetRawBits64(1);
955                     break;
956                 }
957 
958                 frame.AssignValue(inst, result, llvm_module);
959 
960                 if (log)
961                 {
962                     log->Printf("Interpreted a %s", inst->getOpcodeName());
963                     log->Printf("  L : %s", frame.SummarizeValue(lhs).c_str());
964                     log->Printf("  R : %s", frame.SummarizeValue(rhs).c_str());
965                     log->Printf("  = : %s", frame.SummarizeValue(inst).c_str());
966                 }
967             }
968             break;
969         case Instruction::Alloca:
970             {
971                 const AllocaInst *alloca_inst = dyn_cast<AllocaInst>(inst);
972 
973                 if (!alloca_inst)
974                 {
975                     if (log)
976                         log->Printf("getOpcode() returns Alloca, but instruction is not an AllocaInst");
977 
978                     return false;
979                 }
980 
981                 if (alloca_inst->isArrayAllocation())
982                 {
983                     if (log)
984                         log->Printf("AllocaInsts are not handled if isArrayAllocation() is true");
985 
986                     return false;
987                 }
988 
989                 // The semantics of Alloca are:
990                 //   Create a region R of virtual memory of type T, backed by a data buffer
991                 //   Create a region P of virtual memory of type T*, backed by a data buffer
992                 //   Write the virtual address of R into P
993 
994                 Type *T = alloca_inst->getAllocatedType();
995                 Type *Tptr = alloca_inst->getType();
996 
997                 Memory::Region R = memory.Malloc(T);
998 
999                 if (R.IsInvalid())
1000                 {
1001                     if (log)
1002                         log->Printf("Couldn't allocate memory for an AllocaInst");
1003 
1004                     return false;
1005                 }
1006 
1007                 Memory::Region P = memory.Malloc(Tptr);
1008 
1009                 if (P.IsInvalid())
1010                 {
1011                     if (log)
1012                         log->Printf("Couldn't allocate the result pointer for an AllocaInst");
1013 
1014                     return false;
1015                 }
1016 
1017                 DataEncoderSP P_encoder = memory.GetEncoder(P);
1018 
1019                 if (P_encoder->PutAddress(0, R.m_base) == UINT32_MAX)
1020                 {
1021                     if (log)
1022                         log->Printf("Couldn't write the reseult pointer for an AllocaInst");
1023 
1024                     return false;
1025                 }
1026 
1027                 frame.m_values[alloca_inst] = P;
1028 
1029                 if (log)
1030                 {
1031                     log->Printf("Interpreted an AllocaInst");
1032                     log->Printf("  R : %s", memory.SummarizeRegion(R).c_str());
1033                     log->Printf("  P : %s", frame.SummarizeValue(alloca_inst).c_str());
1034                 }
1035             }
1036             break;
1037         case Instruction::BitCast:
1038             {
1039                 const BitCastInst *bit_cast_inst = dyn_cast<BitCastInst>(inst);
1040 
1041                 if (!bit_cast_inst)
1042                 {
1043                     if (log)
1044                         log->Printf("getOpcode() returns BitCast, but instruction is not a BitCastInst");
1045 
1046                     return false;
1047                 }
1048 
1049                 Value *source = bit_cast_inst->getOperand(0);
1050 
1051                 lldb_private::Scalar S;
1052 
1053                 if (!frame.EvaluateValue(S, source, llvm_module))
1054                 {
1055                     if (log)
1056                         log->Printf("Couldn't evaluate %s", PrintValue(source).c_str());
1057 
1058                     return false;
1059                 }
1060 
1061                 frame.AssignValue(inst, S, llvm_module);
1062             }
1063             break;
1064         case Instruction::Br:
1065             {
1066                 const BranchInst *br_inst = dyn_cast<BranchInst>(inst);
1067 
1068                 if (!br_inst)
1069                 {
1070                     if (log)
1071                         log->Printf("getOpcode() returns Br, but instruction is not a BranchInst");
1072 
1073                     return false;
1074                 }
1075 
1076                 if (br_inst->isConditional())
1077                 {
1078                     Value *condition = br_inst->getCondition();
1079 
1080                     lldb_private::Scalar C;
1081 
1082                     if (!frame.EvaluateValue(C, condition, llvm_module))
1083                     {
1084                         if (log)
1085                             log->Printf("Couldn't evaluate %s", PrintValue(condition).c_str());
1086 
1087                         return false;
1088                     }
1089 
1090                     if (C.GetRawBits64(0))
1091                         frame.Jump(br_inst->getSuccessor(0));
1092                     else
1093                         frame.Jump(br_inst->getSuccessor(1));
1094 
1095                     if (log)
1096                     {
1097                         log->Printf("Interpreted a BrInst with a condition");
1098                         log->Printf("  cond : %s", frame.SummarizeValue(condition).c_str());
1099                     }
1100                 }
1101                 else
1102                 {
1103                     frame.Jump(br_inst->getSuccessor(0));
1104 
1105                     if (log)
1106                     {
1107                         log->Printf("Interpreted a BrInst with no condition");
1108                     }
1109                 }
1110             }
1111             continue;
1112         case Instruction::GetElementPtr:
1113             {
1114                 const GetElementPtrInst *gep_inst = dyn_cast<GetElementPtrInst>(inst);
1115 
1116                 if (!gep_inst)
1117                 {
1118                     if (log)
1119                         log->Printf("getOpcode() returns GetElementPtr, but instruction is not a GetElementPtrInst");
1120 
1121                     return false;
1122                 }
1123 
1124                 const Value *pointer_operand = gep_inst->getPointerOperand();
1125                 Type *pointer_type = pointer_operand->getType();
1126 
1127                 lldb_private::Scalar P;
1128 
1129                 if (!frame.EvaluateValue(P, pointer_operand, llvm_module))
1130                     return false;
1131 
1132                 SmallVector <Value *, 8> indices (gep_inst->idx_begin(),
1133                                                   gep_inst->idx_end());
1134 
1135                 uint64_t offset = target_data.getIndexedOffset(pointer_type, indices);
1136 
1137                 lldb_private::Scalar Poffset = P + offset;
1138 
1139                 frame.AssignValue(inst, Poffset, llvm_module);
1140 
1141                 if (log)
1142                 {
1143                     log->Printf("Interpreted a GetElementPtrInst");
1144                     log->Printf("  P       : %s", frame.SummarizeValue(pointer_operand).c_str());
1145                     log->Printf("  Poffset : %s", frame.SummarizeValue(inst).c_str());
1146                 }
1147             }
1148             break;
1149         case Instruction::ICmp:
1150             {
1151                 const ICmpInst *icmp_inst = dyn_cast<ICmpInst>(inst);
1152 
1153                 if (!icmp_inst)
1154                 {
1155                     if (log)
1156                         log->Printf("getOpcode() returns ICmp, but instruction is not an ICmpInst");
1157 
1158                     return false;
1159                 }
1160 
1161                 CmpInst::Predicate predicate = icmp_inst->getPredicate();
1162 
1163                 Value *lhs = inst->getOperand(0);
1164                 Value *rhs = inst->getOperand(1);
1165 
1166                 lldb_private::Scalar L;
1167                 lldb_private::Scalar R;
1168 
1169                 if (!frame.EvaluateValue(L, lhs, llvm_module))
1170                 {
1171                     if (log)
1172                         log->Printf("Couldn't evaluate %s", PrintValue(lhs).c_str());
1173 
1174                     return false;
1175                 }
1176 
1177                 if (!frame.EvaluateValue(R, rhs, llvm_module))
1178                 {
1179                     if (log)
1180                         log->Printf("Couldn't evaluate %s", PrintValue(rhs).c_str());
1181 
1182                     return false;
1183                 }
1184 
1185                 lldb_private::Scalar result;
1186 
1187                 switch (predicate)
1188                 {
1189                 default:
1190                     return false;
1191                 case CmpInst::ICMP_EQ:
1192                     result = (L == R);
1193                     break;
1194                 case CmpInst::ICMP_NE:
1195                     result = (L != R);
1196                     break;
1197                 case CmpInst::ICMP_UGT:
1198                     result = (L.GetRawBits64(0) > R.GetRawBits64(0));
1199                     break;
1200                 case CmpInst::ICMP_UGE:
1201                     result = (L.GetRawBits64(0) >= R.GetRawBits64(0));
1202                     break;
1203                 case CmpInst::ICMP_ULT:
1204                     result = (L.GetRawBits64(0) < R.GetRawBits64(0));
1205                     break;
1206                 case CmpInst::ICMP_ULE:
1207                     result = (L.GetRawBits64(0) <= R.GetRawBits64(0));
1208                     break;
1209                 case CmpInst::ICMP_SGT:
1210                     result = (L > R);
1211                     break;
1212                 case CmpInst::ICMP_SGE:
1213                     result = (L >= R);
1214                     break;
1215                 case CmpInst::ICMP_SLT:
1216                     result = (L < R);
1217                     break;
1218                 case CmpInst::ICMP_SLE:
1219                     result = (L <= R);
1220                     break;
1221                 }
1222 
1223                 frame.AssignValue(inst, result, llvm_module);
1224 
1225                 if (log)
1226                 {
1227                     log->Printf("Interpreted an ICmpInst");
1228                     log->Printf("  L : %s", frame.SummarizeValue(lhs).c_str());
1229                     log->Printf("  R : %s", frame.SummarizeValue(rhs).c_str());
1230                     log->Printf("  = : %s", frame.SummarizeValue(inst).c_str());
1231                 }
1232             }
1233             break;
1234         case Instruction::Load:
1235             {
1236                 const LoadInst *load_inst = dyn_cast<LoadInst>(inst);
1237 
1238                 if (!load_inst)
1239                 {
1240                     if (log)
1241                         log->Printf("getOpcode() returns Load, but instruction is not a LoadInst");
1242 
1243                     return false;
1244                 }
1245 
1246                 // The semantics of Load are:
1247                 //   Create a region D that will contain the loaded data
1248                 //   Resolve the region P containing a pointer
1249                 //   Dereference P to get the region R that the data should be loaded from
1250                 //   Transfer a unit of type type(D) from R to D
1251 
1252                 const Value *pointer_operand = load_inst->getPointerOperand();
1253 
1254                 Type *pointer_ty = pointer_operand->getType();
1255                 PointerType *pointer_ptr_ty = dyn_cast<PointerType>(pointer_ty);
1256                 if (!pointer_ptr_ty)
1257                     return false;
1258                 Type *target_ty = pointer_ptr_ty->getElementType();
1259 
1260                 Memory::Region D = frame.ResolveValue(load_inst, llvm_module);
1261                 Memory::Region P = frame.ResolveValue(pointer_operand, llvm_module);
1262 
1263                 if (D.IsInvalid())
1264                 {
1265                     if (log)
1266                         log->Printf("LoadInst's value doesn't resolve to anything");
1267 
1268                     return false;
1269                 }
1270 
1271                 if (P.IsInvalid())
1272                 {
1273                     if (log)
1274                         log->Printf("LoadInst's pointer doesn't resolve to anything");
1275 
1276                     return false;
1277                 }
1278 
1279                 DataExtractorSP P_extractor(memory.GetExtractor(P));
1280                 DataEncoderSP D_encoder(memory.GetEncoder(D));
1281 
1282                 uint32_t offset = 0;
1283                 lldb::addr_t pointer = P_extractor->GetAddress(&offset);
1284 
1285                 Memory::Region R = memory.Lookup(pointer, target_ty);
1286 
1287                 memory.Read(D_encoder->GetDataStart(), R.m_base, target_data.getTypeStoreSize(target_ty));
1288 
1289                 if (log)
1290                 {
1291                     log->Printf("Interpreted a LoadInst");
1292                     log->Printf("  P : %s", frame.SummarizeValue(pointer_operand).c_str());
1293                     log->Printf("  R : %s", memory.SummarizeRegion(R).c_str());
1294                     log->Printf("  D : %s", frame.SummarizeValue(load_inst).c_str());
1295                 }
1296             }
1297             break;
1298         case Instruction::Ret:
1299             {
1300                 if (result_name.IsEmpty())
1301                     return true;
1302 
1303                 GlobalValue *result_value = llvm_module.getNamedValue(result_name.GetCString());
1304                 return frame.ConstructResult(result, result_value, result_name, result_type, llvm_module);
1305             }
1306         case Instruction::Store:
1307             {
1308                 const StoreInst *store_inst = dyn_cast<StoreInst>(inst);
1309 
1310                 if (!store_inst)
1311                 {
1312                     if (log)
1313                         log->Printf("getOpcode() returns Store, but instruction is not a StoreInst");
1314 
1315                     return false;
1316                 }
1317 
1318                 // The semantics of Store are:
1319                 //   Resolve the region D containing the data to be stored
1320                 //   Resolve the region P containing a pointer
1321                 //   Dereference P to get the region R that the data should be stored in
1322                 //   Transfer a unit of type type(D) from D to R
1323 
1324                 const Value *value_operand = store_inst->getValueOperand();
1325                 const Value *pointer_operand = store_inst->getPointerOperand();
1326 
1327                 Type *pointer_ty = pointer_operand->getType();
1328                 PointerType *pointer_ptr_ty = dyn_cast<PointerType>(pointer_ty);
1329                 if (!pointer_ptr_ty)
1330                     return false;
1331                 Type *target_ty = pointer_ptr_ty->getElementType();
1332 
1333                 Memory::Region D = frame.ResolveValue(value_operand, llvm_module);
1334                 Memory::Region P = frame.ResolveValue(pointer_operand, llvm_module);
1335 
1336                 if (D.IsInvalid())
1337                 {
1338                     if (log)
1339                         log->Printf("StoreInst's value doesn't resolve to anything");
1340 
1341                     return false;
1342                 }
1343 
1344                 if (P.IsInvalid())
1345                 {
1346                     if (log)
1347                         log->Printf("StoreInst's pointer doesn't resolve to anything");
1348 
1349                     return false;
1350                 }
1351 
1352                 DataExtractorSP P_extractor(memory.GetExtractor(P));
1353                 DataExtractorSP D_extractor(memory.GetExtractor(D));
1354 
1355                 if (!P_extractor || !D_extractor)
1356                     return false;
1357 
1358                 uint32_t offset = 0;
1359                 lldb::addr_t pointer = P_extractor->GetAddress(&offset);
1360 
1361                 Memory::Region R = memory.Lookup(pointer, target_ty);
1362 
1363                 if (R.IsInvalid())
1364                 {
1365                     if (log)
1366                         log->Printf("StoreInst's pointer doesn't point to a valid target");
1367 
1368                     return false;
1369                 }
1370 
1371                 memory.Write(R.m_base, D_extractor->GetDataStart(), target_data.getTypeStoreSize(target_ty));
1372 
1373                 if (log)
1374                 {
1375                     log->Printf("Interpreted a StoreInst");
1376                     log->Printf("  D : %s", frame.SummarizeValue(value_operand).c_str());
1377                     log->Printf("  P : %s", frame.SummarizeValue(pointer_operand).c_str());
1378                     log->Printf("  R : %s", memory.SummarizeRegion(R).c_str());
1379                 }
1380             }
1381             break;
1382         }
1383 
1384         ++frame.m_ii;
1385     }
1386 
1387     if (num_insts >= 4096)
1388         return false;
1389 
1390     return false;
1391 }