1 //===-- DWARFExpression.cpp -------------------------------------*- C++ -*-===//
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 "lldb/Expression/DWARFExpression.h"
10 
11 #include <inttypes.h>
12 
13 #include <vector>
14 
15 #include "lldb/Core/Module.h"
16 #include "lldb/Core/Value.h"
17 #include "lldb/Core/dwarf.h"
18 #include "lldb/Utility/DataEncoder.h"
19 #include "lldb/Utility/Log.h"
20 #include "lldb/Utility/RegisterValue.h"
21 #include "lldb/Utility/Scalar.h"
22 #include "lldb/Utility/StreamString.h"
23 #include "lldb/Utility/VMRange.h"
24 
25 #include "lldb/Host/Host.h"
26 #include "lldb/Utility/Endian.h"
27 
28 #include "lldb/Symbol/Function.h"
29 
30 #include "lldb/Target/ABI.h"
31 #include "lldb/Target/ExecutionContext.h"
32 #include "lldb/Target/Process.h"
33 #include "lldb/Target/RegisterContext.h"
34 #include "lldb/Target/StackFrame.h"
35 #include "lldb/Target/StackID.h"
36 #include "lldb/Target/Thread.h"
37 
38 #include "Plugins/SymbolFile/DWARF/DWARFUnit.h"
39 
40 using namespace lldb;
41 using namespace lldb_private;
42 
43 static lldb::addr_t
44 ReadAddressFromDebugAddrSection(const DWARFUnit *dwarf_cu,
45                                 uint32_t index) {
46   uint32_t index_size = dwarf_cu->GetAddressByteSize();
47   dw_offset_t addr_base = dwarf_cu->GetAddrBase();
48   lldb::offset_t offset = addr_base + index * index_size;
49   return dwarf_cu->GetSymbolFileDWARF()->get_debug_addr_data().GetMaxU64(
50       &offset, index_size);
51 }
52 
53 // DWARFExpression constructor
54 DWARFExpression::DWARFExpression(DWARFUnit *dwarf_cu)
55     : m_module_wp(), m_data(), m_dwarf_cu(dwarf_cu),
56       m_reg_kind(eRegisterKindDWARF), m_loclist_slide(LLDB_INVALID_ADDRESS) {}
57 
58 DWARFExpression::DWARFExpression(const DWARFExpression &rhs)
59     : m_module_wp(rhs.m_module_wp), m_data(rhs.m_data),
60       m_dwarf_cu(rhs.m_dwarf_cu), m_reg_kind(rhs.m_reg_kind),
61       m_loclist_slide(rhs.m_loclist_slide) {}
62 
63 DWARFExpression::DWARFExpression(lldb::ModuleSP module_sp,
64                                  const DataExtractor &data,
65                                  DWARFUnit *dwarf_cu,
66                                  lldb::offset_t data_offset,
67                                  lldb::offset_t data_length)
68     : m_module_wp(), m_data(data, data_offset, data_length),
69       m_dwarf_cu(dwarf_cu), m_reg_kind(eRegisterKindDWARF),
70       m_loclist_slide(LLDB_INVALID_ADDRESS) {
71   if (module_sp)
72     m_module_wp = module_sp;
73 }
74 
75 // Destructor
76 DWARFExpression::~DWARFExpression() {}
77 
78 bool DWARFExpression::IsValid() const { return m_data.GetByteSize() > 0; }
79 
80 void DWARFExpression::SetOpcodeData(const DataExtractor &data) {
81   m_data = data;
82 }
83 
84 void DWARFExpression::CopyOpcodeData(lldb::ModuleSP module_sp,
85                                      const DataExtractor &data,
86                                      lldb::offset_t data_offset,
87                                      lldb::offset_t data_length) {
88   const uint8_t *bytes = data.PeekData(data_offset, data_length);
89   if (bytes) {
90     m_module_wp = module_sp;
91     m_data.SetData(DataBufferSP(new DataBufferHeap(bytes, data_length)));
92     m_data.SetByteOrder(data.GetByteOrder());
93     m_data.SetAddressByteSize(data.GetAddressByteSize());
94   }
95 }
96 
97 void DWARFExpression::CopyOpcodeData(const void *data,
98                                      lldb::offset_t data_length,
99                                      ByteOrder byte_order,
100                                      uint8_t addr_byte_size) {
101   if (data && data_length) {
102     m_data.SetData(DataBufferSP(new DataBufferHeap(data, data_length)));
103     m_data.SetByteOrder(byte_order);
104     m_data.SetAddressByteSize(addr_byte_size);
105   }
106 }
107 
108 void DWARFExpression::CopyOpcodeData(uint64_t const_value,
109                                      lldb::offset_t const_value_byte_size,
110                                      uint8_t addr_byte_size) {
111   if (const_value_byte_size) {
112     m_data.SetData(
113         DataBufferSP(new DataBufferHeap(&const_value, const_value_byte_size)));
114     m_data.SetByteOrder(endian::InlHostByteOrder());
115     m_data.SetAddressByteSize(addr_byte_size);
116   }
117 }
118 
119 void DWARFExpression::SetOpcodeData(lldb::ModuleSP module_sp,
120                                     const DataExtractor &data,
121                                     lldb::offset_t data_offset,
122                                     lldb::offset_t data_length) {
123   m_module_wp = module_sp;
124   m_data.SetData(data, data_offset, data_length);
125 }
126 
127 void DWARFExpression::DumpLocation(Stream *s, lldb::offset_t offset,
128                                    lldb::offset_t length,
129                                    lldb::DescriptionLevel level,
130                                    ABI *abi) const {
131   if (!m_data.ValidOffsetForDataOfSize(offset, length))
132     return;
133   const lldb::offset_t start_offset = offset;
134   const lldb::offset_t end_offset = offset + length;
135   while (m_data.ValidOffset(offset) && offset < end_offset) {
136     const lldb::offset_t op_offset = offset;
137     const uint8_t op = m_data.GetU8(&offset);
138 
139     switch (level) {
140     default:
141       break;
142 
143     case lldb::eDescriptionLevelBrief:
144       if (op_offset > start_offset)
145         s->PutChar(' ');
146       break;
147 
148     case lldb::eDescriptionLevelFull:
149     case lldb::eDescriptionLevelVerbose:
150       if (op_offset > start_offset)
151         s->EOL();
152       s->Indent();
153       if (level == lldb::eDescriptionLevelFull)
154         break;
155       // Fall through for verbose and print offset and DW_OP prefix..
156       s->Printf("0x%8.8" PRIx64 ": %s", op_offset,
157                 op >= DW_OP_APPLE_uninit ? "DW_OP_APPLE_" : "DW_OP_");
158       break;
159     }
160 
161     switch (op) {
162     case DW_OP_addr:
163       *s << "DW_OP_addr(" << m_data.GetAddress(&offset) << ") ";
164       break; // 0x03 1 address
165     case DW_OP_deref:
166       *s << "DW_OP_deref";
167       break; // 0x06
168     case DW_OP_const1u:
169       s->Printf("DW_OP_const1u(0x%2.2x)", m_data.GetU8(&offset));
170       break; // 0x08 1 1-byte constant
171     case DW_OP_const1s:
172       s->Printf("DW_OP_const1s(0x%2.2x)", m_data.GetU8(&offset));
173       break; // 0x09 1 1-byte constant
174     case DW_OP_const2u:
175       s->Printf("DW_OP_const2u(0x%4.4x)", m_data.GetU16(&offset));
176       break; // 0x0a 1 2-byte constant
177     case DW_OP_const2s:
178       s->Printf("DW_OP_const2s(0x%4.4x)", m_data.GetU16(&offset));
179       break; // 0x0b 1 2-byte constant
180     case DW_OP_const4u:
181       s->Printf("DW_OP_const4u(0x%8.8x)", m_data.GetU32(&offset));
182       break; // 0x0c 1 4-byte constant
183     case DW_OP_const4s:
184       s->Printf("DW_OP_const4s(0x%8.8x)", m_data.GetU32(&offset));
185       break; // 0x0d 1 4-byte constant
186     case DW_OP_const8u:
187       s->Printf("DW_OP_const8u(0x%16.16" PRIx64 ")", m_data.GetU64(&offset));
188       break; // 0x0e 1 8-byte constant
189     case DW_OP_const8s:
190       s->Printf("DW_OP_const8s(0x%16.16" PRIx64 ")", m_data.GetU64(&offset));
191       break; // 0x0f 1 8-byte constant
192     case DW_OP_constu:
193       s->Printf("DW_OP_constu(0x%" PRIx64 ")", m_data.GetULEB128(&offset));
194       break; // 0x10 1 ULEB128 constant
195     case DW_OP_consts:
196       s->Printf("DW_OP_consts(0x%" PRId64 ")", m_data.GetSLEB128(&offset));
197       break; // 0x11 1 SLEB128 constant
198     case DW_OP_dup:
199       s->PutCString("DW_OP_dup");
200       break; // 0x12
201     case DW_OP_drop:
202       s->PutCString("DW_OP_drop");
203       break; // 0x13
204     case DW_OP_over:
205       s->PutCString("DW_OP_over");
206       break; // 0x14
207     case DW_OP_pick:
208       s->Printf("DW_OP_pick(0x%2.2x)", m_data.GetU8(&offset));
209       break; // 0x15 1 1-byte stack index
210     case DW_OP_swap:
211       s->PutCString("DW_OP_swap");
212       break; // 0x16
213     case DW_OP_rot:
214       s->PutCString("DW_OP_rot");
215       break; // 0x17
216     case DW_OP_xderef:
217       s->PutCString("DW_OP_xderef");
218       break; // 0x18
219     case DW_OP_abs:
220       s->PutCString("DW_OP_abs");
221       break; // 0x19
222     case DW_OP_and:
223       s->PutCString("DW_OP_and");
224       break; // 0x1a
225     case DW_OP_div:
226       s->PutCString("DW_OP_div");
227       break; // 0x1b
228     case DW_OP_minus:
229       s->PutCString("DW_OP_minus");
230       break; // 0x1c
231     case DW_OP_mod:
232       s->PutCString("DW_OP_mod");
233       break; // 0x1d
234     case DW_OP_mul:
235       s->PutCString("DW_OP_mul");
236       break; // 0x1e
237     case DW_OP_neg:
238       s->PutCString("DW_OP_neg");
239       break; // 0x1f
240     case DW_OP_not:
241       s->PutCString("DW_OP_not");
242       break; // 0x20
243     case DW_OP_or:
244       s->PutCString("DW_OP_or");
245       break; // 0x21
246     case DW_OP_plus:
247       s->PutCString("DW_OP_plus");
248       break;                // 0x22
249     case DW_OP_plus_uconst: // 0x23 1 ULEB128 addend
250       s->Printf("DW_OP_plus_uconst(0x%" PRIx64 ")",
251                 m_data.GetULEB128(&offset));
252       break;
253 
254     case DW_OP_shl:
255       s->PutCString("DW_OP_shl");
256       break; // 0x24
257     case DW_OP_shr:
258       s->PutCString("DW_OP_shr");
259       break; // 0x25
260     case DW_OP_shra:
261       s->PutCString("DW_OP_shra");
262       break; // 0x26
263     case DW_OP_xor:
264       s->PutCString("DW_OP_xor");
265       break; // 0x27
266     case DW_OP_skip:
267       s->Printf("DW_OP_skip(0x%4.4x)", m_data.GetU16(&offset));
268       break; // 0x2f 1 signed 2-byte constant
269     case DW_OP_bra:
270       s->Printf("DW_OP_bra(0x%4.4x)", m_data.GetU16(&offset));
271       break; // 0x28 1 signed 2-byte constant
272     case DW_OP_eq:
273       s->PutCString("DW_OP_eq");
274       break; // 0x29
275     case DW_OP_ge:
276       s->PutCString("DW_OP_ge");
277       break; // 0x2a
278     case DW_OP_gt:
279       s->PutCString("DW_OP_gt");
280       break; // 0x2b
281     case DW_OP_le:
282       s->PutCString("DW_OP_le");
283       break; // 0x2c
284     case DW_OP_lt:
285       s->PutCString("DW_OP_lt");
286       break; // 0x2d
287     case DW_OP_ne:
288       s->PutCString("DW_OP_ne");
289       break; // 0x2e
290 
291     case DW_OP_lit0:  // 0x30
292     case DW_OP_lit1:  // 0x31
293     case DW_OP_lit2:  // 0x32
294     case DW_OP_lit3:  // 0x33
295     case DW_OP_lit4:  // 0x34
296     case DW_OP_lit5:  // 0x35
297     case DW_OP_lit6:  // 0x36
298     case DW_OP_lit7:  // 0x37
299     case DW_OP_lit8:  // 0x38
300     case DW_OP_lit9:  // 0x39
301     case DW_OP_lit10: // 0x3A
302     case DW_OP_lit11: // 0x3B
303     case DW_OP_lit12: // 0x3C
304     case DW_OP_lit13: // 0x3D
305     case DW_OP_lit14: // 0x3E
306     case DW_OP_lit15: // 0x3F
307     case DW_OP_lit16: // 0x40
308     case DW_OP_lit17: // 0x41
309     case DW_OP_lit18: // 0x42
310     case DW_OP_lit19: // 0x43
311     case DW_OP_lit20: // 0x44
312     case DW_OP_lit21: // 0x45
313     case DW_OP_lit22: // 0x46
314     case DW_OP_lit23: // 0x47
315     case DW_OP_lit24: // 0x48
316     case DW_OP_lit25: // 0x49
317     case DW_OP_lit26: // 0x4A
318     case DW_OP_lit27: // 0x4B
319     case DW_OP_lit28: // 0x4C
320     case DW_OP_lit29: // 0x4D
321     case DW_OP_lit30: // 0x4E
322     case DW_OP_lit31:
323       s->Printf("DW_OP_lit%i", op - DW_OP_lit0);
324       break; // 0x4f
325 
326     case DW_OP_reg0:  // 0x50
327     case DW_OP_reg1:  // 0x51
328     case DW_OP_reg2:  // 0x52
329     case DW_OP_reg3:  // 0x53
330     case DW_OP_reg4:  // 0x54
331     case DW_OP_reg5:  // 0x55
332     case DW_OP_reg6:  // 0x56
333     case DW_OP_reg7:  // 0x57
334     case DW_OP_reg8:  // 0x58
335     case DW_OP_reg9:  // 0x59
336     case DW_OP_reg10: // 0x5A
337     case DW_OP_reg11: // 0x5B
338     case DW_OP_reg12: // 0x5C
339     case DW_OP_reg13: // 0x5D
340     case DW_OP_reg14: // 0x5E
341     case DW_OP_reg15: // 0x5F
342     case DW_OP_reg16: // 0x60
343     case DW_OP_reg17: // 0x61
344     case DW_OP_reg18: // 0x62
345     case DW_OP_reg19: // 0x63
346     case DW_OP_reg20: // 0x64
347     case DW_OP_reg21: // 0x65
348     case DW_OP_reg22: // 0x66
349     case DW_OP_reg23: // 0x67
350     case DW_OP_reg24: // 0x68
351     case DW_OP_reg25: // 0x69
352     case DW_OP_reg26: // 0x6A
353     case DW_OP_reg27: // 0x6B
354     case DW_OP_reg28: // 0x6C
355     case DW_OP_reg29: // 0x6D
356     case DW_OP_reg30: // 0x6E
357     case DW_OP_reg31: // 0x6F
358     {
359       uint32_t reg_num = op - DW_OP_reg0;
360       if (abi) {
361         RegisterInfo reg_info;
362         if (abi->GetRegisterInfoByKind(m_reg_kind, reg_num, reg_info)) {
363           if (reg_info.name) {
364             s->PutCString(reg_info.name);
365             break;
366           } else if (reg_info.alt_name) {
367             s->PutCString(reg_info.alt_name);
368             break;
369           }
370         }
371       }
372       s->Printf("DW_OP_reg%u", reg_num);
373       break;
374     } break;
375 
376     case DW_OP_breg0:
377     case DW_OP_breg1:
378     case DW_OP_breg2:
379     case DW_OP_breg3:
380     case DW_OP_breg4:
381     case DW_OP_breg5:
382     case DW_OP_breg6:
383     case DW_OP_breg7:
384     case DW_OP_breg8:
385     case DW_OP_breg9:
386     case DW_OP_breg10:
387     case DW_OP_breg11:
388     case DW_OP_breg12:
389     case DW_OP_breg13:
390     case DW_OP_breg14:
391     case DW_OP_breg15:
392     case DW_OP_breg16:
393     case DW_OP_breg17:
394     case DW_OP_breg18:
395     case DW_OP_breg19:
396     case DW_OP_breg20:
397     case DW_OP_breg21:
398     case DW_OP_breg22:
399     case DW_OP_breg23:
400     case DW_OP_breg24:
401     case DW_OP_breg25:
402     case DW_OP_breg26:
403     case DW_OP_breg27:
404     case DW_OP_breg28:
405     case DW_OP_breg29:
406     case DW_OP_breg30:
407     case DW_OP_breg31: {
408       uint32_t reg_num = op - DW_OP_breg0;
409       int64_t reg_offset = m_data.GetSLEB128(&offset);
410       if (abi) {
411         RegisterInfo reg_info;
412         if (abi->GetRegisterInfoByKind(m_reg_kind, reg_num, reg_info)) {
413           if (reg_info.name) {
414             s->Printf("[%s%+" PRIi64 "]", reg_info.name, reg_offset);
415             break;
416           } else if (reg_info.alt_name) {
417             s->Printf("[%s%+" PRIi64 "]", reg_info.alt_name, reg_offset);
418             break;
419           }
420         }
421       }
422       s->Printf("DW_OP_breg%i(0x%" PRIx64 ")", reg_num, reg_offset);
423     } break;
424 
425     case DW_OP_regx: // 0x90 1 ULEB128 register
426     {
427       uint32_t reg_num = m_data.GetULEB128(&offset);
428       if (abi) {
429         RegisterInfo reg_info;
430         if (abi->GetRegisterInfoByKind(m_reg_kind, reg_num, reg_info)) {
431           if (reg_info.name) {
432             s->PutCString(reg_info.name);
433             break;
434           } else if (reg_info.alt_name) {
435             s->PutCString(reg_info.alt_name);
436             break;
437           }
438         }
439       }
440       s->Printf("DW_OP_regx(%" PRIu32 ")", reg_num);
441       break;
442     } break;
443     case DW_OP_fbreg: // 0x91 1 SLEB128 offset
444       s->Printf("DW_OP_fbreg(%" PRIi64 ")", m_data.GetSLEB128(&offset));
445       break;
446     case DW_OP_bregx: // 0x92 2 ULEB128 register followed by SLEB128 offset
447     {
448       uint32_t reg_num = m_data.GetULEB128(&offset);
449       int64_t reg_offset = m_data.GetSLEB128(&offset);
450       if (abi) {
451         RegisterInfo reg_info;
452         if (abi->GetRegisterInfoByKind(m_reg_kind, reg_num, reg_info)) {
453           if (reg_info.name) {
454             s->Printf("[%s%+" PRIi64 "]", reg_info.name, reg_offset);
455             break;
456           } else if (reg_info.alt_name) {
457             s->Printf("[%s%+" PRIi64 "]", reg_info.alt_name, reg_offset);
458             break;
459           }
460         }
461       }
462       s->Printf("DW_OP_bregx(reg=%" PRIu32 ",offset=%" PRIi64 ")", reg_num,
463                 reg_offset);
464     } break;
465     case DW_OP_piece: // 0x93 1 ULEB128 size of piece addressed
466       s->Printf("DW_OP_piece(0x%" PRIx64 ")", m_data.GetULEB128(&offset));
467       break;
468     case DW_OP_deref_size: // 0x94 1 1-byte size of data retrieved
469       s->Printf("DW_OP_deref_size(0x%2.2x)", m_data.GetU8(&offset));
470       break;
471     case DW_OP_xderef_size: // 0x95 1 1-byte size of data retrieved
472       s->Printf("DW_OP_xderef_size(0x%2.2x)", m_data.GetU8(&offset));
473       break;
474     case DW_OP_nop:
475       s->PutCString("DW_OP_nop");
476       break; // 0x96
477     case DW_OP_push_object_address:
478       s->PutCString("DW_OP_push_object_address");
479       break;          // 0x97 DWARF3
480     case DW_OP_call2: // 0x98 DWARF3 1 2-byte offset of DIE
481       s->Printf("DW_OP_call2(0x%4.4x)", m_data.GetU16(&offset));
482       break;
483     case DW_OP_call4: // 0x99 DWARF3 1 4-byte offset of DIE
484       s->Printf("DW_OP_call4(0x%8.8x)", m_data.GetU32(&offset));
485       break;
486     case DW_OP_call_ref: // 0x9a DWARF3 1 4- or 8-byte offset of DIE
487       s->Printf("DW_OP_call_ref(0x%8.8" PRIx64 ")", m_data.GetAddress(&offset));
488       break;
489     //      case DW_OP_call_frame_cfa: s << "call_frame_cfa"; break;
490     //      // 0x9c DWARF3
491     //      case DW_OP_bit_piece: // 0x9d DWARF3 2
492     //          s->Printf("DW_OP_bit_piece(0x%x, 0x%x)",
493     //          m_data.GetULEB128(&offset), m_data.GetULEB128(&offset));
494     //          break;
495     //      case DW_OP_lo_user:     s->PutCString("DW_OP_lo_user"); break;
496     //      // 0xe0
497     //      case DW_OP_hi_user:     s->PutCString("DW_OP_hi_user"); break;
498     //      // 0xff
499     //        case DW_OP_APPLE_extern:
500     //            s->Printf("DW_OP_APPLE_extern(%" PRIu64 ")",
501     //            m_data.GetULEB128(&offset));
502     //            break;
503     //        case DW_OP_APPLE_array_ref:
504     //            s->PutCString("DW_OP_APPLE_array_ref");
505     //            break;
506     case DW_OP_form_tls_address:
507       s->PutCString("DW_OP_form_tls_address"); // 0x9b
508       break;
509     case DW_OP_GNU_addr_index: // 0xfb
510       s->Printf("DW_OP_GNU_addr_index(0x%" PRIx64 ")",
511                 m_data.GetULEB128(&offset));
512       break;
513     case DW_OP_addrx:
514       s->Printf("DW_OP_addrx(0x%" PRIx64 ")",
515                 m_data.GetULEB128(&offset));
516       break;
517     case DW_OP_GNU_const_index: // 0xfc
518       s->Printf("DW_OP_GNU_const_index(0x%" PRIx64 ")",
519                 m_data.GetULEB128(&offset));
520       break;
521     case DW_OP_GNU_push_tls_address:
522       s->PutCString("DW_OP_GNU_push_tls_address"); // 0xe0
523       break;
524     case DW_OP_APPLE_uninit:
525       s->PutCString("DW_OP_APPLE_uninit"); // 0xF0
526       break;
527       //        case DW_OP_APPLE_assign:        // 0xF1 - pops value off and
528       //        assigns it to second item on stack (2nd item must have
529       //        assignable context)
530       //            s->PutCString("DW_OP_APPLE_assign");
531       //            break;
532       //        case DW_OP_APPLE_address_of:    // 0xF2 - gets the address of
533       //        the top stack item (top item must be a variable, or have
534       //        value_type that is an address already)
535       //            s->PutCString("DW_OP_APPLE_address_of");
536       //            break;
537       //        case DW_OP_APPLE_value_of:      // 0xF3 - pops the value off the
538       //        stack and pushes the value of that object (top item must be a
539       //        variable, or expression local)
540       //            s->PutCString("DW_OP_APPLE_value_of");
541       //            break;
542       //        case DW_OP_APPLE_deref_type:    // 0xF4 - gets the address of
543       //        the top stack item (top item must be a variable, or a clang
544       //        type)
545       //            s->PutCString("DW_OP_APPLE_deref_type");
546       //            break;
547       //        case DW_OP_APPLE_expr_local:    // 0xF5 - ULEB128 expression
548       //        local index
549       //            s->Printf("DW_OP_APPLE_expr_local(%" PRIu64 ")",
550       //            m_data.GetULEB128(&offset));
551       //            break;
552       //        case DW_OP_APPLE_constf:        // 0xF6 - 1 byte float size,
553       //        followed by constant float data
554       //            {
555       //                uint8_t float_length = m_data.GetU8(&offset);
556       //                s->Printf("DW_OP_APPLE_constf(<%u> ", float_length);
557       //                m_data.Dump(s, offset, eFormatHex, float_length, 1,
558       //                UINT32_MAX, DW_INVALID_ADDRESS, 0, 0);
559       //                s->PutChar(')');
560       //                // Consume the float data
561       //                m_data.GetData(&offset, float_length);
562       //            }
563       //            break;
564       //        case DW_OP_APPLE_scalar_cast:
565       //            s->Printf("DW_OP_APPLE_scalar_cast(%s)",
566       //            Scalar::GetValueTypeAsCString
567       //            ((Scalar::Type)m_data.GetU8(&offset)));
568       //            break;
569       //        case DW_OP_APPLE_clang_cast:
570       //            {
571       //                clang::Type *clang_type = (clang::Type
572       //                *)m_data.GetMaxU64(&offset, sizeof(void*));
573       //                s->Printf("DW_OP_APPLE_clang_cast(%p)", clang_type);
574       //            }
575       //            break;
576       //        case DW_OP_APPLE_clear:
577       //            s->PutCString("DW_OP_APPLE_clear");
578       //            break;
579       //        case DW_OP_APPLE_error:         // 0xFF - Stops expression
580       //        evaluation and returns an error (no args)
581       //            s->PutCString("DW_OP_APPLE_error");
582       //            break;
583     }
584   }
585 }
586 
587 void DWARFExpression::SetLocationListSlide(addr_t slide) {
588   m_loclist_slide = slide;
589 }
590 
591 int DWARFExpression::GetRegisterKind() { return m_reg_kind; }
592 
593 void DWARFExpression::SetRegisterKind(RegisterKind reg_kind) {
594   m_reg_kind = reg_kind;
595 }
596 
597 bool DWARFExpression::IsLocationList() const {
598   return m_loclist_slide != LLDB_INVALID_ADDRESS;
599 }
600 
601 void DWARFExpression::GetDescription(Stream *s, lldb::DescriptionLevel level,
602                                      addr_t location_list_base_addr,
603                                      ABI *abi) const {
604   if (IsLocationList()) {
605     // We have a location list
606     lldb::offset_t offset = 0;
607     uint32_t count = 0;
608     addr_t curr_base_addr = location_list_base_addr;
609     while (m_data.ValidOffset(offset)) {
610       addr_t begin_addr_offset = LLDB_INVALID_ADDRESS;
611       addr_t end_addr_offset = LLDB_INVALID_ADDRESS;
612       if (!AddressRangeForLocationListEntry(m_dwarf_cu, m_data, &offset,
613                                             begin_addr_offset, end_addr_offset))
614         break;
615 
616       if (begin_addr_offset == 0 && end_addr_offset == 0)
617         break;
618 
619       if (begin_addr_offset < end_addr_offset) {
620         if (count > 0)
621           s->PutCString(", ");
622         VMRange addr_range(curr_base_addr + begin_addr_offset,
623                            curr_base_addr + end_addr_offset);
624         addr_range.Dump(s, 0, 8);
625         s->PutChar('{');
626         lldb::offset_t location_length = m_data.GetU16(&offset);
627         DumpLocation(s, offset, location_length, level, abi);
628         s->PutChar('}');
629         offset += location_length;
630       } else {
631         if ((m_data.GetAddressByteSize() == 4 &&
632              (begin_addr_offset == UINT32_MAX)) ||
633             (m_data.GetAddressByteSize() == 8 &&
634              (begin_addr_offset == UINT64_MAX))) {
635           curr_base_addr = end_addr_offset + location_list_base_addr;
636           // We have a new base address
637           if (count > 0)
638             s->PutCString(", ");
639           *s << "base_addr = " << end_addr_offset;
640         }
641       }
642 
643       count++;
644     }
645   } else {
646     // We have a normal location that contains DW_OP location opcodes
647     DumpLocation(s, 0, m_data.GetByteSize(), level, abi);
648   }
649 }
650 
651 static bool ReadRegisterValueAsScalar(RegisterContext *reg_ctx,
652                                       lldb::RegisterKind reg_kind,
653                                       uint32_t reg_num, Status *error_ptr,
654                                       Value &value) {
655   if (reg_ctx == NULL) {
656     if (error_ptr)
657       error_ptr->SetErrorStringWithFormat("No register context in frame.\n");
658   } else {
659     uint32_t native_reg =
660         reg_ctx->ConvertRegisterKindToRegisterNumber(reg_kind, reg_num);
661     if (native_reg == LLDB_INVALID_REGNUM) {
662       if (error_ptr)
663         error_ptr->SetErrorStringWithFormat("Unable to convert register "
664                                             "kind=%u reg_num=%u to a native "
665                                             "register number.\n",
666                                             reg_kind, reg_num);
667     } else {
668       const RegisterInfo *reg_info =
669           reg_ctx->GetRegisterInfoAtIndex(native_reg);
670       RegisterValue reg_value;
671       if (reg_ctx->ReadRegister(reg_info, reg_value)) {
672         if (reg_value.GetScalarValue(value.GetScalar())) {
673           value.SetValueType(Value::eValueTypeScalar);
674           value.SetContext(Value::eContextTypeRegisterInfo,
675                            const_cast<RegisterInfo *>(reg_info));
676           if (error_ptr)
677             error_ptr->Clear();
678           return true;
679         } else {
680           // If we get this error, then we need to implement a value buffer in
681           // the dwarf expression evaluation function...
682           if (error_ptr)
683             error_ptr->SetErrorStringWithFormat(
684                 "register %s can't be converted to a scalar value",
685                 reg_info->name);
686         }
687       } else {
688         if (error_ptr)
689           error_ptr->SetErrorStringWithFormat("register %s is not available",
690                                               reg_info->name);
691       }
692     }
693   }
694   return false;
695 }
696 
697 // bool
698 // DWARFExpression::LocationListContainsLoadAddress (Process* process, const
699 // Address &addr) const
700 //{
701 //    return LocationListContainsLoadAddress(process,
702 //    addr.GetLoadAddress(process));
703 //}
704 //
705 // bool
706 // DWARFExpression::LocationListContainsLoadAddress (Process* process, addr_t
707 // load_addr) const
708 //{
709 //    if (load_addr == LLDB_INVALID_ADDRESS)
710 //        return false;
711 //
712 //    if (IsLocationList())
713 //    {
714 //        lldb::offset_t offset = 0;
715 //
716 //        addr_t loc_list_base_addr = m_loclist_slide.GetLoadAddress(process);
717 //
718 //        if (loc_list_base_addr == LLDB_INVALID_ADDRESS)
719 //            return false;
720 //
721 //        while (m_data.ValidOffset(offset))
722 //        {
723 //            // We need to figure out what the value is for the location.
724 //            addr_t lo_pc = m_data.GetAddress(&offset);
725 //            addr_t hi_pc = m_data.GetAddress(&offset);
726 //            if (lo_pc == 0 && hi_pc == 0)
727 //                break;
728 //            else
729 //            {
730 //                lo_pc += loc_list_base_addr;
731 //                hi_pc += loc_list_base_addr;
732 //
733 //                if (lo_pc <= load_addr && load_addr < hi_pc)
734 //                    return true;
735 //
736 //                offset += m_data.GetU16(&offset);
737 //            }
738 //        }
739 //    }
740 //    return false;
741 //}
742 
743 static offset_t GetOpcodeDataSize(const DataExtractor &data,
744                                   const lldb::offset_t data_offset,
745                                   const uint8_t op) {
746   lldb::offset_t offset = data_offset;
747   switch (op) {
748   case DW_OP_addr:
749   case DW_OP_call_ref: // 0x9a 1 address sized offset of DIE (DWARF3)
750     return data.GetAddressByteSize();
751 
752   // Opcodes with no arguments
753   case DW_OP_deref:                // 0x06
754   case DW_OP_dup:                  // 0x12
755   case DW_OP_drop:                 // 0x13
756   case DW_OP_over:                 // 0x14
757   case DW_OP_swap:                 // 0x16
758   case DW_OP_rot:                  // 0x17
759   case DW_OP_xderef:               // 0x18
760   case DW_OP_abs:                  // 0x19
761   case DW_OP_and:                  // 0x1a
762   case DW_OP_div:                  // 0x1b
763   case DW_OP_minus:                // 0x1c
764   case DW_OP_mod:                  // 0x1d
765   case DW_OP_mul:                  // 0x1e
766   case DW_OP_neg:                  // 0x1f
767   case DW_OP_not:                  // 0x20
768   case DW_OP_or:                   // 0x21
769   case DW_OP_plus:                 // 0x22
770   case DW_OP_shl:                  // 0x24
771   case DW_OP_shr:                  // 0x25
772   case DW_OP_shra:                 // 0x26
773   case DW_OP_xor:                  // 0x27
774   case DW_OP_eq:                   // 0x29
775   case DW_OP_ge:                   // 0x2a
776   case DW_OP_gt:                   // 0x2b
777   case DW_OP_le:                   // 0x2c
778   case DW_OP_lt:                   // 0x2d
779   case DW_OP_ne:                   // 0x2e
780   case DW_OP_lit0:                 // 0x30
781   case DW_OP_lit1:                 // 0x31
782   case DW_OP_lit2:                 // 0x32
783   case DW_OP_lit3:                 // 0x33
784   case DW_OP_lit4:                 // 0x34
785   case DW_OP_lit5:                 // 0x35
786   case DW_OP_lit6:                 // 0x36
787   case DW_OP_lit7:                 // 0x37
788   case DW_OP_lit8:                 // 0x38
789   case DW_OP_lit9:                 // 0x39
790   case DW_OP_lit10:                // 0x3A
791   case DW_OP_lit11:                // 0x3B
792   case DW_OP_lit12:                // 0x3C
793   case DW_OP_lit13:                // 0x3D
794   case DW_OP_lit14:                // 0x3E
795   case DW_OP_lit15:                // 0x3F
796   case DW_OP_lit16:                // 0x40
797   case DW_OP_lit17:                // 0x41
798   case DW_OP_lit18:                // 0x42
799   case DW_OP_lit19:                // 0x43
800   case DW_OP_lit20:                // 0x44
801   case DW_OP_lit21:                // 0x45
802   case DW_OP_lit22:                // 0x46
803   case DW_OP_lit23:                // 0x47
804   case DW_OP_lit24:                // 0x48
805   case DW_OP_lit25:                // 0x49
806   case DW_OP_lit26:                // 0x4A
807   case DW_OP_lit27:                // 0x4B
808   case DW_OP_lit28:                // 0x4C
809   case DW_OP_lit29:                // 0x4D
810   case DW_OP_lit30:                // 0x4E
811   case DW_OP_lit31:                // 0x4f
812   case DW_OP_reg0:                 // 0x50
813   case DW_OP_reg1:                 // 0x51
814   case DW_OP_reg2:                 // 0x52
815   case DW_OP_reg3:                 // 0x53
816   case DW_OP_reg4:                 // 0x54
817   case DW_OP_reg5:                 // 0x55
818   case DW_OP_reg6:                 // 0x56
819   case DW_OP_reg7:                 // 0x57
820   case DW_OP_reg8:                 // 0x58
821   case DW_OP_reg9:                 // 0x59
822   case DW_OP_reg10:                // 0x5A
823   case DW_OP_reg11:                // 0x5B
824   case DW_OP_reg12:                // 0x5C
825   case DW_OP_reg13:                // 0x5D
826   case DW_OP_reg14:                // 0x5E
827   case DW_OP_reg15:                // 0x5F
828   case DW_OP_reg16:                // 0x60
829   case DW_OP_reg17:                // 0x61
830   case DW_OP_reg18:                // 0x62
831   case DW_OP_reg19:                // 0x63
832   case DW_OP_reg20:                // 0x64
833   case DW_OP_reg21:                // 0x65
834   case DW_OP_reg22:                // 0x66
835   case DW_OP_reg23:                // 0x67
836   case DW_OP_reg24:                // 0x68
837   case DW_OP_reg25:                // 0x69
838   case DW_OP_reg26:                // 0x6A
839   case DW_OP_reg27:                // 0x6B
840   case DW_OP_reg28:                // 0x6C
841   case DW_OP_reg29:                // 0x6D
842   case DW_OP_reg30:                // 0x6E
843   case DW_OP_reg31:                // 0x6F
844   case DW_OP_nop:                  // 0x96
845   case DW_OP_push_object_address:  // 0x97 DWARF3
846   case DW_OP_form_tls_address:     // 0x9b DWARF3
847   case DW_OP_call_frame_cfa:       // 0x9c DWARF3
848   case DW_OP_stack_value:          // 0x9f DWARF4
849   case DW_OP_GNU_push_tls_address: // 0xe0 GNU extension
850     return 0;
851 
852   // Opcodes with a single 1 byte arguments
853   case DW_OP_const1u:     // 0x08 1 1-byte constant
854   case DW_OP_const1s:     // 0x09 1 1-byte constant
855   case DW_OP_pick:        // 0x15 1 1-byte stack index
856   case DW_OP_deref_size:  // 0x94 1 1-byte size of data retrieved
857   case DW_OP_xderef_size: // 0x95 1 1-byte size of data retrieved
858     return 1;
859 
860   // Opcodes with a single 2 byte arguments
861   case DW_OP_const2u: // 0x0a 1 2-byte constant
862   case DW_OP_const2s: // 0x0b 1 2-byte constant
863   case DW_OP_skip:    // 0x2f 1 signed 2-byte constant
864   case DW_OP_bra:     // 0x28 1 signed 2-byte constant
865   case DW_OP_call2:   // 0x98 1 2-byte offset of DIE (DWARF3)
866     return 2;
867 
868   // Opcodes with a single 4 byte arguments
869   case DW_OP_const4u: // 0x0c 1 4-byte constant
870   case DW_OP_const4s: // 0x0d 1 4-byte constant
871   case DW_OP_call4:   // 0x99 1 4-byte offset of DIE (DWARF3)
872     return 4;
873 
874   // Opcodes with a single 8 byte arguments
875   case DW_OP_const8u: // 0x0e 1 8-byte constant
876   case DW_OP_const8s: // 0x0f 1 8-byte constant
877     return 8;
878 
879   // All opcodes that have a single ULEB (signed or unsigned) argument
880   case DW_OP_addrx:           // 0xa1 1 ULEB128 index
881   case DW_OP_constu:          // 0x10 1 ULEB128 constant
882   case DW_OP_consts:          // 0x11 1 SLEB128 constant
883   case DW_OP_plus_uconst:     // 0x23 1 ULEB128 addend
884   case DW_OP_breg0:           // 0x70 1 ULEB128 register
885   case DW_OP_breg1:           // 0x71 1 ULEB128 register
886   case DW_OP_breg2:           // 0x72 1 ULEB128 register
887   case DW_OP_breg3:           // 0x73 1 ULEB128 register
888   case DW_OP_breg4:           // 0x74 1 ULEB128 register
889   case DW_OP_breg5:           // 0x75 1 ULEB128 register
890   case DW_OP_breg6:           // 0x76 1 ULEB128 register
891   case DW_OP_breg7:           // 0x77 1 ULEB128 register
892   case DW_OP_breg8:           // 0x78 1 ULEB128 register
893   case DW_OP_breg9:           // 0x79 1 ULEB128 register
894   case DW_OP_breg10:          // 0x7a 1 ULEB128 register
895   case DW_OP_breg11:          // 0x7b 1 ULEB128 register
896   case DW_OP_breg12:          // 0x7c 1 ULEB128 register
897   case DW_OP_breg13:          // 0x7d 1 ULEB128 register
898   case DW_OP_breg14:          // 0x7e 1 ULEB128 register
899   case DW_OP_breg15:          // 0x7f 1 ULEB128 register
900   case DW_OP_breg16:          // 0x80 1 ULEB128 register
901   case DW_OP_breg17:          // 0x81 1 ULEB128 register
902   case DW_OP_breg18:          // 0x82 1 ULEB128 register
903   case DW_OP_breg19:          // 0x83 1 ULEB128 register
904   case DW_OP_breg20:          // 0x84 1 ULEB128 register
905   case DW_OP_breg21:          // 0x85 1 ULEB128 register
906   case DW_OP_breg22:          // 0x86 1 ULEB128 register
907   case DW_OP_breg23:          // 0x87 1 ULEB128 register
908   case DW_OP_breg24:          // 0x88 1 ULEB128 register
909   case DW_OP_breg25:          // 0x89 1 ULEB128 register
910   case DW_OP_breg26:          // 0x8a 1 ULEB128 register
911   case DW_OP_breg27:          // 0x8b 1 ULEB128 register
912   case DW_OP_breg28:          // 0x8c 1 ULEB128 register
913   case DW_OP_breg29:          // 0x8d 1 ULEB128 register
914   case DW_OP_breg30:          // 0x8e 1 ULEB128 register
915   case DW_OP_breg31:          // 0x8f 1 ULEB128 register
916   case DW_OP_regx:            // 0x90 1 ULEB128 register
917   case DW_OP_fbreg:           // 0x91 1 SLEB128 offset
918   case DW_OP_piece:           // 0x93 1 ULEB128 size of piece addressed
919   case DW_OP_GNU_addr_index:  // 0xfb 1 ULEB128 index
920   case DW_OP_GNU_const_index: // 0xfc 1 ULEB128 index
921     data.Skip_LEB128(&offset);
922     return offset - data_offset;
923 
924   // All opcodes that have a 2 ULEB (signed or unsigned) arguments
925   case DW_OP_bregx:     // 0x92 2 ULEB128 register followed by SLEB128 offset
926   case DW_OP_bit_piece: // 0x9d ULEB128 bit size, ULEB128 bit offset (DWARF3);
927     data.Skip_LEB128(&offset);
928     data.Skip_LEB128(&offset);
929     return offset - data_offset;
930 
931   case DW_OP_implicit_value: // 0x9e ULEB128 size followed by block of that size
932                              // (DWARF4)
933   {
934     uint64_t block_len = data.Skip_LEB128(&offset);
935     offset += block_len;
936     return offset - data_offset;
937   }
938 
939   default:
940     break;
941   }
942   return LLDB_INVALID_OFFSET;
943 }
944 
945 lldb::addr_t DWARFExpression::GetLocation_DW_OP_addr(uint32_t op_addr_idx,
946                                                      bool &error) const {
947   error = false;
948   if (IsLocationList())
949     return LLDB_INVALID_ADDRESS;
950   lldb::offset_t offset = 0;
951   uint32_t curr_op_addr_idx = 0;
952   while (m_data.ValidOffset(offset)) {
953     const uint8_t op = m_data.GetU8(&offset);
954 
955     if (op == DW_OP_addr) {
956       const lldb::addr_t op_file_addr = m_data.GetAddress(&offset);
957       if (curr_op_addr_idx == op_addr_idx)
958         return op_file_addr;
959       else
960         ++curr_op_addr_idx;
961     } else if (op == DW_OP_GNU_addr_index || op == DW_OP_addrx) {
962       uint64_t index = m_data.GetULEB128(&offset);
963       if (curr_op_addr_idx == op_addr_idx) {
964         if (!m_dwarf_cu) {
965           error = true;
966           break;
967         }
968 
969         return ReadAddressFromDebugAddrSection(m_dwarf_cu, index);
970       } else
971         ++curr_op_addr_idx;
972     } else {
973       const offset_t op_arg_size = GetOpcodeDataSize(m_data, offset, op);
974       if (op_arg_size == LLDB_INVALID_OFFSET) {
975         error = true;
976         break;
977       }
978       offset += op_arg_size;
979     }
980   }
981   return LLDB_INVALID_ADDRESS;
982 }
983 
984 bool DWARFExpression::Update_DW_OP_addr(lldb::addr_t file_addr) {
985   if (IsLocationList())
986     return false;
987   lldb::offset_t offset = 0;
988   while (m_data.ValidOffset(offset)) {
989     const uint8_t op = m_data.GetU8(&offset);
990 
991     if (op == DW_OP_addr) {
992       const uint32_t addr_byte_size = m_data.GetAddressByteSize();
993       // We have to make a copy of the data as we don't know if this data is
994       // from a read only memory mapped buffer, so we duplicate all of the data
995       // first, then modify it, and if all goes well, we then replace the data
996       // for this expression
997 
998       // So first we copy the data into a heap buffer
999       std::unique_ptr<DataBufferHeap> head_data_up(
1000           new DataBufferHeap(m_data.GetDataStart(), m_data.GetByteSize()));
1001 
1002       // Make en encoder so we can write the address into the buffer using the
1003       // correct byte order (endianness)
1004       DataEncoder encoder(head_data_up->GetBytes(), head_data_up->GetByteSize(),
1005                           m_data.GetByteOrder(), addr_byte_size);
1006 
1007       // Replace the address in the new buffer
1008       if (encoder.PutMaxU64(offset, addr_byte_size, file_addr) == UINT32_MAX)
1009         return false;
1010 
1011       // All went well, so now we can reset the data using a shared pointer to
1012       // the heap data so "m_data" will now correctly manage the heap data.
1013       m_data.SetData(DataBufferSP(head_data_up.release()));
1014       return true;
1015     } else {
1016       const offset_t op_arg_size = GetOpcodeDataSize(m_data, offset, op);
1017       if (op_arg_size == LLDB_INVALID_OFFSET)
1018         break;
1019       offset += op_arg_size;
1020     }
1021   }
1022   return false;
1023 }
1024 
1025 bool DWARFExpression::ContainsThreadLocalStorage() const {
1026   // We are assuming for now that any thread local variable will not have a
1027   // location list. This has been true for all thread local variables we have
1028   // seen so far produced by any compiler.
1029   if (IsLocationList())
1030     return false;
1031   lldb::offset_t offset = 0;
1032   while (m_data.ValidOffset(offset)) {
1033     const uint8_t op = m_data.GetU8(&offset);
1034 
1035     if (op == DW_OP_form_tls_address || op == DW_OP_GNU_push_tls_address)
1036       return true;
1037     const offset_t op_arg_size = GetOpcodeDataSize(m_data, offset, op);
1038     if (op_arg_size == LLDB_INVALID_OFFSET)
1039       return false;
1040     else
1041       offset += op_arg_size;
1042   }
1043   return false;
1044 }
1045 bool DWARFExpression::LinkThreadLocalStorage(
1046     lldb::ModuleSP new_module_sp,
1047     std::function<lldb::addr_t(lldb::addr_t file_addr)> const
1048         &link_address_callback) {
1049   // We are assuming for now that any thread local variable will not have a
1050   // location list. This has been true for all thread local variables we have
1051   // seen so far produced by any compiler.
1052   if (IsLocationList())
1053     return false;
1054 
1055   const uint32_t addr_byte_size = m_data.GetAddressByteSize();
1056   // We have to make a copy of the data as we don't know if this data is from a
1057   // read only memory mapped buffer, so we duplicate all of the data first,
1058   // then modify it, and if all goes well, we then replace the data for this
1059   // expression
1060 
1061   // So first we copy the data into a heap buffer
1062   std::shared_ptr<DataBufferHeap> heap_data_sp(
1063       new DataBufferHeap(m_data.GetDataStart(), m_data.GetByteSize()));
1064 
1065   // Make en encoder so we can write the address into the buffer using the
1066   // correct byte order (endianness)
1067   DataEncoder encoder(heap_data_sp->GetBytes(), heap_data_sp->GetByteSize(),
1068                       m_data.GetByteOrder(), addr_byte_size);
1069 
1070   lldb::offset_t offset = 0;
1071   lldb::offset_t const_offset = 0;
1072   lldb::addr_t const_value = 0;
1073   size_t const_byte_size = 0;
1074   while (m_data.ValidOffset(offset)) {
1075     const uint8_t op = m_data.GetU8(&offset);
1076 
1077     bool decoded_data = false;
1078     switch (op) {
1079     case DW_OP_const4u:
1080       // Remember the const offset in case we later have a
1081       // DW_OP_form_tls_address or DW_OP_GNU_push_tls_address
1082       const_offset = offset;
1083       const_value = m_data.GetU32(&offset);
1084       decoded_data = true;
1085       const_byte_size = 4;
1086       break;
1087 
1088     case DW_OP_const8u:
1089       // Remember the const offset in case we later have a
1090       // DW_OP_form_tls_address or DW_OP_GNU_push_tls_address
1091       const_offset = offset;
1092       const_value = m_data.GetU64(&offset);
1093       decoded_data = true;
1094       const_byte_size = 8;
1095       break;
1096 
1097     case DW_OP_form_tls_address:
1098     case DW_OP_GNU_push_tls_address:
1099       // DW_OP_form_tls_address and DW_OP_GNU_push_tls_address must be preceded
1100       // by a file address on the stack. We assume that DW_OP_const4u or
1101       // DW_OP_const8u is used for these values, and we check that the last
1102       // opcode we got before either of these was DW_OP_const4u or
1103       // DW_OP_const8u. If so, then we can link the value accodingly. For
1104       // Darwin, the value in the DW_OP_const4u or DW_OP_const8u is the file
1105       // address of a structure that contains a function pointer, the pthread
1106       // key and the offset into the data pointed to by the pthread key. So we
1107       // must link this address and also set the module of this expression to
1108       // the new_module_sp so we can resolve the file address correctly
1109       if (const_byte_size > 0) {
1110         lldb::addr_t linked_file_addr = link_address_callback(const_value);
1111         if (linked_file_addr == LLDB_INVALID_ADDRESS)
1112           return false;
1113         // Replace the address in the new buffer
1114         if (encoder.PutMaxU64(const_offset, const_byte_size,
1115                               linked_file_addr) == UINT32_MAX)
1116           return false;
1117       }
1118       break;
1119 
1120     default:
1121       const_offset = 0;
1122       const_value = 0;
1123       const_byte_size = 0;
1124       break;
1125     }
1126 
1127     if (!decoded_data) {
1128       const offset_t op_arg_size = GetOpcodeDataSize(m_data, offset, op);
1129       if (op_arg_size == LLDB_INVALID_OFFSET)
1130         return false;
1131       else
1132         offset += op_arg_size;
1133     }
1134   }
1135 
1136   // If we linked the TLS address correctly, update the module so that when the
1137   // expression is evaluated it can resolve the file address to a load address
1138   // and read the
1139   // TLS data
1140   m_module_wp = new_module_sp;
1141   m_data.SetData(heap_data_sp);
1142   return true;
1143 }
1144 
1145 bool DWARFExpression::LocationListContainsAddress(
1146     lldb::addr_t loclist_base_addr, lldb::addr_t addr) const {
1147   if (addr == LLDB_INVALID_ADDRESS)
1148     return false;
1149 
1150   if (IsLocationList()) {
1151     lldb::offset_t offset = 0;
1152 
1153     if (loclist_base_addr == LLDB_INVALID_ADDRESS)
1154       return false;
1155 
1156     while (m_data.ValidOffset(offset)) {
1157       // We need to figure out what the value is for the location.
1158       addr_t lo_pc = LLDB_INVALID_ADDRESS;
1159       addr_t hi_pc = LLDB_INVALID_ADDRESS;
1160       if (!AddressRangeForLocationListEntry(m_dwarf_cu, m_data, &offset, lo_pc,
1161                                             hi_pc))
1162         break;
1163 
1164       if (lo_pc == 0 && hi_pc == 0)
1165         break;
1166 
1167       lo_pc += loclist_base_addr - m_loclist_slide;
1168       hi_pc += loclist_base_addr - m_loclist_slide;
1169 
1170       if (lo_pc <= addr && addr < hi_pc)
1171         return true;
1172 
1173       offset += m_data.GetU16(&offset);
1174     }
1175   }
1176   return false;
1177 }
1178 
1179 bool DWARFExpression::GetLocation(addr_t base_addr, addr_t pc,
1180                                   lldb::offset_t &offset,
1181                                   lldb::offset_t &length) {
1182   offset = 0;
1183   if (!IsLocationList()) {
1184     length = m_data.GetByteSize();
1185     return true;
1186   }
1187 
1188   if (base_addr != LLDB_INVALID_ADDRESS && pc != LLDB_INVALID_ADDRESS) {
1189     addr_t curr_base_addr = base_addr;
1190 
1191     while (m_data.ValidOffset(offset)) {
1192       // We need to figure out what the value is for the location.
1193       addr_t lo_pc = LLDB_INVALID_ADDRESS;
1194       addr_t hi_pc = LLDB_INVALID_ADDRESS;
1195       if (!AddressRangeForLocationListEntry(m_dwarf_cu, m_data, &offset, lo_pc,
1196                                             hi_pc))
1197         break;
1198 
1199       if (lo_pc == 0 && hi_pc == 0)
1200         break;
1201 
1202       lo_pc += curr_base_addr - m_loclist_slide;
1203       hi_pc += curr_base_addr - m_loclist_slide;
1204 
1205       length = m_data.GetU16(&offset);
1206 
1207       if (length > 0 && lo_pc <= pc && pc < hi_pc)
1208         return true;
1209 
1210       offset += length;
1211     }
1212   }
1213   offset = LLDB_INVALID_OFFSET;
1214   length = 0;
1215   return false;
1216 }
1217 
1218 bool DWARFExpression::DumpLocationForAddress(Stream *s,
1219                                              lldb::DescriptionLevel level,
1220                                              addr_t base_addr, addr_t address,
1221                                              ABI *abi) {
1222   lldb::offset_t offset = 0;
1223   lldb::offset_t length = 0;
1224 
1225   if (GetLocation(base_addr, address, offset, length)) {
1226     if (length > 0) {
1227       DumpLocation(s, offset, length, level, abi);
1228       return true;
1229     }
1230   }
1231   return false;
1232 }
1233 
1234 bool DWARFExpression::Evaluate(ExecutionContextScope *exe_scope,
1235                                lldb::addr_t loclist_base_load_addr,
1236                                const Value *initial_value_ptr,
1237                                const Value *object_address_ptr, Value &result,
1238                                Status *error_ptr) const {
1239   ExecutionContext exe_ctx(exe_scope);
1240   return Evaluate(&exe_ctx, nullptr, loclist_base_load_addr, initial_value_ptr,
1241                   object_address_ptr, result, error_ptr);
1242 }
1243 
1244 bool DWARFExpression::Evaluate(ExecutionContext *exe_ctx,
1245                                RegisterContext *reg_ctx,
1246                                lldb::addr_t loclist_base_load_addr,
1247                                const Value *initial_value_ptr,
1248                                const Value *object_address_ptr, Value &result,
1249                                Status *error_ptr) const {
1250   ModuleSP module_sp = m_module_wp.lock();
1251 
1252   if (IsLocationList()) {
1253     lldb::offset_t offset = 0;
1254     addr_t pc;
1255     StackFrame *frame = NULL;
1256     if (reg_ctx)
1257       pc = reg_ctx->GetPC();
1258     else {
1259       frame = exe_ctx->GetFramePtr();
1260       if (!frame)
1261         return false;
1262       RegisterContextSP reg_ctx_sp = frame->GetRegisterContext();
1263       if (!reg_ctx_sp)
1264         return false;
1265       pc = reg_ctx_sp->GetPC();
1266     }
1267 
1268     if (loclist_base_load_addr != LLDB_INVALID_ADDRESS) {
1269       if (pc == LLDB_INVALID_ADDRESS) {
1270         if (error_ptr)
1271           error_ptr->SetErrorString("Invalid PC in frame.");
1272         return false;
1273       }
1274 
1275       addr_t curr_loclist_base_load_addr = loclist_base_load_addr;
1276 
1277       while (m_data.ValidOffset(offset)) {
1278         // We need to figure out what the value is for the location.
1279         addr_t lo_pc = LLDB_INVALID_ADDRESS;
1280         addr_t hi_pc = LLDB_INVALID_ADDRESS;
1281         if (!AddressRangeForLocationListEntry(m_dwarf_cu, m_data, &offset,
1282                                               lo_pc, hi_pc))
1283           break;
1284 
1285         if (lo_pc == 0 && hi_pc == 0)
1286           break;
1287 
1288         lo_pc += curr_loclist_base_load_addr - m_loclist_slide;
1289         hi_pc += curr_loclist_base_load_addr - m_loclist_slide;
1290 
1291         uint16_t length = m_data.GetU16(&offset);
1292 
1293         if (length > 0 && lo_pc <= pc && pc < hi_pc) {
1294           return DWARFExpression::Evaluate(
1295               exe_ctx, reg_ctx, module_sp, m_data, m_dwarf_cu, offset, length,
1296               m_reg_kind, initial_value_ptr, object_address_ptr, result,
1297               error_ptr);
1298         }
1299         offset += length;
1300       }
1301     }
1302     if (error_ptr)
1303       error_ptr->SetErrorString("variable not available");
1304     return false;
1305   }
1306 
1307   // Not a location list, just a single expression.
1308   return DWARFExpression::Evaluate(
1309       exe_ctx, reg_ctx, module_sp, m_data, m_dwarf_cu, 0, m_data.GetByteSize(),
1310       m_reg_kind, initial_value_ptr, object_address_ptr, result, error_ptr);
1311 }
1312 
1313 bool DWARFExpression::Evaluate(
1314     ExecutionContext *exe_ctx, RegisterContext *reg_ctx,
1315     lldb::ModuleSP module_sp, const DataExtractor &opcodes,
1316     DWARFUnit *dwarf_cu, const lldb::offset_t opcodes_offset,
1317     const lldb::offset_t opcodes_length, const lldb::RegisterKind reg_kind,
1318     const Value *initial_value_ptr, const Value *object_address_ptr,
1319     Value &result, Status *error_ptr) {
1320 
1321   if (opcodes_length == 0) {
1322     if (error_ptr)
1323       error_ptr->SetErrorString(
1324           "no location, value may have been optimized out");
1325     return false;
1326   }
1327   std::vector<Value> stack;
1328 
1329   Process *process = NULL;
1330   StackFrame *frame = NULL;
1331 
1332   if (exe_ctx) {
1333     process = exe_ctx->GetProcessPtr();
1334     frame = exe_ctx->GetFramePtr();
1335   }
1336   if (reg_ctx == NULL && frame)
1337     reg_ctx = frame->GetRegisterContext().get();
1338 
1339   if (initial_value_ptr)
1340     stack.push_back(*initial_value_ptr);
1341 
1342   lldb::offset_t offset = opcodes_offset;
1343   const lldb::offset_t end_offset = opcodes_offset + opcodes_length;
1344   Value tmp;
1345   uint32_t reg_num;
1346 
1347   /// Insertion point for evaluating multi-piece expression.
1348   uint64_t op_piece_offset = 0;
1349   Value pieces; // Used for DW_OP_piece
1350 
1351   // Make sure all of the data is available in opcodes.
1352   if (!opcodes.ValidOffsetForDataOfSize(opcodes_offset, opcodes_length)) {
1353     if (error_ptr)
1354       error_ptr->SetErrorString(
1355           "invalid offset and/or length for opcodes buffer.");
1356     return false;
1357   }
1358   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_EXPRESSIONS));
1359 
1360   while (opcodes.ValidOffset(offset) && offset < end_offset) {
1361     const lldb::offset_t op_offset = offset;
1362     const uint8_t op = opcodes.GetU8(&offset);
1363 
1364     if (log && log->GetVerbose()) {
1365       size_t count = stack.size();
1366       log->Printf("Stack before operation has %" PRIu64 " values:",
1367                   (uint64_t)count);
1368       for (size_t i = 0; i < count; ++i) {
1369         StreamString new_value;
1370         new_value.Printf("[%" PRIu64 "]", (uint64_t)i);
1371         stack[i].Dump(&new_value);
1372         log->Printf("  %s", new_value.GetData());
1373       }
1374       log->Printf("0x%8.8" PRIx64 ": %s", op_offset, DW_OP_value_to_name(op));
1375     }
1376 
1377     switch (op) {
1378     // The DW_OP_addr operation has a single operand that encodes a machine
1379     // address and whose size is the size of an address on the target machine.
1380     case DW_OP_addr:
1381       stack.push_back(Scalar(opcodes.GetAddress(&offset)));
1382       stack.back().SetValueType(Value::eValueTypeFileAddress);
1383       // Convert the file address to a load address, so subsequent
1384       // DWARF operators can operate on it.
1385       if (frame)
1386         stack.back().ConvertToLoadAddress(module_sp.get(),
1387                                           frame->CalculateTarget().get());
1388       break;
1389 
1390     // The DW_OP_addr_sect_offset4 is used for any location expressions in
1391     // shared libraries that have a location like:
1392     //  DW_OP_addr(0x1000)
1393     // If this address resides in a shared library, then this virtual address
1394     // won't make sense when it is evaluated in the context of a running
1395     // process where shared libraries have been slid. To account for this, this
1396     // new address type where we can store the section pointer and a 4 byte
1397     // offset.
1398     //      case DW_OP_addr_sect_offset4:
1399     //          {
1400     //              result_type = eResultTypeFileAddress;
1401     //              lldb::Section *sect = (lldb::Section
1402     //              *)opcodes.GetMaxU64(&offset, sizeof(void *));
1403     //              lldb::addr_t sect_offset = opcodes.GetU32(&offset);
1404     //
1405     //              Address so_addr (sect, sect_offset);
1406     //              lldb::addr_t load_addr = so_addr.GetLoadAddress();
1407     //              if (load_addr != LLDB_INVALID_ADDRESS)
1408     //              {
1409     //                  // We successfully resolve a file address to a load
1410     //                  // address.
1411     //                  stack.push_back(load_addr);
1412     //                  break;
1413     //              }
1414     //              else
1415     //              {
1416     //                  // We were able
1417     //                  if (error_ptr)
1418     //                      error_ptr->SetErrorStringWithFormat ("Section %s in
1419     //                      %s is not currently loaded.\n",
1420     //                      sect->GetName().AsCString(),
1421     //                      sect->GetModule()->GetFileSpec().GetFilename().AsCString());
1422     //                  return false;
1423     //              }
1424     //          }
1425     //          break;
1426 
1427     // OPCODE: DW_OP_deref
1428     // OPERANDS: none
1429     // DESCRIPTION: Pops the top stack entry and treats it as an address.
1430     // The value retrieved from that address is pushed. The size of the data
1431     // retrieved from the dereferenced address is the size of an address on the
1432     // target machine.
1433     case DW_OP_deref: {
1434       if (stack.empty()) {
1435         if (error_ptr)
1436           error_ptr->SetErrorString("Expression stack empty for DW_OP_deref.");
1437         return false;
1438       }
1439       Value::ValueType value_type = stack.back().GetValueType();
1440       switch (value_type) {
1441       case Value::eValueTypeHostAddress: {
1442         void *src = (void *)stack.back().GetScalar().ULongLong();
1443         intptr_t ptr;
1444         ::memcpy(&ptr, src, sizeof(void *));
1445         stack.back().GetScalar() = ptr;
1446         stack.back().ClearContext();
1447       } break;
1448       case Value::eValueTypeFileAddress: {
1449         auto file_addr = stack.back().GetScalar().ULongLong(
1450             LLDB_INVALID_ADDRESS);
1451         if (!module_sp) {
1452           if (error_ptr)
1453             error_ptr->SetErrorStringWithFormat(
1454                 "need module to resolve file address for DW_OP_deref");
1455           return false;
1456         }
1457         Address so_addr;
1458         if (!module_sp->ResolveFileAddress(file_addr, so_addr)) {
1459           if (error_ptr)
1460             error_ptr->SetErrorStringWithFormat(
1461                 "failed to resolve file address in module");
1462           return false;
1463         }
1464         addr_t load_Addr = so_addr.GetLoadAddress(exe_ctx->GetTargetPtr());
1465         if (load_Addr == LLDB_INVALID_ADDRESS) {
1466           if (error_ptr)
1467             error_ptr->SetErrorStringWithFormat(
1468                 "failed to resolve load address");
1469           return false;
1470         }
1471         stack.back().GetScalar() = load_Addr;
1472         stack.back().SetValueType(Value::eValueTypeLoadAddress);
1473         // Fall through to load address code below...
1474       } LLVM_FALLTHROUGH;
1475       case Value::eValueTypeLoadAddress:
1476         if (exe_ctx) {
1477           if (process) {
1478             lldb::addr_t pointer_addr =
1479                 stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
1480             Status error;
1481             lldb::addr_t pointer_value =
1482                 process->ReadPointerFromMemory(pointer_addr, error);
1483             if (pointer_value != LLDB_INVALID_ADDRESS) {
1484               stack.back().GetScalar() = pointer_value;
1485               stack.back().ClearContext();
1486             } else {
1487               if (error_ptr)
1488                 error_ptr->SetErrorStringWithFormat(
1489                     "Failed to dereference pointer from 0x%" PRIx64
1490                     " for DW_OP_deref: %s\n",
1491                     pointer_addr, error.AsCString());
1492               return false;
1493             }
1494           } else {
1495             if (error_ptr)
1496               error_ptr->SetErrorStringWithFormat(
1497                   "NULL process for DW_OP_deref.\n");
1498             return false;
1499           }
1500         } else {
1501           if (error_ptr)
1502             error_ptr->SetErrorStringWithFormat(
1503                 "NULL execution context for DW_OP_deref.\n");
1504           return false;
1505         }
1506         break;
1507 
1508       default:
1509         break;
1510       }
1511 
1512     } break;
1513 
1514     // OPCODE: DW_OP_deref_size
1515     // OPERANDS: 1
1516     //  1 - uint8_t that specifies the size of the data to dereference.
1517     // DESCRIPTION: Behaves like the DW_OP_deref operation: it pops the top
1518     // stack entry and treats it as an address. The value retrieved from that
1519     // address is pushed. In the DW_OP_deref_size operation, however, the size
1520     // in bytes of the data retrieved from the dereferenced address is
1521     // specified by the single operand. This operand is a 1-byte unsigned
1522     // integral constant whose value may not be larger than the size of an
1523     // address on the target machine. The data retrieved is zero extended to
1524     // the size of an address on the target machine before being pushed on the
1525     // expression stack.
1526     case DW_OP_deref_size: {
1527       if (stack.empty()) {
1528         if (error_ptr)
1529           error_ptr->SetErrorString(
1530               "Expression stack empty for DW_OP_deref_size.");
1531         return false;
1532       }
1533       uint8_t size = opcodes.GetU8(&offset);
1534       Value::ValueType value_type = stack.back().GetValueType();
1535       switch (value_type) {
1536       case Value::eValueTypeHostAddress: {
1537         void *src = (void *)stack.back().GetScalar().ULongLong();
1538         intptr_t ptr;
1539         ::memcpy(&ptr, src, sizeof(void *));
1540         // I can't decide whether the size operand should apply to the bytes in
1541         // their
1542         // lldb-host endianness or the target endianness.. I doubt this'll ever
1543         // come up but I'll opt for assuming big endian regardless.
1544         switch (size) {
1545         case 1:
1546           ptr = ptr & 0xff;
1547           break;
1548         case 2:
1549           ptr = ptr & 0xffff;
1550           break;
1551         case 3:
1552           ptr = ptr & 0xffffff;
1553           break;
1554         case 4:
1555           ptr = ptr & 0xffffffff;
1556           break;
1557         // the casts are added to work around the case where intptr_t is a 32
1558         // bit quantity;
1559         // presumably we won't hit the 5..7 cases if (void*) is 32-bits in this
1560         // program.
1561         case 5:
1562           ptr = (intptr_t)ptr & 0xffffffffffULL;
1563           break;
1564         case 6:
1565           ptr = (intptr_t)ptr & 0xffffffffffffULL;
1566           break;
1567         case 7:
1568           ptr = (intptr_t)ptr & 0xffffffffffffffULL;
1569           break;
1570         default:
1571           break;
1572         }
1573         stack.back().GetScalar() = ptr;
1574         stack.back().ClearContext();
1575       } break;
1576       case Value::eValueTypeLoadAddress:
1577         if (exe_ctx) {
1578           if (process) {
1579             lldb::addr_t pointer_addr =
1580                 stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
1581             uint8_t addr_bytes[sizeof(lldb::addr_t)];
1582             Status error;
1583             if (process->ReadMemory(pointer_addr, &addr_bytes, size, error) ==
1584                 size) {
1585               DataExtractor addr_data(addr_bytes, sizeof(addr_bytes),
1586                                       process->GetByteOrder(), size);
1587               lldb::offset_t addr_data_offset = 0;
1588               switch (size) {
1589               case 1:
1590                 stack.back().GetScalar() = addr_data.GetU8(&addr_data_offset);
1591                 break;
1592               case 2:
1593                 stack.back().GetScalar() = addr_data.GetU16(&addr_data_offset);
1594                 break;
1595               case 4:
1596                 stack.back().GetScalar() = addr_data.GetU32(&addr_data_offset);
1597                 break;
1598               case 8:
1599                 stack.back().GetScalar() = addr_data.GetU64(&addr_data_offset);
1600                 break;
1601               default:
1602                 stack.back().GetScalar() =
1603                     addr_data.GetPointer(&addr_data_offset);
1604               }
1605               stack.back().ClearContext();
1606             } else {
1607               if (error_ptr)
1608                 error_ptr->SetErrorStringWithFormat(
1609                     "Failed to dereference pointer from 0x%" PRIx64
1610                     " for DW_OP_deref: %s\n",
1611                     pointer_addr, error.AsCString());
1612               return false;
1613             }
1614           } else {
1615             if (error_ptr)
1616               error_ptr->SetErrorStringWithFormat(
1617                   "NULL process for DW_OP_deref.\n");
1618             return false;
1619           }
1620         } else {
1621           if (error_ptr)
1622             error_ptr->SetErrorStringWithFormat(
1623                 "NULL execution context for DW_OP_deref.\n");
1624           return false;
1625         }
1626         break;
1627 
1628       default:
1629         break;
1630       }
1631 
1632     } break;
1633 
1634     // OPCODE: DW_OP_xderef_size
1635     // OPERANDS: 1
1636     //  1 - uint8_t that specifies the size of the data to dereference.
1637     // DESCRIPTION: Behaves like the DW_OP_xderef operation: the entry at
1638     // the top of the stack is treated as an address. The second stack entry is
1639     // treated as an "address space identifier" for those architectures that
1640     // support multiple address spaces. The top two stack elements are popped,
1641     // a data item is retrieved through an implementation-defined address
1642     // calculation and pushed as the new stack top. In the DW_OP_xderef_size
1643     // operation, however, the size in bytes of the data retrieved from the
1644     // dereferenced address is specified by the single operand. This operand is
1645     // a 1-byte unsigned integral constant whose value may not be larger than
1646     // the size of an address on the target machine. The data retrieved is zero
1647     // extended to the size of an address on the target machine before being
1648     // pushed on the expression stack.
1649     case DW_OP_xderef_size:
1650       if (error_ptr)
1651         error_ptr->SetErrorString("Unimplemented opcode: DW_OP_xderef_size.");
1652       return false;
1653     // OPCODE: DW_OP_xderef
1654     // OPERANDS: none
1655     // DESCRIPTION: Provides an extended dereference mechanism. The entry at
1656     // the top of the stack is treated as an address. The second stack entry is
1657     // treated as an "address space identifier" for those architectures that
1658     // support multiple address spaces. The top two stack elements are popped,
1659     // a data item is retrieved through an implementation-defined address
1660     // calculation and pushed as the new stack top. The size of the data
1661     // retrieved from the dereferenced address is the size of an address on the
1662     // target machine.
1663     case DW_OP_xderef:
1664       if (error_ptr)
1665         error_ptr->SetErrorString("Unimplemented opcode: DW_OP_xderef.");
1666       return false;
1667 
1668     // All DW_OP_constXXX opcodes have a single operand as noted below:
1669     //
1670     // Opcode           Operand 1
1671     // DW_OP_const1u    1-byte unsigned integer constant DW_OP_const1s
1672     // 1-byte signed integer constant DW_OP_const2u    2-byte unsigned integer
1673     // constant DW_OP_const2s    2-byte signed integer constant DW_OP_const4u
1674     // 4-byte unsigned integer constant DW_OP_const4s    4-byte signed integer
1675     // constant DW_OP_const8u    8-byte unsigned integer constant DW_OP_const8s
1676     // 8-byte signed integer constant DW_OP_constu     unsigned LEB128 integer
1677     // constant DW_OP_consts     signed LEB128 integer constant
1678     case DW_OP_const1u:
1679       stack.push_back(Scalar((uint8_t)opcodes.GetU8(&offset)));
1680       break;
1681     case DW_OP_const1s:
1682       stack.push_back(Scalar((int8_t)opcodes.GetU8(&offset)));
1683       break;
1684     case DW_OP_const2u:
1685       stack.push_back(Scalar((uint16_t)opcodes.GetU16(&offset)));
1686       break;
1687     case DW_OP_const2s:
1688       stack.push_back(Scalar((int16_t)opcodes.GetU16(&offset)));
1689       break;
1690     case DW_OP_const4u:
1691       stack.push_back(Scalar((uint32_t)opcodes.GetU32(&offset)));
1692       break;
1693     case DW_OP_const4s:
1694       stack.push_back(Scalar((int32_t)opcodes.GetU32(&offset)));
1695       break;
1696     case DW_OP_const8u:
1697       stack.push_back(Scalar((uint64_t)opcodes.GetU64(&offset)));
1698       break;
1699     case DW_OP_const8s:
1700       stack.push_back(Scalar((int64_t)opcodes.GetU64(&offset)));
1701       break;
1702     case DW_OP_constu:
1703       stack.push_back(Scalar(opcodes.GetULEB128(&offset)));
1704       break;
1705     case DW_OP_consts:
1706       stack.push_back(Scalar(opcodes.GetSLEB128(&offset)));
1707       break;
1708 
1709     // OPCODE: DW_OP_dup
1710     // OPERANDS: none
1711     // DESCRIPTION: duplicates the value at the top of the stack
1712     case DW_OP_dup:
1713       if (stack.empty()) {
1714         if (error_ptr)
1715           error_ptr->SetErrorString("Expression stack empty for DW_OP_dup.");
1716         return false;
1717       } else
1718         stack.push_back(stack.back());
1719       break;
1720 
1721     // OPCODE: DW_OP_drop
1722     // OPERANDS: none
1723     // DESCRIPTION: pops the value at the top of the stack
1724     case DW_OP_drop:
1725       if (stack.empty()) {
1726         if (error_ptr)
1727           error_ptr->SetErrorString("Expression stack empty for DW_OP_drop.");
1728         return false;
1729       } else
1730         stack.pop_back();
1731       break;
1732 
1733     // OPCODE: DW_OP_over
1734     // OPERANDS: none
1735     // DESCRIPTION: Duplicates the entry currently second in the stack at
1736     // the top of the stack.
1737     case DW_OP_over:
1738       if (stack.size() < 2) {
1739         if (error_ptr)
1740           error_ptr->SetErrorString(
1741               "Expression stack needs at least 2 items for DW_OP_over.");
1742         return false;
1743       } else
1744         stack.push_back(stack[stack.size() - 2]);
1745       break;
1746 
1747     // OPCODE: DW_OP_pick
1748     // OPERANDS: uint8_t index into the current stack
1749     // DESCRIPTION: The stack entry with the specified index (0 through 255,
1750     // inclusive) is pushed on the stack
1751     case DW_OP_pick: {
1752       uint8_t pick_idx = opcodes.GetU8(&offset);
1753       if (pick_idx < stack.size())
1754         stack.push_back(stack[pick_idx]);
1755       else {
1756         if (error_ptr)
1757           error_ptr->SetErrorStringWithFormat(
1758               "Index %u out of range for DW_OP_pick.\n", pick_idx);
1759         return false;
1760       }
1761     } break;
1762 
1763     // OPCODE: DW_OP_swap
1764     // OPERANDS: none
1765     // DESCRIPTION: swaps the top two stack entries. The entry at the top
1766     // of the stack becomes the second stack entry, and the second entry
1767     // becomes the top of the stack
1768     case DW_OP_swap:
1769       if (stack.size() < 2) {
1770         if (error_ptr)
1771           error_ptr->SetErrorString(
1772               "Expression stack needs at least 2 items for DW_OP_swap.");
1773         return false;
1774       } else {
1775         tmp = stack.back();
1776         stack.back() = stack[stack.size() - 2];
1777         stack[stack.size() - 2] = tmp;
1778       }
1779       break;
1780 
1781     // OPCODE: DW_OP_rot
1782     // OPERANDS: none
1783     // DESCRIPTION: Rotates the first three stack entries. The entry at
1784     // the top of the stack becomes the third stack entry, the second entry
1785     // becomes the top of the stack, and the third entry becomes the second
1786     // entry.
1787     case DW_OP_rot:
1788       if (stack.size() < 3) {
1789         if (error_ptr)
1790           error_ptr->SetErrorString(
1791               "Expression stack needs at least 3 items for DW_OP_rot.");
1792         return false;
1793       } else {
1794         size_t last_idx = stack.size() - 1;
1795         Value old_top = stack[last_idx];
1796         stack[last_idx] = stack[last_idx - 1];
1797         stack[last_idx - 1] = stack[last_idx - 2];
1798         stack[last_idx - 2] = old_top;
1799       }
1800       break;
1801 
1802     // OPCODE: DW_OP_abs
1803     // OPERANDS: none
1804     // DESCRIPTION: pops the top stack entry, interprets it as a signed
1805     // value and pushes its absolute value. If the absolute value can not be
1806     // represented, the result is undefined.
1807     case DW_OP_abs:
1808       if (stack.empty()) {
1809         if (error_ptr)
1810           error_ptr->SetErrorString(
1811               "Expression stack needs at least 1 item for DW_OP_abs.");
1812         return false;
1813       } else if (!stack.back().ResolveValue(exe_ctx).AbsoluteValue()) {
1814         if (error_ptr)
1815           error_ptr->SetErrorString(
1816               "Failed to take the absolute value of the first stack item.");
1817         return false;
1818       }
1819       break;
1820 
1821     // OPCODE: DW_OP_and
1822     // OPERANDS: none
1823     // DESCRIPTION: pops the top two stack values, performs a bitwise and
1824     // operation on the two, and pushes the result.
1825     case DW_OP_and:
1826       if (stack.size() < 2) {
1827         if (error_ptr)
1828           error_ptr->SetErrorString(
1829               "Expression stack needs at least 2 items for DW_OP_and.");
1830         return false;
1831       } else {
1832         tmp = stack.back();
1833         stack.pop_back();
1834         stack.back().ResolveValue(exe_ctx) =
1835             stack.back().ResolveValue(exe_ctx) & tmp.ResolveValue(exe_ctx);
1836       }
1837       break;
1838 
1839     // OPCODE: DW_OP_div
1840     // OPERANDS: none
1841     // DESCRIPTION: pops the top two stack values, divides the former second
1842     // entry by the former top of the stack using signed division, and pushes
1843     // the result.
1844     case DW_OP_div:
1845       if (stack.size() < 2) {
1846         if (error_ptr)
1847           error_ptr->SetErrorString(
1848               "Expression stack needs at least 2 items for DW_OP_div.");
1849         return false;
1850       } else {
1851         tmp = stack.back();
1852         if (tmp.ResolveValue(exe_ctx).IsZero()) {
1853           if (error_ptr)
1854             error_ptr->SetErrorString("Divide by zero.");
1855           return false;
1856         } else {
1857           stack.pop_back();
1858           stack.back() =
1859               stack.back().ResolveValue(exe_ctx) / tmp.ResolveValue(exe_ctx);
1860           if (!stack.back().ResolveValue(exe_ctx).IsValid()) {
1861             if (error_ptr)
1862               error_ptr->SetErrorString("Divide failed.");
1863             return false;
1864           }
1865         }
1866       }
1867       break;
1868 
1869     // OPCODE: DW_OP_minus
1870     // OPERANDS: none
1871     // DESCRIPTION: pops the top two stack values, subtracts the former top
1872     // of the stack from the former second entry, and pushes the result.
1873     case DW_OP_minus:
1874       if (stack.size() < 2) {
1875         if (error_ptr)
1876           error_ptr->SetErrorString(
1877               "Expression stack needs at least 2 items for DW_OP_minus.");
1878         return false;
1879       } else {
1880         tmp = stack.back();
1881         stack.pop_back();
1882         stack.back().ResolveValue(exe_ctx) =
1883             stack.back().ResolveValue(exe_ctx) - tmp.ResolveValue(exe_ctx);
1884       }
1885       break;
1886 
1887     // OPCODE: DW_OP_mod
1888     // OPERANDS: none
1889     // DESCRIPTION: pops the top two stack values and pushes the result of
1890     // the calculation: former second stack entry modulo the former top of the
1891     // stack.
1892     case DW_OP_mod:
1893       if (stack.size() < 2) {
1894         if (error_ptr)
1895           error_ptr->SetErrorString(
1896               "Expression stack needs at least 2 items for DW_OP_mod.");
1897         return false;
1898       } else {
1899         tmp = stack.back();
1900         stack.pop_back();
1901         stack.back().ResolveValue(exe_ctx) =
1902             stack.back().ResolveValue(exe_ctx) % tmp.ResolveValue(exe_ctx);
1903       }
1904       break;
1905 
1906     // OPCODE: DW_OP_mul
1907     // OPERANDS: none
1908     // DESCRIPTION: pops the top two stack entries, multiplies them
1909     // together, and pushes the result.
1910     case DW_OP_mul:
1911       if (stack.size() < 2) {
1912         if (error_ptr)
1913           error_ptr->SetErrorString(
1914               "Expression stack needs at least 2 items for DW_OP_mul.");
1915         return false;
1916       } else {
1917         tmp = stack.back();
1918         stack.pop_back();
1919         stack.back().ResolveValue(exe_ctx) =
1920             stack.back().ResolveValue(exe_ctx) * tmp.ResolveValue(exe_ctx);
1921       }
1922       break;
1923 
1924     // OPCODE: DW_OP_neg
1925     // OPERANDS: none
1926     // DESCRIPTION: pops the top stack entry, and pushes its negation.
1927     case DW_OP_neg:
1928       if (stack.empty()) {
1929         if (error_ptr)
1930           error_ptr->SetErrorString(
1931               "Expression stack needs at least 1 item for DW_OP_neg.");
1932         return false;
1933       } else {
1934         if (!stack.back().ResolveValue(exe_ctx).UnaryNegate()) {
1935           if (error_ptr)
1936             error_ptr->SetErrorString("Unary negate failed.");
1937           return false;
1938         }
1939       }
1940       break;
1941 
1942     // OPCODE: DW_OP_not
1943     // OPERANDS: none
1944     // DESCRIPTION: pops the top stack entry, and pushes its bitwise
1945     // complement
1946     case DW_OP_not:
1947       if (stack.empty()) {
1948         if (error_ptr)
1949           error_ptr->SetErrorString(
1950               "Expression stack needs at least 1 item for DW_OP_not.");
1951         return false;
1952       } else {
1953         if (!stack.back().ResolveValue(exe_ctx).OnesComplement()) {
1954           if (error_ptr)
1955             error_ptr->SetErrorString("Logical NOT failed.");
1956           return false;
1957         }
1958       }
1959       break;
1960 
1961     // OPCODE: DW_OP_or
1962     // OPERANDS: none
1963     // DESCRIPTION: pops the top two stack entries, performs a bitwise or
1964     // operation on the two, and pushes the result.
1965     case DW_OP_or:
1966       if (stack.size() < 2) {
1967         if (error_ptr)
1968           error_ptr->SetErrorString(
1969               "Expression stack needs at least 2 items for DW_OP_or.");
1970         return false;
1971       } else {
1972         tmp = stack.back();
1973         stack.pop_back();
1974         stack.back().ResolveValue(exe_ctx) =
1975             stack.back().ResolveValue(exe_ctx) | tmp.ResolveValue(exe_ctx);
1976       }
1977       break;
1978 
1979     // OPCODE: DW_OP_plus
1980     // OPERANDS: none
1981     // DESCRIPTION: pops the top two stack entries, adds them together, and
1982     // pushes the result.
1983     case DW_OP_plus:
1984       if (stack.size() < 2) {
1985         if (error_ptr)
1986           error_ptr->SetErrorString(
1987               "Expression stack needs at least 2 items for DW_OP_plus.");
1988         return false;
1989       } else {
1990         tmp = stack.back();
1991         stack.pop_back();
1992         stack.back().GetScalar() += tmp.GetScalar();
1993       }
1994       break;
1995 
1996     // OPCODE: DW_OP_plus_uconst
1997     // OPERANDS: none
1998     // DESCRIPTION: pops the top stack entry, adds it to the unsigned LEB128
1999     // constant operand and pushes the result.
2000     case DW_OP_plus_uconst:
2001       if (stack.empty()) {
2002         if (error_ptr)
2003           error_ptr->SetErrorString(
2004               "Expression stack needs at least 1 item for DW_OP_plus_uconst.");
2005         return false;
2006       } else {
2007         const uint64_t uconst_value = opcodes.GetULEB128(&offset);
2008         // Implicit conversion from a UINT to a Scalar...
2009         stack.back().GetScalar() += uconst_value;
2010         if (!stack.back().GetScalar().IsValid()) {
2011           if (error_ptr)
2012             error_ptr->SetErrorString("DW_OP_plus_uconst failed.");
2013           return false;
2014         }
2015       }
2016       break;
2017 
2018     // OPCODE: DW_OP_shl
2019     // OPERANDS: none
2020     // DESCRIPTION:  pops the top two stack entries, shifts the former
2021     // second entry left by the number of bits specified by the former top of
2022     // the stack, and pushes the result.
2023     case DW_OP_shl:
2024       if (stack.size() < 2) {
2025         if (error_ptr)
2026           error_ptr->SetErrorString(
2027               "Expression stack needs at least 2 items for DW_OP_shl.");
2028         return false;
2029       } else {
2030         tmp = stack.back();
2031         stack.pop_back();
2032         stack.back().ResolveValue(exe_ctx) <<= tmp.ResolveValue(exe_ctx);
2033       }
2034       break;
2035 
2036     // OPCODE: DW_OP_shr
2037     // OPERANDS: none
2038     // DESCRIPTION: pops the top two stack entries, shifts the former second
2039     // entry right logically (filling with zero bits) by the number of bits
2040     // specified by the former top of the stack, and pushes the result.
2041     case DW_OP_shr:
2042       if (stack.size() < 2) {
2043         if (error_ptr)
2044           error_ptr->SetErrorString(
2045               "Expression stack needs at least 2 items for DW_OP_shr.");
2046         return false;
2047       } else {
2048         tmp = stack.back();
2049         stack.pop_back();
2050         if (!stack.back().ResolveValue(exe_ctx).ShiftRightLogical(
2051                 tmp.ResolveValue(exe_ctx))) {
2052           if (error_ptr)
2053             error_ptr->SetErrorString("DW_OP_shr failed.");
2054           return false;
2055         }
2056       }
2057       break;
2058 
2059     // OPCODE: DW_OP_shra
2060     // OPERANDS: none
2061     // DESCRIPTION: pops the top two stack entries, shifts the former second
2062     // entry right arithmetically (divide the magnitude by 2, keep the same
2063     // sign for the result) by the number of bits specified by the former top
2064     // of the stack, and pushes the result.
2065     case DW_OP_shra:
2066       if (stack.size() < 2) {
2067         if (error_ptr)
2068           error_ptr->SetErrorString(
2069               "Expression stack needs at least 2 items for DW_OP_shra.");
2070         return false;
2071       } else {
2072         tmp = stack.back();
2073         stack.pop_back();
2074         stack.back().ResolveValue(exe_ctx) >>= tmp.ResolveValue(exe_ctx);
2075       }
2076       break;
2077 
2078     // OPCODE: DW_OP_xor
2079     // OPERANDS: none
2080     // DESCRIPTION: pops the top two stack entries, performs the bitwise
2081     // exclusive-or operation on the two, and pushes the result.
2082     case DW_OP_xor:
2083       if (stack.size() < 2) {
2084         if (error_ptr)
2085           error_ptr->SetErrorString(
2086               "Expression stack needs at least 2 items for DW_OP_xor.");
2087         return false;
2088       } else {
2089         tmp = stack.back();
2090         stack.pop_back();
2091         stack.back().ResolveValue(exe_ctx) =
2092             stack.back().ResolveValue(exe_ctx) ^ tmp.ResolveValue(exe_ctx);
2093       }
2094       break;
2095 
2096     // OPCODE: DW_OP_skip
2097     // OPERANDS: int16_t
2098     // DESCRIPTION:  An unconditional branch. Its single operand is a 2-byte
2099     // signed integer constant. The 2-byte constant is the number of bytes of
2100     // the DWARF expression to skip forward or backward from the current
2101     // operation, beginning after the 2-byte constant.
2102     case DW_OP_skip: {
2103       int16_t skip_offset = (int16_t)opcodes.GetU16(&offset);
2104       lldb::offset_t new_offset = offset + skip_offset;
2105       if (new_offset >= opcodes_offset && new_offset < end_offset)
2106         offset = new_offset;
2107       else {
2108         if (error_ptr)
2109           error_ptr->SetErrorString("Invalid opcode offset in DW_OP_skip.");
2110         return false;
2111       }
2112     } break;
2113 
2114     // OPCODE: DW_OP_bra
2115     // OPERANDS: int16_t
2116     // DESCRIPTION: A conditional branch. Its single operand is a 2-byte
2117     // signed integer constant. This operation pops the top of stack. If the
2118     // value popped is not the constant 0, the 2-byte constant operand is the
2119     // number of bytes of the DWARF expression to skip forward or backward from
2120     // the current operation, beginning after the 2-byte constant.
2121     case DW_OP_bra:
2122       if (stack.empty()) {
2123         if (error_ptr)
2124           error_ptr->SetErrorString(
2125               "Expression stack needs at least 1 item for DW_OP_bra.");
2126         return false;
2127       } else {
2128         tmp = stack.back();
2129         stack.pop_back();
2130         int16_t bra_offset = (int16_t)opcodes.GetU16(&offset);
2131         Scalar zero(0);
2132         if (tmp.ResolveValue(exe_ctx) != zero) {
2133           lldb::offset_t new_offset = offset + bra_offset;
2134           if (new_offset >= opcodes_offset && new_offset < end_offset)
2135             offset = new_offset;
2136           else {
2137             if (error_ptr)
2138               error_ptr->SetErrorString("Invalid opcode offset in DW_OP_bra.");
2139             return false;
2140           }
2141         }
2142       }
2143       break;
2144 
2145     // OPCODE: DW_OP_eq
2146     // OPERANDS: none
2147     // DESCRIPTION: pops the top two stack values, compares using the
2148     // equals (==) operator.
2149     // STACK RESULT: push the constant value 1 onto the stack if the result
2150     // of the operation is true or the constant value 0 if the result of the
2151     // operation is false.
2152     case DW_OP_eq:
2153       if (stack.size() < 2) {
2154         if (error_ptr)
2155           error_ptr->SetErrorString(
2156               "Expression stack needs at least 2 items for DW_OP_eq.");
2157         return false;
2158       } else {
2159         tmp = stack.back();
2160         stack.pop_back();
2161         stack.back().ResolveValue(exe_ctx) =
2162             stack.back().ResolveValue(exe_ctx) == tmp.ResolveValue(exe_ctx);
2163       }
2164       break;
2165 
2166     // OPCODE: DW_OP_ge
2167     // OPERANDS: none
2168     // DESCRIPTION: pops the top two stack values, compares using the
2169     // greater than or equal to (>=) operator.
2170     // STACK RESULT: push the constant value 1 onto the stack if the result
2171     // of the operation is true or the constant value 0 if the result of the
2172     // operation is false.
2173     case DW_OP_ge:
2174       if (stack.size() < 2) {
2175         if (error_ptr)
2176           error_ptr->SetErrorString(
2177               "Expression stack needs at least 2 items for DW_OP_ge.");
2178         return false;
2179       } else {
2180         tmp = stack.back();
2181         stack.pop_back();
2182         stack.back().ResolveValue(exe_ctx) =
2183             stack.back().ResolveValue(exe_ctx) >= tmp.ResolveValue(exe_ctx);
2184       }
2185       break;
2186 
2187     // OPCODE: DW_OP_gt
2188     // OPERANDS: none
2189     // DESCRIPTION: pops the top two stack values, compares using the
2190     // greater than (>) operator.
2191     // STACK RESULT: push the constant value 1 onto the stack if the result
2192     // of the operation is true or the constant value 0 if the result of the
2193     // operation is false.
2194     case DW_OP_gt:
2195       if (stack.size() < 2) {
2196         if (error_ptr)
2197           error_ptr->SetErrorString(
2198               "Expression stack needs at least 2 items for DW_OP_gt.");
2199         return false;
2200       } else {
2201         tmp = stack.back();
2202         stack.pop_back();
2203         stack.back().ResolveValue(exe_ctx) =
2204             stack.back().ResolveValue(exe_ctx) > tmp.ResolveValue(exe_ctx);
2205       }
2206       break;
2207 
2208     // OPCODE: DW_OP_le
2209     // OPERANDS: none
2210     // DESCRIPTION: pops the top two stack values, compares using the
2211     // less than or equal to (<=) operator.
2212     // STACK RESULT: push the constant value 1 onto the stack if the result
2213     // of the operation is true or the constant value 0 if the result of the
2214     // operation is false.
2215     case DW_OP_le:
2216       if (stack.size() < 2) {
2217         if (error_ptr)
2218           error_ptr->SetErrorString(
2219               "Expression stack needs at least 2 items for DW_OP_le.");
2220         return false;
2221       } else {
2222         tmp = stack.back();
2223         stack.pop_back();
2224         stack.back().ResolveValue(exe_ctx) =
2225             stack.back().ResolveValue(exe_ctx) <= tmp.ResolveValue(exe_ctx);
2226       }
2227       break;
2228 
2229     // OPCODE: DW_OP_lt
2230     // OPERANDS: none
2231     // DESCRIPTION: pops the top two stack values, compares using the
2232     // less than (<) operator.
2233     // STACK RESULT: push the constant value 1 onto the stack if the result
2234     // of the operation is true or the constant value 0 if the result of the
2235     // operation is false.
2236     case DW_OP_lt:
2237       if (stack.size() < 2) {
2238         if (error_ptr)
2239           error_ptr->SetErrorString(
2240               "Expression stack needs at least 2 items for DW_OP_lt.");
2241         return false;
2242       } else {
2243         tmp = stack.back();
2244         stack.pop_back();
2245         stack.back().ResolveValue(exe_ctx) =
2246             stack.back().ResolveValue(exe_ctx) < tmp.ResolveValue(exe_ctx);
2247       }
2248       break;
2249 
2250     // OPCODE: DW_OP_ne
2251     // OPERANDS: none
2252     // DESCRIPTION: pops the top two stack values, compares using the
2253     // not equal (!=) operator.
2254     // STACK RESULT: push the constant value 1 onto the stack if the result
2255     // of the operation is true or the constant value 0 if the result of the
2256     // operation is false.
2257     case DW_OP_ne:
2258       if (stack.size() < 2) {
2259         if (error_ptr)
2260           error_ptr->SetErrorString(
2261               "Expression stack needs at least 2 items for DW_OP_ne.");
2262         return false;
2263       } else {
2264         tmp = stack.back();
2265         stack.pop_back();
2266         stack.back().ResolveValue(exe_ctx) =
2267             stack.back().ResolveValue(exe_ctx) != tmp.ResolveValue(exe_ctx);
2268       }
2269       break;
2270 
2271     // OPCODE: DW_OP_litn
2272     // OPERANDS: none
2273     // DESCRIPTION: encode the unsigned literal values from 0 through 31.
2274     // STACK RESULT: push the unsigned literal constant value onto the top
2275     // of the stack.
2276     case DW_OP_lit0:
2277     case DW_OP_lit1:
2278     case DW_OP_lit2:
2279     case DW_OP_lit3:
2280     case DW_OP_lit4:
2281     case DW_OP_lit5:
2282     case DW_OP_lit6:
2283     case DW_OP_lit7:
2284     case DW_OP_lit8:
2285     case DW_OP_lit9:
2286     case DW_OP_lit10:
2287     case DW_OP_lit11:
2288     case DW_OP_lit12:
2289     case DW_OP_lit13:
2290     case DW_OP_lit14:
2291     case DW_OP_lit15:
2292     case DW_OP_lit16:
2293     case DW_OP_lit17:
2294     case DW_OP_lit18:
2295     case DW_OP_lit19:
2296     case DW_OP_lit20:
2297     case DW_OP_lit21:
2298     case DW_OP_lit22:
2299     case DW_OP_lit23:
2300     case DW_OP_lit24:
2301     case DW_OP_lit25:
2302     case DW_OP_lit26:
2303     case DW_OP_lit27:
2304     case DW_OP_lit28:
2305     case DW_OP_lit29:
2306     case DW_OP_lit30:
2307     case DW_OP_lit31:
2308       stack.push_back(Scalar((uint64_t)(op - DW_OP_lit0)));
2309       break;
2310 
2311     // OPCODE: DW_OP_regN
2312     // OPERANDS: none
2313     // DESCRIPTION: Push the value in register n on the top of the stack.
2314     case DW_OP_reg0:
2315     case DW_OP_reg1:
2316     case DW_OP_reg2:
2317     case DW_OP_reg3:
2318     case DW_OP_reg4:
2319     case DW_OP_reg5:
2320     case DW_OP_reg6:
2321     case DW_OP_reg7:
2322     case DW_OP_reg8:
2323     case DW_OP_reg9:
2324     case DW_OP_reg10:
2325     case DW_OP_reg11:
2326     case DW_OP_reg12:
2327     case DW_OP_reg13:
2328     case DW_OP_reg14:
2329     case DW_OP_reg15:
2330     case DW_OP_reg16:
2331     case DW_OP_reg17:
2332     case DW_OP_reg18:
2333     case DW_OP_reg19:
2334     case DW_OP_reg20:
2335     case DW_OP_reg21:
2336     case DW_OP_reg22:
2337     case DW_OP_reg23:
2338     case DW_OP_reg24:
2339     case DW_OP_reg25:
2340     case DW_OP_reg26:
2341     case DW_OP_reg27:
2342     case DW_OP_reg28:
2343     case DW_OP_reg29:
2344     case DW_OP_reg30:
2345     case DW_OP_reg31: {
2346       reg_num = op - DW_OP_reg0;
2347 
2348       if (ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, error_ptr, tmp))
2349         stack.push_back(tmp);
2350       else
2351         return false;
2352     } break;
2353     // OPCODE: DW_OP_regx
2354     // OPERANDS:
2355     //      ULEB128 literal operand that encodes the register.
2356     // DESCRIPTION: Push the value in register on the top of the stack.
2357     case DW_OP_regx: {
2358       reg_num = opcodes.GetULEB128(&offset);
2359       if (ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, error_ptr, tmp))
2360         stack.push_back(tmp);
2361       else
2362         return false;
2363     } break;
2364 
2365     // OPCODE: DW_OP_bregN
2366     // OPERANDS:
2367     //      SLEB128 offset from register N
2368     // DESCRIPTION: Value is in memory at the address specified by register
2369     // N plus an offset.
2370     case DW_OP_breg0:
2371     case DW_OP_breg1:
2372     case DW_OP_breg2:
2373     case DW_OP_breg3:
2374     case DW_OP_breg4:
2375     case DW_OP_breg5:
2376     case DW_OP_breg6:
2377     case DW_OP_breg7:
2378     case DW_OP_breg8:
2379     case DW_OP_breg9:
2380     case DW_OP_breg10:
2381     case DW_OP_breg11:
2382     case DW_OP_breg12:
2383     case DW_OP_breg13:
2384     case DW_OP_breg14:
2385     case DW_OP_breg15:
2386     case DW_OP_breg16:
2387     case DW_OP_breg17:
2388     case DW_OP_breg18:
2389     case DW_OP_breg19:
2390     case DW_OP_breg20:
2391     case DW_OP_breg21:
2392     case DW_OP_breg22:
2393     case DW_OP_breg23:
2394     case DW_OP_breg24:
2395     case DW_OP_breg25:
2396     case DW_OP_breg26:
2397     case DW_OP_breg27:
2398     case DW_OP_breg28:
2399     case DW_OP_breg29:
2400     case DW_OP_breg30:
2401     case DW_OP_breg31: {
2402       reg_num = op - DW_OP_breg0;
2403 
2404       if (ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, error_ptr,
2405                                     tmp)) {
2406         int64_t breg_offset = opcodes.GetSLEB128(&offset);
2407         tmp.ResolveValue(exe_ctx) += (uint64_t)breg_offset;
2408         tmp.ClearContext();
2409         stack.push_back(tmp);
2410         stack.back().SetValueType(Value::eValueTypeLoadAddress);
2411       } else
2412         return false;
2413     } break;
2414     // OPCODE: DW_OP_bregx
2415     // OPERANDS: 2
2416     //      ULEB128 literal operand that encodes the register.
2417     //      SLEB128 offset from register N
2418     // DESCRIPTION: Value is in memory at the address specified by register
2419     // N plus an offset.
2420     case DW_OP_bregx: {
2421       reg_num = opcodes.GetULEB128(&offset);
2422 
2423       if (ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, error_ptr,
2424                                     tmp)) {
2425         int64_t breg_offset = opcodes.GetSLEB128(&offset);
2426         tmp.ResolveValue(exe_ctx) += (uint64_t)breg_offset;
2427         tmp.ClearContext();
2428         stack.push_back(tmp);
2429         stack.back().SetValueType(Value::eValueTypeLoadAddress);
2430       } else
2431         return false;
2432     } break;
2433 
2434     case DW_OP_fbreg:
2435       if (exe_ctx) {
2436         if (frame) {
2437           Scalar value;
2438           if (frame->GetFrameBaseValue(value, error_ptr)) {
2439             int64_t fbreg_offset = opcodes.GetSLEB128(&offset);
2440             value += fbreg_offset;
2441             stack.push_back(value);
2442             stack.back().SetValueType(Value::eValueTypeLoadAddress);
2443           } else
2444             return false;
2445         } else {
2446           if (error_ptr)
2447             error_ptr->SetErrorString(
2448                 "Invalid stack frame in context for DW_OP_fbreg opcode.");
2449           return false;
2450         }
2451       } else {
2452         if (error_ptr)
2453           error_ptr->SetErrorStringWithFormat(
2454               "NULL execution context for DW_OP_fbreg.\n");
2455         return false;
2456       }
2457 
2458       break;
2459 
2460     // OPCODE: DW_OP_nop
2461     // OPERANDS: none
2462     // DESCRIPTION: A place holder. It has no effect on the location stack
2463     // or any of its values.
2464     case DW_OP_nop:
2465       break;
2466 
2467     // OPCODE: DW_OP_piece
2468     // OPERANDS: 1
2469     //      ULEB128: byte size of the piece
2470     // DESCRIPTION: The operand describes the size in bytes of the piece of
2471     // the object referenced by the DWARF expression whose result is at the top
2472     // of the stack. If the piece is located in a register, but does not occupy
2473     // the entire register, the placement of the piece within that register is
2474     // defined by the ABI.
2475     //
2476     // Many compilers store a single variable in sets of registers, or store a
2477     // variable partially in memory and partially in registers. DW_OP_piece
2478     // provides a way of describing how large a part of a variable a particular
2479     // DWARF expression refers to.
2480     case DW_OP_piece: {
2481       const uint64_t piece_byte_size = opcodes.GetULEB128(&offset);
2482 
2483       if (piece_byte_size > 0) {
2484         Value curr_piece;
2485 
2486         if (stack.empty()) {
2487           // In a multi-piece expression, this means that the current piece is
2488           // not available. Fill with zeros for now by resizing the data and
2489           // appending it
2490           curr_piece.ResizeData(piece_byte_size);
2491           ::memset(curr_piece.GetBuffer().GetBytes(), 0, piece_byte_size);
2492           pieces.AppendDataToHostBuffer(curr_piece);
2493         } else {
2494           Status error;
2495           // Extract the current piece into "curr_piece"
2496           Value curr_piece_source_value(stack.back());
2497           stack.pop_back();
2498 
2499           const Value::ValueType curr_piece_source_value_type =
2500               curr_piece_source_value.GetValueType();
2501           switch (curr_piece_source_value_type) {
2502           case Value::eValueTypeLoadAddress:
2503             if (process) {
2504               if (curr_piece.ResizeData(piece_byte_size) == piece_byte_size) {
2505                 lldb::addr_t load_addr =
2506                     curr_piece_source_value.GetScalar().ULongLong(
2507                         LLDB_INVALID_ADDRESS);
2508                 if (process->ReadMemory(
2509                         load_addr, curr_piece.GetBuffer().GetBytes(),
2510                         piece_byte_size, error) != piece_byte_size) {
2511                   if (error_ptr)
2512                     error_ptr->SetErrorStringWithFormat(
2513                         "failed to read memory DW_OP_piece(%" PRIu64
2514                         ") from 0x%" PRIx64,
2515                         piece_byte_size, load_addr);
2516                   return false;
2517                 }
2518               } else {
2519                 if (error_ptr)
2520                   error_ptr->SetErrorStringWithFormat(
2521                       "failed to resize the piece memory buffer for "
2522                       "DW_OP_piece(%" PRIu64 ")",
2523                       piece_byte_size);
2524                 return false;
2525               }
2526             }
2527             break;
2528 
2529           case Value::eValueTypeFileAddress:
2530           case Value::eValueTypeHostAddress:
2531             if (error_ptr) {
2532               lldb::addr_t addr = curr_piece_source_value.GetScalar().ULongLong(
2533                   LLDB_INVALID_ADDRESS);
2534               error_ptr->SetErrorStringWithFormat(
2535                   "failed to read memory DW_OP_piece(%" PRIu64
2536                   ") from %s address 0x%" PRIx64,
2537                   piece_byte_size, curr_piece_source_value.GetValueType() ==
2538                                            Value::eValueTypeFileAddress
2539                                        ? "file"
2540                                        : "host",
2541                   addr);
2542             }
2543             return false;
2544 
2545           case Value::eValueTypeScalar: {
2546             uint32_t bit_size = piece_byte_size * 8;
2547             uint32_t bit_offset = 0;
2548             if (!curr_piece_source_value.GetScalar().ExtractBitfield(
2549                     bit_size, bit_offset)) {
2550               if (error_ptr)
2551                 error_ptr->SetErrorStringWithFormat(
2552                     "unable to extract %" PRIu64 " bytes from a %" PRIu64
2553                     " byte scalar value.",
2554                     piece_byte_size,
2555                     (uint64_t)curr_piece_source_value.GetScalar()
2556                         .GetByteSize());
2557               return false;
2558             }
2559             curr_piece = curr_piece_source_value;
2560           } break;
2561 
2562           case Value::eValueTypeVector: {
2563             if (curr_piece_source_value.GetVector().length >= piece_byte_size)
2564               curr_piece_source_value.GetVector().length = piece_byte_size;
2565             else {
2566               if (error_ptr)
2567                 error_ptr->SetErrorStringWithFormat(
2568                     "unable to extract %" PRIu64 " bytes from a %" PRIu64
2569                     " byte vector value.",
2570                     piece_byte_size,
2571                     (uint64_t)curr_piece_source_value.GetVector().length);
2572               return false;
2573             }
2574           } break;
2575           }
2576 
2577           // Check if this is the first piece?
2578           if (op_piece_offset == 0) {
2579             // This is the first piece, we should push it back onto the stack
2580             // so subsequent pieces will be able to access this piece and add
2581             // to it
2582             if (pieces.AppendDataToHostBuffer(curr_piece) == 0) {
2583               if (error_ptr)
2584                 error_ptr->SetErrorString("failed to append piece data");
2585               return false;
2586             }
2587           } else {
2588             // If this is the second or later piece there should be a value on
2589             // the stack
2590             if (pieces.GetBuffer().GetByteSize() != op_piece_offset) {
2591               if (error_ptr)
2592                 error_ptr->SetErrorStringWithFormat(
2593                     "DW_OP_piece for offset %" PRIu64
2594                     " but top of stack is of size %" PRIu64,
2595                     op_piece_offset, pieces.GetBuffer().GetByteSize());
2596               return false;
2597             }
2598 
2599             if (pieces.AppendDataToHostBuffer(curr_piece) == 0) {
2600               if (error_ptr)
2601                 error_ptr->SetErrorString("failed to append piece data");
2602               return false;
2603             }
2604           }
2605           op_piece_offset += piece_byte_size;
2606         }
2607       }
2608     } break;
2609 
2610     case DW_OP_bit_piece: // 0x9d ULEB128 bit size, ULEB128 bit offset (DWARF3);
2611       if (stack.size() < 1) {
2612         if (error_ptr)
2613           error_ptr->SetErrorString(
2614               "Expression stack needs at least 1 item for DW_OP_bit_piece.");
2615         return false;
2616       } else {
2617         const uint64_t piece_bit_size = opcodes.GetULEB128(&offset);
2618         const uint64_t piece_bit_offset = opcodes.GetULEB128(&offset);
2619         switch (stack.back().GetValueType()) {
2620         case Value::eValueTypeScalar: {
2621           if (!stack.back().GetScalar().ExtractBitfield(piece_bit_size,
2622                                                         piece_bit_offset)) {
2623             if (error_ptr)
2624               error_ptr->SetErrorStringWithFormat(
2625                   "unable to extract %" PRIu64 " bit value with %" PRIu64
2626                   " bit offset from a %" PRIu64 " bit scalar value.",
2627                   piece_bit_size, piece_bit_offset,
2628                   (uint64_t)(stack.back().GetScalar().GetByteSize() * 8));
2629             return false;
2630           }
2631         } break;
2632 
2633         case Value::eValueTypeFileAddress:
2634         case Value::eValueTypeLoadAddress:
2635         case Value::eValueTypeHostAddress:
2636           if (error_ptr) {
2637             error_ptr->SetErrorStringWithFormat(
2638                 "unable to extract DW_OP_bit_piece(bit_size = %" PRIu64
2639                 ", bit_offset = %" PRIu64 ") from an address value.",
2640                 piece_bit_size, piece_bit_offset);
2641           }
2642           return false;
2643 
2644         case Value::eValueTypeVector:
2645           if (error_ptr) {
2646             error_ptr->SetErrorStringWithFormat(
2647                 "unable to extract DW_OP_bit_piece(bit_size = %" PRIu64
2648                 ", bit_offset = %" PRIu64 ") from a vector value.",
2649                 piece_bit_size, piece_bit_offset);
2650           }
2651           return false;
2652         }
2653       }
2654       break;
2655 
2656     // OPCODE: DW_OP_push_object_address
2657     // OPERANDS: none
2658     // DESCRIPTION: Pushes the address of the object currently being
2659     // evaluated as part of evaluation of a user presented expression. This
2660     // object may correspond to an independent variable described by its own
2661     // DIE or it may be a component of an array, structure, or class whose
2662     // address has been dynamically determined by an earlier step during user
2663     // expression evaluation.
2664     case DW_OP_push_object_address:
2665       if (object_address_ptr)
2666         stack.push_back(*object_address_ptr);
2667       else {
2668         if (error_ptr)
2669           error_ptr->SetErrorString("DW_OP_push_object_address used without "
2670                                     "specifying an object address");
2671         return false;
2672       }
2673       break;
2674 
2675     // OPCODE: DW_OP_call2
2676     // OPERANDS:
2677     //      uint16_t compile unit relative offset of a DIE
2678     // DESCRIPTION: Performs subroutine calls during evaluation
2679     // of a DWARF expression. The operand is the 2-byte unsigned offset of a
2680     // debugging information entry in the current compilation unit.
2681     //
2682     // Operand interpretation is exactly like that for DW_FORM_ref2.
2683     //
2684     // This operation transfers control of DWARF expression evaluation to the
2685     // DW_AT_location attribute of the referenced DIE. If there is no such
2686     // attribute, then there is no effect. Execution of the DWARF expression of
2687     // a DW_AT_location attribute may add to and/or remove from values on the
2688     // stack. Execution returns to the point following the call when the end of
2689     // the attribute is reached. Values on the stack at the time of the call
2690     // may be used as parameters by the called expression and values left on
2691     // the stack by the called expression may be used as return values by prior
2692     // agreement between the calling and called expressions.
2693     case DW_OP_call2:
2694       if (error_ptr)
2695         error_ptr->SetErrorString("Unimplemented opcode DW_OP_call2.");
2696       return false;
2697     // OPCODE: DW_OP_call4
2698     // OPERANDS: 1
2699     //      uint32_t compile unit relative offset of a DIE
2700     // DESCRIPTION: Performs a subroutine call during evaluation of a DWARF
2701     // expression. For DW_OP_call4, the operand is a 4-byte unsigned offset of
2702     // a debugging information entry in  the current compilation unit.
2703     //
2704     // Operand interpretation DW_OP_call4 is exactly like that for
2705     // DW_FORM_ref4.
2706     //
2707     // This operation transfers control of DWARF expression evaluation to the
2708     // DW_AT_location attribute of the referenced DIE. If there is no such
2709     // attribute, then there is no effect. Execution of the DWARF expression of
2710     // a DW_AT_location attribute may add to and/or remove from values on the
2711     // stack. Execution returns to the point following the call when the end of
2712     // the attribute is reached. Values on the stack at the time of the call
2713     // may be used as parameters by the called expression and values left on
2714     // the stack by the called expression may be used as return values by prior
2715     // agreement between the calling and called expressions.
2716     case DW_OP_call4:
2717       if (error_ptr)
2718         error_ptr->SetErrorString("Unimplemented opcode DW_OP_call4.");
2719       return false;
2720 
2721     // OPCODE: DW_OP_stack_value
2722     // OPERANDS: None
2723     // DESCRIPTION: Specifies that the object does not exist in memory but
2724     // rather is a constant value.  The value from the top of the stack is the
2725     // value to be used.  This is the actual object value and not the location.
2726     case DW_OP_stack_value:
2727       stack.back().SetValueType(Value::eValueTypeScalar);
2728       break;
2729 
2730     // OPCODE: DW_OP_call_frame_cfa
2731     // OPERANDS: None
2732     // DESCRIPTION: Specifies a DWARF expression that pushes the value of
2733     // the canonical frame address consistent with the call frame information
2734     // located in .debug_frame (or in the FDEs of the eh_frame section).
2735     case DW_OP_call_frame_cfa:
2736       if (frame) {
2737         // Note that we don't have to parse FDEs because this DWARF expression
2738         // is commonly evaluated with a valid stack frame.
2739         StackID id = frame->GetStackID();
2740         addr_t cfa = id.GetCallFrameAddress();
2741         if (cfa != LLDB_INVALID_ADDRESS) {
2742           stack.push_back(Scalar(cfa));
2743           stack.back().SetValueType(Value::eValueTypeLoadAddress);
2744         } else if (error_ptr)
2745           error_ptr->SetErrorString("Stack frame does not include a canonical "
2746                                     "frame address for DW_OP_call_frame_cfa "
2747                                     "opcode.");
2748       } else {
2749         if (error_ptr)
2750           error_ptr->SetErrorString("Invalid stack frame in context for "
2751                                     "DW_OP_call_frame_cfa opcode.");
2752         return false;
2753       }
2754       break;
2755 
2756     // OPCODE: DW_OP_form_tls_address (or the old pre-DWARFv3 vendor extension
2757     // opcode, DW_OP_GNU_push_tls_address)
2758     // OPERANDS: none
2759     // DESCRIPTION: Pops a TLS offset from the stack, converts it to
2760     // an address in the current thread's thread-local storage block, and
2761     // pushes it on the stack.
2762     case DW_OP_form_tls_address:
2763     case DW_OP_GNU_push_tls_address: {
2764       if (stack.size() < 1) {
2765         if (error_ptr) {
2766           if (op == DW_OP_form_tls_address)
2767             error_ptr->SetErrorString(
2768                 "DW_OP_form_tls_address needs an argument.");
2769           else
2770             error_ptr->SetErrorString(
2771                 "DW_OP_GNU_push_tls_address needs an argument.");
2772         }
2773         return false;
2774       }
2775 
2776       if (!exe_ctx || !module_sp) {
2777         if (error_ptr)
2778           error_ptr->SetErrorString("No context to evaluate TLS within.");
2779         return false;
2780       }
2781 
2782       Thread *thread = exe_ctx->GetThreadPtr();
2783       if (!thread) {
2784         if (error_ptr)
2785           error_ptr->SetErrorString("No thread to evaluate TLS within.");
2786         return false;
2787       }
2788 
2789       // Lookup the TLS block address for this thread and module.
2790       const addr_t tls_file_addr =
2791           stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
2792       const addr_t tls_load_addr =
2793           thread->GetThreadLocalData(module_sp, tls_file_addr);
2794 
2795       if (tls_load_addr == LLDB_INVALID_ADDRESS) {
2796         if (error_ptr)
2797           error_ptr->SetErrorString(
2798               "No TLS data currently exists for this thread.");
2799         return false;
2800       }
2801 
2802       stack.back().GetScalar() = tls_load_addr;
2803       stack.back().SetValueType(Value::eValueTypeLoadAddress);
2804     } break;
2805 
2806     // OPCODE: DW_OP_addrx (DW_OP_GNU_addr_index is the legacy name.)
2807     // OPERANDS: 1
2808     //      ULEB128: index to the .debug_addr section
2809     // DESCRIPTION: Pushes an address to the stack from the .debug_addr
2810     // section with the base address specified by the DW_AT_addr_base attribute
2811     // and the 0 based index is the ULEB128 encoded index.
2812     case DW_OP_addrx:
2813     case DW_OP_GNU_addr_index: {
2814       if (!dwarf_cu) {
2815         if (error_ptr)
2816           error_ptr->SetErrorString("DW_OP_GNU_addr_index found without a "
2817                                     "compile unit being specified");
2818         return false;
2819       }
2820       uint64_t index = opcodes.GetULEB128(&offset);
2821       uint32_t index_size = dwarf_cu->GetAddressByteSize();
2822       dw_offset_t addr_base = dwarf_cu->GetAddrBase();
2823       lldb::offset_t offset = addr_base + index * index_size;
2824       uint64_t value =
2825           dwarf_cu->GetSymbolFileDWARF()->get_debug_addr_data().GetMaxU64(
2826               &offset, index_size);
2827       stack.push_back(Scalar(value));
2828       stack.back().SetValueType(Value::eValueTypeFileAddress);
2829     } break;
2830 
2831     // OPCODE: DW_OP_GNU_const_index
2832     // OPERANDS: 1
2833     //      ULEB128: index to the .debug_addr section
2834     // DESCRIPTION: Pushes an constant with the size of a machine address to
2835     // the stack from the .debug_addr section with the base address specified
2836     // by the DW_AT_addr_base attribute and the 0 based index is the ULEB128
2837     // encoded index.
2838     case DW_OP_GNU_const_index: {
2839       if (!dwarf_cu) {
2840         if (error_ptr)
2841           error_ptr->SetErrorString("DW_OP_GNU_const_index found without a "
2842                                     "compile unit being specified");
2843         return false;
2844       }
2845       uint64_t index = opcodes.GetULEB128(&offset);
2846       uint32_t index_size = dwarf_cu->GetAddressByteSize();
2847       dw_offset_t addr_base = dwarf_cu->GetAddrBase();
2848       lldb::offset_t offset = addr_base + index * index_size;
2849       const DWARFDataExtractor &debug_addr =
2850           dwarf_cu->GetSymbolFileDWARF()->get_debug_addr_data();
2851       switch (index_size) {
2852       case 4:
2853         stack.push_back(Scalar(debug_addr.GetU32(&offset)));
2854         break;
2855       case 8:
2856         stack.push_back(Scalar(debug_addr.GetU64(&offset)));
2857         break;
2858       default:
2859         assert(false && "Unhandled index size");
2860         return false;
2861       }
2862     } break;
2863 
2864     default:
2865       if (log)
2866         log->Printf("Unhandled opcode %s in DWARFExpression.",
2867                     DW_OP_value_to_name(op));
2868       break;
2869     }
2870   }
2871 
2872   if (stack.empty()) {
2873     // Nothing on the stack, check if we created a piece value from DW_OP_piece
2874     // or DW_OP_bit_piece opcodes
2875     if (pieces.GetBuffer().GetByteSize()) {
2876       result = pieces;
2877     } else {
2878       if (error_ptr)
2879         error_ptr->SetErrorString("Stack empty after evaluation.");
2880       return false;
2881     }
2882   } else {
2883     if (log && log->GetVerbose()) {
2884       size_t count = stack.size();
2885       log->Printf("Stack after operation has %" PRIu64 " values:",
2886                   (uint64_t)count);
2887       for (size_t i = 0; i < count; ++i) {
2888         StreamString new_value;
2889         new_value.Printf("[%" PRIu64 "]", (uint64_t)i);
2890         stack[i].Dump(&new_value);
2891         log->Printf("  %s", new_value.GetData());
2892       }
2893     }
2894     result = stack.back();
2895   }
2896   return true; // Return true on success
2897 }
2898 
2899 size_t DWARFExpression::LocationListSize(const DWARFUnit *dwarf_cu,
2900                                          const DataExtractor &debug_loc_data,
2901                                          lldb::offset_t offset) {
2902   const lldb::offset_t debug_loc_offset = offset;
2903   while (debug_loc_data.ValidOffset(offset)) {
2904     lldb::addr_t start_addr = LLDB_INVALID_ADDRESS;
2905     lldb::addr_t end_addr = LLDB_INVALID_ADDRESS;
2906     if (!AddressRangeForLocationListEntry(dwarf_cu, debug_loc_data, &offset,
2907                                           start_addr, end_addr))
2908       break;
2909 
2910     if (start_addr == 0 && end_addr == 0)
2911       break;
2912 
2913     uint16_t loc_length = debug_loc_data.GetU16(&offset);
2914     offset += loc_length;
2915   }
2916 
2917   if (offset > debug_loc_offset)
2918     return offset - debug_loc_offset;
2919   return 0;
2920 }
2921 
2922 bool DWARFExpression::AddressRangeForLocationListEntry(
2923     const DWARFUnit *dwarf_cu, const DataExtractor &debug_loc_data,
2924     lldb::offset_t *offset_ptr, lldb::addr_t &low_pc, lldb::addr_t &high_pc) {
2925   if (!debug_loc_data.ValidOffset(*offset_ptr))
2926     return false;
2927 
2928   DWARFExpression::LocationListFormat format =
2929       dwarf_cu->GetSymbolFileDWARF()->GetLocationListFormat();
2930   switch (format) {
2931   case NonLocationList:
2932     return false;
2933   case RegularLocationList:
2934     low_pc = debug_loc_data.GetAddress(offset_ptr);
2935     high_pc = debug_loc_data.GetAddress(offset_ptr);
2936     return true;
2937   case SplitDwarfLocationList:
2938   case LocLists:
2939     switch (debug_loc_data.GetU8(offset_ptr)) {
2940     case DW_LLE_end_of_list:
2941       return false;
2942     case DW_LLE_startx_endx: {
2943       uint64_t index = debug_loc_data.GetULEB128(offset_ptr);
2944       low_pc = ReadAddressFromDebugAddrSection(dwarf_cu, index);
2945       index = debug_loc_data.GetULEB128(offset_ptr);
2946       high_pc = ReadAddressFromDebugAddrSection(dwarf_cu, index);
2947       return true;
2948     }
2949     case DW_LLE_startx_length: {
2950       uint64_t index = debug_loc_data.GetULEB128(offset_ptr);
2951       low_pc = ReadAddressFromDebugAddrSection(dwarf_cu, index);
2952       uint64_t length = (format == LocLists)
2953                             ? debug_loc_data.GetULEB128(offset_ptr)
2954                             : debug_loc_data.GetU32(offset_ptr);
2955       high_pc = low_pc + length;
2956       return true;
2957     }
2958     case DW_LLE_start_length: {
2959       low_pc = debug_loc_data.GetAddress(offset_ptr);
2960       high_pc = low_pc + debug_loc_data.GetULEB128(offset_ptr);
2961       return true;
2962     }
2963     case DW_LLE_start_end: {
2964       low_pc = debug_loc_data.GetAddress(offset_ptr);
2965       high_pc = debug_loc_data.GetAddress(offset_ptr);
2966       return true;
2967     }
2968     default:
2969       // Not supported entry type
2970       lldbassert(false && "Not supported location list type");
2971       return false;
2972     }
2973   }
2974   assert(false && "Not supported location list type");
2975   return false;
2976 }
2977 
2978 static bool print_dwarf_exp_op(Stream &s, const DataExtractor &data,
2979                                lldb::offset_t *offset_ptr, int address_size,
2980                                int dwarf_ref_size) {
2981   uint8_t opcode = data.GetU8(offset_ptr);
2982   DRC_class opcode_class;
2983   uint64_t uint;
2984   int64_t sint;
2985 
2986   int size;
2987 
2988   opcode_class = DW_OP_value_to_class(opcode) & (~DRC_DWARFv3);
2989 
2990   s.Printf("%s ", DW_OP_value_to_name(opcode));
2991 
2992   /* Does this take zero parameters?  If so we can shortcut this function.  */
2993   if (opcode_class == DRC_ZEROOPERANDS)
2994     return true;
2995 
2996   if (opcode_class == DRC_TWOOPERANDS && opcode == DW_OP_bregx) {
2997     uint = data.GetULEB128(offset_ptr);
2998     sint = data.GetSLEB128(offset_ptr);
2999     s.Printf("%" PRIu64 " %" PRIi64, uint, sint);
3000     return true;
3001   }
3002   if (opcode_class != DRC_ONEOPERAND) {
3003     s.Printf("UNKNOWN OP %u", opcode);
3004     return false;
3005   }
3006 
3007   switch (opcode) {
3008   case DW_OP_addr:
3009     size = address_size;
3010     break;
3011   case DW_OP_const1u:
3012     size = 1;
3013     break;
3014   case DW_OP_const1s:
3015     size = -1;
3016     break;
3017   case DW_OP_const2u:
3018     size = 2;
3019     break;
3020   case DW_OP_const2s:
3021     size = -2;
3022     break;
3023   case DW_OP_const4u:
3024     size = 4;
3025     break;
3026   case DW_OP_const4s:
3027     size = -4;
3028     break;
3029   case DW_OP_const8u:
3030     size = 8;
3031     break;
3032   case DW_OP_const8s:
3033     size = -8;
3034     break;
3035   case DW_OP_constu:
3036     size = 128;
3037     break;
3038   case DW_OP_consts:
3039     size = -128;
3040     break;
3041   case DW_OP_fbreg:
3042     size = -128;
3043     break;
3044   case DW_OP_breg0:
3045   case DW_OP_breg1:
3046   case DW_OP_breg2:
3047   case DW_OP_breg3:
3048   case DW_OP_breg4:
3049   case DW_OP_breg5:
3050   case DW_OP_breg6:
3051   case DW_OP_breg7:
3052   case DW_OP_breg8:
3053   case DW_OP_breg9:
3054   case DW_OP_breg10:
3055   case DW_OP_breg11:
3056   case DW_OP_breg12:
3057   case DW_OP_breg13:
3058   case DW_OP_breg14:
3059   case DW_OP_breg15:
3060   case DW_OP_breg16:
3061   case DW_OP_breg17:
3062   case DW_OP_breg18:
3063   case DW_OP_breg19:
3064   case DW_OP_breg20:
3065   case DW_OP_breg21:
3066   case DW_OP_breg22:
3067   case DW_OP_breg23:
3068   case DW_OP_breg24:
3069   case DW_OP_breg25:
3070   case DW_OP_breg26:
3071   case DW_OP_breg27:
3072   case DW_OP_breg28:
3073   case DW_OP_breg29:
3074   case DW_OP_breg30:
3075   case DW_OP_breg31:
3076     size = -128;
3077     break;
3078   case DW_OP_pick:
3079   case DW_OP_deref_size:
3080   case DW_OP_xderef_size:
3081     size = 1;
3082     break;
3083   case DW_OP_skip:
3084   case DW_OP_bra:
3085     size = -2;
3086     break;
3087   case DW_OP_call2:
3088     size = 2;
3089     break;
3090   case DW_OP_call4:
3091     size = 4;
3092     break;
3093   case DW_OP_call_ref:
3094     size = dwarf_ref_size;
3095     break;
3096   case DW_OP_addrx:
3097   case DW_OP_piece:
3098   case DW_OP_plus_uconst:
3099   case DW_OP_regx:
3100   case DW_OP_GNU_addr_index:
3101   case DW_OP_GNU_const_index:
3102     size = 128;
3103     break;
3104   default:
3105     s.Printf("UNKNOWN ONE-OPERAND OPCODE, #%u", opcode);
3106     return false;
3107   }
3108 
3109   switch (size) {
3110   case -1:
3111     sint = (int8_t)data.GetU8(offset_ptr);
3112     s.Printf("%+" PRIi64, sint);
3113     break;
3114   case -2:
3115     sint = (int16_t)data.GetU16(offset_ptr);
3116     s.Printf("%+" PRIi64, sint);
3117     break;
3118   case -4:
3119     sint = (int32_t)data.GetU32(offset_ptr);
3120     s.Printf("%+" PRIi64, sint);
3121     break;
3122   case -8:
3123     sint = (int64_t)data.GetU64(offset_ptr);
3124     s.Printf("%+" PRIi64, sint);
3125     break;
3126   case -128:
3127     sint = data.GetSLEB128(offset_ptr);
3128     s.Printf("%+" PRIi64, sint);
3129     break;
3130   case 1:
3131     uint = data.GetU8(offset_ptr);
3132     s.Printf("0x%2.2" PRIx64, uint);
3133     break;
3134   case 2:
3135     uint = data.GetU16(offset_ptr);
3136     s.Printf("0x%4.4" PRIx64, uint);
3137     break;
3138   case 4:
3139     uint = data.GetU32(offset_ptr);
3140     s.Printf("0x%8.8" PRIx64, uint);
3141     break;
3142   case 8:
3143     uint = data.GetU64(offset_ptr);
3144     s.Printf("0x%16.16" PRIx64, uint);
3145     break;
3146   case 128:
3147     uint = data.GetULEB128(offset_ptr);
3148     s.Printf("0x%" PRIx64, uint);
3149     break;
3150   }
3151 
3152   return true;
3153 }
3154 
3155 bool DWARFExpression::PrintDWARFExpression(Stream &s, const DataExtractor &data,
3156                                            int address_size, int dwarf_ref_size,
3157                                            bool location_expression) {
3158   int op_count = 0;
3159   lldb::offset_t offset = 0;
3160   while (data.ValidOffset(offset)) {
3161     if (location_expression && op_count > 0)
3162       return false;
3163     if (op_count > 0)
3164       s.PutCString(", ");
3165     if (!print_dwarf_exp_op(s, data, &offset, address_size, dwarf_ref_size))
3166       return false;
3167     op_count++;
3168   }
3169 
3170   return true;
3171 }
3172 
3173 void DWARFExpression::PrintDWARFLocationList(
3174     Stream &s, const DWARFUnit *cu, const DataExtractor &debug_loc_data,
3175     lldb::offset_t offset) {
3176   uint64_t start_addr, end_addr;
3177   uint32_t addr_size = DWARFUnit::GetAddressByteSize(cu);
3178   s.SetAddressByteSize(DWARFUnit::GetAddressByteSize(cu));
3179   dw_addr_t base_addr = cu ? cu->GetBaseAddress() : 0;
3180   while (debug_loc_data.ValidOffset(offset)) {
3181     start_addr = debug_loc_data.GetMaxU64(&offset, addr_size);
3182     end_addr = debug_loc_data.GetMaxU64(&offset, addr_size);
3183 
3184     if (start_addr == 0 && end_addr == 0)
3185       break;
3186 
3187     s.PutCString("\n            ");
3188     s.Indent();
3189     if (cu)
3190       s.AddressRange(start_addr + base_addr, end_addr + base_addr,
3191                      cu->GetAddressByteSize(), NULL, ": ");
3192     uint32_t loc_length = debug_loc_data.GetU16(&offset);
3193 
3194     DataExtractor locationData(debug_loc_data, offset, loc_length);
3195     PrintDWARFExpression(s, locationData, addr_size, 4, false);
3196     offset += loc_length;
3197   }
3198 }
3199 
3200 bool DWARFExpression::GetOpAndEndOffsets(StackFrame &frame,
3201                                          lldb::offset_t &op_offset,
3202                                          lldb::offset_t &end_offset) {
3203   SymbolContext sc = frame.GetSymbolContext(eSymbolContextFunction);
3204   if (!sc.function) {
3205     return false;
3206   }
3207 
3208   addr_t loclist_base_file_addr =
3209       sc.function->GetAddressRange().GetBaseAddress().GetFileAddress();
3210   if (loclist_base_file_addr == LLDB_INVALID_ADDRESS) {
3211     return false;
3212   }
3213 
3214   addr_t pc_file_addr = frame.GetFrameCodeAddress().GetFileAddress();
3215   lldb::offset_t opcodes_offset, opcodes_length;
3216   if (!GetLocation(loclist_base_file_addr, pc_file_addr, opcodes_offset,
3217                    opcodes_length)) {
3218     return false;
3219   }
3220 
3221   if (opcodes_length == 0) {
3222     return false;
3223   }
3224 
3225   op_offset = opcodes_offset;
3226   end_offset = opcodes_offset + opcodes_length;
3227   return true;
3228 }
3229 
3230 bool DWARFExpression::MatchesOperand(StackFrame &frame,
3231                                      const Instruction::Operand &operand) {
3232   using namespace OperandMatchers;
3233 
3234   lldb::offset_t op_offset;
3235   lldb::offset_t end_offset;
3236   if (!GetOpAndEndOffsets(frame, op_offset, end_offset)) {
3237     return false;
3238   }
3239 
3240   if (!m_data.ValidOffset(op_offset) || op_offset >= end_offset) {
3241     return false;
3242   }
3243 
3244   RegisterContextSP reg_ctx_sp = frame.GetRegisterContext();
3245   if (!reg_ctx_sp) {
3246     return false;
3247   }
3248 
3249   DataExtractor opcodes = m_data;
3250   uint8_t opcode = opcodes.GetU8(&op_offset);
3251 
3252   if (opcode == DW_OP_fbreg) {
3253     int64_t offset = opcodes.GetSLEB128(&op_offset);
3254 
3255     DWARFExpression *fb_expr = frame.GetFrameBaseExpression(nullptr);
3256     if (!fb_expr) {
3257       return false;
3258     }
3259 
3260     auto recurse = [&frame, fb_expr](const Instruction::Operand &child) {
3261       return fb_expr->MatchesOperand(frame, child);
3262     };
3263 
3264     if (!offset &&
3265         MatchUnaryOp(MatchOpType(Instruction::Operand::Type::Dereference),
3266                      recurse)(operand)) {
3267       return true;
3268     }
3269 
3270     return MatchUnaryOp(
3271         MatchOpType(Instruction::Operand::Type::Dereference),
3272         MatchBinaryOp(MatchOpType(Instruction::Operand::Type::Sum),
3273                       MatchImmOp(offset), recurse))(operand);
3274   }
3275 
3276   bool dereference = false;
3277   const RegisterInfo *reg = nullptr;
3278   int64_t offset = 0;
3279 
3280   if (opcode >= DW_OP_reg0 && opcode <= DW_OP_reg31) {
3281     reg = reg_ctx_sp->GetRegisterInfo(m_reg_kind, opcode - DW_OP_reg0);
3282   } else if (opcode >= DW_OP_breg0 && opcode <= DW_OP_breg31) {
3283     offset = opcodes.GetSLEB128(&op_offset);
3284     reg = reg_ctx_sp->GetRegisterInfo(m_reg_kind, opcode - DW_OP_breg0);
3285   } else if (opcode == DW_OP_regx) {
3286     uint32_t reg_num = static_cast<uint32_t>(opcodes.GetULEB128(&op_offset));
3287     reg = reg_ctx_sp->GetRegisterInfo(m_reg_kind, reg_num);
3288   } else if (opcode == DW_OP_bregx) {
3289     uint32_t reg_num = static_cast<uint32_t>(opcodes.GetULEB128(&op_offset));
3290     offset = opcodes.GetSLEB128(&op_offset);
3291     reg = reg_ctx_sp->GetRegisterInfo(m_reg_kind, reg_num);
3292   } else {
3293     return false;
3294   }
3295 
3296   if (!reg) {
3297     return false;
3298   }
3299 
3300   if (dereference) {
3301     if (!offset &&
3302         MatchUnaryOp(MatchOpType(Instruction::Operand::Type::Dereference),
3303                      MatchRegOp(*reg))(operand)) {
3304       return true;
3305     }
3306 
3307     return MatchUnaryOp(
3308         MatchOpType(Instruction::Operand::Type::Dereference),
3309         MatchBinaryOp(MatchOpType(Instruction::Operand::Type::Sum),
3310                       MatchRegOp(*reg),
3311                       MatchImmOp(offset)))(operand);
3312   } else {
3313     return MatchRegOp(*reg)(operand);
3314   }
3315 }
3316 
3317