1 //===-- UnwindAssemblyInstEmulation.cpp --------------------------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "UnwindAssemblyInstEmulation.h"
11 
12 #include "lldb/Core/Address.h"
13 #include "lldb/Core/ArchSpec.h"
14 #include "lldb/Core/DataBufferHeap.h"
15 #include "lldb/Core/DataExtractor.h"
16 #include "lldb/Core/Disassembler.h"
17 #include "lldb/Core/Error.h"
18 #include "lldb/Core/Log.h"
19 #include "lldb/Core/PluginManager.h"
20 #include "lldb/Core/StreamString.h"
21 #include "lldb/Target/ExecutionContext.h"
22 #include "lldb/Target/Process.h"
23 #include "lldb/Target/Thread.h"
24 #include "lldb/Target/Target.h"
25 
26 using namespace lldb;
27 using namespace lldb_private;
28 
29 
30 
31 //-----------------------------------------------------------------------------------------------
32 //  UnwindAssemblyInstEmulation method definitions
33 //-----------------------------------------------------------------------------------------------
34 
35 bool
36 UnwindAssemblyInstEmulation::GetNonCallSiteUnwindPlanFromAssembly (AddressRange& range,
37                                                                    Thread& thread,
38                                                                    UnwindPlan& unwind_plan)
39 {
40     if (range.GetByteSize() > 0 &&
41         range.GetBaseAddress().IsValid() &&
42         m_inst_emulator_ap.get())
43     {
44 
45         // The the instruction emulation subclass setup the unwind plan for the
46         // first instruction.
47         m_inst_emulator_ap->CreateFunctionEntryUnwind (unwind_plan);
48 
49         // CreateFunctionEntryUnwind should have created the first row. If it
50         // doesn't, then we are done.
51         if (unwind_plan.GetRowCount() == 0)
52             return false;
53 
54         ExecutionContext exe_ctx;
55         thread.CalculateExecutionContext(exe_ctx);
56         DisassemblerSP disasm_sp (Disassembler::DisassembleRange (m_arch,
57                                                                   NULL,
58                                                                   NULL,
59                                                                   exe_ctx,
60                                                                   range));
61 
62         Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
63 
64         if (disasm_sp)
65         {
66 
67             m_range_ptr = ⦥
68             m_thread_ptr = &thread;
69             m_unwind_plan_ptr = &unwind_plan;
70 
71             const uint32_t addr_byte_size = m_arch.GetAddressByteSize();
72             const bool show_address = true;
73             const bool show_bytes = true;
74             m_inst_emulator_ap->GetRegisterInfo (unwind_plan.GetRegisterKind(),
75                                                  unwind_plan.GetInitialCFARegister(),
76                                                  m_cfa_reg_info);
77 
78             m_fp_is_cfa = false;
79             m_register_values.clear();
80             m_pushed_regs.clear();
81 
82             // Initialize the CFA with a known value. In the 32 bit case
83             // it will be 0x80000000, and in the 64 bit case 0x8000000000000000.
84             // We use the address byte size to be safe for any future addresss sizes
85             m_initial_sp = (1ull << ((addr_byte_size * 8) - 1));
86             RegisterValue cfa_reg_value;
87             cfa_reg_value.SetUInt (m_initial_sp, m_cfa_reg_info.byte_size);
88             SetRegisterValue (m_cfa_reg_info, cfa_reg_value);
89 
90             const InstructionList &inst_list = disasm_sp->GetInstructionList ();
91             const size_t num_instructions = inst_list.GetSize();
92 
93             if (num_instructions > 0)
94             {
95                 Instruction *inst = inst_list.GetInstructionAtIndex (0).get();
96                 const addr_t base_addr = inst->GetAddress().GetFileAddress();
97 
98                 // Make a copy of the current instruction Row and save it in m_curr_row
99                 // so we can add updates as we process the instructions.
100                 UnwindPlan::RowSP last_row = unwind_plan.GetLastRow();
101                 UnwindPlan::Row *newrow = new UnwindPlan::Row;
102                 if (last_row.get())
103                     *newrow = *last_row.get();
104                 m_curr_row.reset(newrow);
105 
106                 // Once we've seen the initial prologue instructions complete, save a
107                 // copy of the CFI at that point into prologue_completed_row for possible
108                 // use later.
109                 int instructions_since_last_prologue_insn = 0;     // # of insns since last CFI was update
110 
111                 bool reinstate_prologue_next_instruction = false;  // Next iteration, re-install the prologue row of CFI
112 
113                 bool last_instruction_restored_return_addr_reg = false;  // re-install the prologue row of CFI if the next instruction is a branch immediate
114 
115                 bool return_address_register_has_been_saved = false; // if we've seen the ra register get saved yet
116 
117                 UnwindPlan::RowSP prologue_completed_row;          // copy of prologue row of CFI
118 
119                 // cache the pc register number (in whatever register numbering this UnwindPlan uses) for
120                 // quick reference during instruction parsing.
121                 uint32_t pc_reg_num = LLDB_INVALID_REGNUM;
122                 RegisterInfo pc_reg_info;
123                 if (m_inst_emulator_ap->GetRegisterInfo (eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC, pc_reg_info))
124                     pc_reg_num = pc_reg_info.kinds[unwind_plan.GetRegisterKind()];
125                 else
126                     pc_reg_num = LLDB_INVALID_REGNUM;
127 
128                 // cache the return address register number (in whatever register numbering this UnwindPlan uses) for
129                 // quick reference during instruction parsing.
130                 uint32_t ra_reg_num = LLDB_INVALID_REGNUM;
131                 RegisterInfo ra_reg_info;
132                 if (m_inst_emulator_ap->GetRegisterInfo (eRegisterKindGeneric, LLDB_REGNUM_GENERIC_RA, ra_reg_info))
133                     ra_reg_num = ra_reg_info.kinds[unwind_plan.GetRegisterKind()];
134                 else
135                     ra_reg_num = LLDB_INVALID_REGNUM;
136 
137                 for (size_t idx=0; idx<num_instructions; ++idx)
138                 {
139                     m_curr_row_modified = false;
140                     m_curr_insn_restored_a_register = false;
141                     inst = inst_list.GetInstructionAtIndex (idx).get();
142                     if (inst)
143                     {
144                         if (log && log->GetVerbose ())
145                         {
146                             StreamString strm;
147                             inst->Dump(&strm, inst_list.GetMaxOpcocdeByteSize (), show_address, show_bytes, NULL);
148                             log->PutCString (strm.GetData());
149                         }
150 
151                         m_inst_emulator_ap->SetInstruction (inst->GetOpcode(),
152                                                             inst->GetAddress(),
153                                                             exe_ctx.GetTargetPtr());
154 
155                         m_inst_emulator_ap->EvaluateInstruction (eEmulateInstructionOptionIgnoreConditions);
156 
157                         // Were there any changes to the CFI while evaluating this instruction?
158                         if (m_curr_row_modified)
159                         {
160                             reinstate_prologue_next_instruction = false;
161                             m_curr_row->SetOffset (inst->GetAddress().GetFileAddress() + inst->GetOpcode().GetByteSize() - base_addr);
162                             // Append the new row
163                             unwind_plan.AppendRow (m_curr_row);
164 
165                             // Allocate a new Row for m_curr_row, copy the current state into it
166                             UnwindPlan::Row *newrow = new UnwindPlan::Row;
167                             *newrow = *m_curr_row.get();
168                             m_curr_row.reset(newrow);
169 
170                             // If m_curr_insn_restored_a_register == true, we're looking at an epilogue instruction.
171                             // Set instructions_since_last_prologue_insn to a very high number so we don't append
172                             // any of these epilogue instructions to our prologue_complete row.
173                             if (m_curr_insn_restored_a_register == false && instructions_since_last_prologue_insn < 8)
174                               instructions_since_last_prologue_insn = 0;
175                             else
176                               instructions_since_last_prologue_insn = 99;
177 
178                             UnwindPlan::Row::RegisterLocation pc_regloc;
179                             UnwindPlan::Row::RegisterLocation ra_regloc;
180 
181                             // While parsing the instructions of this function, if we've ever
182                             // seen the return address register (aka lr on arm) in a non-IsSame() state,
183                             // it has been saved on the stack.  If it's evern back to IsSame(), we've
184                             // executed an epilogue.
185                             if (ra_reg_num != LLDB_INVALID_REGNUM
186                                 && m_curr_row->GetRegisterInfo (ra_reg_num, ra_regloc)
187                                 && !ra_regloc.IsSame())
188                             {
189                                 return_address_register_has_been_saved = true;
190                             }
191 
192                             // If the caller's pc is "same", we've just executed an epilogue and we return to the caller
193                             // after this instruction completes executing.
194                             // If there are any instructions past this, there must have been flow control over this
195                             // epilogue so we'll reinstate the original prologue setup instructions.
196                             if (prologue_completed_row.get()
197                                 && pc_reg_num != LLDB_INVALID_REGNUM
198                                 && m_curr_row->GetRegisterInfo (pc_reg_num, pc_regloc)
199                                 && pc_regloc.IsSame())
200                             {
201                                 if (log && log->GetVerbose())
202                                     log->Printf("UnwindAssemblyInstEmulation::GetNonCallSiteUnwindPlanFromAssembly -- pc is <same>, restore prologue instructions.");
203                                 reinstate_prologue_next_instruction = true;
204                             }
205                             else if (prologue_completed_row.get()
206                                      && return_address_register_has_been_saved
207                                      && ra_reg_num != LLDB_INVALID_REGNUM
208                                      && m_curr_row->GetRegisterInfo (ra_reg_num, ra_regloc)
209                                      && ra_regloc.IsSame())
210                             {
211                                 if (log && log->GetVerbose())
212                                     log->Printf("UnwindAssemblyInstEmulation::GetNonCallSiteUnwindPlanFromAssembly -- lr is <same>, restore prologue instruction if the next instruction is a branch immediate.");
213                                 last_instruction_restored_return_addr_reg = true;
214                             }
215                         }
216                         else
217                         {
218                             // If the previous instruction was a return-to-caller (epilogue), and we're still executing
219                             // instructions in this function, there must be a code path that jumps over that epilogue.
220                             // Also detect the case where we epilogue & branch imm to another function (tail-call opt)
221                             // instead of a normal pop lr-into-pc exit.
222                             // Reinstate the frame setup from the prologue.
223                             if (reinstate_prologue_next_instruction
224                                 || (m_curr_insn_is_branch_immediate && last_instruction_restored_return_addr_reg))
225                             {
226                                 if (log && log->GetVerbose())
227                                     log->Printf("UnwindAssemblyInstEmulation::GetNonCallSiteUnwindPlanFromAssembly -- Reinstating prologue instruction set");
228                                 UnwindPlan::Row *newrow = new UnwindPlan::Row;
229                                 *newrow = *prologue_completed_row.get();
230                                 m_curr_row.reset(newrow);
231                                 m_curr_row->SetOffset (inst->GetAddress().GetFileAddress() + inst->GetOpcode().GetByteSize() - base_addr);
232                                 unwind_plan.AppendRow(m_curr_row);
233 
234                                 newrow = new UnwindPlan::Row;
235                                 *newrow = *m_curr_row.get();
236                                 m_curr_row.reset(newrow);
237 
238                                 reinstate_prologue_next_instruction = false;
239                                 last_instruction_restored_return_addr_reg = false;
240                                 m_curr_insn_is_branch_immediate = false;
241                             }
242 
243                             // clear both of these if either one wasn't set
244                             if (last_instruction_restored_return_addr_reg)
245                             {
246                                 last_instruction_restored_return_addr_reg = false;
247                             }
248                             if (m_curr_insn_is_branch_immediate)
249                             {
250                                 m_curr_insn_is_branch_immediate = false;
251                             }
252 
253                             // Stop updating the prologue instructions if we've seen 8 non-prologue instructions
254                             // in a row.
255                             if (instructions_since_last_prologue_insn++ < 8)
256                             {
257                                 UnwindPlan::Row *newrow = new UnwindPlan::Row;
258                                 *newrow = *m_curr_row.get();
259                                 prologue_completed_row.reset(newrow);
260                                 if (log && log->GetVerbose())
261                                     log->Printf("UnwindAssemblyInstEmulation::GetNonCallSiteUnwindPlanFromAssembly -- saving a copy of the current row as the prologue row.");
262                             }
263                         }
264                     }
265                 }
266             }
267         }
268 
269         if (log && log->GetVerbose ())
270         {
271             StreamString strm;
272             lldb::addr_t base_addr = range.GetBaseAddress().GetLoadAddress(thread.CalculateTarget().get());
273             strm.Printf ("Resulting unwind rows for [0x%" PRIx64 " - 0x%" PRIx64 "):", base_addr, base_addr + range.GetByteSize());
274             unwind_plan.Dump(strm, &thread, base_addr);
275             log->PutCString (strm.GetData());
276         }
277         return unwind_plan.GetRowCount() > 0;
278     }
279     return false;
280 }
281 
282 bool
283 UnwindAssemblyInstEmulation::GetFastUnwindPlan (AddressRange& func,
284                                                 Thread& thread,
285                                                 UnwindPlan &unwind_plan)
286 {
287     return false;
288 }
289 
290 bool
291 UnwindAssemblyInstEmulation::FirstNonPrologueInsn (AddressRange& func,
292                                                    const ExecutionContext &exe_ctx,
293                                                    Address& first_non_prologue_insn)
294 {
295     return false;
296 }
297 
298 UnwindAssembly *
299 UnwindAssemblyInstEmulation::CreateInstance (const ArchSpec &arch)
300 {
301     std::unique_ptr<EmulateInstruction> inst_emulator_ap (EmulateInstruction::FindPlugin (arch, eInstructionTypePrologueEpilogue, NULL));
302     // Make sure that all prologue instructions are handled
303     if (inst_emulator_ap.get())
304         return new UnwindAssemblyInstEmulation (arch, inst_emulator_ap.release());
305     return NULL;
306 }
307 
308 
309 //------------------------------------------------------------------
310 // PluginInterface protocol in UnwindAssemblyParser_x86
311 //------------------------------------------------------------------
312 ConstString
313 UnwindAssemblyInstEmulation::GetPluginName()
314 {
315     return GetPluginNameStatic();
316 }
317 
318 uint32_t
319 UnwindAssemblyInstEmulation::GetPluginVersion()
320 {
321     return 1;
322 }
323 
324 void
325 UnwindAssemblyInstEmulation::Initialize()
326 {
327     PluginManager::RegisterPlugin (GetPluginNameStatic(),
328                                    GetPluginDescriptionStatic(),
329                                    CreateInstance);
330 }
331 
332 void
333 UnwindAssemblyInstEmulation::Terminate()
334 {
335     PluginManager::UnregisterPlugin (CreateInstance);
336 }
337 
338 
339 ConstString
340 UnwindAssemblyInstEmulation::GetPluginNameStatic()
341 {
342     static ConstString g_name("inst-emulation");
343     return g_name;
344 }
345 
346 const char *
347 UnwindAssemblyInstEmulation::GetPluginDescriptionStatic()
348 {
349     return "Instruction emulation based unwind information.";
350 }
351 
352 
353 uint64_t
354 UnwindAssemblyInstEmulation::MakeRegisterKindValuePair (const RegisterInfo &reg_info)
355 {
356     uint32_t reg_kind, reg_num;
357     if (EmulateInstruction::GetBestRegisterKindAndNumber (&reg_info, reg_kind, reg_num))
358         return (uint64_t)reg_kind << 24 | reg_num;
359     return 0ull;
360 }
361 
362 void
363 UnwindAssemblyInstEmulation::SetRegisterValue (const RegisterInfo &reg_info, const RegisterValue &reg_value)
364 {
365     m_register_values[MakeRegisterKindValuePair (reg_info)] = reg_value;
366 }
367 
368 bool
369 UnwindAssemblyInstEmulation::GetRegisterValue (const RegisterInfo &reg_info, RegisterValue &reg_value)
370 {
371     const uint64_t reg_id = MakeRegisterKindValuePair (reg_info);
372     RegisterValueMap::const_iterator pos = m_register_values.find(reg_id);
373     if (pos != m_register_values.end())
374     {
375         reg_value = pos->second;
376         return true; // We had a real value that comes from an opcode that wrote
377                      // to it...
378     }
379     // We are making up a value that is recognizable...
380     reg_value.SetUInt(reg_id, reg_info.byte_size);
381     return false;
382 }
383 
384 
385 size_t
386 UnwindAssemblyInstEmulation::ReadMemory (EmulateInstruction *instruction,
387                                          void *baton,
388                                          const EmulateInstruction::Context &context,
389                                          lldb::addr_t addr,
390                                          void *dst,
391                                          size_t dst_len)
392 {
393     Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
394 
395     if (log && log->GetVerbose ())
396     {
397         StreamString strm;
398         strm.Printf ("UnwindAssemblyInstEmulation::ReadMemory    (addr = 0x%16.16" PRIx64 ", dst = %p, dst_len = %" PRIu64 ", context = ",
399                      addr,
400                      dst,
401                      (uint64_t)dst_len);
402         context.Dump(strm, instruction);
403         log->PutCString (strm.GetData ());
404     }
405     memset (dst, 0, dst_len);
406     return dst_len;
407 }
408 
409 size_t
410 UnwindAssemblyInstEmulation::WriteMemory (EmulateInstruction *instruction,
411                                           void *baton,
412                                           const EmulateInstruction::Context &context,
413                                           lldb::addr_t addr,
414                                           const void *dst,
415                                           size_t dst_len)
416 {
417     if (baton && dst && dst_len)
418         return ((UnwindAssemblyInstEmulation *)baton)->WriteMemory (instruction, context, addr, dst, dst_len);
419     return 0;
420 }
421 
422 size_t
423 UnwindAssemblyInstEmulation::WriteMemory (EmulateInstruction *instruction,
424                                           const EmulateInstruction::Context &context,
425                                           lldb::addr_t addr,
426                                           const void *dst,
427                                           size_t dst_len)
428 {
429     DataExtractor data (dst,
430                         dst_len,
431                         instruction->GetArchitecture ().GetByteOrder(),
432                         instruction->GetArchitecture ().GetAddressByteSize());
433 
434     Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
435 
436     if (log && log->GetVerbose ())
437     {
438         StreamString strm;
439 
440         strm.PutCString ("UnwindAssemblyInstEmulation::WriteMemory   (");
441         data.Dump(&strm, 0, eFormatBytes, 1, dst_len, UINT32_MAX, addr, 0, 0);
442         strm.PutCString (", context = ");
443         context.Dump(strm, instruction);
444         log->PutCString (strm.GetData());
445     }
446 
447     const bool can_replace = true;
448     const bool cant_replace = false;
449 
450     switch (context.type)
451     {
452         default:
453         case EmulateInstruction::eContextInvalid:
454         case EmulateInstruction::eContextReadOpcode:
455         case EmulateInstruction::eContextImmediate:
456         case EmulateInstruction::eContextAdjustBaseRegister:
457         case EmulateInstruction::eContextRegisterPlusOffset:
458         case EmulateInstruction::eContextAdjustPC:
459         case EmulateInstruction::eContextRegisterStore:
460         case EmulateInstruction::eContextRegisterLoad:
461         case EmulateInstruction::eContextRelativeBranchImmediate:
462         case EmulateInstruction::eContextAbsoluteBranchRegister:
463         case EmulateInstruction::eContextSupervisorCall:
464         case EmulateInstruction::eContextTableBranchReadMemory:
465         case EmulateInstruction::eContextWriteRegisterRandomBits:
466         case EmulateInstruction::eContextWriteMemoryRandomBits:
467         case EmulateInstruction::eContextArithmetic:
468         case EmulateInstruction::eContextAdvancePC:
469         case EmulateInstruction::eContextReturnFromException:
470         case EmulateInstruction::eContextPopRegisterOffStack:
471         case EmulateInstruction::eContextAdjustStackPointer:
472             break;
473 
474         case EmulateInstruction::eContextPushRegisterOnStack:
475             {
476                 uint32_t reg_num = LLDB_INVALID_REGNUM;
477                 bool is_return_address_reg = false;
478                 const uint32_t unwind_reg_kind = m_unwind_plan_ptr->GetRegisterKind();
479                 if (context.info_type == EmulateInstruction::eInfoTypeRegisterToRegisterPlusOffset)
480                 {
481                     reg_num = context.info.RegisterToRegisterPlusOffset.data_reg.kinds[unwind_reg_kind];
482                     if (context.info.RegisterToRegisterPlusOffset.data_reg.kinds[eRegisterKindGeneric] == LLDB_REGNUM_GENERIC_RA)
483                         is_return_address_reg = true;
484                 }
485                 else
486                 {
487                     assert (!"unhandled case, add code to handle this!");
488                 }
489 
490                 if (reg_num != LLDB_INVALID_REGNUM)
491                 {
492                     if (m_pushed_regs.find (reg_num) == m_pushed_regs.end())
493                     {
494                         m_pushed_regs[reg_num] = addr;
495                         const int32_t offset = addr - m_initial_sp;
496                         m_curr_row->SetRegisterLocationToAtCFAPlusOffset (reg_num, offset, cant_replace);
497                         m_curr_row_modified = true;
498                         if (is_return_address_reg)
499                         {
500                             // This push was pushing the return address register,
501                             // so this is also how we will unwind the PC...
502                             RegisterInfo pc_reg_info;
503                             if (instruction->GetRegisterInfo (eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC, pc_reg_info))
504                             {
505                                 uint32_t pc_reg_num = pc_reg_info.kinds[unwind_reg_kind];
506                                 if (pc_reg_num != LLDB_INVALID_REGNUM)
507                                 {
508                                     m_curr_row->SetRegisterLocationToAtCFAPlusOffset (pc_reg_num, offset, can_replace);
509                                     m_curr_row_modified = true;
510                                 }
511                             }
512                         }
513                     }
514                 }
515             }
516             break;
517 
518     }
519 
520     return dst_len;
521 }
522 
523 bool
524 UnwindAssemblyInstEmulation::ReadRegister (EmulateInstruction *instruction,
525                                            void *baton,
526                                            const RegisterInfo *reg_info,
527                                            RegisterValue &reg_value)
528 {
529 
530     if (baton && reg_info)
531         return ((UnwindAssemblyInstEmulation *)baton)->ReadRegister (instruction, reg_info, reg_value);
532     return false;
533 }
534 bool
535 UnwindAssemblyInstEmulation::ReadRegister (EmulateInstruction *instruction,
536                                            const RegisterInfo *reg_info,
537                                            RegisterValue &reg_value)
538 {
539     bool synthetic = GetRegisterValue (*reg_info, reg_value);
540 
541     Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
542 
543     if (log && log->GetVerbose ())
544     {
545 
546         StreamString strm;
547         strm.Printf ("UnwindAssemblyInstEmulation::ReadRegister  (name = \"%s\") => synthetic_value = %i, value = ", reg_info->name, synthetic);
548         reg_value.Dump(&strm, reg_info, false, false, eFormatDefault);
549         log->PutCString(strm.GetData());
550     }
551     return true;
552 }
553 
554 bool
555 UnwindAssemblyInstEmulation::WriteRegister (EmulateInstruction *instruction,
556                                             void *baton,
557                                             const EmulateInstruction::Context &context,
558                                             const RegisterInfo *reg_info,
559                                             const RegisterValue &reg_value)
560 {
561     if (baton && reg_info)
562         return ((UnwindAssemblyInstEmulation *)baton)->WriteRegister (instruction, context, reg_info, reg_value);
563     return false;
564 }
565 bool
566 UnwindAssemblyInstEmulation::WriteRegister (EmulateInstruction *instruction,
567                                             const EmulateInstruction::Context &context,
568                                             const RegisterInfo *reg_info,
569                                             const RegisterValue &reg_value)
570 {
571     Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
572 
573     if (log && log->GetVerbose ())
574     {
575 
576         StreamString strm;
577         strm.Printf ("UnwindAssemblyInstEmulation::WriteRegister (name = \"%s\", value = ", reg_info->name);
578         reg_value.Dump(&strm, reg_info, false, false, eFormatDefault);
579         strm.PutCString (", context = ");
580         context.Dump(strm, instruction);
581         log->PutCString(strm.GetData());
582     }
583 
584     const bool must_replace = true;
585     SetRegisterValue (*reg_info, reg_value);
586 
587     switch (context.type)
588     {
589         case EmulateInstruction::eContextInvalid:
590         case EmulateInstruction::eContextReadOpcode:
591         case EmulateInstruction::eContextImmediate:
592         case EmulateInstruction::eContextAdjustBaseRegister:
593         case EmulateInstruction::eContextRegisterPlusOffset:
594         case EmulateInstruction::eContextAdjustPC:
595         case EmulateInstruction::eContextRegisterStore:
596         case EmulateInstruction::eContextRegisterLoad:
597         case EmulateInstruction::eContextAbsoluteBranchRegister:
598         case EmulateInstruction::eContextSupervisorCall:
599         case EmulateInstruction::eContextTableBranchReadMemory:
600         case EmulateInstruction::eContextWriteRegisterRandomBits:
601         case EmulateInstruction::eContextWriteMemoryRandomBits:
602         case EmulateInstruction::eContextArithmetic:
603         case EmulateInstruction::eContextAdvancePC:
604         case EmulateInstruction::eContextReturnFromException:
605         case EmulateInstruction::eContextPushRegisterOnStack:
606 //            {
607 //                const uint32_t reg_num = reg_info->kinds[m_unwind_plan_ptr->GetRegisterKind()];
608 //                if (reg_num != LLDB_INVALID_REGNUM)
609 //                {
610 //                    const bool can_replace_only_if_unspecified = true;
611 //
612 //                    m_curr_row.SetRegisterLocationToUndefined (reg_num,
613 //                                                               can_replace_only_if_unspecified,
614 //                                                               can_replace_only_if_unspecified);
615 //                    m_curr_row_modified = true;
616 //                }
617 //            }
618             break;
619 
620         case EmulateInstruction::eContextRelativeBranchImmediate:
621             {
622 
623                 {
624                     m_curr_insn_is_branch_immediate = true;
625                 }
626             }
627             break;
628 
629         case EmulateInstruction::eContextPopRegisterOffStack:
630             {
631                 const uint32_t reg_num = reg_info->kinds[m_unwind_plan_ptr->GetRegisterKind()];
632                 if (reg_num != LLDB_INVALID_REGNUM)
633                 {
634                     m_curr_row->SetRegisterLocationToSame (reg_num, must_replace);
635                     m_curr_row_modified = true;
636                     m_curr_insn_restored_a_register = true;
637                 }
638             }
639             break;
640 
641         case EmulateInstruction::eContextSetFramePointer:
642             if (!m_fp_is_cfa)
643             {
644                 m_fp_is_cfa = true;
645                 m_cfa_reg_info = *reg_info;
646                 const uint32_t cfa_reg_num = reg_info->kinds[m_unwind_plan_ptr->GetRegisterKind()];
647                 assert (cfa_reg_num != LLDB_INVALID_REGNUM);
648                 m_curr_row->SetCFARegister(cfa_reg_num);
649                 m_curr_row->SetCFAOffset(m_initial_sp - reg_value.GetAsUInt64());
650                 m_curr_row_modified = true;
651             }
652             break;
653 
654         case EmulateInstruction::eContextAdjustStackPointer:
655             // If we have created a frame using the frame pointer, don't follow
656             // subsequent adjustments to the stack pointer.
657             if (!m_fp_is_cfa)
658             {
659                 m_curr_row->SetCFAOffset (m_initial_sp - reg_value.GetAsUInt64());
660                 m_curr_row_modified = true;
661             }
662             break;
663     }
664     return true;
665 }
666 
667 
668