1 //===-- CompactUnwindInfo.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 
11 // C Includes
12 // C++ Includes
13 #include <algorithm>
14 
15 #include "lldb/Core/ArchSpec.h"
16 #include "lldb/Core/DataBufferHeap.h"
17 #include "lldb/Core/Log.h"
18 #include "lldb/Core/Module.h"
19 #include "lldb/Core/Section.h"
20 #include "lldb/Core/Section.h"
21 #include "lldb/Core/StreamString.h"
22 #include "lldb/Symbol/CompactUnwindInfo.h"
23 #include "lldb/Symbol/ObjectFile.h"
24 #include "lldb/Symbol/UnwindPlan.h"
25 #include "lldb/Target/Process.h"
26 #include "lldb/Target/Target.h"
27 
28 #include "llvm/Support/MathExtras.h"
29 
30 using namespace lldb;
31 using namespace lldb_private;
32 
33 
34 namespace lldb_private {
35 
36     // Constants from <mach-o/compact_unwind_encoding.h>
37 
38     FLAGS_ANONYMOUS_ENUM()
39     {
40         UNWIND_IS_NOT_FUNCTION_START           = 0x80000000,
41         UNWIND_HAS_LSDA                        = 0x40000000,
42         UNWIND_PERSONALITY_MASK                = 0x30000000,
43     };
44 
45     FLAGS_ANONYMOUS_ENUM()
46     {
47         UNWIND_X86_MODE_MASK                         = 0x0F000000,
48         UNWIND_X86_MODE_EBP_FRAME                    = 0x01000000,
49         UNWIND_X86_MODE_STACK_IMMD                   = 0x02000000,
50         UNWIND_X86_MODE_STACK_IND                    = 0x03000000,
51         UNWIND_X86_MODE_DWARF                        = 0x04000000,
52 
53         UNWIND_X86_EBP_FRAME_REGISTERS               = 0x00007FFF,
54         UNWIND_X86_EBP_FRAME_OFFSET                  = 0x00FF0000,
55 
56         UNWIND_X86_FRAMELESS_STACK_SIZE              = 0x00FF0000,
57         UNWIND_X86_FRAMELESS_STACK_ADJUST            = 0x0000E000,
58         UNWIND_X86_FRAMELESS_STACK_REG_COUNT         = 0x00001C00,
59         UNWIND_X86_FRAMELESS_STACK_REG_PERMUTATION   = 0x000003FF,
60 
61         UNWIND_X86_DWARF_SECTION_OFFSET              = 0x00FFFFFF,
62     };
63 
64     enum
65     {
66         UNWIND_X86_REG_NONE     = 0,
67         UNWIND_X86_REG_EBX      = 1,
68         UNWIND_X86_REG_ECX      = 2,
69         UNWIND_X86_REG_EDX      = 3,
70         UNWIND_X86_REG_EDI      = 4,
71         UNWIND_X86_REG_ESI      = 5,
72         UNWIND_X86_REG_EBP      = 6,
73     };
74 
75     FLAGS_ANONYMOUS_ENUM()
76     {
77         UNWIND_X86_64_MODE_MASK                         = 0x0F000000,
78         UNWIND_X86_64_MODE_RBP_FRAME                    = 0x01000000,
79         UNWIND_X86_64_MODE_STACK_IMMD                   = 0x02000000,
80         UNWIND_X86_64_MODE_STACK_IND                    = 0x03000000,
81         UNWIND_X86_64_MODE_DWARF                        = 0x04000000,
82 
83         UNWIND_X86_64_RBP_FRAME_REGISTERS               = 0x00007FFF,
84         UNWIND_X86_64_RBP_FRAME_OFFSET                  = 0x00FF0000,
85 
86         UNWIND_X86_64_FRAMELESS_STACK_SIZE              = 0x00FF0000,
87         UNWIND_X86_64_FRAMELESS_STACK_ADJUST            = 0x0000E000,
88         UNWIND_X86_64_FRAMELESS_STACK_REG_COUNT         = 0x00001C00,
89         UNWIND_X86_64_FRAMELESS_STACK_REG_PERMUTATION   = 0x000003FF,
90 
91         UNWIND_X86_64_DWARF_SECTION_OFFSET              = 0x00FFFFFF,
92     };
93 
94     enum
95     {
96         UNWIND_X86_64_REG_NONE       = 0,
97         UNWIND_X86_64_REG_RBX        = 1,
98         UNWIND_X86_64_REG_R12        = 2,
99         UNWIND_X86_64_REG_R13        = 3,
100         UNWIND_X86_64_REG_R14        = 4,
101         UNWIND_X86_64_REG_R15        = 5,
102         UNWIND_X86_64_REG_RBP        = 6,
103     };
104 };
105 
106 
107 #ifndef UNWIND_SECOND_LEVEL_REGULAR
108 #define UNWIND_SECOND_LEVEL_REGULAR 2
109 #endif
110 
111 #ifndef UNWIND_SECOND_LEVEL_COMPRESSED
112 #define UNWIND_SECOND_LEVEL_COMPRESSED 3
113 #endif
114 
115 #ifndef UNWIND_INFO_COMPRESSED_ENTRY_FUNC_OFFSET
116 #define UNWIND_INFO_COMPRESSED_ENTRY_FUNC_OFFSET(entry)            (entry & 0x00FFFFFF)
117 #endif
118 
119 #ifndef UNWIND_INFO_COMPRESSED_ENTRY_ENCODING_INDEX
120 #define UNWIND_INFO_COMPRESSED_ENTRY_ENCODING_INDEX(entry)        ((entry >> 24) & 0xFF)
121 #endif
122 
123 #define EXTRACT_BITS(value, mask) \
124         ( (value >> llvm::countTrailingZeros(static_cast<uint32_t>(mask), llvm::ZB_Width)) & \
125           (((1 << llvm::countPopulation(static_cast<uint32_t>(mask))))-1) )
126 
127 
128 
129 //----------------------
130 // constructor
131 //----------------------
132 
133 
134 CompactUnwindInfo::CompactUnwindInfo(ObjectFile& objfile, SectionSP& section_sp) :
135     m_objfile (objfile),
136     m_section_sp (section_sp),
137     m_section_contents_if_encrypted (),
138     m_mutex (),
139     m_indexes (),
140     m_indexes_computed (eLazyBoolCalculate),
141     m_unwindinfo_data (),
142     m_unwindinfo_data_computed (false),
143     m_unwind_header ()
144 {
145 
146 }
147 
148 //----------------------
149 // destructor
150 //----------------------
151 
152 CompactUnwindInfo::~CompactUnwindInfo()
153 {
154 }
155 
156 bool
157 CompactUnwindInfo::GetUnwindPlan (Target &target, Address addr, UnwindPlan& unwind_plan)
158 {
159     if (!IsValid (target.GetProcessSP()))
160     {
161         return false;
162     }
163     FunctionInfo function_info;
164     if (GetCompactUnwindInfoForFunction (target, addr, function_info))
165     {
166         // shortcut return for functions that have no compact unwind
167         if (function_info.encoding == 0)
168             return false;
169 
170         ArchSpec arch;
171         if (m_objfile.GetArchitecture (arch))
172         {
173 
174             Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
175             if (log && log->GetVerbose())
176             {
177                 StreamString strm;
178                 addr.Dump (&strm, NULL, Address::DumpStyle::DumpStyleResolvedDescriptionNoFunctionArguments, Address::DumpStyle::DumpStyleFileAddress, arch.GetAddressByteSize());
179                 log->Printf ("Got compact unwind encoding 0x%x for function %s", function_info.encoding, strm.GetData());
180             }
181 
182             if (function_info.valid_range_offset_start != 0 && function_info.valid_range_offset_end != 0)
183             {
184                 SectionList *sl = m_objfile.GetSectionList ();
185                 if (sl)
186                 {
187                     addr_t func_range_start_file_addr =
188                               function_info.valid_range_offset_start + m_objfile.GetHeaderAddress().GetFileAddress();
189                     AddressRange func_range (func_range_start_file_addr,
190                                       function_info.valid_range_offset_end - function_info.valid_range_offset_start,
191                                       sl);
192                     unwind_plan.SetPlanValidAddressRange (func_range);
193                 }
194             }
195 
196             if (arch.GetTriple().getArch() == llvm::Triple::x86_64)
197             {
198                 return CreateUnwindPlan_x86_64 (target, function_info, unwind_plan, addr);
199             }
200             if (arch.GetTriple().getArch() == llvm::Triple::x86)
201             {
202                 return CreateUnwindPlan_i386 (target, function_info, unwind_plan, addr);
203             }
204         }
205     }
206     return false;
207 }
208 
209 bool
210 CompactUnwindInfo::IsValid (const ProcessSP &process_sp)
211 {
212     if (m_section_sp.get() == nullptr)
213         return false;
214 
215     if (m_indexes_computed == eLazyBoolYes && m_unwindinfo_data_computed)
216         return true;
217 
218     ScanIndex (process_sp);
219 
220     return m_indexes_computed == eLazyBoolYes && m_unwindinfo_data_computed;
221 }
222 
223 void
224 CompactUnwindInfo::ScanIndex (const ProcessSP &process_sp)
225 {
226     Mutex::Locker locker(m_mutex);
227     if (m_indexes_computed == eLazyBoolYes && m_unwindinfo_data_computed)
228         return;
229 
230     // We can't read the index for some reason.
231     if (m_indexes_computed == eLazyBoolNo)
232     {
233         return;
234     }
235 
236     Log *log (GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
237     if (log)
238         m_objfile.GetModule()->LogMessage(log, "Reading compact unwind first-level indexes");
239 
240     if (m_unwindinfo_data_computed == false)
241     {
242         if (m_section_sp->IsEncrypted())
243         {
244             // Can't get section contents of a protected/encrypted section until we have a live
245             // process and can read them out of memory.
246             if (process_sp.get() == nullptr)
247                 return;
248             m_section_contents_if_encrypted.reset (new DataBufferHeap (m_section_sp->GetByteSize(), 0));
249             Error error;
250             if (process_sp->ReadMemory (
251                         m_section_sp->GetLoadBaseAddress (&process_sp->GetTarget()),
252                         m_section_contents_if_encrypted->GetBytes(),
253                         m_section_sp->GetByteSize(), error) == m_section_sp->GetByteSize() && error.Success())
254             {
255                 m_unwindinfo_data.SetAddressByteSize (process_sp->GetTarget().GetArchitecture().GetAddressByteSize());
256                 m_unwindinfo_data.SetByteOrder (process_sp->GetTarget().GetArchitecture().GetByteOrder());
257                 m_unwindinfo_data.SetData (m_section_contents_if_encrypted, 0);
258             }
259         }
260         else
261         {
262             m_objfile.ReadSectionData (m_section_sp.get(), m_unwindinfo_data);
263         }
264         if (m_unwindinfo_data.GetByteSize() != m_section_sp->GetByteSize())
265             return;
266         m_unwindinfo_data_computed = true;
267     }
268 
269     if (m_unwindinfo_data.GetByteSize() > 0)
270     {
271         offset_t offset = 0;
272 
273                 // struct unwind_info_section_header
274                 // {
275                 // uint32_t    version;            // UNWIND_SECTION_VERSION
276                 // uint32_t    commonEncodingsArraySectionOffset;
277                 // uint32_t    commonEncodingsArrayCount;
278                 // uint32_t    personalityArraySectionOffset;
279                 // uint32_t    personalityArrayCount;
280                 // uint32_t    indexSectionOffset;
281                 // uint32_t    indexCount;
282 
283         m_unwind_header.version = m_unwindinfo_data.GetU32(&offset);
284         m_unwind_header.common_encodings_array_offset = m_unwindinfo_data.GetU32(&offset);
285         m_unwind_header.common_encodings_array_count = m_unwindinfo_data.GetU32(&offset);
286         m_unwind_header.personality_array_offset = m_unwindinfo_data.GetU32(&offset);
287         m_unwind_header.personality_array_count = m_unwindinfo_data.GetU32(&offset);
288         uint32_t indexSectionOffset = m_unwindinfo_data.GetU32(&offset);
289 
290         uint32_t indexCount = m_unwindinfo_data.GetU32(&offset);
291 
292         if (m_unwind_header.common_encodings_array_offset > m_unwindinfo_data.GetByteSize()
293             || m_unwind_header.personality_array_offset > m_unwindinfo_data.GetByteSize()
294             || indexSectionOffset > m_unwindinfo_data.GetByteSize()
295             || offset > m_unwindinfo_data.GetByteSize())
296         {
297             Host::SystemLog (Host::eSystemLogError,
298                     "error: Invalid offset encountered in compact unwind info, skipping\n");
299             // don't trust anything from this compact_unwind section if it looks
300             // blatently invalid data in the header.
301             m_indexes_computed = eLazyBoolNo;
302             return;
303         }
304 
305         // Parse the basic information from the indexes
306         // We wait to scan the second level page info until it's needed
307 
308             // struct unwind_info_section_header_index_entry
309             // {
310             //     uint32_t        functionOffset;
311             //     uint32_t        secondLevelPagesSectionOffset;
312             //     uint32_t        lsdaIndexArraySectionOffset;
313             // };
314 
315         offset = indexSectionOffset;
316         for (uint32_t idx = 0; idx < indexCount; idx++)
317         {
318             uint32_t function_offset = m_unwindinfo_data.GetU32(&offset);      // functionOffset
319             uint32_t second_level_offset = m_unwindinfo_data.GetU32(&offset);  // secondLevelPagesSectionOffset
320             uint32_t lsda_offset = m_unwindinfo_data.GetU32(&offset);          // lsdaIndexArraySectionOffset
321 
322             if (second_level_offset > m_section_sp->GetByteSize() || lsda_offset > m_section_sp->GetByteSize())
323             {
324                 m_indexes_computed = eLazyBoolNo;
325             }
326 
327             UnwindIndex this_index;
328             this_index.function_offset = function_offset;     //
329             this_index.second_level = second_level_offset;
330             this_index.lsda_array_start = lsda_offset;
331 
332             if (m_indexes.size() > 0)
333             {
334                 m_indexes[m_indexes.size() - 1].lsda_array_end = lsda_offset;
335             }
336 
337             if (second_level_offset == 0)
338             {
339                 this_index.sentinal_entry = true;
340             }
341 
342             m_indexes.push_back (this_index);
343         }
344         m_indexes_computed = eLazyBoolYes;
345     }
346     else
347     {
348         m_indexes_computed = eLazyBoolNo;
349     }
350 }
351 
352 uint32_t
353 CompactUnwindInfo::GetLSDAForFunctionOffset (uint32_t lsda_offset, uint32_t lsda_count, uint32_t function_offset)
354 {
355         // struct unwind_info_section_header_lsda_index_entry
356         // {
357         //         uint32_t        functionOffset;
358         //         uint32_t        lsdaOffset;
359         // };
360 
361     offset_t first_entry = lsda_offset;
362     uint32_t low = 0;
363     uint32_t high = lsda_count;
364     while (low < high)
365     {
366         uint32_t mid = (low + high) / 2;
367         offset_t offset = first_entry + (mid * 8);
368         uint32_t mid_func_offset = m_unwindinfo_data.GetU32(&offset);  // functionOffset
369         uint32_t mid_lsda_offset = m_unwindinfo_data.GetU32(&offset);  // lsdaOffset
370         if (mid_func_offset == function_offset)
371         {
372             return mid_lsda_offset;
373         }
374         if (mid_func_offset < function_offset)
375         {
376             low = mid + 1;
377         }
378         else
379         {
380             high = mid;
381         }
382     }
383     return 0;
384 }
385 
386 lldb::offset_t
387 CompactUnwindInfo::BinarySearchRegularSecondPage (uint32_t entry_page_offset, uint32_t entry_count, uint32_t function_offset, uint32_t *entry_func_start_offset, uint32_t *entry_func_end_offset)
388 {
389     // typedef uint32_t compact_unwind_encoding_t;
390     // struct unwind_info_regular_second_level_entry
391     // {
392     //     uint32_t                    functionOffset;
393     //     compact_unwind_encoding_t    encoding;
394 
395     offset_t first_entry = entry_page_offset;
396 
397     uint32_t low = 0;
398     uint32_t high = entry_count;
399     uint32_t last = high - 1;
400     while (low < high)
401     {
402         uint32_t mid = (low + high) / 2;
403         offset_t offset = first_entry + (mid * 8);
404         uint32_t mid_func_offset = m_unwindinfo_data.GetU32(&offset);   // functionOffset
405         uint32_t next_func_offset = 0;
406         if (mid < last)
407         {
408             offset = first_entry + ((mid + 1) * 8);
409             next_func_offset = m_unwindinfo_data.GetU32(&offset);       // functionOffset
410         }
411         if (mid_func_offset <= function_offset)
412         {
413             if (mid == last || (next_func_offset > function_offset))
414             {
415                 if (entry_func_start_offset)
416                     *entry_func_start_offset = mid_func_offset;
417                 if (mid != last && entry_func_end_offset)
418                     *entry_func_end_offset = next_func_offset;
419                 return first_entry + (mid * 8);
420             }
421             else
422             {
423                 low = mid + 1;
424             }
425         }
426         else
427         {
428             high = mid;
429         }
430     }
431     return LLDB_INVALID_OFFSET;
432 }
433 
434 uint32_t
435 CompactUnwindInfo::BinarySearchCompressedSecondPage (uint32_t entry_page_offset, uint32_t entry_count, uint32_t function_offset_to_find, uint32_t function_offset_base, uint32_t *entry_func_start_offset, uint32_t *entry_func_end_offset)
436 {
437     offset_t first_entry = entry_page_offset;
438 
439     uint32_t low = 0;
440     uint32_t high = entry_count;
441     uint32_t last = high - 1;
442     while (low < high)
443     {
444         uint32_t mid = (low + high) / 2;
445         offset_t offset = first_entry + (mid * 4);
446         uint32_t entry = m_unwindinfo_data.GetU32(&offset);   // entry
447         uint32_t mid_func_offset = UNWIND_INFO_COMPRESSED_ENTRY_FUNC_OFFSET (entry);
448         mid_func_offset += function_offset_base;
449         uint32_t next_func_offset = 0;
450         if (mid < last)
451         {
452             offset = first_entry + ((mid + 1) * 4);
453             uint32_t next_entry = m_unwindinfo_data.GetU32(&offset);       // entry
454             next_func_offset = UNWIND_INFO_COMPRESSED_ENTRY_FUNC_OFFSET (next_entry);
455             next_func_offset += function_offset_base;
456         }
457         if (mid_func_offset <= function_offset_to_find)
458         {
459             if (mid == last || (next_func_offset > function_offset_to_find))
460             {
461                 if (entry_func_start_offset)
462                     *entry_func_start_offset = mid_func_offset;
463                 if (mid != last && entry_func_end_offset)
464                     *entry_func_end_offset = next_func_offset;
465                 return UNWIND_INFO_COMPRESSED_ENTRY_ENCODING_INDEX (entry);
466             }
467             else
468             {
469                 low = mid + 1;
470             }
471         }
472         else
473         {
474             high = mid;
475         }
476     }
477 
478     return UINT32_MAX;
479 }
480 
481 bool
482 CompactUnwindInfo::GetCompactUnwindInfoForFunction (Target &target, Address address, FunctionInfo &unwind_info)
483 {
484     unwind_info.encoding = 0;
485     unwind_info.lsda_address.Clear();
486     unwind_info.personality_ptr_address.Clear();
487 
488     if (!IsValid (target.GetProcessSP()))
489         return false;
490 
491     addr_t text_section_file_address = LLDB_INVALID_ADDRESS;
492     SectionList *sl = m_objfile.GetSectionList ();
493     if (sl)
494     {
495         SectionSP text_sect = sl->FindSectionByType (eSectionTypeCode, true);
496         if (text_sect.get())
497         {
498            text_section_file_address = text_sect->GetFileAddress();
499         }
500     }
501     if (text_section_file_address == LLDB_INVALID_ADDRESS)
502         return false;
503 
504     addr_t function_offset = address.GetFileAddress() - m_objfile.GetHeaderAddress().GetFileAddress();
505 
506     UnwindIndex key;
507     key.function_offset = function_offset;
508 
509     std::vector<UnwindIndex>::const_iterator it;
510     it = std::lower_bound (m_indexes.begin(), m_indexes.end(), key);
511     if (it == m_indexes.end())
512     {
513         return false;
514     }
515 
516     if (it->function_offset != key.function_offset)
517     {
518         if (it != m_indexes.begin())
519             --it;
520     }
521 
522     if (it->sentinal_entry == true)
523     {
524         return false;
525     }
526 
527     auto next_it = it + 1;
528     if (next_it != m_indexes.begin())
529     {
530         // initialize the function offset end range to be the start of the
531         // next index offset.  If we find an entry which is at the end of
532         // the index table, this will establish the range end.
533         unwind_info.valid_range_offset_end = next_it->function_offset;
534     }
535 
536     offset_t second_page_offset = it->second_level;
537     offset_t lsda_array_start = it->lsda_array_start;
538     offset_t lsda_array_count = (it->lsda_array_end - it->lsda_array_start) / 8;
539 
540     offset_t offset = second_page_offset;
541     uint32_t kind = m_unwindinfo_data.GetU32(&offset);  // UNWIND_SECOND_LEVEL_REGULAR or UNWIND_SECOND_LEVEL_COMPRESSED
542 
543     if (kind == UNWIND_SECOND_LEVEL_REGULAR)
544     {
545             // struct unwind_info_regular_second_level_page_header
546             // {
547             //     uint32_t    kind;    // UNWIND_SECOND_LEVEL_REGULAR
548             //     uint16_t    entryPageOffset;
549             //     uint16_t    entryCount;
550 
551             // typedef uint32_t compact_unwind_encoding_t;
552             // struct unwind_info_regular_second_level_entry
553             // {
554             //     uint32_t                    functionOffset;
555             //     compact_unwind_encoding_t    encoding;
556 
557         uint16_t entry_page_offset = m_unwindinfo_data.GetU16(&offset); // entryPageOffset
558         uint16_t entry_count = m_unwindinfo_data.GetU16(&offset);       // entryCount
559 
560         offset_t entry_offset = BinarySearchRegularSecondPage (second_page_offset + entry_page_offset, entry_count, function_offset, &unwind_info.valid_range_offset_start, &unwind_info.valid_range_offset_end);
561         if (entry_offset == LLDB_INVALID_OFFSET)
562         {
563             return false;
564         }
565         entry_offset += 4;                                              // skip over functionOffset
566         unwind_info.encoding = m_unwindinfo_data.GetU32(&entry_offset); // encoding
567         if (unwind_info.encoding & UNWIND_HAS_LSDA)
568         {
569             SectionList *sl = m_objfile.GetSectionList ();
570             if (sl)
571             {
572                 uint32_t lsda_offset = GetLSDAForFunctionOffset (lsda_array_start, lsda_array_count, function_offset);
573                 addr_t objfile_header_file_address = m_objfile.GetHeaderAddress().GetFileAddress();
574                 unwind_info.lsda_address.ResolveAddressUsingFileSections (objfile_header_file_address + lsda_offset, sl);
575             }
576         }
577         if (unwind_info.encoding & UNWIND_PERSONALITY_MASK)
578         {
579             uint32_t personality_index = EXTRACT_BITS (unwind_info.encoding, UNWIND_PERSONALITY_MASK);
580 
581             if (personality_index > 0)
582             {
583                 personality_index--;
584                 if (personality_index < m_unwind_header.personality_array_count)
585                 {
586                     offset_t offset = m_unwind_header.personality_array_offset;
587                     offset += 4 * personality_index;
588                     SectionList *sl = m_objfile.GetSectionList ();
589                     if (sl)
590                     {
591                         uint32_t personality_offset = m_unwindinfo_data.GetU32(&offset);
592                         addr_t objfile_header_file_address = m_objfile.GetHeaderAddress().GetFileAddress();
593                         unwind_info.personality_ptr_address.ResolveAddressUsingFileSections (objfile_header_file_address + personality_offset, sl);
594                     }
595                 }
596             }
597         }
598         return true;
599     }
600     else if (kind == UNWIND_SECOND_LEVEL_COMPRESSED)
601     {
602             // struct unwind_info_compressed_second_level_page_header
603             // {
604             //     uint32_t    kind;    // UNWIND_SECOND_LEVEL_COMPRESSED
605             //     uint16_t    entryPageOffset;         // offset from this 2nd lvl page idx to array of entries
606             //                                          // (an entry has a function offset and index into the encodings)
607             //                                          // NB function offset from the entry in the compressed page
608             //                                          // must be added to the index's functionOffset value.
609             //     uint16_t    entryCount;
610             //     uint16_t    encodingsPageOffset;     // offset from this 2nd lvl page idx to array of encodings
611             //     uint16_t    encodingsCount;
612 
613         uint16_t entry_page_offset = m_unwindinfo_data.GetU16(&offset);     // entryPageOffset
614         uint16_t entry_count = m_unwindinfo_data.GetU16(&offset);           // entryCount
615         uint16_t encodings_page_offset = m_unwindinfo_data.GetU16(&offset); // encodingsPageOffset
616         uint16_t encodings_count = m_unwindinfo_data.GetU16(&offset);       // encodingsCount
617 
618         uint32_t encoding_index = BinarySearchCompressedSecondPage (second_page_offset + entry_page_offset, entry_count, function_offset, it->function_offset, &unwind_info.valid_range_offset_start, &unwind_info.valid_range_offset_end);
619         if (encoding_index == UINT32_MAX || encoding_index >= encodings_count + m_unwind_header.common_encodings_array_count)
620         {
621             return false;
622         }
623         uint32_t encoding = 0;
624         if (encoding_index < m_unwind_header.common_encodings_array_count)
625         {
626             offset = m_unwind_header.common_encodings_array_offset + (encoding_index * sizeof (uint32_t));
627             encoding = m_unwindinfo_data.GetU32(&offset);   // encoding entry from the commonEncodingsArray
628         }
629         else
630         {
631             uint32_t page_specific_entry_index = encoding_index - m_unwind_header.common_encodings_array_count;
632             offset = second_page_offset + encodings_page_offset + (page_specific_entry_index * sizeof (uint32_t));
633             encoding = m_unwindinfo_data.GetU32(&offset);   // encoding entry from the page-specific encoding array
634         }
635         if (encoding == 0)
636             return false;
637 
638         unwind_info.encoding = encoding;
639         if (unwind_info.encoding & UNWIND_HAS_LSDA)
640         {
641             SectionList *sl = m_objfile.GetSectionList ();
642             if (sl)
643             {
644                 uint32_t lsda_offset = GetLSDAForFunctionOffset (lsda_array_start, lsda_array_count, function_offset);
645                 addr_t objfile_header_file_address = m_objfile.GetHeaderAddress().GetFileAddress();
646                 unwind_info.lsda_address.ResolveAddressUsingFileSections (objfile_header_file_address + lsda_offset, sl);
647             }
648         }
649         if (unwind_info.encoding & UNWIND_PERSONALITY_MASK)
650         {
651             uint32_t personality_index = EXTRACT_BITS (unwind_info.encoding, UNWIND_PERSONALITY_MASK);
652 
653             if (personality_index > 0)
654             {
655                 personality_index--;
656                 if (personality_index < m_unwind_header.personality_array_count)
657                 {
658                     offset_t offset = m_unwind_header.personality_array_offset;
659                     offset += 4 * personality_index;
660                     SectionList *sl = m_objfile.GetSectionList ();
661                     if (sl)
662                     {
663                         uint32_t personality_offset = m_unwindinfo_data.GetU32(&offset);
664                         addr_t objfile_header_file_address = m_objfile.GetHeaderAddress().GetFileAddress();
665                         unwind_info.personality_ptr_address.ResolveAddressUsingFileSections (objfile_header_file_address + personality_offset, sl);
666                     }
667                 }
668             }
669         }
670         return true;
671     }
672     return false;
673 }
674 
675 enum x86_64_eh_regnum {
676     rax = 0,
677     rdx = 1,
678     rcx = 2,
679     rbx = 3,
680     rsi = 4,
681     rdi = 5,
682     rbp = 6,
683     rsp = 7,
684     r8 = 8,
685     r9 = 9,
686     r10 = 10,
687     r11 = 11,
688     r12 = 12,
689     r13 = 13,
690     r14 = 14,
691     r15 = 15,
692     rip = 16   // this is officially the Return Address register number, but close enough
693 };
694 
695 // Convert the compact_unwind_info.h register numbering scheme
696 // to eRegisterKindGCC (eh_frame) register numbering scheme.
697 uint32_t
698 translate_to_eh_frame_regnum_x86_64 (uint32_t unwind_regno)
699 {
700     switch (unwind_regno)
701     {
702         case UNWIND_X86_64_REG_RBX:
703             return x86_64_eh_regnum::rbx;
704         case UNWIND_X86_64_REG_R12:
705             return x86_64_eh_regnum::r12;
706         case UNWIND_X86_64_REG_R13:
707             return x86_64_eh_regnum::r13;
708         case UNWIND_X86_64_REG_R14:
709             return x86_64_eh_regnum::r14;
710         case UNWIND_X86_64_REG_R15:
711             return x86_64_eh_regnum::r15;
712         case UNWIND_X86_64_REG_RBP:
713             return x86_64_eh_regnum::rbp;
714         default:
715             return LLDB_INVALID_REGNUM;
716     }
717 }
718 
719 bool
720 CompactUnwindInfo::CreateUnwindPlan_x86_64 (Target &target, FunctionInfo &function_info, UnwindPlan &unwind_plan, Address pc_or_function_start)
721 {
722     unwind_plan.SetSourceName ("compact unwind info");
723     unwind_plan.SetSourcedFromCompiler (eLazyBoolYes);
724     unwind_plan.SetUnwindPlanValidAtAllInstructions (eLazyBoolNo);
725     unwind_plan.SetRegisterKind (eRegisterKindGCC);
726 
727     unwind_plan.SetLSDAAddress (function_info.lsda_address);
728     unwind_plan.SetPersonalityFunctionPtr (function_info.personality_ptr_address);
729 
730     UnwindPlan::RowSP row (new UnwindPlan::Row);
731 
732     const int wordsize = 8;
733     int mode = function_info.encoding & UNWIND_X86_64_MODE_MASK;
734     switch (mode)
735     {
736         case UNWIND_X86_64_MODE_RBP_FRAME:
737         {
738             row->GetCFAValue().SetIsRegisterPlusOffset (
739                     translate_to_eh_frame_regnum_x86_64 (UNWIND_X86_64_REG_RBP),
740                     2 * wordsize);
741             row->SetOffset (0);
742             row->SetRegisterLocationToAtCFAPlusOffset (x86_64_eh_regnum::rbp, wordsize * -2, true);
743             row->SetRegisterLocationToAtCFAPlusOffset (x86_64_eh_regnum::rip, wordsize * -1, true);
744             row->SetRegisterLocationToIsCFAPlusOffset (x86_64_eh_regnum::rsp, 0, true);
745 
746             uint32_t saved_registers_offset = EXTRACT_BITS (function_info.encoding, UNWIND_X86_64_RBP_FRAME_OFFSET);
747 
748             uint32_t saved_registers_locations = EXTRACT_BITS (function_info.encoding, UNWIND_X86_64_RBP_FRAME_REGISTERS);
749 
750             saved_registers_offset += 2;
751 
752             for (int i = 0; i < 5; i++)
753             {
754                 uint32_t regnum = saved_registers_locations & 0x7;
755                 switch (regnum)
756                 {
757                     case UNWIND_X86_64_REG_NONE:
758                         break;
759                     case UNWIND_X86_64_REG_RBX:
760                     case UNWIND_X86_64_REG_R12:
761                     case UNWIND_X86_64_REG_R13:
762                     case UNWIND_X86_64_REG_R14:
763                     case UNWIND_X86_64_REG_R15:
764                         row->SetRegisterLocationToAtCFAPlusOffset (translate_to_eh_frame_regnum_x86_64 (regnum), wordsize * -saved_registers_offset, true);
765                         break;
766                 }
767                 saved_registers_offset--;
768                 saved_registers_locations >>= 3;
769             }
770             unwind_plan.AppendRow (row);
771             return true;
772         }
773         break;
774 
775         case UNWIND_X86_64_MODE_STACK_IND:
776         {
777             // The clang in Xcode 6 is emitting incorrect compact unwind encodings for this
778             // style of unwind.  It was fixed in llvm r217020.
779             return false;
780         }
781         break;
782 
783         case UNWIND_X86_64_MODE_STACK_IMMD:
784         {
785             uint32_t stack_size = EXTRACT_BITS (function_info.encoding, UNWIND_X86_64_FRAMELESS_STACK_SIZE);
786             uint32_t register_count = EXTRACT_BITS (function_info.encoding, UNWIND_X86_64_FRAMELESS_STACK_REG_COUNT);
787             uint32_t permutation = EXTRACT_BITS (function_info.encoding, UNWIND_X86_64_FRAMELESS_STACK_REG_PERMUTATION);
788 
789             if (mode == UNWIND_X86_64_MODE_STACK_IND && function_info.valid_range_offset_start != 0)
790             {
791                 uint32_t stack_adjust = EXTRACT_BITS (function_info.encoding, UNWIND_X86_64_FRAMELESS_STACK_ADJUST);
792 
793                 // offset into the function instructions; 0 == beginning of first instruction
794                 uint32_t offset_to_subl_insn = EXTRACT_BITS (function_info.encoding, UNWIND_X86_64_FRAMELESS_STACK_SIZE);
795 
796                 SectionList *sl = m_objfile.GetSectionList ();
797                 if (sl)
798                 {
799                     ProcessSP process_sp = target.GetProcessSP();
800                     if (process_sp)
801                     {
802                         Address subl_payload_addr (function_info.valid_range_offset_start, sl);
803                         subl_payload_addr.Slide (offset_to_subl_insn);
804                         Error error;
805                         uint64_t large_stack_size = process_sp->ReadUnsignedIntegerFromMemory (subl_payload_addr.GetLoadAddress (&target),
806                                 4, 0, error);
807                         if (large_stack_size != 0 && error.Success ())
808                         {
809                             // Got the large stack frame size correctly - use it
810                             stack_size = large_stack_size + (stack_adjust * wordsize);
811                         }
812                         else
813                         {
814                             return false;
815                         }
816                     }
817                     else
818                     {
819                         return false;
820                     }
821                 }
822                 else
823                 {
824                     return false;
825                 }
826             }
827 
828             int32_t offset = mode == UNWIND_X86_64_MODE_STACK_IND ? stack_size : stack_size * wordsize;
829             row->GetCFAValue().SetIsRegisterPlusOffset (x86_64_eh_regnum::rsp, offset);
830 
831             row->SetOffset (0);
832             row->SetRegisterLocationToAtCFAPlusOffset (x86_64_eh_regnum::rip, wordsize * -1, true);
833             row->SetRegisterLocationToIsCFAPlusOffset (x86_64_eh_regnum::rsp, 0, true);
834 
835             if (register_count > 0)
836             {
837 
838                 // We need to include (up to) 6 registers in 10 bits.
839                 // That would be 18 bits if we just used 3 bits per reg to indicate
840                 // the order they're saved on the stack.
841                 //
842                 // This is done with Lehmer code permutation, e.g. see
843                 // http://stackoverflow.com/questions/1506078/fast-permutation-number-permutation-mapping-algorithms
844                 int permunreg[6] = {0, 0, 0, 0, 0, 0};
845 
846                 // This decodes the variable-base number in the 10 bits
847                 // and gives us the Lehmer code sequence which can then
848                 // be decoded.
849 
850                 switch (register_count)
851                 {
852                     case 6:
853                         permunreg[0] = permutation/120;    // 120 == 5!
854                         permutation -= (permunreg[0]*120);
855                         permunreg[1] = permutation/24;     // 24 == 4!
856                         permutation -= (permunreg[1]*24);
857                         permunreg[2] = permutation/6;      // 6 == 3!
858                         permutation -= (permunreg[2]*6);
859                         permunreg[3] = permutation/2;      // 2 == 2!
860                         permutation -= (permunreg[3]*2);
861                         permunreg[4] = permutation;        // 1 == 1!
862                         permunreg[5] = 0;
863                         break;
864                     case 5:
865                         permunreg[0] = permutation/120;
866                         permutation -= (permunreg[0]*120);
867                         permunreg[1] = permutation/24;
868                         permutation -= (permunreg[1]*24);
869                         permunreg[2] = permutation/6;
870                         permutation -= (permunreg[2]*6);
871                         permunreg[3] = permutation/2;
872                         permutation -= (permunreg[3]*2);
873                         permunreg[4] = permutation;
874                         break;
875                     case 4:
876                         permunreg[0] = permutation/60;
877                         permutation -= (permunreg[0]*60);
878                         permunreg[1] = permutation/12;
879                         permutation -= (permunreg[1]*12);
880                         permunreg[2] = permutation/3;
881                         permutation -= (permunreg[2]*3);
882                         permunreg[3] = permutation;
883                         break;
884                     case 3:
885                         permunreg[0] = permutation/20;
886                         permutation -= (permunreg[0]*20);
887                         permunreg[1] = permutation/4;
888                         permutation -= (permunreg[1]*4);
889                         permunreg[2] = permutation;
890                         break;
891                     case 2:
892                         permunreg[0] = permutation/5;
893                         permutation -= (permunreg[0]*5);
894                         permunreg[1] = permutation;
895                         break;
896                     case 1:
897                         permunreg[0] = permutation;
898                         break;
899                 }
900 
901                 // Decode the Lehmer code for this permutation of
902                 // the registers v. http://en.wikipedia.org/wiki/Lehmer_code
903 
904                 int registers[6] = { UNWIND_X86_64_REG_NONE, UNWIND_X86_64_REG_NONE, UNWIND_X86_64_REG_NONE, UNWIND_X86_64_REG_NONE, UNWIND_X86_64_REG_NONE, UNWIND_X86_64_REG_NONE };
905                 bool used[7] = { false, false, false, false, false, false, false };
906                 for (uint32_t i = 0; i < register_count; i++)
907                 {
908                     int renum = 0;
909                     for (int j = 1; j < 7; j++)
910                     {
911                         if (used[j] == false)
912                         {
913                             if (renum == permunreg[i])
914                             {
915                                 registers[i] = j;
916                                 used[j] = true;
917                                 break;
918                             }
919                             renum++;
920                         }
921                     }
922                 }
923 
924                 uint32_t saved_registers_offset = 1;
925                 saved_registers_offset++;
926 
927                 for (int i = (sizeof (registers) / sizeof (int)) - 1; i >= 0; i--)
928                 {
929                     switch (registers[i])
930                     {
931                         case UNWIND_X86_64_REG_NONE:
932                             break;
933                         case UNWIND_X86_64_REG_RBX:
934                         case UNWIND_X86_64_REG_R12:
935                         case UNWIND_X86_64_REG_R13:
936                         case UNWIND_X86_64_REG_R14:
937                         case UNWIND_X86_64_REG_R15:
938                         case UNWIND_X86_64_REG_RBP:
939                             row->SetRegisterLocationToAtCFAPlusOffset (translate_to_eh_frame_regnum_x86_64 (registers[i]), wordsize * -saved_registers_offset, true);
940                             saved_registers_offset++;
941                         break;
942                     }
943                 }
944             }
945             unwind_plan.AppendRow (row);
946             return true;
947         }
948         break;
949 
950         case UNWIND_X86_64_MODE_DWARF:
951         {
952             return false;
953         }
954         break;
955 
956         case 0:
957         {
958             return false;
959         }
960         break;
961     }
962     return false;
963 }
964 
965 enum i386_eh_regnum {
966     eax = 0,
967     ecx = 1,
968     edx = 2,
969     ebx = 3,
970     ebp = 4,
971     esp = 5,
972     esi = 6,
973     edi = 7,
974     eip = 8    // this is officially the Return Address register number, but close enough
975 };
976 
977 // Convert the compact_unwind_info.h register numbering scheme
978 // to eRegisterKindGCC (eh_frame) register numbering scheme.
979 uint32_t
980 translate_to_eh_frame_regnum_i386 (uint32_t unwind_regno)
981 {
982     switch (unwind_regno)
983     {
984         case UNWIND_X86_REG_EBX:
985             return i386_eh_regnum::ebx;
986         case UNWIND_X86_REG_ECX:
987             return i386_eh_regnum::ecx;
988         case UNWIND_X86_REG_EDX:
989             return i386_eh_regnum::edx;
990         case UNWIND_X86_REG_EDI:
991             return i386_eh_regnum::edi;
992         case UNWIND_X86_REG_ESI:
993             return i386_eh_regnum::esi;
994         case UNWIND_X86_REG_EBP:
995             return i386_eh_regnum::ebp;
996         default:
997             return LLDB_INVALID_REGNUM;
998     }
999 }
1000 
1001 
1002 bool
1003 CompactUnwindInfo::CreateUnwindPlan_i386 (Target &target, FunctionInfo &function_info, UnwindPlan &unwind_plan, Address pc_or_function_start)
1004 {
1005     unwind_plan.SetSourceName ("compact unwind info");
1006     unwind_plan.SetSourcedFromCompiler (eLazyBoolYes);
1007     unwind_plan.SetUnwindPlanValidAtAllInstructions (eLazyBoolNo);
1008     unwind_plan.SetRegisterKind (eRegisterKindGCC);
1009 
1010     unwind_plan.SetLSDAAddress (function_info.lsda_address);
1011     unwind_plan.SetPersonalityFunctionPtr (function_info.personality_ptr_address);
1012 
1013     UnwindPlan::RowSP row (new UnwindPlan::Row);
1014 
1015     const int wordsize = 4;
1016     int mode = function_info.encoding & UNWIND_X86_MODE_MASK;
1017     switch (mode)
1018     {
1019         case UNWIND_X86_MODE_EBP_FRAME:
1020         {
1021             row->GetCFAValue().SetIsRegisterPlusOffset (
1022                     translate_to_eh_frame_regnum_i386 (UNWIND_X86_REG_EBP), 2 * wordsize);
1023             row->SetOffset (0);
1024             row->SetRegisterLocationToAtCFAPlusOffset (i386_eh_regnum::ebp, wordsize * -2, true);
1025             row->SetRegisterLocationToAtCFAPlusOffset (i386_eh_regnum::eip, wordsize * -1, true);
1026             row->SetRegisterLocationToIsCFAPlusOffset (i386_eh_regnum::esp, 0, true);
1027 
1028             uint32_t saved_registers_offset = EXTRACT_BITS (function_info.encoding, UNWIND_X86_EBP_FRAME_OFFSET);
1029 
1030             uint32_t saved_registers_locations = EXTRACT_BITS (function_info.encoding, UNWIND_X86_EBP_FRAME_REGISTERS);
1031 
1032             saved_registers_offset += 2;
1033 
1034             for (int i = 0; i < 5; i++)
1035             {
1036                 uint32_t regnum = saved_registers_locations & 0x7;
1037                 switch (regnum)
1038                 {
1039                     case UNWIND_X86_REG_NONE:
1040                         break;
1041                     case UNWIND_X86_REG_EBX:
1042                     case UNWIND_X86_REG_ECX:
1043                     case UNWIND_X86_REG_EDX:
1044                     case UNWIND_X86_REG_EDI:
1045                     case UNWIND_X86_REG_ESI:
1046                         row->SetRegisterLocationToAtCFAPlusOffset (translate_to_eh_frame_regnum_i386 (regnum), wordsize * -saved_registers_offset, true);
1047                         break;
1048                 }
1049                 saved_registers_offset--;
1050                 saved_registers_locations >>= 3;
1051             }
1052             unwind_plan.AppendRow (row);
1053             return true;
1054         }
1055         break;
1056 
1057         case UNWIND_X86_MODE_STACK_IND:
1058         case UNWIND_X86_MODE_STACK_IMMD:
1059         {
1060             uint32_t stack_size = EXTRACT_BITS (function_info.encoding, UNWIND_X86_FRAMELESS_STACK_SIZE);
1061             uint32_t register_count = EXTRACT_BITS (function_info.encoding, UNWIND_X86_FRAMELESS_STACK_REG_COUNT);
1062             uint32_t permutation = EXTRACT_BITS (function_info.encoding, UNWIND_X86_FRAMELESS_STACK_REG_PERMUTATION);
1063 
1064             if (mode == UNWIND_X86_MODE_STACK_IND && function_info.valid_range_offset_start != 0)
1065             {
1066                 uint32_t stack_adjust = EXTRACT_BITS (function_info.encoding, UNWIND_X86_FRAMELESS_STACK_ADJUST);
1067 
1068                 // offset into the function instructions; 0 == beginning of first instruction
1069                 uint32_t offset_to_subl_insn = EXTRACT_BITS (function_info.encoding, UNWIND_X86_FRAMELESS_STACK_SIZE);
1070 
1071                 SectionList *sl = m_objfile.GetSectionList ();
1072                 if (sl)
1073                 {
1074                     ProcessSP process_sp = target.GetProcessSP();
1075                     if (process_sp)
1076                     {
1077                         Address subl_payload_addr (function_info.valid_range_offset_start, sl);
1078                         subl_payload_addr.Slide (offset_to_subl_insn);
1079                         Error error;
1080                         uint64_t large_stack_size = process_sp->ReadUnsignedIntegerFromMemory (subl_payload_addr.GetLoadAddress (&target),
1081                                 4, 0, error);
1082                         if (large_stack_size != 0 && error.Success ())
1083                         {
1084                             // Got the large stack frame size correctly - use it
1085                             stack_size = large_stack_size + (stack_adjust * wordsize);
1086                         }
1087                         else
1088                         {
1089                             return false;
1090                         }
1091                     }
1092                     else
1093                     {
1094                         return false;
1095                     }
1096                 }
1097                 else
1098                 {
1099                     return false;
1100                 }
1101             }
1102 
1103             int32_t offset = mode == UNWIND_X86_MODE_STACK_IND ? stack_size : stack_size * wordsize;
1104             row->GetCFAValue().SetIsRegisterPlusOffset (i386_eh_regnum::esp, offset);
1105             row->SetOffset (0);
1106             row->SetRegisterLocationToAtCFAPlusOffset (i386_eh_regnum::eip, wordsize * -1, true);
1107             row->SetRegisterLocationToIsCFAPlusOffset (i386_eh_regnum::esp, 0, true);
1108 
1109             if (register_count > 0)
1110             {
1111 
1112                 // We need to include (up to) 6 registers in 10 bits.
1113                 // That would be 18 bits if we just used 3 bits per reg to indicate
1114                 // the order they're saved on the stack.
1115                 //
1116                 // This is done with Lehmer code permutation, e.g. see
1117                 // http://stackoverflow.com/questions/1506078/fast-permutation-number-permutation-mapping-algorithms
1118                 int permunreg[6] = {0, 0, 0, 0, 0, 0};
1119 
1120                 // This decodes the variable-base number in the 10 bits
1121                 // and gives us the Lehmer code sequence which can then
1122                 // be decoded.
1123 
1124                 switch (register_count)
1125                 {
1126                     case 6:
1127                         permunreg[0] = permutation/120;    // 120 == 5!
1128                         permutation -= (permunreg[0]*120);
1129                         permunreg[1] = permutation/24;     // 24 == 4!
1130                         permutation -= (permunreg[1]*24);
1131                         permunreg[2] = permutation/6;      // 6 == 3!
1132                         permutation -= (permunreg[2]*6);
1133                         permunreg[3] = permutation/2;      // 2 == 2!
1134                         permutation -= (permunreg[3]*2);
1135                         permunreg[4] = permutation;        // 1 == 1!
1136                         permunreg[5] = 0;
1137                         break;
1138                     case 5:
1139                         permunreg[0] = permutation/120;
1140                         permutation -= (permunreg[0]*120);
1141                         permunreg[1] = permutation/24;
1142                         permutation -= (permunreg[1]*24);
1143                         permunreg[2] = permutation/6;
1144                         permutation -= (permunreg[2]*6);
1145                         permunreg[3] = permutation/2;
1146                         permutation -= (permunreg[3]*2);
1147                         permunreg[4] = permutation;
1148                         break;
1149                     case 4:
1150                         permunreg[0] = permutation/60;
1151                         permutation -= (permunreg[0]*60);
1152                         permunreg[1] = permutation/12;
1153                         permutation -= (permunreg[1]*12);
1154                         permunreg[2] = permutation/3;
1155                         permutation -= (permunreg[2]*3);
1156                         permunreg[3] = permutation;
1157                         break;
1158                     case 3:
1159                         permunreg[0] = permutation/20;
1160                         permutation -= (permunreg[0]*20);
1161                         permunreg[1] = permutation/4;
1162                         permutation -= (permunreg[1]*4);
1163                         permunreg[2] = permutation;
1164                         break;
1165                     case 2:
1166                         permunreg[0] = permutation/5;
1167                         permutation -= (permunreg[0]*5);
1168                         permunreg[1] = permutation;
1169                         break;
1170                     case 1:
1171                         permunreg[0] = permutation;
1172                         break;
1173                 }
1174 
1175                 // Decode the Lehmer code for this permutation of
1176                 // the registers v. http://en.wikipedia.org/wiki/Lehmer_code
1177 
1178                 int registers[6] = { UNWIND_X86_REG_NONE, UNWIND_X86_REG_NONE, UNWIND_X86_REG_NONE, UNWIND_X86_REG_NONE, UNWIND_X86_REG_NONE, UNWIND_X86_REG_NONE };
1179                 bool used[7] = { false, false, false, false, false, false, false };
1180                 for (uint32_t i = 0; i < register_count; i++)
1181                 {
1182                     int renum = 0;
1183                     for (int j = 1; j < 7; j++)
1184                     {
1185                         if (used[j] == false)
1186                         {
1187                             if (renum == permunreg[i])
1188                             {
1189                                 registers[i] = j;
1190                                 used[j] = true;
1191                                 break;
1192                             }
1193                             renum++;
1194                         }
1195                     }
1196                 }
1197 
1198                 uint32_t saved_registers_offset = 1;
1199                 saved_registers_offset++;
1200 
1201                 for (int i = (sizeof (registers) / sizeof (int)) - 1; i >= 0; i--)
1202                 {
1203                     switch (registers[i])
1204                     {
1205                         case UNWIND_X86_REG_NONE:
1206                             break;
1207                         case UNWIND_X86_REG_EBX:
1208                         case UNWIND_X86_REG_ECX:
1209                         case UNWIND_X86_REG_EDX:
1210                         case UNWIND_X86_REG_EDI:
1211                         case UNWIND_X86_REG_ESI:
1212                         case UNWIND_X86_REG_EBP:
1213                             row->SetRegisterLocationToAtCFAPlusOffset (translate_to_eh_frame_regnum_i386 (registers[i]), wordsize * -saved_registers_offset, true);
1214                             saved_registers_offset++;
1215                         break;
1216                     }
1217                 }
1218             }
1219 
1220             unwind_plan.AppendRow (row);
1221             return true;
1222         }
1223         break;
1224 
1225         case UNWIND_X86_MODE_DWARF:
1226         {
1227             return false;
1228         }
1229         break;
1230     }
1231     return false;
1232 }
1233