comparison lld/MachO/UnwindInfoSection.cpp @ 207:2e18cbf3894f

LLVM12
author Shinji KONO <kono@ie.u-ryukyu.ac.jp>
date Tue, 08 Jun 2021 06:07:14 +0900
parents
children 5f17cb93ff66
comparison
equal deleted inserted replaced
173:0572611fdcc8 207:2e18cbf3894f
1 //===- UnwindInfoSection.cpp ----------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #include "UnwindInfoSection.h"
10 #include "ConcatOutputSection.h"
11 #include "Config.h"
12 #include "InputSection.h"
13 #include "OutputSection.h"
14 #include "OutputSegment.h"
15 #include "SymbolTable.h"
16 #include "Symbols.h"
17 #include "SyntheticSections.h"
18 #include "Target.h"
19
20 #include "lld/Common/ErrorHandler.h"
21 #include "lld/Common/Memory.h"
22 #include "llvm/ADT/STLExtras.h"
23 #include "llvm/ADT/SmallVector.h"
24 #include "llvm/BinaryFormat/MachO.h"
25
26 using namespace llvm;
27 using namespace llvm::MachO;
28 using namespace lld;
29 using namespace lld::macho;
30
31 #define COMMON_ENCODINGS_MAX 127
32 #define COMPACT_ENCODINGS_MAX 256
33
34 #define SECOND_LEVEL_PAGE_BYTES 4096
35 #define SECOND_LEVEL_PAGE_WORDS (SECOND_LEVEL_PAGE_BYTES / sizeof(uint32_t))
36 #define REGULAR_SECOND_LEVEL_ENTRIES_MAX \
37 ((SECOND_LEVEL_PAGE_BYTES - \
38 sizeof(unwind_info_regular_second_level_page_header)) / \
39 sizeof(unwind_info_regular_second_level_entry))
40 #define COMPRESSED_SECOND_LEVEL_ENTRIES_MAX \
41 ((SECOND_LEVEL_PAGE_BYTES - \
42 sizeof(unwind_info_compressed_second_level_page_header)) / \
43 sizeof(uint32_t))
44
45 #define COMPRESSED_ENTRY_FUNC_OFFSET_BITS 24
46 #define COMPRESSED_ENTRY_FUNC_OFFSET_MASK \
47 UNWIND_INFO_COMPRESSED_ENTRY_FUNC_OFFSET(~0)
48
49 // Compact Unwind format is a Mach-O evolution of DWARF Unwind that
50 // optimizes space and exception-time lookup. Most DWARF unwind
51 // entries can be replaced with Compact Unwind entries, but the ones
52 // that cannot are retained in DWARF form.
53 //
54 // This comment will address macro-level organization of the pre-link
55 // and post-link compact unwind tables. For micro-level organization
56 // pertaining to the bitfield layout of the 32-bit compact unwind
57 // entries, see libunwind/include/mach-o/compact_unwind_encoding.h
58 //
59 // Important clarifying factoids:
60 //
61 // * __LD,__compact_unwind is the compact unwind format for compiler
62 // output and linker input. It is never a final output. It could be
63 // an intermediate output with the `-r` option which retains relocs.
64 //
65 // * __TEXT,__unwind_info is the compact unwind format for final
66 // linker output. It is never an input.
67 //
68 // * __TEXT,__eh_frame is the DWARF format for both linker input and output.
69 //
70 // * __TEXT,__unwind_info entries are divided into 4 KiB pages (2nd
71 // level) by ascending address, and the pages are referenced by an
72 // index (1st level) in the section header.
73 //
74 // * Following the headers in __TEXT,__unwind_info, the bulk of the
75 // section contains a vector of compact unwind entries
76 // `{functionOffset, encoding}` sorted by ascending `functionOffset`.
77 // Adjacent entries with the same encoding can be folded to great
78 // advantage, achieving a 3-order-of-magnitude reduction in the
79 // number of entries.
80 //
81 // * The __TEXT,__unwind_info format can accommodate up to 127 unique
82 // encodings for the space-efficient compressed format. In practice,
83 // fewer than a dozen unique encodings are used by C++ programs of
84 // all sizes. Therefore, we don't even bother implementing the regular
85 // non-compressed format. Time will tell if anyone in the field ever
86 // overflows the 127-encodings limit.
87 //
88 // Refer to the definition of unwind_info_section_header in
89 // compact_unwind_encoding.h for an overview of the format we are encoding
90 // here.
91
92 // TODO(gkm): prune __eh_frame entries superseded by __unwind_info, PR50410
93 // TODO(gkm): how do we align the 2nd-level pages?
94
95 using EncodingMap = llvm::DenseMap<compact_unwind_encoding_t, size_t>;
96
97 struct SecondLevelPage {
98 uint32_t kind;
99 size_t entryIndex;
100 size_t entryCount;
101 size_t byteCount;
102 std::vector<compact_unwind_encoding_t> localEncodings;
103 EncodingMap localEncodingIndexes;
104 };
105
106 template <class Ptr> class UnwindInfoSectionImpl : public UnwindInfoSection {
107 public:
108 void prepareRelocations(InputSection *) override;
109 void finalize() override;
110 void writeTo(uint8_t *buf) const override;
111
112 private:
113 std::vector<std::pair<compact_unwind_encoding_t, size_t>> commonEncodings;
114 EncodingMap commonEncodingIndexes;
115 // Indices of personality functions within the GOT.
116 std::vector<uint32_t> personalities;
117 SmallDenseMap<std::pair<InputSection *, uint64_t /* addend */>, Symbol *>
118 personalityTable;
119 std::vector<unwind_info_section_header_lsda_index_entry> lsdaEntries;
120 // Map of function offset (from the image base) to an index within the LSDA
121 // array.
122 llvm::DenseMap<uint32_t, uint32_t> functionToLsdaIndex;
123 std::vector<CompactUnwindEntry<Ptr>> cuVector;
124 std::vector<CompactUnwindEntry<Ptr> *> cuPtrVector;
125 std::vector<SecondLevelPage> secondLevelPages;
126 uint64_t level2PagesOffset = 0;
127 };
128
129 // Compact unwind relocations have different semantics, so we handle them in a
130 // separate code path from regular relocations. First, we do not wish to add
131 // rebase opcodes for __LD,__compact_unwind, because that section doesn't
132 // actually end up in the final binary. Second, personality pointers always
133 // reside in the GOT and must be treated specially.
134 template <class Ptr>
135 void UnwindInfoSectionImpl<Ptr>::prepareRelocations(InputSection *isec) {
136 assert(isec->segname == segment_names::ld &&
137 isec->name == section_names::compactUnwind);
138 assert(!isec->shouldOmitFromOutput() &&
139 "__compact_unwind section should not be omitted");
140
141 // FIXME: This could skip relocations for CompactUnwindEntries that
142 // point to dead-stripped functions. That might save some amount of
143 // work. But since there are usually just few personality functions
144 // that are referenced from many places, at least some of them likely
145 // live, it wouldn't reduce number of got entries.
146 for (Reloc &r : isec->relocs) {
147 assert(target->hasAttr(r.type, RelocAttrBits::UNSIGNED));
148 if (r.offset % sizeof(CompactUnwindEntry<Ptr>) !=
149 offsetof(CompactUnwindEntry<Ptr>, personality))
150 continue;
151
152 if (auto *s = r.referent.dyn_cast<Symbol *>()) {
153 if (auto *undefined = dyn_cast<Undefined>(s)) {
154 treatUndefinedSymbol(*undefined);
155 // treatUndefinedSymbol() can replace s with a DylibSymbol; re-check.
156 if (isa<Undefined>(s))
157 continue;
158 }
159 if (auto *defined = dyn_cast<Defined>(s)) {
160 // Check if we have created a synthetic symbol at the same address.
161 Symbol *&personality =
162 personalityTable[{defined->isec, defined->value}];
163 if (personality == nullptr) {
164 personality = defined;
165 in.got->addEntry(defined);
166 } else if (personality != defined) {
167 r.referent = personality;
168 }
169 continue;
170 }
171 assert(isa<DylibSymbol>(s));
172 in.got->addEntry(s);
173 continue;
174 }
175
176 if (auto *referentIsec = r.referent.dyn_cast<InputSection *>()) {
177 assert(!referentIsec->isCoalescedWeak());
178
179 // Personality functions can be referenced via section relocations
180 // if they live in the same object file. Create placeholder synthetic
181 // symbols for them in the GOT.
182 Symbol *&s = personalityTable[{referentIsec, r.addend}];
183 if (s == nullptr) {
184 // This runs after dead stripping, so the noDeadStrip argument does not
185 // matter.
186 s = make<Defined>("<internal>", /*file=*/nullptr, referentIsec,
187 r.addend, /*size=*/0, /*isWeakDef=*/false,
188 /*isExternal=*/false, /*isPrivateExtern=*/false,
189 /*isThumb=*/false, /*isReferencedDynamically=*/false,
190 /*noDeadStrip=*/false);
191 in.got->addEntry(s);
192 }
193 r.referent = s;
194 r.addend = 0;
195 }
196 }
197 }
198
199 // Unwind info lives in __DATA, and finalization of __TEXT will occur before
200 // finalization of __DATA. Moreover, the finalization of unwind info depends on
201 // the exact addresses that it references. So it is safe for compact unwind to
202 // reference addresses in __TEXT, but not addresses in any other segment.
203 static void checkTextSegment(InputSection *isec) {
204 if (isec->segname != segment_names::text)
205 error("compact unwind references address in " + toString(isec) +
206 " which is not in segment __TEXT");
207 }
208
209 // We need to apply the relocations to the pre-link compact unwind section
210 // before converting it to post-link form. There should only be absolute
211 // relocations here: since we are not emitting the pre-link CU section, there
212 // is no source address to make a relative location meaningful.
213 template <class Ptr>
214 static void
215 relocateCompactUnwind(ConcatOutputSection *compactUnwindSection,
216 std::vector<CompactUnwindEntry<Ptr>> &cuVector) {
217 for (const InputSection *isec : compactUnwindSection->inputs) {
218 assert(isec->parent == compactUnwindSection);
219
220 uint8_t *buf =
221 reinterpret_cast<uint8_t *>(cuVector.data()) + isec->outSecFileOff;
222 memcpy(buf, isec->data.data(), isec->data.size());
223
224 for (const Reloc &r : isec->relocs) {
225 uint64_t referentVA = 0;
226 if (auto *referentSym = r.referent.dyn_cast<Symbol *>()) {
227 if (!isa<Undefined>(referentSym)) {
228 assert(referentSym->isInGot());
229 if (auto *defined = dyn_cast<Defined>(referentSym))
230 checkTextSegment(defined->isec);
231 // At this point in the link, we may not yet know the final address of
232 // the GOT, so we just encode the index. We make it a 1-based index so
233 // that we can distinguish the null pointer case.
234 referentVA = referentSym->gotIndex + 1;
235 }
236 } else if (auto *referentIsec = r.referent.dyn_cast<InputSection *>()) {
237 checkTextSegment(referentIsec);
238 if (referentIsec->shouldOmitFromOutput())
239 referentVA = UINT64_MAX; // Tombstone value
240 else
241 referentVA = referentIsec->getVA() + r.addend;
242 }
243
244 writeAddress(buf + r.offset, referentVA, r.length);
245 }
246 }
247 }
248
249 // There should only be a handful of unique personality pointers, so we can
250 // encode them as 2-bit indices into a small array.
251 template <class Ptr>
252 void encodePersonalities(
253 const std::vector<CompactUnwindEntry<Ptr> *> &cuPtrVector,
254 std::vector<uint32_t> &personalities) {
255 for (CompactUnwindEntry<Ptr> *cu : cuPtrVector) {
256 if (cu->personality == 0)
257 continue;
258 // Linear search is fast enough for a small array.
259 auto it = find(personalities, cu->personality);
260 uint32_t personalityIndex; // 1-based index
261 if (it != personalities.end()) {
262 personalityIndex = std::distance(personalities.begin(), it) + 1;
263 } else {
264 personalities.push_back(cu->personality);
265 personalityIndex = personalities.size();
266 }
267 cu->encoding |=
268 personalityIndex << countTrailingZeros(
269 static_cast<compact_unwind_encoding_t>(UNWIND_PERSONALITY_MASK));
270 }
271 if (personalities.size() > 3)
272 error("too many personalities (" + std::to_string(personalities.size()) +
273 ") for compact unwind to encode");
274 }
275
276 // Scan the __LD,__compact_unwind entries and compute the space needs of
277 // __TEXT,__unwind_info and __TEXT,__eh_frame
278 template <class Ptr> void UnwindInfoSectionImpl<Ptr>::finalize() {
279 if (compactUnwindSection == nullptr)
280 return;
281
282 // At this point, the address space for __TEXT,__text has been
283 // assigned, so we can relocate the __LD,__compact_unwind entries
284 // into a temporary buffer. Relocation is necessary in order to sort
285 // the CU entries by function address. Sorting is necessary so that
286 // we can fold adjacent CU entries with identical
287 // encoding+personality+lsda. Folding is necessary because it reduces
288 // the number of CU entries by as much as 3 orders of magnitude!
289 compactUnwindSection->finalize();
290 assert(compactUnwindSection->getSize() % sizeof(CompactUnwindEntry<Ptr>) ==
291 0);
292 size_t cuCount =
293 compactUnwindSection->getSize() / sizeof(CompactUnwindEntry<Ptr>);
294 cuVector.resize(cuCount);
295 relocateCompactUnwind(compactUnwindSection, cuVector);
296
297 // Rather than sort & fold the 32-byte entries directly, we create a
298 // vector of pointers to entries and sort & fold that instead.
299 cuPtrVector.reserve(cuCount);
300 for (CompactUnwindEntry<Ptr> &cuEntry : cuVector)
301 cuPtrVector.emplace_back(&cuEntry);
302 llvm::sort(cuPtrVector, [](const CompactUnwindEntry<Ptr> *a,
303 const CompactUnwindEntry<Ptr> *b) {
304 return a->functionAddress < b->functionAddress;
305 });
306
307 // Dead-stripped functions get a functionAddress of UINT64_MAX in
308 // relocateCompactUnwind(). Filter them out here.
309 // FIXME: This doesn't yet collect associated data like LSDAs kept
310 // alive only by a now-removed CompactUnwindEntry or other comdat-like
311 // data (`kindNoneGroupSubordinate*` in ld64).
312 CompactUnwindEntry<Ptr> tombstone;
313 tombstone.functionAddress = static_cast<Ptr>(UINT64_MAX);
314 cuPtrVector.erase(
315 std::lower_bound(cuPtrVector.begin(), cuPtrVector.end(), &tombstone,
316 [](const CompactUnwindEntry<Ptr> *a,
317 const CompactUnwindEntry<Ptr> *b) {
318 return a->functionAddress < b->functionAddress;
319 }),
320 cuPtrVector.end());
321
322 // Fold adjacent entries with matching encoding+personality+lsda
323 // We use three iterators on the same cuPtrVector to fold in-situ:
324 // (1) `foldBegin` is the first of a potential sequence of matching entries
325 // (2) `foldEnd` is the first non-matching entry after `foldBegin`.
326 // The semi-open interval [ foldBegin .. foldEnd ) contains a range
327 // entries that can be folded into a single entry and written to ...
328 // (3) `foldWrite`
329 auto foldWrite = cuPtrVector.begin();
330 for (auto foldBegin = cuPtrVector.begin(); foldBegin < cuPtrVector.end();) {
331 auto foldEnd = foldBegin;
332 while (++foldEnd < cuPtrVector.end() &&
333 (*foldBegin)->encoding == (*foldEnd)->encoding &&
334 (*foldBegin)->personality == (*foldEnd)->personality &&
335 (*foldBegin)->lsda == (*foldEnd)->lsda)
336 ;
337 *foldWrite++ = *foldBegin;
338 foldBegin = foldEnd;
339 }
340 cuPtrVector.erase(foldWrite, cuPtrVector.end());
341
342 encodePersonalities(cuPtrVector, personalities);
343
344 // Count frequencies of the folded encodings
345 EncodingMap encodingFrequencies;
346 for (const CompactUnwindEntry<Ptr> *cuPtrEntry : cuPtrVector)
347 encodingFrequencies[cuPtrEntry->encoding]++;
348
349 // Make a vector of encodings, sorted by descending frequency
350 for (const auto &frequency : encodingFrequencies)
351 commonEncodings.emplace_back(frequency);
352 llvm::sort(commonEncodings,
353 [](const std::pair<compact_unwind_encoding_t, size_t> &a,
354 const std::pair<compact_unwind_encoding_t, size_t> &b) {
355 if (a.second == b.second)
356 // When frequencies match, secondarily sort on encoding
357 // to maintain parity with validate-unwind-info.py
358 return a.first > b.first;
359 return a.second > b.second;
360 });
361
362 // Truncate the vector to 127 elements.
363 // Common encoding indexes are limited to 0..126, while encoding
364 // indexes 127..255 are local to each second-level page
365 if (commonEncodings.size() > COMMON_ENCODINGS_MAX)
366 commonEncodings.resize(COMMON_ENCODINGS_MAX);
367
368 // Create a map from encoding to common-encoding-table index
369 for (size_t i = 0; i < commonEncodings.size(); i++)
370 commonEncodingIndexes[commonEncodings[i].first] = i;
371
372 // Split folded encodings into pages, where each page is limited by ...
373 // (a) 4 KiB capacity
374 // (b) 24-bit difference between first & final function address
375 // (c) 8-bit compact-encoding-table index,
376 // for which 0..126 references the global common-encodings table,
377 // and 127..255 references a local per-second-level-page table.
378 // First we try the compact format and determine how many entries fit.
379 // If more entries fit in the regular format, we use that.
380 for (size_t i = 0; i < cuPtrVector.size();) {
381 secondLevelPages.emplace_back();
382 SecondLevelPage &page = secondLevelPages.back();
383 page.entryIndex = i;
384 uintptr_t functionAddressMax =
385 cuPtrVector[i]->functionAddress + COMPRESSED_ENTRY_FUNC_OFFSET_MASK;
386 size_t n = commonEncodings.size();
387 size_t wordsRemaining =
388 SECOND_LEVEL_PAGE_WORDS -
389 sizeof(unwind_info_compressed_second_level_page_header) /
390 sizeof(uint32_t);
391 while (wordsRemaining >= 1 && i < cuPtrVector.size()) {
392 const CompactUnwindEntry<Ptr> *cuPtr = cuPtrVector[i];
393 if (cuPtr->functionAddress >= functionAddressMax) {
394 break;
395 } else if (commonEncodingIndexes.count(cuPtr->encoding) ||
396 page.localEncodingIndexes.count(cuPtr->encoding)) {
397 i++;
398 wordsRemaining--;
399 } else if (wordsRemaining >= 2 && n < COMPACT_ENCODINGS_MAX) {
400 page.localEncodings.emplace_back(cuPtr->encoding);
401 page.localEncodingIndexes[cuPtr->encoding] = n++;
402 i++;
403 wordsRemaining -= 2;
404 } else {
405 break;
406 }
407 }
408 page.entryCount = i - page.entryIndex;
409
410 // If this is not the final page, see if it's possible to fit more
411 // entries by using the regular format. This can happen when there
412 // are many unique encodings, and we we saturated the local
413 // encoding table early.
414 if (i < cuPtrVector.size() &&
415 page.entryCount < REGULAR_SECOND_LEVEL_ENTRIES_MAX) {
416 page.kind = UNWIND_SECOND_LEVEL_REGULAR;
417 page.entryCount = std::min(REGULAR_SECOND_LEVEL_ENTRIES_MAX,
418 cuPtrVector.size() - page.entryIndex);
419 i = page.entryIndex + page.entryCount;
420 } else {
421 page.kind = UNWIND_SECOND_LEVEL_COMPRESSED;
422 }
423 }
424
425 for (const CompactUnwindEntry<Ptr> *cu : cuPtrVector) {
426 uint32_t functionOffset = cu->functionAddress - in.header->addr;
427 functionToLsdaIndex[functionOffset] = lsdaEntries.size();
428 if (cu->lsda != 0)
429 lsdaEntries.push_back(
430 {functionOffset, static_cast<uint32_t>(cu->lsda - in.header->addr)});
431 }
432
433 // compute size of __TEXT,__unwind_info section
434 level2PagesOffset =
435 sizeof(unwind_info_section_header) +
436 commonEncodings.size() * sizeof(uint32_t) +
437 personalities.size() * sizeof(uint32_t) +
438 // The extra second-level-page entry is for the sentinel
439 (secondLevelPages.size() + 1) *
440 sizeof(unwind_info_section_header_index_entry) +
441 lsdaEntries.size() * sizeof(unwind_info_section_header_lsda_index_entry);
442 unwindInfoSize =
443 level2PagesOffset + secondLevelPages.size() * SECOND_LEVEL_PAGE_BYTES;
444 }
445
446 // All inputs are relocated and output addresses are known, so write!
447
448 template <class Ptr>
449 void UnwindInfoSectionImpl<Ptr>::writeTo(uint8_t *buf) const {
450 // section header
451 auto *uip = reinterpret_cast<unwind_info_section_header *>(buf);
452 uip->version = 1;
453 uip->commonEncodingsArraySectionOffset = sizeof(unwind_info_section_header);
454 uip->commonEncodingsArrayCount = commonEncodings.size();
455 uip->personalityArraySectionOffset =
456 uip->commonEncodingsArraySectionOffset +
457 (uip->commonEncodingsArrayCount * sizeof(uint32_t));
458 uip->personalityArrayCount = personalities.size();
459 uip->indexSectionOffset = uip->personalityArraySectionOffset +
460 (uip->personalityArrayCount * sizeof(uint32_t));
461 uip->indexCount = secondLevelPages.size() + 1;
462
463 // Common encodings
464 auto *i32p = reinterpret_cast<uint32_t *>(&uip[1]);
465 for (const auto &encoding : commonEncodings)
466 *i32p++ = encoding.first;
467
468 // Personalities
469 for (const uint32_t &personality : personalities)
470 *i32p++ =
471 in.got->addr + (personality - 1) * target->wordSize - in.header->addr;
472
473 // Level-1 index
474 uint32_t lsdaOffset =
475 uip->indexSectionOffset +
476 uip->indexCount * sizeof(unwind_info_section_header_index_entry);
477 uint64_t l2PagesOffset = level2PagesOffset;
478 auto *iep = reinterpret_cast<unwind_info_section_header_index_entry *>(i32p);
479 for (const SecondLevelPage &page : secondLevelPages) {
480 iep->functionOffset =
481 cuPtrVector[page.entryIndex]->functionAddress - in.header->addr;
482 iep->secondLevelPagesSectionOffset = l2PagesOffset;
483 iep->lsdaIndexArraySectionOffset =
484 lsdaOffset + functionToLsdaIndex.lookup(iep->functionOffset) *
485 sizeof(unwind_info_section_header_lsda_index_entry);
486 iep++;
487 l2PagesOffset += SECOND_LEVEL_PAGE_BYTES;
488 }
489 // Level-1 sentinel
490 const CompactUnwindEntry<Ptr> &cuEnd = cuVector.back();
491 iep->functionOffset = cuEnd.functionAddress + cuEnd.functionLength;
492 iep->secondLevelPagesSectionOffset = 0;
493 iep->lsdaIndexArraySectionOffset =
494 lsdaOffset +
495 lsdaEntries.size() * sizeof(unwind_info_section_header_lsda_index_entry);
496 iep++;
497
498 // LSDAs
499 size_t lsdaBytes =
500 lsdaEntries.size() * sizeof(unwind_info_section_header_lsda_index_entry);
501 if (lsdaBytes > 0)
502 memcpy(iep, lsdaEntries.data(), lsdaBytes);
503
504 // Level-2 pages
505 auto *pp = reinterpret_cast<uint32_t *>(reinterpret_cast<uint8_t *>(iep) +
506 lsdaBytes);
507 for (const SecondLevelPage &page : secondLevelPages) {
508 if (page.kind == UNWIND_SECOND_LEVEL_COMPRESSED) {
509 uintptr_t functionAddressBase =
510 cuPtrVector[page.entryIndex]->functionAddress;
511 auto *p2p =
512 reinterpret_cast<unwind_info_compressed_second_level_page_header *>(
513 pp);
514 p2p->kind = page.kind;
515 p2p->entryPageOffset =
516 sizeof(unwind_info_compressed_second_level_page_header);
517 p2p->entryCount = page.entryCount;
518 p2p->encodingsPageOffset =
519 p2p->entryPageOffset + p2p->entryCount * sizeof(uint32_t);
520 p2p->encodingsCount = page.localEncodings.size();
521 auto *ep = reinterpret_cast<uint32_t *>(&p2p[1]);
522 for (size_t i = 0; i < page.entryCount; i++) {
523 const CompactUnwindEntry<Ptr> *cuep = cuPtrVector[page.entryIndex + i];
524 auto it = commonEncodingIndexes.find(cuep->encoding);
525 if (it == commonEncodingIndexes.end())
526 it = page.localEncodingIndexes.find(cuep->encoding);
527 *ep++ = (it->second << COMPRESSED_ENTRY_FUNC_OFFSET_BITS) |
528 (cuep->functionAddress - functionAddressBase);
529 }
530 if (page.localEncodings.size() != 0)
531 memcpy(ep, page.localEncodings.data(),
532 page.localEncodings.size() * sizeof(uint32_t));
533 } else {
534 auto *p2p =
535 reinterpret_cast<unwind_info_regular_second_level_page_header *>(pp);
536 p2p->kind = page.kind;
537 p2p->entryPageOffset =
538 sizeof(unwind_info_regular_second_level_page_header);
539 p2p->entryCount = page.entryCount;
540 auto *ep = reinterpret_cast<uint32_t *>(&p2p[1]);
541 for (size_t i = 0; i < page.entryCount; i++) {
542 const CompactUnwindEntry<Ptr> *cuep = cuPtrVector[page.entryIndex + i];
543 *ep++ = cuep->functionAddress;
544 *ep++ = cuep->encoding;
545 }
546 }
547 pp += SECOND_LEVEL_PAGE_WORDS;
548 }
549 }
550
551 UnwindInfoSection *macho::makeUnwindInfoSection() {
552 if (target->wordSize == 8)
553 return make<UnwindInfoSectionImpl<uint64_t>>();
554 else
555 return make<UnwindInfoSectionImpl<uint32_t>>();
556 }