LLVM 18.0.0git
MachOLinkGraphBuilder.cpp
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1//=--------- MachOLinkGraphBuilder.cpp - MachO LinkGraph builder ----------===//
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// Generic MachO LinkGraph building code.
10//
11//===----------------------------------------------------------------------===//
12
14#include <optional>
15
16#define DEBUG_TYPE "jitlink"
17
18static const char *CommonSectionName = "__common";
19
20namespace llvm {
21namespace jitlink {
22
24
26
27 // We only operate on relocatable objects.
28 if (!Obj.isRelocatableObject())
29 return make_error<JITLinkError>("Object is not a relocatable MachO");
30
31 if (auto Err = createNormalizedSections())
32 return std::move(Err);
33
34 if (auto Err = createNormalizedSymbols())
35 return std::move(Err);
36
37 if (auto Err = graphifyRegularSymbols())
38 return std::move(Err);
39
40 if (auto Err = graphifySectionsWithCustomParsers())
41 return std::move(Err);
42
43 if (auto Err = addRelocations())
44 return std::move(Err);
45
46 return std::move(G);
47}
48
50 const object::MachOObjectFile &Obj, Triple TT, SubtargetFeatures Features,
52 : Obj(Obj),
53 G(std::make_unique<LinkGraph>(std::string(Obj.getFileName()),
54 std::move(TT), std::move(Features),
55 getPointerSize(Obj), getEndianness(Obj),
56 std::move(GetEdgeKindName))) {
57 auto &MachHeader = Obj.getHeader64();
58 SubsectionsViaSymbols = MachHeader.flags & MachO::MH_SUBSECTIONS_VIA_SYMBOLS;
59}
60
63 assert(!CustomSectionParserFunctions.count(SectionName) &&
64 "Custom parser for this section already exists");
65 CustomSectionParserFunctions[SectionName] = std::move(Parser);
66}
67
70 return Linkage::Weak;
71 return Linkage::Strong;
72}
73
75 if (Type & MachO::N_EXT) {
76 if ((Type & MachO::N_PEXT) || Name.startswith("l"))
77 return Scope::Hidden;
78 else
79 return Scope::Default;
80 }
81 return Scope::Local;
82}
83
85 return NSym.Desc & MachO::N_ALT_ENTRY;
86}
87
89 return (NSec.Flags & MachO::S_ATTR_DEBUG &&
90 strcmp(NSec.SegName, "__DWARF") == 0);
91}
92
94 switch (NSec.Flags & MachO::SECTION_TYPE) {
98 return true;
99 default:
100 return false;
101 }
102}
103
104unsigned
105MachOLinkGraphBuilder::getPointerSize(const object::MachOObjectFile &Obj) {
106 return Obj.is64Bit() ? 8 : 4;
107}
108
110MachOLinkGraphBuilder::getEndianness(const object::MachOObjectFile &Obj) {
112}
113
114Section &MachOLinkGraphBuilder::getCommonSection() {
115 if (!CommonSection)
116 CommonSection = &G->createSection(CommonSectionName,
118 return *CommonSection;
119}
120
121Error MachOLinkGraphBuilder::createNormalizedSections() {
122 // Build normalized sections. Verifies that section data is in-range (for
123 // sections with content) and that address ranges are non-overlapping.
124
125 LLVM_DEBUG(dbgs() << "Creating normalized sections...\n");
126
127 for (auto &SecRef : Obj.sections()) {
128 NormalizedSection NSec;
129 uint32_t DataOffset = 0;
130
131 auto SecIndex = Obj.getSectionIndex(SecRef.getRawDataRefImpl());
132
133 if (Obj.is64Bit()) {
134 const MachO::section_64 &Sec64 =
135 Obj.getSection64(SecRef.getRawDataRefImpl());
136
137 memcpy(&NSec.SectName, &Sec64.sectname, 16);
138 NSec.SectName[16] = '\0';
139 memcpy(&NSec.SegName, Sec64.segname, 16);
140 NSec.SegName[16] = '\0';
141
142 NSec.Address = orc::ExecutorAddr(Sec64.addr);
143 NSec.Size = Sec64.size;
144 NSec.Alignment = 1ULL << Sec64.align;
145 NSec.Flags = Sec64.flags;
146 DataOffset = Sec64.offset;
147 } else {
148 const MachO::section &Sec32 = Obj.getSection(SecRef.getRawDataRefImpl());
149
150 memcpy(&NSec.SectName, &Sec32.sectname, 16);
151 NSec.SectName[16] = '\0';
152 memcpy(&NSec.SegName, Sec32.segname, 16);
153 NSec.SegName[16] = '\0';
154
155 NSec.Address = orc::ExecutorAddr(Sec32.addr);
156 NSec.Size = Sec32.size;
157 NSec.Alignment = 1ULL << Sec32.align;
158 NSec.Flags = Sec32.flags;
159 DataOffset = Sec32.offset;
160 }
161
162 LLVM_DEBUG({
163 dbgs() << " " << NSec.SegName << "," << NSec.SectName << ": "
164 << formatv("{0:x16}", NSec.Address) << " -- "
165 << formatv("{0:x16}", NSec.Address + NSec.Size)
166 << ", align: " << NSec.Alignment << ", index: " << SecIndex
167 << "\n";
168 });
169
170 // Get the section data if any.
171 if (!isZeroFillSection(NSec)) {
172 if (DataOffset + NSec.Size > Obj.getData().size())
173 return make_error<JITLinkError>(
174 "Section data extends past end of file");
175
176 NSec.Data = Obj.getData().data() + DataOffset;
177 }
178
179 // Get prot flags.
180 // FIXME: Make sure this test is correct (it's probably missing cases
181 // as-is).
182 orc::MemProt Prot;
183 if (NSec.Flags & MachO::S_ATTR_PURE_INSTRUCTIONS)
185 else
187
188 auto FullyQualifiedName =
189 G->allocateContent(StringRef(NSec.SegName) + "," + NSec.SectName);
190 NSec.GraphSection = &G->createSection(
191 StringRef(FullyQualifiedName.data(), FullyQualifiedName.size()), Prot);
192
193 // TODO: Are there any other criteria for NoAlloc lifetime?
194 if (NSec.Flags & MachO::S_ATTR_DEBUG)
195 NSec.GraphSection->setMemLifetime(orc::MemLifetime::NoAlloc);
196
197 IndexToSection.insert(std::make_pair(SecIndex, std::move(NSec)));
198 }
199
200 std::vector<NormalizedSection *> Sections;
201 Sections.reserve(IndexToSection.size());
202 for (auto &KV : IndexToSection)
203 Sections.push_back(&KV.second);
204
205 // If we didn't end up creating any sections then bail out. The code below
206 // assumes that we have at least one section.
207 if (Sections.empty())
208 return Error::success();
209
210 llvm::sort(Sections,
211 [](const NormalizedSection *LHS, const NormalizedSection *RHS) {
212 assert(LHS && RHS && "Null section?");
213 if (LHS->Address != RHS->Address)
214 return LHS->Address < RHS->Address;
215 return LHS->Size < RHS->Size;
216 });
217
218 for (unsigned I = 0, E = Sections.size() - 1; I != E; ++I) {
219 auto &Cur = *Sections[I];
220 auto &Next = *Sections[I + 1];
221 if (Next.Address < Cur.Address + Cur.Size)
222 return make_error<JITLinkError>(
223 "Address range for section " +
224 formatv("\"{0}/{1}\" [ {2:x16} -- {3:x16} ] ", Cur.SegName,
225 Cur.SectName, Cur.Address, Cur.Address + Cur.Size) +
226 "overlaps section \"" + Next.SegName + "/" + Next.SectName + "\"" +
227 formatv("\"{0}/{1}\" [ {2:x16} -- {3:x16} ] ", Next.SegName,
228 Next.SectName, Next.Address, Next.Address + Next.Size));
229 }
230
231 return Error::success();
232}
233
234Error MachOLinkGraphBuilder::createNormalizedSymbols() {
235 LLVM_DEBUG(dbgs() << "Creating normalized symbols...\n");
236
237 for (auto &SymRef : Obj.symbols()) {
238
239 unsigned SymbolIndex = Obj.getSymbolIndex(SymRef.getRawDataRefImpl());
241 uint32_t NStrX;
242 uint8_t Type;
243 uint8_t Sect;
245
246 if (Obj.is64Bit()) {
247 const MachO::nlist_64 &NL64 =
248 Obj.getSymbol64TableEntry(SymRef.getRawDataRefImpl());
249 Value = NL64.n_value;
250 NStrX = NL64.n_strx;
251 Type = NL64.n_type;
252 Sect = NL64.n_sect;
253 Desc = NL64.n_desc;
254 } else {
255 const MachO::nlist &NL32 =
256 Obj.getSymbolTableEntry(SymRef.getRawDataRefImpl());
257 Value = NL32.n_value;
258 NStrX = NL32.n_strx;
259 Type = NL32.n_type;
260 Sect = NL32.n_sect;
261 Desc = NL32.n_desc;
262 }
263
264 // Skip stabs.
265 // FIXME: Are there other symbols we should be skipping?
266 if (Type & MachO::N_STAB)
267 continue;
268
269 std::optional<StringRef> Name;
270 if (NStrX) {
271 if (auto NameOrErr = SymRef.getName())
272 Name = *NameOrErr;
273 else
274 return NameOrErr.takeError();
275 } else if (Type & MachO::N_EXT)
276 return make_error<JITLinkError>("Symbol at index " +
277 formatv("{0}", SymbolIndex) +
278 " has no name (string table index 0), "
279 "but N_EXT bit is set");
280
281 LLVM_DEBUG({
282 dbgs() << " ";
283 if (!Name)
284 dbgs() << "<anonymous symbol>";
285 else
286 dbgs() << *Name;
287 dbgs() << ": value = " << formatv("{0:x16}", Value)
288 << ", type = " << formatv("{0:x2}", Type)
289 << ", desc = " << formatv("{0:x4}", Desc) << ", sect = ";
290 if (Sect)
291 dbgs() << static_cast<unsigned>(Sect - 1);
292 else
293 dbgs() << "none";
294 dbgs() << "\n";
295 });
296
297 // If this symbol has a section, verify that the addresses line up.
298 if (Sect != 0) {
299 auto NSec = findSectionByIndex(Sect - 1);
300 if (!NSec)
301 return NSec.takeError();
302
303 if (orc::ExecutorAddr(Value) < NSec->Address ||
304 orc::ExecutorAddr(Value) > NSec->Address + NSec->Size)
305 return make_error<JITLinkError>("Address " + formatv("{0:x}", Value) +
306 " for symbol " + *Name +
307 " does not fall within section");
308
309 if (!NSec->GraphSection) {
310 LLVM_DEBUG({
311 dbgs() << " Skipping: Symbol is in section " << NSec->SegName << "/"
312 << NSec->SectName
313 << " which has no associated graph section.\n";
314 });
315 continue;
316 }
317 }
318
319 IndexToSymbol[SymbolIndex] =
320 &createNormalizedSymbol(*Name, Value, Type, Sect, Desc,
321 getLinkage(Desc), getScope(*Name, Type));
322 }
323
324 return Error::success();
325}
326
327void MachOLinkGraphBuilder::addSectionStartSymAndBlock(
328 unsigned SecIndex, Section &GraphSec, orc::ExecutorAddr Address,
329 const char *Data, orc::ExecutorAddrDiff Size, uint32_t Alignment,
330 bool IsLive) {
331 Block &B =
332 Data ? G->createContentBlock(GraphSec, ArrayRef<char>(Data, Size),
333 Address, Alignment, 0)
334 : G->createZeroFillBlock(GraphSec, Size, Address, Alignment, 0);
335 auto &Sym = G->addAnonymousSymbol(B, 0, Size, false, IsLive);
336 auto SecI = IndexToSection.find(SecIndex);
337 assert(SecI != IndexToSection.end() && "SecIndex invalid");
338 auto &NSec = SecI->second;
339 assert(!NSec.CanonicalSymbols.count(Sym.getAddress()) &&
340 "Anonymous block start symbol clashes with existing symbol address");
341 NSec.CanonicalSymbols[Sym.getAddress()] = &Sym;
342}
343
344Error MachOLinkGraphBuilder::graphifyRegularSymbols() {
345
346 LLVM_DEBUG(dbgs() << "Creating graph symbols...\n");
347
348 /// We only have 256 section indexes: Use a vector rather than a map.
349 std::vector<std::vector<NormalizedSymbol *>> SecIndexToSymbols;
350 SecIndexToSymbols.resize(256);
351
352 // Create commons, externs, and absolutes, and partition all other symbols by
353 // section.
354 for (auto &KV : IndexToSymbol) {
355 auto &NSym = *KV.second;
356
357 switch (NSym.Type & MachO::N_TYPE) {
358 case MachO::N_UNDF:
359 if (NSym.Value) {
360 if (!NSym.Name)
361 return make_error<JITLinkError>("Anonymous common symbol at index " +
362 Twine(KV.first));
363 NSym.GraphSymbol = &G->addDefinedSymbol(
364 G->createZeroFillBlock(getCommonSection(),
365 orc::ExecutorAddrDiff(NSym.Value),
366 orc::ExecutorAddr(),
367 1ull << MachO::GET_COMM_ALIGN(NSym.Desc), 0),
368 0, *NSym.Name, orc::ExecutorAddrDiff(NSym.Value), Linkage::Strong,
369 NSym.S, false, NSym.Desc & MachO::N_NO_DEAD_STRIP);
370 } else {
371 if (!NSym.Name)
372 return make_error<JITLinkError>("Anonymous external symbol at "
373 "index " +
374 Twine(KV.first));
375 NSym.GraphSymbol = &G->addExternalSymbol(
376 *NSym.Name, 0, (NSym.Desc & MachO::N_WEAK_REF) != 0);
377 }
378 break;
379 case MachO::N_ABS:
380 if (!NSym.Name)
381 return make_error<JITLinkError>("Anonymous absolute symbol at index " +
382 Twine(KV.first));
383 NSym.GraphSymbol = &G->addAbsoluteSymbol(
384 *NSym.Name, orc::ExecutorAddr(NSym.Value), 0, Linkage::Strong,
385 getScope(*NSym.Name, NSym.Type), NSym.Desc & MachO::N_NO_DEAD_STRIP);
386 break;
387 case MachO::N_SECT:
388 SecIndexToSymbols[NSym.Sect - 1].push_back(&NSym);
389 break;
390 case MachO::N_PBUD:
391 return make_error<JITLinkError>(
392 "Unupported N_PBUD symbol " +
393 (NSym.Name ? ("\"" + *NSym.Name + "\"") : Twine("<anon>")) +
394 " at index " + Twine(KV.first));
395 case MachO::N_INDR:
396 return make_error<JITLinkError>(
397 "Unupported N_INDR symbol " +
398 (NSym.Name ? ("\"" + *NSym.Name + "\"") : Twine("<anon>")) +
399 " at index " + Twine(KV.first));
400 default:
401 return make_error<JITLinkError>(
402 "Unrecognized symbol type " + Twine(NSym.Type & MachO::N_TYPE) +
403 " for symbol " +
404 (NSym.Name ? ("\"" + *NSym.Name + "\"") : Twine("<anon>")) +
405 " at index " + Twine(KV.first));
406 }
407 }
408
409 // Loop over sections performing regular graphification for those that
410 // don't have custom parsers.
411 for (auto &KV : IndexToSection) {
412 auto SecIndex = KV.first;
413 auto &NSec = KV.second;
414
415 if (!NSec.GraphSection) {
416 LLVM_DEBUG({
417 dbgs() << " " << NSec.SegName << "/" << NSec.SectName
418 << " has no graph section. Skipping.\n";
419 });
420 continue;
421 }
422
423 // Skip sections with custom parsers.
424 if (CustomSectionParserFunctions.count(NSec.GraphSection->getName())) {
425 LLVM_DEBUG({
426 dbgs() << " Skipping section " << NSec.GraphSection->getName()
427 << " as it has a custom parser.\n";
428 });
429 continue;
430 } else if ((NSec.Flags & MachO::SECTION_TYPE) ==
432 if (auto Err = graphifyCStringSection(
433 NSec, std::move(SecIndexToSymbols[SecIndex])))
434 return Err;
435 continue;
436 } else
437 LLVM_DEBUG({
438 dbgs() << " Graphifying regular section "
439 << NSec.GraphSection->getName() << "...\n";
440 });
441
442 bool SectionIsNoDeadStrip = NSec.Flags & MachO::S_ATTR_NO_DEAD_STRIP;
443 bool SectionIsText = NSec.Flags & MachO::S_ATTR_PURE_INSTRUCTIONS;
444
445 auto &SecNSymStack = SecIndexToSymbols[SecIndex];
446
447 // If this section is non-empty but there are no symbols covering it then
448 // create one block and anonymous symbol to cover the entire section.
449 if (SecNSymStack.empty()) {
450 if (NSec.Size > 0) {
451 LLVM_DEBUG({
452 dbgs() << " Section non-empty, but contains no symbols. "
453 "Creating anonymous block to cover "
454 << formatv("{0:x16}", NSec.Address) << " -- "
455 << formatv("{0:x16}", NSec.Address + NSec.Size) << "\n";
456 });
457 addSectionStartSymAndBlock(SecIndex, *NSec.GraphSection, NSec.Address,
458 NSec.Data, NSec.Size, NSec.Alignment,
459 SectionIsNoDeadStrip);
460 } else
461 LLVM_DEBUG({
462 dbgs() << " Section empty and contains no symbols. Skipping.\n";
463 });
464 continue;
465 }
466
467 // Sort the symbol stack in by address, alt-entry status, scope, and name.
468 // We sort in reverse order so that symbols will be visited in the right
469 // order when we pop off the stack below.
470 llvm::sort(SecNSymStack, [](const NormalizedSymbol *LHS,
471 const NormalizedSymbol *RHS) {
472 if (LHS->Value != RHS->Value)
473 return LHS->Value > RHS->Value;
475 return isAltEntry(*RHS);
476 if (LHS->S != RHS->S)
477 return static_cast<uint8_t>(LHS->S) < static_cast<uint8_t>(RHS->S);
478 return LHS->Name < RHS->Name;
479 });
480
481 // The first symbol in a section can not be an alt-entry symbol.
482 if (!SecNSymStack.empty() && isAltEntry(*SecNSymStack.back()))
483 return make_error<JITLinkError>(
484 "First symbol in " + NSec.GraphSection->getName() + " is alt-entry");
485
486 // If the section is non-empty but there is no symbol covering the start
487 // address then add an anonymous one.
488 if (orc::ExecutorAddr(SecNSymStack.back()->Value) != NSec.Address) {
489 auto AnonBlockSize =
490 orc::ExecutorAddr(SecNSymStack.back()->Value) - NSec.Address;
491 LLVM_DEBUG({
492 dbgs() << " Section start not covered by symbol. "
493 << "Creating anonymous block to cover [ " << NSec.Address
494 << " -- " << (NSec.Address + AnonBlockSize) << " ]\n";
495 });
496 addSectionStartSymAndBlock(SecIndex, *NSec.GraphSection, NSec.Address,
497 NSec.Data, AnonBlockSize, NSec.Alignment,
498 SectionIsNoDeadStrip);
499 }
500
501 // Visit section symbols in order by popping off the reverse-sorted stack,
502 // building graph symbols as we go.
503 //
504 // If MH_SUBSECTIONS_VIA_SYMBOLS is set we'll build a block for each
505 // alt-entry chain.
506 //
507 // If MH_SUBSECTIONS_VIA_SYMBOLS is not set then we'll just build one block
508 // for the whole section.
509 while (!SecNSymStack.empty()) {
510 SmallVector<NormalizedSymbol *, 8> BlockSyms;
511
512 // Get the symbols in this alt-entry chain, or the whole section (if
513 // !SubsectionsViaSymbols).
514 BlockSyms.push_back(SecNSymStack.back());
515 SecNSymStack.pop_back();
516 while (!SecNSymStack.empty() &&
517 (isAltEntry(*SecNSymStack.back()) ||
518 SecNSymStack.back()->Value == BlockSyms.back()->Value ||
519 !SubsectionsViaSymbols)) {
520 BlockSyms.push_back(SecNSymStack.back());
521 SecNSymStack.pop_back();
522 }
523
524 // BlockNSyms now contains the block symbols in reverse canonical order.
525 auto BlockStart = orc::ExecutorAddr(BlockSyms.front()->Value);
526 orc::ExecutorAddr BlockEnd =
527 SecNSymStack.empty() ? NSec.Address + NSec.Size
528 : orc::ExecutorAddr(SecNSymStack.back()->Value);
529 orc::ExecutorAddrDiff BlockOffset = BlockStart - NSec.Address;
530 orc::ExecutorAddrDiff BlockSize = BlockEnd - BlockStart;
531
532 LLVM_DEBUG({
533 dbgs() << " Creating block for " << formatv("{0:x16}", BlockStart)
534 << " -- " << formatv("{0:x16}", BlockEnd) << ": "
535 << NSec.GraphSection->getName() << " + "
536 << formatv("{0:x16}", BlockOffset) << " with "
537 << BlockSyms.size() << " symbol(s)...\n";
538 });
539
540 Block &B =
541 NSec.Data
542 ? G->createContentBlock(
543 *NSec.GraphSection,
544 ArrayRef<char>(NSec.Data + BlockOffset, BlockSize),
545 BlockStart, NSec.Alignment, BlockStart % NSec.Alignment)
546 : G->createZeroFillBlock(*NSec.GraphSection, BlockSize,
547 BlockStart, NSec.Alignment,
548 BlockStart % NSec.Alignment);
549
550 std::optional<orc::ExecutorAddr> LastCanonicalAddr;
551 auto SymEnd = BlockEnd;
552 while (!BlockSyms.empty()) {
553 auto &NSym = *BlockSyms.back();
554 BlockSyms.pop_back();
555
556 bool SymLive =
557 (NSym.Desc & MachO::N_NO_DEAD_STRIP) || SectionIsNoDeadStrip;
558
559 auto &Sym = createStandardGraphSymbol(
560 NSym, B, SymEnd - orc::ExecutorAddr(NSym.Value), SectionIsText,
561 SymLive, LastCanonicalAddr != orc::ExecutorAddr(NSym.Value));
562
563 if (LastCanonicalAddr != Sym.getAddress()) {
564 if (LastCanonicalAddr)
565 SymEnd = *LastCanonicalAddr;
566 LastCanonicalAddr = Sym.getAddress();
567 }
568 }
569 }
570 }
571
572 return Error::success();
573}
574
575Symbol &MachOLinkGraphBuilder::createStandardGraphSymbol(NormalizedSymbol &NSym,
576 Block &B, size_t Size,
577 bool IsText,
578 bool IsNoDeadStrip,
579 bool IsCanonical) {
580
581 LLVM_DEBUG({
582 dbgs() << " " << formatv("{0:x16}", NSym.Value) << " -- "
583 << formatv("{0:x16}", NSym.Value + Size) << ": ";
584 if (!NSym.Name)
585 dbgs() << "<anonymous symbol>";
586 else
587 dbgs() << NSym.Name;
588 if (IsText)
589 dbgs() << " [text]";
590 if (IsNoDeadStrip)
591 dbgs() << " [no-dead-strip]";
592 if (!IsCanonical)
593 dbgs() << " [non-canonical]";
594 dbgs() << "\n";
595 });
596
597 auto SymOffset = orc::ExecutorAddr(NSym.Value) - B.getAddress();
598 auto &Sym =
599 NSym.Name
600 ? G->addDefinedSymbol(B, SymOffset, *NSym.Name, Size, NSym.L, NSym.S,
601 IsText, IsNoDeadStrip)
602 : G->addAnonymousSymbol(B, SymOffset, Size, IsText, IsNoDeadStrip);
603 NSym.GraphSymbol = &Sym;
604
605 if (IsCanonical)
606 setCanonicalSymbol(getSectionByIndex(NSym.Sect - 1), Sym);
607
608 return Sym;
609}
610
611Error MachOLinkGraphBuilder::graphifySectionsWithCustomParsers() {
612 // Graphify special sections.
613 for (auto &KV : IndexToSection) {
614 auto &NSec = KV.second;
615
616 // Skip non-graph sections.
617 if (!NSec.GraphSection)
618 continue;
619
620 auto HI = CustomSectionParserFunctions.find(NSec.GraphSection->getName());
621 if (HI != CustomSectionParserFunctions.end()) {
622 auto &Parse = HI->second;
623 if (auto Err = Parse(NSec))
624 return Err;
625 }
626 }
627
628 return Error::success();
629}
630
631Error MachOLinkGraphBuilder::graphifyCStringSection(
632 NormalizedSection &NSec, std::vector<NormalizedSymbol *> NSyms) {
633 assert(NSec.GraphSection && "C string literal section missing graph section");
634 assert(NSec.Data && "C string literal section has no data");
635
636 LLVM_DEBUG({
637 dbgs() << " Graphifying C-string literal section "
638 << NSec.GraphSection->getName() << "\n";
639 });
640
641 if (NSec.Data[NSec.Size - 1] != '\0')
642 return make_error<JITLinkError>("C string literal section " +
643 NSec.GraphSection->getName() +
644 " does not end with null terminator");
645
646 /// Sort into reverse order to use as a stack.
647 llvm::sort(NSyms,
648 [](const NormalizedSymbol *LHS, const NormalizedSymbol *RHS) {
649 if (LHS->Value != RHS->Value)
650 return LHS->Value > RHS->Value;
651 if (LHS->L != RHS->L)
652 return LHS->L > RHS->L;
653 if (LHS->S != RHS->S)
654 return LHS->S > RHS->S;
655 if (RHS->Name) {
656 if (!LHS->Name)
657 return true;
658 return *LHS->Name > *RHS->Name;
659 }
660 return false;
661 });
662
663 bool SectionIsNoDeadStrip = NSec.Flags & MachO::S_ATTR_NO_DEAD_STRIP;
664 bool SectionIsText = NSec.Flags & MachO::S_ATTR_PURE_INSTRUCTIONS;
665 orc::ExecutorAddrDiff BlockStart = 0;
666
667 // Scan section for null characters.
668 for (size_t I = 0; I != NSec.Size; ++I) {
669 if (NSec.Data[I] == '\0') {
670 size_t BlockSize = I + 1 - BlockStart;
671 // Create a block for this null terminated string.
672 auto &B = G->createContentBlock(*NSec.GraphSection,
673 {NSec.Data + BlockStart, BlockSize},
674 NSec.Address + BlockStart, NSec.Alignment,
675 BlockStart % NSec.Alignment);
676
677 LLVM_DEBUG({
678 dbgs() << " Created block " << B.getRange()
679 << ", align = " << B.getAlignment()
680 << ", align-ofs = " << B.getAlignmentOffset() << " for \"";
681 for (size_t J = 0; J != std::min(B.getSize(), size_t(16)); ++J)
682 switch (B.getContent()[J]) {
683 case '\0': break;
684 case '\n': dbgs() << "\\n"; break;
685 case '\t': dbgs() << "\\t"; break;
686 default: dbgs() << B.getContent()[J]; break;
687 }
688 if (B.getSize() > 16)
689 dbgs() << "...";
690 dbgs() << "\"\n";
691 });
692
693 // If there's no symbol at the start of this block then create one.
694 if (NSyms.empty() ||
695 orc::ExecutorAddr(NSyms.back()->Value) != B.getAddress()) {
696 auto &S = G->addAnonymousSymbol(B, 0, BlockSize, false, false);
697 setCanonicalSymbol(NSec, S);
698 LLVM_DEBUG({
699 dbgs() << " Adding symbol for c-string block " << B.getRange()
700 << ": <anonymous symbol> at offset 0\n";
701 });
702 }
703
704 // Process any remaining symbols that point into this block.
705 auto LastCanonicalAddr = B.getAddress() + BlockSize;
706 while (!NSyms.empty() && orc::ExecutorAddr(NSyms.back()->Value) <
707 B.getAddress() + BlockSize) {
708 auto &NSym = *NSyms.back();
709 size_t SymSize = (B.getAddress() + BlockSize) -
710 orc::ExecutorAddr(NSyms.back()->Value);
711 bool SymLive =
712 (NSym.Desc & MachO::N_NO_DEAD_STRIP) || SectionIsNoDeadStrip;
713
714 bool IsCanonical = false;
715 if (LastCanonicalAddr != orc::ExecutorAddr(NSym.Value)) {
716 IsCanonical = true;
717 LastCanonicalAddr = orc::ExecutorAddr(NSym.Value);
718 }
719
720 auto &Sym = createStandardGraphSymbol(NSym, B, SymSize, SectionIsText,
721 SymLive, IsCanonical);
722 (void)Sym;
723 LLVM_DEBUG({
724 dbgs() << " Adding symbol for c-string block " << B.getRange()
725 << ": "
726 << (Sym.hasName() ? Sym.getName() : "<anonymous symbol>")
727 << " at offset " << formatv("{0:x}", Sym.getOffset()) << "\n";
728 });
729
730 NSyms.pop_back();
731 }
732
733 BlockStart += BlockSize;
734 }
735 }
736
737 assert(llvm::all_of(NSec.GraphSection->blocks(),
738 [](Block *B) { return isCStringBlock(*B); }) &&
739 "All blocks in section should hold single c-strings");
740
741 return Error::success();
742}
743
745 auto *CUSec = G.findSectionByName(CompactUnwindSectionName);
746 if (!CUSec)
747 return Error::success();
748
749 if (!G.getTargetTriple().isOSBinFormatMachO())
750 return make_error<JITLinkError>(
751 "Error linking " + G.getName() +
752 ": compact unwind splitting not supported on non-macho target " +
753 G.getTargetTriple().str());
754
755 unsigned CURecordSize = 0;
756 unsigned PersonalityEdgeOffset = 0;
757 unsigned LSDAEdgeOffset = 0;
758 switch (G.getTargetTriple().getArch()) {
759 case Triple::aarch64:
760 case Triple::x86_64:
761 // 64-bit compact-unwind record format:
762 // Range start: 8 bytes.
763 // Range size: 4 bytes.
764 // CU encoding: 4 bytes.
765 // Personality: 8 bytes.
766 // LSDA: 8 bytes.
767 CURecordSize = 32;
768 PersonalityEdgeOffset = 16;
769 LSDAEdgeOffset = 24;
770 break;
771 default:
772 return make_error<JITLinkError>(
773 "Error linking " + G.getName() +
774 ": compact unwind splitting not supported on " +
775 G.getTargetTriple().getArchName());
776 }
777
778 std::vector<Block *> OriginalBlocks(CUSec->blocks().begin(),
779 CUSec->blocks().end());
780 LLVM_DEBUG({
781 dbgs() << "In " << G.getName() << " splitting compact unwind section "
782 << CompactUnwindSectionName << " containing "
783 << OriginalBlocks.size() << " initial blocks...\n";
784 });
785
786 while (!OriginalBlocks.empty()) {
787 auto *B = OriginalBlocks.back();
788 OriginalBlocks.pop_back();
789
790 if (B->getSize() == 0) {
791 LLVM_DEBUG({
792 dbgs() << " Skipping empty block at "
793 << formatv("{0:x16}", B->getAddress()) << "\n";
794 });
795 continue;
796 }
797
798 LLVM_DEBUG({
799 dbgs() << " Splitting block at " << formatv("{0:x16}", B->getAddress())
800 << " into " << (B->getSize() / CURecordSize)
801 << " compact unwind record(s)\n";
802 });
803
804 if (B->getSize() % CURecordSize)
805 return make_error<JITLinkError>(
806 "Error splitting compact unwind record in " + G.getName() +
807 ": block at " + formatv("{0:x}", B->getAddress()) + " has size " +
808 formatv("{0:x}", B->getSize()) +
809 " (not a multiple of CU record size of " +
810 formatv("{0:x}", CURecordSize) + ")");
811
812 unsigned NumBlocks = B->getSize() / CURecordSize;
814
815 for (unsigned I = 0; I != NumBlocks; ++I) {
816 auto &CURec = G.splitBlock(*B, CURecordSize, &C);
817 bool AddedKeepAlive = false;
818
819 for (auto &E : CURec.edges()) {
820 if (E.getOffset() == 0) {
821 LLVM_DEBUG({
822 dbgs() << " Updating compact unwind record at "
823 << formatv("{0:x16}", CURec.getAddress()) << " to point to "
824 << (E.getTarget().hasName() ? E.getTarget().getName()
825 : StringRef())
826 << " (at " << formatv("{0:x16}", E.getTarget().getAddress())
827 << ")\n";
828 });
829
830 if (E.getTarget().isExternal())
831 return make_error<JITLinkError>(
832 "Error adding keep-alive edge for compact unwind record at " +
833 formatv("{0:x}", CURec.getAddress()) + ": target " +
834 E.getTarget().getName() + " is an external symbol");
835 auto &TgtBlock = E.getTarget().getBlock();
836 auto &CURecSym =
837 G.addAnonymousSymbol(CURec, 0, CURecordSize, false, false);
838 TgtBlock.addEdge(Edge::KeepAlive, 0, CURecSym, 0);
839 AddedKeepAlive = true;
840 } else if (E.getOffset() != PersonalityEdgeOffset &&
841 E.getOffset() != LSDAEdgeOffset)
842 return make_error<JITLinkError>("Unexpected edge at offset " +
843 formatv("{0:x}", E.getOffset()) +
844 " in compact unwind record at " +
845 formatv("{0:x}", CURec.getAddress()));
846 }
847
848 if (!AddedKeepAlive)
849 return make_error<JITLinkError>(
850 "Error adding keep-alive edge for compact unwind record at " +
851 formatv("{0:x}", CURec.getAddress()) +
852 ": no outgoing target edge at offset 0");
853 }
854 }
855 return Error::success();
856}
857
858} // end namespace jitlink
859} // end namespace llvm
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
static const char * CommonSectionName
static Expected< StringRef > getFileName(const DebugStringTableSubsectionRef &Strings, const DebugChecksumsSubsectionRef &Checksums, uint32_t FileID)
static uint64_t getPointerSize(const Value *V, const DataLayout &DL, const TargetLibraryInfo &TLI, const Function *F)
#define LLVM_DEBUG(X)
Definition: Debug.h:101
std::string Name
uint64_t Size
Symbol * Sym
Definition: ELF_riscv.cpp:468
#define I(x, y, z)
Definition: MD5.cpp:58
#define G(x, y, z)
Definition: MD5.cpp:56
static const char * CommonSectionName
if(VerifyEach)
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
static const int BlockSize
Definition: TarWriter.cpp:33
Value * RHS
Value * LHS
Lightweight error class with error context and mandatory checking.
Definition: Error.h:160
static ErrorSuccess success()
Create a success value.
Definition: Error.h:334
Tagged union holding either a T or a Error.
Definition: Error.h:474
iterator end()
Definition: StringMap.h:205
iterator find(StringRef Key)
Definition: StringMap.h:218
size_type count(StringRef Key) const
count - Return 1 if the element is in the map, 0 otherwise.
Definition: StringMap.h:257
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:50
constexpr size_t size() const
size - Get the string size.
Definition: StringRef.h:137
const char * data() const
data - Get a pointer to the start of the string (which may not be null terminated).
Definition: StringRef.h:131
Manages the enabling and disabling of subtarget specific features.
Triple - Helper class for working with autoconf configuration names.
Definition: Triple.h:44
The instances of the Type class are immutable: once they are created, they are never changed.
Definition: Type.h:45
StringRef getData() const
Definition: Binary.cpp:39
bool isLittleEndian() const
Definition: Binary.h:155
const MachO::mach_header_64 & getHeader64() const
Expected< SectionRef > getSection(unsigned SectionIndex) const
uint64_t getSymbolIndex(DataRefImpl Symb) const
MachO::nlist getSymbolTableEntry(DataRefImpl DRI) const
MachO::section_64 getSection64(DataRefImpl DRI) const
bool isRelocatableObject() const override
True if this is a relocatable object (.o/.obj).
MachO::nlist_64 getSymbol64TableEntry(DataRefImpl DRI) const
uint64_t getSectionIndex(DataRefImpl Sec) const override
section_iterator_range sections() const
Definition: ObjectFile.h:328
symbol_iterator_range symbols() const
Definition: ObjectFile.h:320
@ C
The default llvm calling convention, compatible with C.
Definition: CallingConv.h:34
@ S_GB_ZEROFILL
S_GB_ZEROFILL - Zero fill on demand section (that can be larger than 4 gigabytes).
Definition: MachO.h:155
@ S_THREAD_LOCAL_ZEROFILL
S_THREAD_LOCAL_ZEROFILL - Thread local zerofill section.
Definition: MachO.h:169
@ S_CSTRING_LITERALS
S_CSTRING_LITERALS - Section with literal C strings.
Definition: MachO.h:131
@ S_ZEROFILL
S_ZEROFILL - Zero fill on demand section.
Definition: MachO.h:129
@ MH_SUBSECTIONS_VIA_SYMBOLS
Definition: MachO.h:73
uint8_t GET_COMM_ALIGN(uint16_t n_desc)
Definition: MachO.h:1551
@ SECTION_TYPE
Definition: MachO.h:114
@ N_SECT
Definition: MachO.h:318
@ N_PBUD
Definition: MachO.h:319
@ N_INDR
Definition: MachO.h:320
@ N_UNDF
Definition: MachO.h:316
@ S_ATTR_DEBUG
S_ATTR_DEBUG - A debug section.
Definition: MachO.h:207
@ S_ATTR_NO_DEAD_STRIP
S_ATTR_NO_DEAD_STRIP - No dead stripping.
Definition: MachO.h:200
@ S_ATTR_PURE_INSTRUCTIONS
S_ATTR_PURE_INSTRUCTIONS - Section contains only true machine instructions.
Definition: MachO.h:192
@ N_WEAK_DEF
Definition: MachO.h:346
@ N_NO_DEAD_STRIP
Definition: MachO.h:344
@ N_ALT_ENTRY
Definition: MachO.h:348
@ N_WEAK_REF
Definition: MachO.h:345
@ N_TYPE
Definition: MachO.h:309
@ N_PEXT
Definition: MachO.h:308
@ N_STAB
Definition: MachO.h:307
Type
MessagePack types as defined in the standard, with the exception of Integer being divided into a sign...
Definition: MsgPackReader.h:48
MemProt
Describes Read/Write/Exec permissions for memory.
Definition: MemoryFlags.h:27
uint64_t ExecutorAddrDiff
@ NoAlloc
NoAlloc memory should not be allocated by the JITLinkMemoryManager at all.
NodeAddr< BlockNode * > Block
Definition: RDFGraph.h:392
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
auto formatv(const char *Fmt, Ts &&... Vals) -> formatv_object< decltype(std::make_tuple(detail::build_format_adapter(std::forward< Ts >(Vals))...))>
bool all_of(R &&range, UnaryPredicate P)
Provide wrappers to std::all_of which take ranges instead of having to pass begin/end explicitly.
Definition: STLExtras.h:1727
Op::Description Desc
void sort(IteratorTy Start, IteratorTy End)
Definition: STLExtras.h:1652
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:163
OutputIt move(R &&Range, OutputIt Out)
Provide wrappers to std::move which take ranges instead of having to pass begin/end explicitly.
Definition: STLExtras.h:1854
Implement std::hash so that hash_code can be used in STL containers.
Definition: BitVector.h:858
Description of the encoding of one expression Op.