Bug Summary

File:src/gnu/usr.bin/clang/liblldELF/../../../llvm/llvm/include/llvm/Object/IRSymtab.h
Warning:line 328, column 20
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -cc1 -triple amd64-unknown-openbsd7.0 -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name InputFiles.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model static -mframe-pointer=all -relaxed-aliasing -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/usr/src/gnu/usr.bin/clang/liblldELF/obj -resource-dir /usr/local/lib/clang/13.0.0 -I /usr/src/gnu/usr.bin/clang/liblldELF/obj/../include/lld/ELF -I /usr/src/gnu/usr.bin/clang/liblldELF/../../../llvm/lld/include -I /usr/src/gnu/usr.bin/clang/liblldELF/../../../llvm/lld/ELF -I /usr/src/gnu/usr.bin/clang/liblldELF/../../../llvm/llvm/include -I /usr/src/gnu/usr.bin/clang/liblldELF/../include -I /usr/src/gnu/usr.bin/clang/liblldELF/obj -I /usr/src/gnu/usr.bin/clang/liblldELF/obj/../include -D NDEBUG -D __STDC_LIMIT_MACROS -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D LLVM_PREFIX="/usr" -internal-isystem /usr/include/c++/v1 -internal-isystem /usr/local/lib/clang/13.0.0/include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/usr/src/gnu/usr.bin/clang/liblldELF/obj -ferror-limit 19 -fvisibility-inlines-hidden -fwrapv -stack-protector 2 -fno-rtti -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-valloc -fno-builtin-free -fno-builtin-strdup -fno-builtin-strndup -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /home/ben/Projects/vmm/scan-build/2022-01-12-194120-40624-1 -x c++ /usr/src/gnu/usr.bin/clang/liblldELF/../../../llvm/lld/ELF/InputFiles.cpp

/usr/src/gnu/usr.bin/clang/liblldELF/../../../llvm/lld/ELF/InputFiles.cpp

1//===- InputFiles.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 "InputFiles.h"
10#include "Driver.h"
11#include "InputSection.h"
12#include "LinkerScript.h"
13#include "SymbolTable.h"
14#include "Symbols.h"
15#include "SyntheticSections.h"
16#include "lld/Common/DWARF.h"
17#include "lld/Common/ErrorHandler.h"
18#include "lld/Common/Memory.h"
19#include "llvm/ADT/STLExtras.h"
20#include "llvm/CodeGen/Analysis.h"
21#include "llvm/IR/LLVMContext.h"
22#include "llvm/IR/Module.h"
23#include "llvm/LTO/LTO.h"
24#include "llvm/MC/StringTableBuilder.h"
25#include "llvm/Object/ELFObjectFile.h"
26#include "llvm/Support/ARMAttributeParser.h"
27#include "llvm/Support/ARMBuildAttributes.h"
28#include "llvm/Support/Endian.h"
29#include "llvm/Support/Path.h"
30#include "llvm/Support/RISCVAttributeParser.h"
31#include "llvm/Support/TarWriter.h"
32#include "llvm/Support/raw_ostream.h"
33
34using namespace llvm;
35using namespace llvm::ELF;
36using namespace llvm::object;
37using namespace llvm::sys;
38using namespace llvm::sys::fs;
39using namespace llvm::support::endian;
40using namespace lld;
41using namespace lld::elf;
42
43bool InputFile::isInGroup;
44uint32_t InputFile::nextGroupId;
45
46std::vector<ArchiveFile *> elf::archiveFiles;
47std::vector<BinaryFile *> elf::binaryFiles;
48std::vector<BitcodeFile *> elf::bitcodeFiles;
49std::vector<LazyObjFile *> elf::lazyObjFiles;
50std::vector<InputFile *> elf::objectFiles;
51std::vector<SharedFile *> elf::sharedFiles;
52
53std::unique_ptr<TarWriter> elf::tar;
54
55// Returns "<internal>", "foo.a(bar.o)" or "baz.o".
56std::string lld::toString(const InputFile *f) {
57 if (!f)
58 return "<internal>";
59
60 if (f->toStringCache.empty()) {
61 if (f->archiveName.empty())
62 f->toStringCache = std::string(f->getName());
63 else
64 f->toStringCache = (f->archiveName + "(" + f->getName() + ")").str();
65 }
66 return f->toStringCache;
67}
68
69static ELFKind getELFKind(MemoryBufferRef mb, StringRef archiveName) {
70 unsigned char size;
71 unsigned char endian;
72 std::tie(size, endian) = getElfArchType(mb.getBuffer());
73
74 auto report = [&](StringRef msg) {
75 StringRef filename = mb.getBufferIdentifier();
76 if (archiveName.empty())
77 fatal(filename + ": " + msg);
78 else
79 fatal(archiveName + "(" + filename + "): " + msg);
80 };
81
82 if (!mb.getBuffer().startswith(ElfMagic))
83 report("not an ELF file");
84 if (endian != ELFDATA2LSB && endian != ELFDATA2MSB)
85 report("corrupted ELF file: invalid data encoding");
86 if (size != ELFCLASS32 && size != ELFCLASS64)
87 report("corrupted ELF file: invalid file class");
88
89 size_t bufSize = mb.getBuffer().size();
90 if ((size == ELFCLASS32 && bufSize < sizeof(Elf32_Ehdr)) ||
91 (size == ELFCLASS64 && bufSize < sizeof(Elf64_Ehdr)))
92 report("corrupted ELF file: file is too short");
93
94 if (size == ELFCLASS32)
95 return (endian == ELFDATA2LSB) ? ELF32LEKind : ELF32BEKind;
96 return (endian == ELFDATA2LSB) ? ELF64LEKind : ELF64BEKind;
97}
98
99InputFile::InputFile(Kind k, MemoryBufferRef m)
100 : mb(m), groupId(nextGroupId), fileKind(k) {
101 // All files within the same --{start,end}-group get the same group ID.
102 // Otherwise, a new file will get a new group ID.
103 if (!isInGroup)
104 ++nextGroupId;
105}
106
107Optional<MemoryBufferRef> elf::readFile(StringRef path) {
108 llvm::TimeTraceScope timeScope("Load input files", path);
109
110 // The --chroot option changes our virtual root directory.
111 // This is useful when you are dealing with files created by --reproduce.
112 if (!config->chroot.empty() && path.startswith("/"))
113 path = saver.save(config->chroot + path);
114
115 log(path);
116 config->dependencyFiles.insert(llvm::CachedHashString(path));
117
118 auto mbOrErr = MemoryBuffer::getFile(path, /*IsText=*/false,
119 /*RequiresNullTerminator=*/false);
120 if (auto ec = mbOrErr.getError()) {
121 error("cannot open " + path + ": " + ec.message());
122 return None;
123 }
124
125 std::unique_ptr<MemoryBuffer> &mb = *mbOrErr;
126 MemoryBufferRef mbref = mb->getMemBufferRef();
127 make<std::unique_ptr<MemoryBuffer>>(std::move(mb)); // take MB ownership
128
129 if (tar)
130 tar->append(relativeToRoot(path), mbref.getBuffer());
131 return mbref;
132}
133
134// All input object files must be for the same architecture
135// (e.g. it does not make sense to link x86 object files with
136// MIPS object files.) This function checks for that error.
137static bool isCompatible(InputFile *file) {
138 if (!file->isElf() && !isa<BitcodeFile>(file))
139 return true;
140
141 if (file->ekind == config->ekind && file->emachine == config->emachine) {
142 if (config->emachine != EM_MIPS)
143 return true;
144 if (isMipsN32Abi(file) == config->mipsN32Abi)
145 return true;
146 }
147
148 StringRef target =
149 !config->bfdname.empty() ? config->bfdname : config->emulation;
150 if (!target.empty()) {
151 error(toString(file) + " is incompatible with " + target);
152 return false;
153 }
154
155 InputFile *existing;
156 if (!objectFiles.empty())
157 existing = objectFiles[0];
158 else if (!sharedFiles.empty())
159 existing = sharedFiles[0];
160 else if (!bitcodeFiles.empty())
161 existing = bitcodeFiles[0];
162 else
163 llvm_unreachable("Must have -m, OUTPUT_FORMAT or existing input file to "__builtin_unreachable()
164 "determine target emulation")__builtin_unreachable();
165
166 error(toString(file) + " is incompatible with " + toString(existing));
167 return false;
168}
169
170template <class ELFT> static void doParseFile(InputFile *file) {
171 if (!isCompatible(file))
172 return;
173
174 // Binary file
175 if (auto *f = dyn_cast<BinaryFile>(file)) {
176 binaryFiles.push_back(f);
177 f->parse();
178 return;
179 }
180
181 // .a file
182 if (auto *f = dyn_cast<ArchiveFile>(file)) {
183 archiveFiles.push_back(f);
184 f->parse();
185 return;
186 }
187
188 // Lazy object file
189 if (auto *f = dyn_cast<LazyObjFile>(file)) {
190 lazyObjFiles.push_back(f);
191 f->parse<ELFT>();
192 return;
193 }
194
195 if (config->trace)
196 message(toString(file));
197
198 // .so file
199 if (auto *f = dyn_cast<SharedFile>(file)) {
200 f->parse<ELFT>();
201 return;
202 }
203
204 // LLVM bitcode file
205 if (auto *f = dyn_cast<BitcodeFile>(file)) {
206 bitcodeFiles.push_back(f);
207 f->parse<ELFT>();
208 return;
209 }
210
211 // Regular object file
212 objectFiles.push_back(file);
213 cast<ObjFile<ELFT>>(file)->parse();
214}
215
216// Add symbols in File to the symbol table.
217void elf::parseFile(InputFile *file) {
218 switch (config->ekind) {
219 case ELF32LEKind:
220 doParseFile<ELF32LE>(file);
221 return;
222 case ELF32BEKind:
223 doParseFile<ELF32BE>(file);
224 return;
225 case ELF64LEKind:
226 doParseFile<ELF64LE>(file);
227 return;
228 case ELF64BEKind:
229 doParseFile<ELF64BE>(file);
230 return;
231 default:
232 llvm_unreachable("unknown ELFT")__builtin_unreachable();
233 }
234}
235
236// Concatenates arguments to construct a string representing an error location.
237static std::string createFileLineMsg(StringRef path, unsigned line) {
238 std::string filename = std::string(path::filename(path));
239 std::string lineno = ":" + std::to_string(line);
240 if (filename == path)
241 return filename + lineno;
242 return filename + lineno + " (" + path.str() + lineno + ")";
243}
244
245template <class ELFT>
246static std::string getSrcMsgAux(ObjFile<ELFT> &file, const Symbol &sym,
247 InputSectionBase &sec, uint64_t offset) {
248 // In DWARF, functions and variables are stored to different places.
249 // First, lookup a function for a given offset.
250 if (Optional<DILineInfo> info = file.getDILineInfo(&sec, offset))
251 return createFileLineMsg(info->FileName, info->Line);
252
253 // If it failed, lookup again as a variable.
254 if (Optional<std::pair<std::string, unsigned>> fileLine =
255 file.getVariableLoc(sym.getName()))
256 return createFileLineMsg(fileLine->first, fileLine->second);
257
258 // File.sourceFile contains STT_FILE symbol, and that is a last resort.
259 return std::string(file.sourceFile);
260}
261
262std::string InputFile::getSrcMsg(const Symbol &sym, InputSectionBase &sec,
263 uint64_t offset) {
264 if (kind() != ObjKind)
265 return "";
266 switch (config->ekind) {
267 default:
268 llvm_unreachable("Invalid kind")__builtin_unreachable();
269 case ELF32LEKind:
270 return getSrcMsgAux(cast<ObjFile<ELF32LE>>(*this), sym, sec, offset);
271 case ELF32BEKind:
272 return getSrcMsgAux(cast<ObjFile<ELF32BE>>(*this), sym, sec, offset);
273 case ELF64LEKind:
274 return getSrcMsgAux(cast<ObjFile<ELF64LE>>(*this), sym, sec, offset);
275 case ELF64BEKind:
276 return getSrcMsgAux(cast<ObjFile<ELF64BE>>(*this), sym, sec, offset);
277 }
278}
279
280StringRef InputFile::getNameForScript() const {
281 if (archiveName.empty())
282 return getName();
283
284 if (nameForScriptCache.empty())
285 nameForScriptCache = (archiveName + Twine(':') + getName()).str();
286
287 return nameForScriptCache;
288}
289
290template <class ELFT> DWARFCache *ObjFile<ELFT>::getDwarf() {
291 llvm::call_once(initDwarf, [this]() {
292 dwarf = std::make_unique<DWARFCache>(std::make_unique<DWARFContext>(
293 std::make_unique<LLDDwarfObj<ELFT>>(this), "",
294 [&](Error err) { warn(getName() + ": " + toString(std::move(err))); },
295 [&](Error warning) {
296 warn(getName() + ": " + toString(std::move(warning)));
297 }));
298 });
299
300 return dwarf.get();
301}
302
303// Returns the pair of file name and line number describing location of data
304// object (variable, array, etc) definition.
305template <class ELFT>
306Optional<std::pair<std::string, unsigned>>
307ObjFile<ELFT>::getVariableLoc(StringRef name) {
308 return getDwarf()->getVariableLoc(name);
309}
310
311// Returns source line information for a given offset
312// using DWARF debug info.
313template <class ELFT>
314Optional<DILineInfo> ObjFile<ELFT>::getDILineInfo(InputSectionBase *s,
315 uint64_t offset) {
316 // Detect SectionIndex for specified section.
317 uint64_t sectionIndex = object::SectionedAddress::UndefSection;
318 ArrayRef<InputSectionBase *> sections = s->file->getSections();
319 for (uint64_t curIndex = 0; curIndex < sections.size(); ++curIndex) {
320 if (s == sections[curIndex]) {
321 sectionIndex = curIndex;
322 break;
323 }
324 }
325
326 return getDwarf()->getDILineInfo(offset, sectionIndex);
327}
328
329ELFFileBase::ELFFileBase(Kind k, MemoryBufferRef mb) : InputFile(k, mb) {
330 ekind = getELFKind(mb, "");
331
332 switch (ekind) {
333 case ELF32LEKind:
334 init<ELF32LE>();
335 break;
336 case ELF32BEKind:
337 init<ELF32BE>();
338 break;
339 case ELF64LEKind:
340 init<ELF64LE>();
341 break;
342 case ELF64BEKind:
343 init<ELF64BE>();
344 break;
345 default:
346 llvm_unreachable("getELFKind")__builtin_unreachable();
347 }
348}
349
350template <typename Elf_Shdr>
351static const Elf_Shdr *findSection(ArrayRef<Elf_Shdr> sections, uint32_t type) {
352 for (const Elf_Shdr &sec : sections)
353 if (sec.sh_type == type)
354 return &sec;
355 return nullptr;
356}
357
358template <class ELFT> void ELFFileBase::init() {
359 using Elf_Shdr = typename ELFT::Shdr;
360 using Elf_Sym = typename ELFT::Sym;
361
362 // Initialize trivial attributes.
363 const ELFFile<ELFT> &obj = getObj<ELFT>();
364 emachine = obj.getHeader().e_machine;
365 osabi = obj.getHeader().e_ident[llvm::ELF::EI_OSABI];
366 abiVersion = obj.getHeader().e_ident[llvm::ELF::EI_ABIVERSION];
367
368 ArrayRef<Elf_Shdr> sections = CHECK(obj.sections(), this)check2((obj.sections()), [&] { return toString(this); });
369
370 // Find a symbol table.
371 bool isDSO =
372 (identify_magic(mb.getBuffer()) == file_magic::elf_shared_object);
373 const Elf_Shdr *symtabSec =
374 findSection(sections, isDSO ? SHT_DYNSYM : SHT_SYMTAB);
375
376 if (!symtabSec)
377 return;
378
379 // Initialize members corresponding to a symbol table.
380 firstGlobal = symtabSec->sh_info;
381
382 ArrayRef<Elf_Sym> eSyms = CHECK(obj.symbols(symtabSec), this)check2((obj.symbols(symtabSec)), [&] { return toString(this
); })
;
383 if (firstGlobal == 0 || firstGlobal > eSyms.size())
384 fatal(toString(this) + ": invalid sh_info in symbol table");
385
386 elfSyms = reinterpret_cast<const void *>(eSyms.data());
387 numELFSyms = eSyms.size();
388 stringTable = CHECK(obj.getStringTableForSymtab(*symtabSec, sections), this)check2((obj.getStringTableForSymtab(*symtabSec, sections)), [
&] { return toString(this); })
;
389}
390
391template <class ELFT>
392uint32_t ObjFile<ELFT>::getSectionIndex(const Elf_Sym &sym) const {
393 return CHECK(check2((this->getObj().getSectionIndex(sym, getELFSyms<
ELFT>(), shndxTable)), [&] { return toString(this); })
394 this->getObj().getSectionIndex(sym, getELFSyms<ELFT>(), shndxTable),check2((this->getObj().getSectionIndex(sym, getELFSyms<
ELFT>(), shndxTable)), [&] { return toString(this); })
395 this)check2((this->getObj().getSectionIndex(sym, getELFSyms<
ELFT>(), shndxTable)), [&] { return toString(this); })
;
396}
397
398template <class ELFT> ArrayRef<Symbol *> ObjFile<ELFT>::getLocalSymbols() {
399 if (this->symbols.empty())
400 return {};
401 return makeArrayRef(this->symbols).slice(1, this->firstGlobal - 1);
402}
403
404template <class ELFT> ArrayRef<Symbol *> ObjFile<ELFT>::getGlobalSymbols() {
405 return makeArrayRef(this->symbols).slice(this->firstGlobal);
406}
407
408template <class ELFT> void ObjFile<ELFT>::parse(bool ignoreComdats) {
409 // Read a section table. justSymbols is usually false.
410 if (this->justSymbols)
411 initializeJustSymbols();
412 else
413 initializeSections(ignoreComdats);
414
415 // Read a symbol table.
416 initializeSymbols();
417}
418
419// Sections with SHT_GROUP and comdat bits define comdat section groups.
420// They are identified and deduplicated by group name. This function
421// returns a group name.
422template <class ELFT>
423StringRef ObjFile<ELFT>::getShtGroupSignature(ArrayRef<Elf_Shdr> sections,
424 const Elf_Shdr &sec) {
425 typename ELFT::SymRange symbols = this->getELFSyms<ELFT>();
426 if (sec.sh_info >= symbols.size())
427 fatal(toString(this) + ": invalid symbol index");
428 const typename ELFT::Sym &sym = symbols[sec.sh_info];
429 StringRef signature = CHECK(sym.getName(this->stringTable), this)check2((sym.getName(this->stringTable)), [&] { return toString
(this); })
;
430
431 // As a special case, if a symbol is a section symbol and has no name,
432 // we use a section name as a signature.
433 //
434 // Such SHT_GROUP sections are invalid from the perspective of the ELF
435 // standard, but GNU gold 1.14 (the newest version as of July 2017) or
436 // older produce such sections as outputs for the -r option, so we need
437 // a bug-compatibility.
438 if (signature.empty() && sym.getType() == STT_SECTION)
439 return getSectionName(sec);
440 return signature;
441}
442
443template <class ELFT>
444bool ObjFile<ELFT>::shouldMerge(const Elf_Shdr &sec, StringRef name) {
445 if (!(sec.sh_flags & SHF_MERGE))
446 return false;
447
448 // On a regular link we don't merge sections if -O0 (default is -O1). This
449 // sometimes makes the linker significantly faster, although the output will
450 // be bigger.
451 //
452 // Doing the same for -r would create a problem as it would combine sections
453 // with different sh_entsize. One option would be to just copy every SHF_MERGE
454 // section as is to the output. While this would produce a valid ELF file with
455 // usable SHF_MERGE sections, tools like (llvm-)?dwarfdump get confused when
456 // they see two .debug_str. We could have separate logic for combining
457 // SHF_MERGE sections based both on their name and sh_entsize, but that seems
458 // to be more trouble than it is worth. Instead, we just use the regular (-O1)
459 // logic for -r.
460 if (config->optimize == 0 && !config->relocatable)
461 return false;
462
463 // A mergeable section with size 0 is useless because they don't have
464 // any data to merge. A mergeable string section with size 0 can be
465 // argued as invalid because it doesn't end with a null character.
466 // We'll avoid a mess by handling them as if they were non-mergeable.
467 if (sec.sh_size == 0)
468 return false;
469
470 // Check for sh_entsize. The ELF spec is not clear about the zero
471 // sh_entsize. It says that "the member [sh_entsize] contains 0 if
472 // the section does not hold a table of fixed-size entries". We know
473 // that Rust 1.13 produces a string mergeable section with a zero
474 // sh_entsize. Here we just accept it rather than being picky about it.
475 uint64_t entSize = sec.sh_entsize;
476 if (entSize == 0)
477 return false;
478 if (sec.sh_size % entSize)
479 fatal(toString(this) + ":(" + name + "): SHF_MERGE section size (" +
480 Twine(sec.sh_size) + ") must be a multiple of sh_entsize (" +
481 Twine(entSize) + ")");
482
483 if (sec.sh_flags & SHF_WRITE)
484 fatal(toString(this) + ":(" + name +
485 "): writable SHF_MERGE section is not supported");
486
487 return true;
488}
489
490// This is for --just-symbols.
491//
492// --just-symbols is a very minor feature that allows you to link your
493// output against other existing program, so that if you load both your
494// program and the other program into memory, your output can refer the
495// other program's symbols.
496//
497// When the option is given, we link "just symbols". The section table is
498// initialized with null pointers.
499template <class ELFT> void ObjFile<ELFT>::initializeJustSymbols() {
500 ArrayRef<Elf_Shdr> sections = CHECK(this->getObj().sections(), this)check2((this->getObj().sections()), [&] { return toString
(this); })
;
501 this->sections.resize(sections.size());
502}
503
504// An ELF object file may contain a `.deplibs` section. If it exists, the
505// section contains a list of library specifiers such as `m` for libm. This
506// function resolves a given name by finding the first matching library checking
507// the various ways that a library can be specified to LLD. This ELF extension
508// is a form of autolinking and is called `dependent libraries`. It is currently
509// unique to LLVM and lld.
510static void addDependentLibrary(StringRef specifier, const InputFile *f) {
511 if (!config->dependentLibraries)
512 return;
513 if (fs::exists(specifier))
514 driver->addFile(specifier, /*withLOption=*/false);
515 else if (Optional<std::string> s = findFromSearchPaths(specifier))
516 driver->addFile(*s, /*withLOption=*/true);
517 else if (Optional<std::string> s = searchLibraryBaseName(specifier))
518 driver->addFile(*s, /*withLOption=*/true);
519 else
520 error(toString(f) +
521 ": unable to find library from dependent library specifier: " +
522 specifier);
523}
524
525// Record the membership of a section group so that in the garbage collection
526// pass, section group members are kept or discarded as a unit.
527template <class ELFT>
528static void handleSectionGroup(ArrayRef<InputSectionBase *> sections,
529 ArrayRef<typename ELFT::Word> entries) {
530 bool hasAlloc = false;
531 for (uint32_t index : entries.slice(1)) {
532 if (index >= sections.size())
533 return;
534 if (InputSectionBase *s = sections[index])
535 if (s != &InputSection::discarded && s->flags & SHF_ALLOC)
536 hasAlloc = true;
537 }
538
539 // If any member has the SHF_ALLOC flag, the whole group is subject to garbage
540 // collection. See the comment in markLive(). This rule retains .debug_types
541 // and .rela.debug_types.
542 if (!hasAlloc)
543 return;
544
545 // Connect the members in a circular doubly-linked list via
546 // nextInSectionGroup.
547 InputSectionBase *head;
548 InputSectionBase *prev = nullptr;
549 for (uint32_t index : entries.slice(1)) {
550 InputSectionBase *s = sections[index];
551 if (!s || s == &InputSection::discarded)
552 continue;
553 if (prev)
554 prev->nextInSectionGroup = s;
555 else
556 head = s;
557 prev = s;
558 }
559 if (prev)
560 prev->nextInSectionGroup = head;
561}
562
563template <class ELFT>
564void ObjFile<ELFT>::initializeSections(bool ignoreComdats) {
565 const ELFFile<ELFT> &obj = this->getObj();
566
567 ArrayRef<Elf_Shdr> objSections = CHECK(obj.sections(), this)check2((obj.sections()), [&] { return toString(this); });
568 uint64_t size = objSections.size();
569 this->sections.resize(size);
570 this->sectionStringTable =
571 CHECK(obj.getSectionStringTable(objSections), this)check2((obj.getSectionStringTable(objSections)), [&] { return
toString(this); })
;
572
573 std::vector<ArrayRef<Elf_Word>> selectedGroups;
574
575 for (size_t i = 0, e = objSections.size(); i < e; ++i) {
576 if (this->sections[i] == &InputSection::discarded)
577 continue;
578 const Elf_Shdr &sec = objSections[i];
579
580 if (sec.sh_type == ELF::SHT_LLVM_CALL_GRAPH_PROFILE)
581 cgProfileSectionIndex = i;
582
583 // SHF_EXCLUDE'ed sections are discarded by the linker. However,
584 // if -r is given, we'll let the final link discard such sections.
585 // This is compatible with GNU.
586 if ((sec.sh_flags & SHF_EXCLUDE) && !config->relocatable) {
587 if (sec.sh_type == SHT_LLVM_ADDRSIG) {
588 // We ignore the address-significance table if we know that the object
589 // file was created by objcopy or ld -r. This is because these tools
590 // will reorder the symbols in the symbol table, invalidating the data
591 // in the address-significance table, which refers to symbols by index.
592 if (sec.sh_link != 0)
593 this->addrsigSec = &sec;
594 else if (config->icf == ICFLevel::Safe)
595 warn(toString(this) +
596 ": --icf=safe conservatively ignores "
597 "SHT_LLVM_ADDRSIG [index " +
598 Twine(i) +
599 "] with sh_link=0 "
600 "(likely created using objcopy or ld -r)");
601 }
602 this->sections[i] = &InputSection::discarded;
603 continue;
604 }
605
606 switch (sec.sh_type) {
607 case SHT_GROUP: {
608 // De-duplicate section groups by their signatures.
609 StringRef signature = getShtGroupSignature(objSections, sec);
610 this->sections[i] = &InputSection::discarded;
611
612 ArrayRef<Elf_Word> entries =
613 CHECK(obj.template getSectionContentsAsArray<Elf_Word>(sec), this)check2((obj.template getSectionContentsAsArray<Elf_Word>
(sec)), [&] { return toString(this); })
;
614 if (entries.empty())
615 fatal(toString(this) + ": empty SHT_GROUP");
616
617 Elf_Word flag = entries[0];
618 if (flag && flag != GRP_COMDAT)
619 fatal(toString(this) + ": unsupported SHT_GROUP format");
620
621 bool keepGroup =
622 (flag & GRP_COMDAT) == 0 || ignoreComdats ||
623 symtab->comdatGroups.try_emplace(CachedHashStringRef(signature), this)
624 .second;
625 if (keepGroup) {
626 if (config->relocatable)
627 this->sections[i] = createInputSection(sec);
628 selectedGroups.push_back(entries);
629 continue;
630 }
631
632 // Otherwise, discard group members.
633 for (uint32_t secIndex : entries.slice(1)) {
634 if (secIndex >= size)
635 fatal(toString(this) +
636 ": invalid section index in group: " + Twine(secIndex));
637 this->sections[secIndex] = &InputSection::discarded;
638 }
639 break;
640 }
641 case SHT_SYMTAB_SHNDX:
642 shndxTable = CHECK(obj.getSHNDXTable(sec, objSections), this)check2((obj.getSHNDXTable(sec, objSections)), [&] { return
toString(this); })
;
643 break;
644 case SHT_SYMTAB:
645 case SHT_STRTAB:
646 case SHT_REL:
647 case SHT_RELA:
648 case SHT_NULL:
649 break;
650 default:
651 this->sections[i] = createInputSection(sec);
652 }
653 }
654
655 // We have a second loop. It is used to:
656 // 1) handle SHF_LINK_ORDER sections.
657 // 2) create SHT_REL[A] sections. In some cases the section header index of a
658 // relocation section may be smaller than that of the relocated section. In
659 // such cases, the relocation section would attempt to reference a target
660 // section that has not yet been created. For simplicity, delay creation of
661 // relocation sections until now.
662 for (size_t i = 0, e = objSections.size(); i < e; ++i) {
663 if (this->sections[i] == &InputSection::discarded)
664 continue;
665 const Elf_Shdr &sec = objSections[i];
666
667 if (sec.sh_type == SHT_REL || sec.sh_type == SHT_RELA)
668 this->sections[i] = createInputSection(sec);
669
670 // A SHF_LINK_ORDER section with sh_link=0 is handled as if it did not have
671 // the flag.
672 if (!(sec.sh_flags & SHF_LINK_ORDER) || !sec.sh_link)
673 continue;
674
675 InputSectionBase *linkSec = nullptr;
676 if (sec.sh_link < this->sections.size())
677 linkSec = this->sections[sec.sh_link];
678 if (!linkSec)
679 fatal(toString(this) + ": invalid sh_link index: " + Twine(sec.sh_link));
680
681 // A SHF_LINK_ORDER section is discarded if its linked-to section is
682 // discarded.
683 InputSection *isec = cast<InputSection>(this->sections[i]);
684 linkSec->dependentSections.push_back(isec);
685 if (!isa<InputSection>(linkSec))
686 error("a section " + isec->name +
687 " with SHF_LINK_ORDER should not refer a non-regular section: " +
688 toString(linkSec));
689 }
690
691 for (ArrayRef<Elf_Word> entries : selectedGroups)
692 handleSectionGroup<ELFT>(this->sections, entries);
693}
694
695// For ARM only, to set the EF_ARM_ABI_FLOAT_SOFT or EF_ARM_ABI_FLOAT_HARD
696// flag in the ELF Header we need to look at Tag_ABI_VFP_args to find out how
697// the input objects have been compiled.
698static void updateARMVFPArgs(const ARMAttributeParser &attributes,
699 const InputFile *f) {
700 Optional<unsigned> attr =
701 attributes.getAttributeValue(ARMBuildAttrs::ABI_VFP_args);
702 if (!attr.hasValue())
703 // If an ABI tag isn't present then it is implicitly given the value of 0
704 // which maps to ARMBuildAttrs::BaseAAPCS. However many assembler files,
705 // including some in glibc that don't use FP args (and should have value 3)
706 // don't have the attribute so we do not consider an implicit value of 0
707 // as a clash.
708 return;
709
710 unsigned vfpArgs = attr.getValue();
711 ARMVFPArgKind arg;
712 switch (vfpArgs) {
713 case ARMBuildAttrs::BaseAAPCS:
714 arg = ARMVFPArgKind::Base;
715 break;
716 case ARMBuildAttrs::HardFPAAPCS:
717 arg = ARMVFPArgKind::VFP;
718 break;
719 case ARMBuildAttrs::ToolChainFPPCS:
720 // Tool chain specific convention that conforms to neither AAPCS variant.
721 arg = ARMVFPArgKind::ToolChain;
722 break;
723 case ARMBuildAttrs::CompatibleFPAAPCS:
724 // Object compatible with all conventions.
725 return;
726 default:
727 error(toString(f) + ": unknown Tag_ABI_VFP_args value: " + Twine(vfpArgs));
728 return;
729 }
730 // Follow ld.bfd and error if there is a mix of calling conventions.
731 if (config->armVFPArgs != arg && config->armVFPArgs != ARMVFPArgKind::Default)
732 error(toString(f) + ": incompatible Tag_ABI_VFP_args");
733 else
734 config->armVFPArgs = arg;
735}
736
737// The ARM support in lld makes some use of instructions that are not available
738// on all ARM architectures. Namely:
739// - Use of BLX instruction for interworking between ARM and Thumb state.
740// - Use of the extended Thumb branch encoding in relocation.
741// - Use of the MOVT/MOVW instructions in Thumb Thunks.
742// The ARM Attributes section contains information about the architecture chosen
743// at compile time. We follow the convention that if at least one input object
744// is compiled with an architecture that supports these features then lld is
745// permitted to use them.
746static void updateSupportedARMFeatures(const ARMAttributeParser &attributes) {
747 Optional<unsigned> attr =
748 attributes.getAttributeValue(ARMBuildAttrs::CPU_arch);
749 if (!attr.hasValue())
750 return;
751 auto arch = attr.getValue();
752 switch (arch) {
753 case ARMBuildAttrs::Pre_v4:
754 case ARMBuildAttrs::v4:
755 case ARMBuildAttrs::v4T:
756 // Architectures prior to v5 do not support BLX instruction
757 break;
758 case ARMBuildAttrs::v5T:
759 case ARMBuildAttrs::v5TE:
760 case ARMBuildAttrs::v5TEJ:
761 case ARMBuildAttrs::v6:
762 case ARMBuildAttrs::v6KZ:
763 case ARMBuildAttrs::v6K:
764 config->armHasBlx = true;
765 // Architectures used in pre-Cortex processors do not support
766 // The J1 = 1 J2 = 1 Thumb branch range extension, with the exception
767 // of Architecture v6T2 (arm1156t2-s and arm1156t2f-s) that do.
768 break;
769 default:
770 // All other Architectures have BLX and extended branch encoding
771 config->armHasBlx = true;
772 config->armJ1J2BranchEncoding = true;
773 if (arch != ARMBuildAttrs::v6_M && arch != ARMBuildAttrs::v6S_M)
774 // All Architectures used in Cortex processors with the exception
775 // of v6-M and v6S-M have the MOVT and MOVW instructions.
776 config->armHasMovtMovw = true;
777 break;
778 }
779}
780
781// If a source file is compiled with x86 hardware-assisted call flow control
782// enabled, the generated object file contains feature flags indicating that
783// fact. This function reads the feature flags and returns it.
784//
785// Essentially we want to read a single 32-bit value in this function, but this
786// function is rather complicated because the value is buried deep inside a
787// .note.gnu.property section.
788//
789// The section consists of one or more NOTE records. Each NOTE record consists
790// of zero or more type-length-value fields. We want to find a field of a
791// certain type. It seems a bit too much to just store a 32-bit value, perhaps
792// the ABI is unnecessarily complicated.
793template <class ELFT> static uint32_t readAndFeatures(const InputSection &sec) {
794 using Elf_Nhdr = typename ELFT::Nhdr;
795 using Elf_Note = typename ELFT::Note;
796
797 uint32_t featuresSet = 0;
798 ArrayRef<uint8_t> data = sec.data();
799 auto reportFatal = [&](const uint8_t *place, const char *msg) {
800 fatal(toString(sec.file) + ":(" + sec.name + "+0x" +
801 Twine::utohexstr(place - sec.data().data()) + "): " + msg);
802 };
803 while (!data.empty()) {
804 // Read one NOTE record.
805 auto *nhdr = reinterpret_cast<const Elf_Nhdr *>(data.data());
806 if (data.size() < sizeof(Elf_Nhdr) || data.size() < nhdr->getSize())
807 reportFatal(data.data(), "data is too short");
808
809 Elf_Note note(*nhdr);
810 if (nhdr->n_type != NT_GNU_PROPERTY_TYPE_0 || note.getName() != "GNU") {
811 data = data.slice(nhdr->getSize());
812 continue;
813 }
814
815 uint32_t featureAndType = config->emachine == EM_AARCH64
816 ? GNU_PROPERTY_AARCH64_FEATURE_1_AND
817 : GNU_PROPERTY_X86_FEATURE_1_AND;
818
819 // Read a body of a NOTE record, which consists of type-length-value fields.
820 ArrayRef<uint8_t> desc = note.getDesc();
821 while (!desc.empty()) {
822 const uint8_t *place = desc.data();
823 if (desc.size() < 8)
824 reportFatal(place, "program property is too short");
825 uint32_t type = read32<ELFT::TargetEndianness>(desc.data());
826 uint32_t size = read32<ELFT::TargetEndianness>(desc.data() + 4);
827 desc = desc.slice(8);
828 if (desc.size() < size)
829 reportFatal(place, "program property is too short");
830
831 if (type == featureAndType) {
832 // We found a FEATURE_1_AND field. There may be more than one of these
833 // in a .note.gnu.property section, for a relocatable object we
834 // accumulate the bits set.
835 if (size < 4)
836 reportFatal(place, "FEATURE_1_AND entry is too short");
837 featuresSet |= read32<ELFT::TargetEndianness>(desc.data());
838 }
839
840 // Padding is present in the note descriptor, if necessary.
841 desc = desc.slice(alignTo<(ELFT::Is64Bits ? 8 : 4)>(size));
842 }
843
844 // Go to next NOTE record to look for more FEATURE_1_AND descriptions.
845 data = data.slice(nhdr->getSize());
846 }
847
848 return featuresSet;
849}
850
851template <class ELFT>
852InputSectionBase *ObjFile<ELFT>::getRelocTarget(const Elf_Shdr &sec) {
853 uint32_t idx = sec.sh_info;
854 if (idx >= this->sections.size())
855 fatal(toString(this) + ": invalid relocated section index: " + Twine(idx));
856 InputSectionBase *target = this->sections[idx];
857
858 // Strictly speaking, a relocation section must be included in the
859 // group of the section it relocates. However, LLVM 3.3 and earlier
860 // would fail to do so, so we gracefully handle that case.
861 if (target == &InputSection::discarded)
862 return nullptr;
863
864 if (!target)
865 fatal(toString(this) + ": unsupported relocation reference");
866 return target;
867}
868
869// Create a regular InputSection class that has the same contents
870// as a given section.
871static InputSection *toRegularSection(MergeInputSection *sec) {
872 return make<InputSection>(sec->file, sec->flags, sec->type, sec->alignment,
873 sec->data(), sec->name);
874}
875
876template <class ELFT>
877InputSectionBase *ObjFile<ELFT>::createInputSection(const Elf_Shdr &sec) {
878 StringRef name = getSectionName(sec);
879
880 if (config->emachine == EM_ARM && sec.sh_type == SHT_ARM_ATTRIBUTES) {
881 ARMAttributeParser attributes;
882 ArrayRef<uint8_t> contents = check(this->getObj().getSectionContents(sec));
883 if (Error e = attributes.parse(contents, config->ekind == ELF32LEKind
884 ? support::little
885 : support::big)) {
886 auto *isec = make<InputSection>(*this, sec, name);
887 warn(toString(isec) + ": " + llvm::toString(std::move(e)));
888 } else {
889 updateSupportedARMFeatures(attributes);
890 updateARMVFPArgs(attributes, this);
891
892 // FIXME: Retain the first attribute section we see. The eglibc ARM
893 // dynamic loaders require the presence of an attribute section for dlopen
894 // to work. In a full implementation we would merge all attribute
895 // sections.
896 if (in.attributes == nullptr) {
897 in.attributes = make<InputSection>(*this, sec, name);
898 return in.attributes;
899 }
900 return &InputSection::discarded;
901 }
902 }
903
904 if (config->emachine == EM_RISCV && sec.sh_type == SHT_RISCV_ATTRIBUTES) {
905 RISCVAttributeParser attributes;
906 ArrayRef<uint8_t> contents = check(this->getObj().getSectionContents(sec));
907 if (Error e = attributes.parse(contents, support::little)) {
908 auto *isec = make<InputSection>(*this, sec, name);
909 warn(toString(isec) + ": " + llvm::toString(std::move(e)));
910 } else {
911 // FIXME: Validate arch tag contains C if and only if EF_RISCV_RVC is
912 // present.
913
914 // FIXME: Retain the first attribute section we see. Tools such as
915 // llvm-objdump make use of the attribute section to determine which
916 // standard extensions to enable. In a full implementation we would merge
917 // all attribute sections.
918 if (in.attributes == nullptr) {
919 in.attributes = make<InputSection>(*this, sec, name);
920 return in.attributes;
921 }
922 return &InputSection::discarded;
923 }
924 }
925
926 switch (sec.sh_type) {
927 case SHT_LLVM_DEPENDENT_LIBRARIES: {
928 if (config->relocatable)
929 break;
930 ArrayRef<char> data =
931 CHECK(this->getObj().template getSectionContentsAsArray<char>(sec), this)check2((this->getObj().template getSectionContentsAsArray<
char>(sec)), [&] { return toString(this); })
;
932 if (!data.empty() && data.back() != '\0') {
933 error(toString(this) +
934 ": corrupted dependent libraries section (unterminated string): " +
935 name);
936 return &InputSection::discarded;
937 }
938 for (const char *d = data.begin(), *e = data.end(); d < e;) {
939 StringRef s(d);
940 addDependentLibrary(s, this);
941 d += s.size() + 1;
942 }
943 return &InputSection::discarded;
944 }
945 case SHT_RELA:
946 case SHT_REL: {
947 // Find a relocation target section and associate this section with that.
948 // Target may have been discarded if it is in a different section group
949 // and the group is discarded, even though it's a violation of the
950 // spec. We handle that situation gracefully by discarding dangling
951 // relocation sections.
952 InputSectionBase *target = getRelocTarget(sec);
953 if (!target)
954 return nullptr;
955
956 // ELF spec allows mergeable sections with relocations, but they are
957 // rare, and it is in practice hard to merge such sections by contents,
958 // because applying relocations at end of linking changes section
959 // contents. So, we simply handle such sections as non-mergeable ones.
960 // Degrading like this is acceptable because section merging is optional.
961 if (auto *ms = dyn_cast<MergeInputSection>(target)) {
962 target = toRegularSection(ms);
963 this->sections[sec.sh_info] = target;
964 }
965
966 if (target->firstRelocation)
967 fatal(toString(this) +
968 ": multiple relocation sections to one section are not supported");
969
970 if (sec.sh_type == SHT_RELA) {
971 ArrayRef<Elf_Rela> rels = CHECK(getObj().relas(sec), this)check2((getObj().relas(sec)), [&] { return toString(this)
; })
;
972 target->firstRelocation = rels.begin();
973 target->numRelocations = rels.size();
974 target->areRelocsRela = true;
975 } else {
976 ArrayRef<Elf_Rel> rels = CHECK(getObj().rels(sec), this)check2((getObj().rels(sec)), [&] { return toString(this);
})
;
977 target->firstRelocation = rels.begin();
978 target->numRelocations = rels.size();
979 target->areRelocsRela = false;
980 }
981 assert(isUInt<31>(target->numRelocations))((void)0);
982
983 // Relocation sections are usually removed from the output, so return
984 // `nullptr` for the normal case. However, if -r or --emit-relocs is
985 // specified, we need to copy them to the output. (Some post link analysis
986 // tools specify --emit-relocs to obtain the information.)
987 if (!config->relocatable && !config->emitRelocs)
988 return nullptr;
989 InputSection *relocSec = make<InputSection>(*this, sec, name);
990 // If the relocated section is discarded (due to /DISCARD/ or
991 // --gc-sections), the relocation section should be discarded as well.
992 target->dependentSections.push_back(relocSec);
993 return relocSec;
994 }
995 }
996
997 // The GNU linker uses .note.GNU-stack section as a marker indicating
998 // that the code in the object file does not expect that the stack is
999 // executable (in terms of NX bit). If all input files have the marker,
1000 // the GNU linker adds a PT_GNU_STACK segment to tells the loader to
1001 // make the stack non-executable. Most object files have this section as
1002 // of 2017.
1003 //
1004 // But making the stack non-executable is a norm today for security
1005 // reasons. Failure to do so may result in a serious security issue.
1006 // Therefore, we make LLD always add PT_GNU_STACK unless it is
1007 // explicitly told to do otherwise (by -z execstack). Because the stack
1008 // executable-ness is controlled solely by command line options,
1009 // .note.GNU-stack sections are simply ignored.
1010 if (name == ".note.GNU-stack")
1011 return &InputSection::discarded;
1012
1013 // Object files that use processor features such as Intel Control-Flow
1014 // Enforcement (CET) or AArch64 Branch Target Identification BTI, use a
1015 // .note.gnu.property section containing a bitfield of feature bits like the
1016 // GNU_PROPERTY_X86_FEATURE_1_IBT flag. Read a bitmap containing the flag.
1017 //
1018 // Since we merge bitmaps from multiple object files to create a new
1019 // .note.gnu.property containing a single AND'ed bitmap, we discard an input
1020 // file's .note.gnu.property section.
1021 if (name == ".note.gnu.property") {
1022 this->andFeatures = readAndFeatures<ELFT>(InputSection(*this, sec, name));
1023 return &InputSection::discarded;
1024 }
1025
1026 // Split stacks is a feature to support a discontiguous stack,
1027 // commonly used in the programming language Go. For the details,
1028 // see https://gcc.gnu.org/wiki/SplitStacks. An object file compiled
1029 // for split stack will include a .note.GNU-split-stack section.
1030 if (name == ".note.GNU-split-stack") {
1031 if (config->relocatable) {
1032 error("cannot mix split-stack and non-split-stack in a relocatable link");
1033 return &InputSection::discarded;
1034 }
1035 this->splitStack = true;
1036 return &InputSection::discarded;
1037 }
1038
1039 // An object file cmpiled for split stack, but where some of the
1040 // functions were compiled with the no_split_stack_attribute will
1041 // include a .note.GNU-no-split-stack section.
1042 if (name == ".note.GNU-no-split-stack") {
1043 this->someNoSplitStack = true;
1044 return &InputSection::discarded;
1045 }
1046
1047 // The linkonce feature is a sort of proto-comdat. Some glibc i386 object
1048 // files contain definitions of symbol "__x86.get_pc_thunk.bx" in linkonce
1049 // sections. Drop those sections to avoid duplicate symbol errors.
1050 // FIXME: This is glibc PR20543, we should remove this hack once that has been
1051 // fixed for a while.
1052 if (name == ".gnu.linkonce.t.__x86.get_pc_thunk.bx" ||
1053 name == ".gnu.linkonce.t.__i686.get_pc_thunk.bx")
1054 return &InputSection::discarded;
1055
1056 // If we are creating a new .build-id section, strip existing .build-id
1057 // sections so that the output won't have more than one .build-id.
1058 // This is not usually a problem because input object files normally don't
1059 // have .build-id sections, but you can create such files by
1060 // "ld.{bfd,gold,lld} -r --build-id", and we want to guard against it.
1061 if (name == ".note.gnu.build-id" && config->buildId != BuildIdKind::None)
1062 return &InputSection::discarded;
1063
1064 // The linker merges EH (exception handling) frames and creates a
1065 // .eh_frame_hdr section for runtime. So we handle them with a special
1066 // class. For relocatable outputs, they are just passed through.
1067 if (name == ".eh_frame" && !config->relocatable)
1068 return make<EhInputSection>(*this, sec, name);
1069
1070 if (shouldMerge(sec, name))
1071 return make<MergeInputSection>(*this, sec, name);
1072 return make<InputSection>(*this, sec, name);
1073}
1074
1075template <class ELFT>
1076StringRef ObjFile<ELFT>::getSectionName(const Elf_Shdr &sec) {
1077 return CHECK(getObj().getSectionName(sec, sectionStringTable), this)check2((getObj().getSectionName(sec, sectionStringTable)), [&
] { return toString(this); })
;
1078}
1079
1080// Initialize this->Symbols. this->Symbols is a parallel array as
1081// its corresponding ELF symbol table.
1082template <class ELFT> void ObjFile<ELFT>::initializeSymbols() {
1083 ArrayRef<Elf_Sym> eSyms = this->getELFSyms<ELFT>();
1084 this->symbols.resize(eSyms.size());
1085
1086 // Fill in InputFile::symbols. Some entries have been initialized
1087 // because of LazyObjFile.
1088 for (size_t i = 0, end = eSyms.size(); i != end; ++i) {
1089 if (this->symbols[i])
1090 continue;
1091 const Elf_Sym &eSym = eSyms[i];
1092 uint32_t secIdx = getSectionIndex(eSym);
1093 if (secIdx >= this->sections.size())
1094 fatal(toString(this) + ": invalid section index: " + Twine(secIdx));
1095 if (eSym.getBinding() != STB_LOCAL) {
1096 if (i < firstGlobal)
1097 error(toString(this) + ": non-local symbol (" + Twine(i) +
1098 ") found at index < .symtab's sh_info (" + Twine(firstGlobal) +
1099 ")");
1100 this->symbols[i] =
1101 symtab->insert(CHECK(eSyms[i].getName(this->stringTable), this)check2((eSyms[i].getName(this->stringTable)), [&] { return
toString(this); })
);
1102 continue;
1103 }
1104
1105 // Handle local symbols. Local symbols are not added to the symbol
1106 // table because they are not visible from other object files. We
1107 // allocate symbol instances and add their pointers to symbols.
1108 if (i >= firstGlobal)
1109 errorOrWarn(toString(this) + ": STB_LOCAL symbol (" + Twine(i) +
1110 ") found at index >= .symtab's sh_info (" +
1111 Twine(firstGlobal) + ")");
1112
1113 InputSectionBase *sec = this->sections[secIdx];
1114 uint8_t type = eSym.getType();
1115 if (type == STT_FILE)
1116 sourceFile = CHECK(eSym.getName(this->stringTable), this)check2((eSym.getName(this->stringTable)), [&] { return
toString(this); })
;
1117 if (this->stringTable.size() <= eSym.st_name)
1118 fatal(toString(this) + ": invalid symbol name offset");
1119 StringRefZ name = this->stringTable.data() + eSym.st_name;
1120
1121 if (eSym.st_shndx == SHN_UNDEF)
1122 this->symbols[i] =
1123 make<Undefined>(this, name, STB_LOCAL, eSym.st_other, type);
1124 else if (sec == &InputSection::discarded)
1125 this->symbols[i] =
1126 make<Undefined>(this, name, STB_LOCAL, eSym.st_other, type,
1127 /*discardedSecIdx=*/secIdx);
1128 else
1129 this->symbols[i] = make<Defined>(this, name, STB_LOCAL, eSym.st_other,
1130 type, eSym.st_value, eSym.st_size, sec);
1131 }
1132
1133 // Symbol resolution of non-local symbols.
1134 SmallVector<unsigned, 32> undefineds;
1135 for (size_t i = firstGlobal, end = eSyms.size(); i != end; ++i) {
1136 const Elf_Sym &eSym = eSyms[i];
1137 uint8_t binding = eSym.getBinding();
1138 if (binding == STB_LOCAL)
1139 continue; // Errored above.
1140
1141 uint32_t secIdx = getSectionIndex(eSym);
1142 InputSectionBase *sec = this->sections[secIdx];
1143 uint8_t stOther = eSym.st_other;
1144 uint8_t type = eSym.getType();
1145 uint64_t value = eSym.st_value;
1146 uint64_t size = eSym.st_size;
1147 StringRefZ name = this->stringTable.data() + eSym.st_name;
1148
1149 // Handle global undefined symbols.
1150 if (eSym.st_shndx == SHN_UNDEF) {
1151 undefineds.push_back(i);
1152 continue;
1153 }
1154
1155 // Handle global common symbols.
1156 if (eSym.st_shndx == SHN_COMMON) {
1157 if (value == 0 || value >= UINT32_MAX0xffffffffU)
1158 fatal(toString(this) + ": common symbol '" + StringRef(name.data) +
1159 "' has invalid alignment: " + Twine(value));
1160 this->symbols[i]->resolve(
1161 CommonSymbol{this, name, binding, stOther, type, value, size});
1162 continue;
1163 }
1164
1165 // If a defined symbol is in a discarded section, handle it as if it
1166 // were an undefined symbol. Such symbol doesn't comply with the
1167 // standard, but in practice, a .eh_frame often directly refer
1168 // COMDAT member sections, and if a comdat group is discarded, some
1169 // defined symbol in a .eh_frame becomes dangling symbols.
1170 if (sec == &InputSection::discarded) {
1171 Undefined und{this, name, binding, stOther, type, secIdx};
1172 Symbol *sym = this->symbols[i];
1173 // !ArchiveFile::parsed or LazyObjFile::fetched means that the file
1174 // containing this object has not finished processing, i.e. this symbol is
1175 // a result of a lazy symbol fetch. We should demote the lazy symbol to an
1176 // Undefined so that any relocations outside of the group to it will
1177 // trigger a discarded section error.
1178 if ((sym->symbolKind == Symbol::LazyArchiveKind &&
1179 !cast<ArchiveFile>(sym->file)->parsed) ||
1180 (sym->symbolKind == Symbol::LazyObjectKind &&
1181 cast<LazyObjFile>(sym->file)->fetched))
1182 sym->replace(und);
1183 else
1184 sym->resolve(und);
1185 continue;
1186 }
1187
1188 // Handle global defined symbols.
1189 if (binding == STB_GLOBAL || binding == STB_WEAK ||
1190 binding == STB_GNU_UNIQUE) {
1191 this->symbols[i]->resolve(
1192 Defined{this, name, binding, stOther, type, value, size, sec});
1193 continue;
1194 }
1195
1196 fatal(toString(this) + ": unexpected binding: " + Twine((int)binding));
1197 }
1198
1199 // Undefined symbols (excluding those defined relative to non-prevailing
1200 // sections) can trigger recursive fetch. Process defined symbols first so
1201 // that the relative order between a defined symbol and an undefined symbol
1202 // does not change the symbol resolution behavior. In addition, a set of
1203 // interconnected symbols will all be resolved to the same file, instead of
1204 // being resolved to different files.
1205 for (unsigned i : undefineds) {
1206 const Elf_Sym &eSym = eSyms[i];
1207 StringRefZ name = this->stringTable.data() + eSym.st_name;
1208 this->symbols[i]->resolve(Undefined{this, name, eSym.getBinding(),
1209 eSym.st_other, eSym.getType()});
1210 this->symbols[i]->referenced = true;
1211 }
1212}
1213
1214ArchiveFile::ArchiveFile(std::unique_ptr<Archive> &&file)
1215 : InputFile(ArchiveKind, file->getMemoryBufferRef()),
1216 file(std::move(file)) {}
1217
1218void ArchiveFile::parse() {
1219 for (const Archive::Symbol &sym : file->symbols())
1220 symtab->addSymbol(LazyArchive{*this, sym});
1221
1222 // Inform a future invocation of ObjFile<ELFT>::initializeSymbols() that this
1223 // archive has been processed.
1224 parsed = true;
1225}
1226
1227// Returns a buffer pointing to a member file containing a given symbol.
1228void ArchiveFile::fetch(const Archive::Symbol &sym) {
1229 Archive::Child c =
1230 CHECK(sym.getMember(), toString(this) +check2((sym.getMember()), [&] { return toString(toString(
this) + ": could not get the member for symbol " + toELFString
(sym)); })
1231 ": could not get the member for symbol " +check2((sym.getMember()), [&] { return toString(toString(
this) + ": could not get the member for symbol " + toELFString
(sym)); })
1232 toELFString(sym))check2((sym.getMember()), [&] { return toString(toString(
this) + ": could not get the member for symbol " + toELFString
(sym)); })
;
1233
1234 if (!seen.insert(c.getChildOffset()).second)
1235 return;
1236
1237 MemoryBufferRef mb =
1238 CHECK(c.getMemoryBufferRef(),check2((c.getMemoryBufferRef()), [&] { return toString(toString
(this) + ": could not get the buffer for the member defining symbol "
+ toELFString(sym)); })
1239 toString(this) +check2((c.getMemoryBufferRef()), [&] { return toString(toString
(this) + ": could not get the buffer for the member defining symbol "
+ toELFString(sym)); })
1240 ": could not get the buffer for the member defining symbol " +check2((c.getMemoryBufferRef()), [&] { return toString(toString
(this) + ": could not get the buffer for the member defining symbol "
+ toELFString(sym)); })
1241 toELFString(sym))check2((c.getMemoryBufferRef()), [&] { return toString(toString
(this) + ": could not get the buffer for the member defining symbol "
+ toELFString(sym)); })
;
1242
1243 if (tar && c.getParent()->isThin())
1244 tar->append(relativeToRoot(CHECK(c.getFullName(), this)check2((c.getFullName()), [&] { return toString(this); })), mb.getBuffer());
1245
1246 InputFile *file = createObjectFile(mb, getName(), c.getChildOffset());
1247 file->groupId = groupId;
1248 parseFile(file);
1249}
1250
1251// The handling of tentative definitions (COMMON symbols) in archives is murky.
1252// A tentative definition will be promoted to a global definition if there are
1253// no non-tentative definitions to dominate it. When we hold a tentative
1254// definition to a symbol and are inspecting archive members for inclusion
1255// there are 2 ways we can proceed:
1256//
1257// 1) Consider the tentative definition a 'real' definition (ie promotion from
1258// tentative to real definition has already happened) and not inspect
1259// archive members for Global/Weak definitions to replace the tentative
1260// definition. An archive member would only be included if it satisfies some
1261// other undefined symbol. This is the behavior Gold uses.
1262//
1263// 2) Consider the tentative definition as still undefined (ie the promotion to
1264// a real definition happens only after all symbol resolution is done).
1265// The linker searches archive members for STB_GLOBAL definitions to
1266// replace the tentative definition with. This is the behavior used by
1267// GNU ld.
1268//
1269// The second behavior is inherited from SysVR4, which based it on the FORTRAN
1270// COMMON BLOCK model. This behavior is needed for proper initialization in old
1271// (pre F90) FORTRAN code that is packaged into an archive.
1272//
1273// The following functions search archive members for definitions to replace
1274// tentative definitions (implementing behavior 2).
1275static bool isBitcodeNonCommonDef(MemoryBufferRef mb, StringRef symName,
1276 StringRef archiveName) {
1277 IRSymtabFile symtabFile = check(readIRSymtab(mb));
1278 for (const irsymtab::Reader::SymbolRef &sym :
1279 symtabFile.TheReader.symbols()) {
3
Calling 'Reader::symbols'
1280 if (sym.isGlobal() && sym.getName() == symName)
1281 return !sym.isUndefined() && !sym.isWeak() && !sym.isCommon();
1282 }
1283 return false;
1284}
1285
1286template <class ELFT>
1287static bool isNonCommonDef(MemoryBufferRef mb, StringRef symName,
1288 StringRef archiveName) {
1289 ObjFile<ELFT> *obj = make<ObjFile<ELFT>>(mb, archiveName);
1290 StringRef stringtable = obj->getStringTable();
1291
1292 for (auto sym : obj->template getGlobalELFSyms<ELFT>()) {
1293 Expected<StringRef> name = sym.getName(stringtable);
1294 if (name && name.get() == symName)
1295 return sym.isDefined() && sym.getBinding() == STB_GLOBAL &&
1296 !sym.isCommon();
1297 }
1298 return false;
1299}
1300
1301static bool isNonCommonDef(MemoryBufferRef mb, StringRef symName,
1302 StringRef archiveName) {
1303 switch (getELFKind(mb, archiveName)) {
1304 case ELF32LEKind:
1305 return isNonCommonDef<ELF32LE>(mb, symName, archiveName);
1306 case ELF32BEKind:
1307 return isNonCommonDef<ELF32BE>(mb, symName, archiveName);
1308 case ELF64LEKind:
1309 return isNonCommonDef<ELF64LE>(mb, symName, archiveName);
1310 case ELF64BEKind:
1311 return isNonCommonDef<ELF64BE>(mb, symName, archiveName);
1312 default:
1313 llvm_unreachable("getELFKind")__builtin_unreachable();
1314 }
1315}
1316
1317bool ArchiveFile::shouldFetchForCommon(const Archive::Symbol &sym) {
1318 Archive::Child c =
1319 CHECK(sym.getMember(), toString(this) +check2((sym.getMember()), [&] { return toString(toString(
this) + ": could not get the member for symbol " + toELFString
(sym)); })
1320 ": could not get the member for symbol " +check2((sym.getMember()), [&] { return toString(toString(
this) + ": could not get the member for symbol " + toELFString
(sym)); })
1321 toELFString(sym))check2((sym.getMember()), [&] { return toString(toString(
this) + ": could not get the member for symbol " + toELFString
(sym)); })
;
1322 MemoryBufferRef mb =
1323 CHECK(c.getMemoryBufferRef(),check2((c.getMemoryBufferRef()), [&] { return toString(toString
(this) + ": could not get the buffer for the member defining symbol "
+ toELFString(sym)); })
1324 toString(this) +check2((c.getMemoryBufferRef()), [&] { return toString(toString
(this) + ": could not get the buffer for the member defining symbol "
+ toELFString(sym)); })
1325 ": could not get the buffer for the member defining symbol " +check2((c.getMemoryBufferRef()), [&] { return toString(toString
(this) + ": could not get the buffer for the member defining symbol "
+ toELFString(sym)); })
1326 toELFString(sym))check2((c.getMemoryBufferRef()), [&] { return toString(toString
(this) + ": could not get the buffer for the member defining symbol "
+ toELFString(sym)); })
;
1327
1328 if (isBitcode(mb))
1329 return isBitcodeNonCommonDef(mb, sym.getName(), getName());
1330
1331 return isNonCommonDef(mb, sym.getName(), getName());
1332}
1333
1334size_t ArchiveFile::getMemberCount() const {
1335 size_t count = 0;
1336 Error err = Error::success();
1337 for (const Archive::Child &c : file->children(err)) {
1338 (void)c;
1339 ++count;
1340 }
1341 // This function is used by --print-archive-stats=, where an error does not
1342 // really matter.
1343 consumeError(std::move(err));
1344 return count;
1345}
1346
1347unsigned SharedFile::vernauxNum;
1348
1349// Parse the version definitions in the object file if present, and return a
1350// vector whose nth element contains a pointer to the Elf_Verdef for version
1351// identifier n. Version identifiers that are not definitions map to nullptr.
1352template <typename ELFT>
1353static std::vector<const void *> parseVerdefs(const uint8_t *base,
1354 const typename ELFT::Shdr *sec) {
1355 if (!sec)
1356 return {};
1357
1358 // We cannot determine the largest verdef identifier without inspecting
1359 // every Elf_Verdef, but both bfd and gold assign verdef identifiers
1360 // sequentially starting from 1, so we predict that the largest identifier
1361 // will be verdefCount.
1362 unsigned verdefCount = sec->sh_info;
1363 std::vector<const void *> verdefs(verdefCount + 1);
1364
1365 // Build the Verdefs array by following the chain of Elf_Verdef objects
1366 // from the start of the .gnu.version_d section.
1367 const uint8_t *verdef = base + sec->sh_offset;
1368 for (unsigned i = 0; i != verdefCount; ++i) {
1369 auto *curVerdef = reinterpret_cast<const typename ELFT::Verdef *>(verdef);
1370 verdef += curVerdef->vd_next;
1371 unsigned verdefIndex = curVerdef->vd_ndx;
1372 verdefs.resize(verdefIndex + 1);
1373 verdefs[verdefIndex] = curVerdef;
1374 }
1375 return verdefs;
1376}
1377
1378// Parse SHT_GNU_verneed to properly set the name of a versioned undefined
1379// symbol. We detect fatal issues which would cause vulnerabilities, but do not
1380// implement sophisticated error checking like in llvm-readobj because the value
1381// of such diagnostics is low.
1382template <typename ELFT>
1383std::vector<uint32_t> SharedFile::parseVerneed(const ELFFile<ELFT> &obj,
1384 const typename ELFT::Shdr *sec) {
1385 if (!sec)
1386 return {};
1387 std::vector<uint32_t> verneeds;
1388 ArrayRef<uint8_t> data = CHECK(obj.getSectionContents(*sec), this)check2((obj.getSectionContents(*sec)), [&] { return toString
(this); })
;
1389 const uint8_t *verneedBuf = data.begin();
1390 for (unsigned i = 0; i != sec->sh_info; ++i) {
1391 if (verneedBuf + sizeof(typename ELFT::Verneed) > data.end())
1392 fatal(toString(this) + " has an invalid Verneed");
1393 auto *vn = reinterpret_cast<const typename ELFT::Verneed *>(verneedBuf);
1394 const uint8_t *vernauxBuf = verneedBuf + vn->vn_aux;
1395 for (unsigned j = 0; j != vn->vn_cnt; ++j) {
1396 if (vernauxBuf + sizeof(typename ELFT::Vernaux) > data.end())
1397 fatal(toString(this) + " has an invalid Vernaux");
1398 auto *aux = reinterpret_cast<const typename ELFT::Vernaux *>(vernauxBuf);
1399 if (aux->vna_name >= this->stringTable.size())
1400 fatal(toString(this) + " has a Vernaux with an invalid vna_name");
1401 uint16_t version = aux->vna_other & VERSYM_VERSION;
1402 if (version >= verneeds.size())
1403 verneeds.resize(version + 1);
1404 verneeds[version] = aux->vna_name;
1405 vernauxBuf += aux->vna_next;
1406 }
1407 verneedBuf += vn->vn_next;
1408 }
1409 return verneeds;
1410}
1411
1412// We do not usually care about alignments of data in shared object
1413// files because the loader takes care of it. However, if we promote a
1414// DSO symbol to point to .bss due to copy relocation, we need to keep
1415// the original alignment requirements. We infer it in this function.
1416template <typename ELFT>
1417static uint64_t getAlignment(ArrayRef<typename ELFT::Shdr> sections,
1418 const typename ELFT::Sym &sym) {
1419 uint64_t ret = UINT64_MAX0xffffffffffffffffULL;
1420 if (sym.st_value)
1421 ret = 1ULL << countTrailingZeros((uint64_t)sym.st_value);
1422 if (0 < sym.st_shndx && sym.st_shndx < sections.size())
1423 ret = std::min<uint64_t>(ret, sections[sym.st_shndx].sh_addralign);
1424 return (ret > UINT32_MAX0xffffffffU) ? 0 : ret;
1425}
1426
1427// Fully parse the shared object file.
1428//
1429// This function parses symbol versions. If a DSO has version information,
1430// the file has a ".gnu.version_d" section which contains symbol version
1431// definitions. Each symbol is associated to one version through a table in
1432// ".gnu.version" section. That table is a parallel array for the symbol
1433// table, and each table entry contains an index in ".gnu.version_d".
1434//
1435// The special index 0 is reserved for VERF_NDX_LOCAL and 1 is for
1436// VER_NDX_GLOBAL. There's no table entry for these special versions in
1437// ".gnu.version_d".
1438//
1439// The file format for symbol versioning is perhaps a bit more complicated
1440// than necessary, but you can easily understand the code if you wrap your
1441// head around the data structure described above.
1442template <class ELFT> void SharedFile::parse() {
1443 using Elf_Dyn = typename ELFT::Dyn;
1444 using Elf_Shdr = typename ELFT::Shdr;
1445 using Elf_Sym = typename ELFT::Sym;
1446 using Elf_Verdef = typename ELFT::Verdef;
1447 using Elf_Versym = typename ELFT::Versym;
1448
1449 ArrayRef<Elf_Dyn> dynamicTags;
1450 const ELFFile<ELFT> obj = this->getObj<ELFT>();
1451 ArrayRef<Elf_Shdr> sections = CHECK(obj.sections(), this)check2((obj.sections()), [&] { return toString(this); });
1452
1453 const Elf_Shdr *versymSec = nullptr;
1454 const Elf_Shdr *verdefSec = nullptr;
1455 const Elf_Shdr *verneedSec = nullptr;
1456
1457 // Search for .dynsym, .dynamic, .symtab, .gnu.version and .gnu.version_d.
1458 for (const Elf_Shdr &sec : sections) {
1459 switch (sec.sh_type) {
1460 default:
1461 continue;
1462 case SHT_DYNAMIC:
1463 dynamicTags =
1464 CHECK(obj.template getSectionContentsAsArray<Elf_Dyn>(sec), this)check2((obj.template getSectionContentsAsArray<Elf_Dyn>
(sec)), [&] { return toString(this); })
;
1465 break;
1466 case SHT_GNU_versym:
1467 versymSec = &sec;
1468 break;
1469 case SHT_GNU_verdef:
1470 verdefSec = &sec;
1471 break;
1472 case SHT_GNU_verneed:
1473 verneedSec = &sec;
1474 break;
1475 }
1476 }
1477
1478 if (versymSec && numELFSyms == 0) {
1479 error("SHT_GNU_versym should be associated with symbol table");
1480 return;
1481 }
1482
1483 // Search for a DT_SONAME tag to initialize this->soName.
1484 for (const Elf_Dyn &dyn : dynamicTags) {
1485 if (dyn.d_tag == DT_NEEDED) {
1486 uint64_t val = dyn.getVal();
1487 if (val >= this->stringTable.size())
1488 fatal(toString(this) + ": invalid DT_NEEDED entry");
1489 dtNeeded.push_back(this->stringTable.data() + val);
1490 } else if (dyn.d_tag == DT_SONAME) {
1491 uint64_t val = dyn.getVal();
1492 if (val >= this->stringTable.size())
1493 fatal(toString(this) + ": invalid DT_SONAME entry");
1494 soName = this->stringTable.data() + val;
1495 }
1496 }
1497
1498 // DSOs are uniquified not by filename but by soname.
1499 DenseMap<StringRef, SharedFile *>::iterator it;
1500 bool wasInserted;
1501 std::tie(it, wasInserted) = symtab->soNames.try_emplace(soName, this);
1502
1503 // If a DSO appears more than once on the command line with and without
1504 // --as-needed, --no-as-needed takes precedence over --as-needed because a
1505 // user can add an extra DSO with --no-as-needed to force it to be added to
1506 // the dependency list.
1507 it->second->isNeeded |= isNeeded;
1508 if (!wasInserted)
1509 return;
1510
1511 sharedFiles.push_back(this);
1512
1513 verdefs = parseVerdefs<ELFT>(obj.base(), verdefSec);
1514 std::vector<uint32_t> verneeds = parseVerneed<ELFT>(obj, verneedSec);
1515
1516 // Parse ".gnu.version" section which is a parallel array for the symbol
1517 // table. If a given file doesn't have a ".gnu.version" section, we use
1518 // VER_NDX_GLOBAL.
1519 size_t size = numELFSyms - firstGlobal;
1520 std::vector<uint16_t> versyms(size, VER_NDX_GLOBAL);
1521 if (versymSec) {
1522 ArrayRef<Elf_Versym> versym =
1523 CHECK(obj.template getSectionContentsAsArray<Elf_Versym>(*versymSec),check2((obj.template getSectionContentsAsArray<Elf_Versym>
(*versymSec)), [&] { return toString(this); })
1524 this)check2((obj.template getSectionContentsAsArray<Elf_Versym>
(*versymSec)), [&] { return toString(this); })
1525 .slice(firstGlobal);
1526 for (size_t i = 0; i < size; ++i)
1527 versyms[i] = versym[i].vs_index;
1528 }
1529
1530 // System libraries can have a lot of symbols with versions. Using a
1531 // fixed buffer for computing the versions name (foo@ver) can save a
1532 // lot of allocations.
1533 SmallString<0> versionedNameBuffer;
1534
1535 // Add symbols to the symbol table.
1536 ArrayRef<Elf_Sym> syms = this->getGlobalELFSyms<ELFT>();
1537 for (size_t i = 0; i < syms.size(); ++i) {
1538 const Elf_Sym &sym = syms[i];
1539
1540 // ELF spec requires that all local symbols precede weak or global
1541 // symbols in each symbol table, and the index of first non-local symbol
1542 // is stored to sh_info. If a local symbol appears after some non-local
1543 // symbol, that's a violation of the spec.
1544 StringRef name = CHECK(sym.getName(this->stringTable), this)check2((sym.getName(this->stringTable)), [&] { return toString
(this); })
;
1545 if (sym.getBinding() == STB_LOCAL) {
1546 warn("found local symbol '" + name +
1547 "' in global part of symbol table in file " + toString(this));
1548 continue;
1549 }
1550
1551 uint16_t idx = versyms[i] & ~VERSYM_HIDDEN;
1552 if (sym.isUndefined()) {
1553 // For unversioned undefined symbols, VER_NDX_GLOBAL makes more sense but
1554 // as of binutils 2.34, GNU ld produces VER_NDX_LOCAL.
1555 if (idx != VER_NDX_LOCAL && idx != VER_NDX_GLOBAL) {
1556 if (idx >= verneeds.size()) {
1557 error("corrupt input file: version need index " + Twine(idx) +
1558 " for symbol " + name + " is out of bounds\n>>> defined in " +
1559 toString(this));
1560 continue;
1561 }
1562 StringRef verName = this->stringTable.data() + verneeds[idx];
1563 versionedNameBuffer.clear();
1564 name =
1565 saver.save((name + "@" + verName).toStringRef(versionedNameBuffer));
1566 }
1567 Symbol *s = symtab->addSymbol(
1568 Undefined{this, name, sym.getBinding(), sym.st_other, sym.getType()});
1569 s->exportDynamic = true;
1570 if (s->isUndefined() && sym.getBinding() != STB_WEAK &&
1571 config->unresolvedSymbolsInShlib != UnresolvedPolicy::Ignore)
1572 requiredSymbols.push_back(s);
1573 continue;
1574 }
1575
1576 // MIPS BFD linker puts _gp_disp symbol into DSO files and incorrectly
1577 // assigns VER_NDX_LOCAL to this section global symbol. Here is a
1578 // workaround for this bug.
1579 if (config->emachine == EM_MIPS && idx == VER_NDX_LOCAL &&
1580 name == "_gp_disp")
1581 continue;
1582
1583 uint32_t alignment = getAlignment<ELFT>(sections, sym);
1584 if (!(versyms[i] & VERSYM_HIDDEN)) {
1585 symtab->addSymbol(SharedSymbol{*this, name, sym.getBinding(),
1586 sym.st_other, sym.getType(), sym.st_value,
1587 sym.st_size, alignment, idx});
1588 }
1589
1590 // Also add the symbol with the versioned name to handle undefined symbols
1591 // with explicit versions.
1592 if (idx == VER_NDX_GLOBAL)
1593 continue;
1594
1595 if (idx >= verdefs.size() || idx == VER_NDX_LOCAL) {
1596 error("corrupt input file: version definition index " + Twine(idx) +
1597 " for symbol " + name + " is out of bounds\n>>> defined in " +
1598 toString(this));
1599 continue;
1600 }
1601
1602 StringRef verName =
1603 this->stringTable.data() +
1604 reinterpret_cast<const Elf_Verdef *>(verdefs[idx])->getAux()->vda_name;
1605 versionedNameBuffer.clear();
1606 name = (name + "@" + verName).toStringRef(versionedNameBuffer);
1607 symtab->addSymbol(SharedSymbol{*this, saver.save(name), sym.getBinding(),
1608 sym.st_other, sym.getType(), sym.st_value,
1609 sym.st_size, alignment, idx});
1610 }
1611}
1612
1613static ELFKind getBitcodeELFKind(const Triple &t) {
1614 if (t.isLittleEndian())
1615 return t.isArch64Bit() ? ELF64LEKind : ELF32LEKind;
1616 return t.isArch64Bit() ? ELF64BEKind : ELF32BEKind;
1617}
1618
1619static uint16_t getBitcodeMachineKind(StringRef path, const Triple &t) {
1620 switch (t.getArch()) {
1621 case Triple::aarch64:
1622 case Triple::aarch64_be:
1623 return EM_AARCH64;
1624 case Triple::amdgcn:
1625 case Triple::r600:
1626 return EM_AMDGPU;
1627 case Triple::arm:
1628 case Triple::thumb:
1629 return EM_ARM;
1630 case Triple::avr:
1631 return EM_AVR;
1632 case Triple::mips:
1633 case Triple::mipsel:
1634 case Triple::mips64:
1635 case Triple::mips64el:
1636 return EM_MIPS;
1637 case Triple::msp430:
1638 return EM_MSP430;
1639 case Triple::ppc:
1640 case Triple::ppcle:
1641 return EM_PPC;
1642 case Triple::ppc64:
1643 case Triple::ppc64le:
1644 return EM_PPC64;
1645 case Triple::riscv32:
1646 case Triple::riscv64:
1647 return EM_RISCV;
1648 case Triple::x86:
1649 return t.isOSIAMCU() ? EM_IAMCU : EM_386;
1650 case Triple::x86_64:
1651 return EM_X86_64;
1652 default:
1653 error(path + ": could not infer e_machine from bitcode target triple " +
1654 t.str());
1655 return EM_NONE;
1656 }
1657}
1658
1659static uint8_t getOsAbi(const Triple &t) {
1660 switch (t.getOS()) {
1661 case Triple::AMDHSA:
1662 return ELF::ELFOSABI_AMDGPU_HSA;
1663 case Triple::AMDPAL:
1664 return ELF::ELFOSABI_AMDGPU_PAL;
1665 case Triple::Mesa3D:
1666 return ELF::ELFOSABI_AMDGPU_MESA3D;
1667 default:
1668 return ELF::ELFOSABI_NONE;
1669 }
1670}
1671
1672BitcodeFile::BitcodeFile(MemoryBufferRef mb, StringRef archiveName,
1673 uint64_t offsetInArchive)
1674 : InputFile(BitcodeKind, mb) {
1675 this->archiveName = std::string(archiveName);
1676
1677 std::string path = mb.getBufferIdentifier().str();
1678 if (config->thinLTOIndexOnly)
1679 path = replaceThinLTOSuffix(mb.getBufferIdentifier());
1680
1681 // ThinLTO assumes that all MemoryBufferRefs given to it have a unique
1682 // name. If two archives define two members with the same name, this
1683 // causes a collision which result in only one of the objects being taken
1684 // into consideration at LTO time (which very likely causes undefined
1685 // symbols later in the link stage). So we append file offset to make
1686 // filename unique.
1687 StringRef name =
1688 archiveName.empty()
1689 ? saver.save(path)
1690 : saver.save(archiveName + "(" + path::filename(path) + " at " +
1691 utostr(offsetInArchive) + ")");
1692 MemoryBufferRef mbref(mb.getBuffer(), name);
1693
1694 obj = CHECK(lto::InputFile::create(mbref), this)check2((lto::InputFile::create(mbref)), [&] { return toString
(this); })
;
1695
1696 Triple t(obj->getTargetTriple());
1697 ekind = getBitcodeELFKind(t);
1698 emachine = getBitcodeMachineKind(mb.getBufferIdentifier(), t);
1699 osabi = getOsAbi(t);
1700}
1701
1702static uint8_t mapVisibility(GlobalValue::VisibilityTypes gvVisibility) {
1703 switch (gvVisibility) {
1704 case GlobalValue::DefaultVisibility:
1705 return STV_DEFAULT;
1706 case GlobalValue::HiddenVisibility:
1707 return STV_HIDDEN;
1708 case GlobalValue::ProtectedVisibility:
1709 return STV_PROTECTED;
1710 }
1711 llvm_unreachable("unknown visibility")__builtin_unreachable();
1712}
1713
1714template <class ELFT>
1715static Symbol *createBitcodeSymbol(const std::vector<bool> &keptComdats,
1716 const lto::InputFile::Symbol &objSym,
1717 BitcodeFile &f) {
1718 StringRef name = saver.save(objSym.getName());
1719 uint8_t binding = objSym.isWeak() ? STB_WEAK : STB_GLOBAL;
1720 uint8_t type = objSym.isTLS() ? STT_TLS : STT_NOTYPE;
1721 uint8_t visibility = mapVisibility(objSym.getVisibility());
1722 bool canOmitFromDynSym = objSym.canBeOmittedFromSymbolTable();
1723
1724 int c = objSym.getComdatIndex();
1725 if (objSym.isUndefined() || (c != -1 && !keptComdats[c])) {
1726 Undefined newSym(&f, name, binding, visibility, type);
1727 if (canOmitFromDynSym)
1728 newSym.exportDynamic = false;
1729 Symbol *ret = symtab->addSymbol(newSym);
1730 ret->referenced = true;
1731 return ret;
1732 }
1733
1734 if (objSym.isCommon())
1735 return symtab->addSymbol(
1736 CommonSymbol{&f, name, binding, visibility, STT_OBJECT,
1737 objSym.getCommonAlignment(), objSym.getCommonSize()});
1738
1739 Defined newSym(&f, name, binding, visibility, type, 0, 0, nullptr);
1740 if (canOmitFromDynSym)
1741 newSym.exportDynamic = false;
1742 return symtab->addSymbol(newSym);
1743}
1744
1745template <class ELFT> void BitcodeFile::parse() {
1746 std::vector<bool> keptComdats;
1747 for (std::pair<StringRef, Comdat::SelectionKind> s : obj->getComdatTable()) {
1748 keptComdats.push_back(
1749 s.second == Comdat::NoDeduplicate ||
1750 symtab->comdatGroups.try_emplace(CachedHashStringRef(s.first), this)
1751 .second);
1752 }
1753
1754 for (const lto::InputFile::Symbol &objSym : obj->symbols())
1755 symbols.push_back(createBitcodeSymbol<ELFT>(keptComdats, objSym, *this));
1756
1757 for (auto l : obj->getDependentLibraries())
1758 addDependentLibrary(l, this);
1759}
1760
1761void BinaryFile::parse() {
1762 ArrayRef<uint8_t> data = arrayRefFromStringRef(mb.getBuffer());
1763 auto *section = make<InputSection>(this, SHF_ALLOC | SHF_WRITE, SHT_PROGBITS,
1764 8, data, ".data");
1765 sections.push_back(section);
1766
1767 // For each input file foo that is embedded to a result as a binary
1768 // blob, we define _binary_foo_{start,end,size} symbols, so that
1769 // user programs can access blobs by name. Non-alphanumeric
1770 // characters in a filename are replaced with underscore.
1771 std::string s = "_binary_" + mb.getBufferIdentifier().str();
1772 for (size_t i = 0; i < s.size(); ++i)
1773 if (!isAlnum(s[i]))
1774 s[i] = '_';
1775
1776 symtab->addSymbol(Defined{nullptr, saver.save(s + "_start"), STB_GLOBAL,
1777 STV_DEFAULT, STT_OBJECT, 0, 0, section});
1778 symtab->addSymbol(Defined{nullptr, saver.save(s + "_end"), STB_GLOBAL,
1779 STV_DEFAULT, STT_OBJECT, data.size(), 0, section});
1780 symtab->addSymbol(Defined{nullptr, saver.save(s + "_size"), STB_GLOBAL,
1781 STV_DEFAULT, STT_OBJECT, data.size(), 0, nullptr});
1782}
1783
1784InputFile *elf::createObjectFile(MemoryBufferRef mb, StringRef archiveName,
1785 uint64_t offsetInArchive) {
1786 if (isBitcode(mb))
1787 return make<BitcodeFile>(mb, archiveName, offsetInArchive);
1788
1789 switch (getELFKind(mb, archiveName)) {
1790 case ELF32LEKind:
1791 return make<ObjFile<ELF32LE>>(mb, archiveName);
1792 case ELF32BEKind:
1793 return make<ObjFile<ELF32BE>>(mb, archiveName);
1794 case ELF64LEKind:
1795 return make<ObjFile<ELF64LE>>(mb, archiveName);
1796 case ELF64BEKind:
1797 return make<ObjFile<ELF64BE>>(mb, archiveName);
1798 default:
1799 llvm_unreachable("getELFKind")__builtin_unreachable();
1800 }
1801}
1802
1803void LazyObjFile::fetch() {
1804 if (fetched)
1805 return;
1806 fetched = true;
1807
1808 InputFile *file = createObjectFile(mb, archiveName, offsetInArchive);
1809 file->groupId = groupId;
1810
1811 // Copy symbol vector so that the new InputFile doesn't have to
1812 // insert the same defined symbols to the symbol table again.
1813 file->symbols = std::move(symbols);
1814
1815 parseFile(file);
1816}
1817
1818template <class ELFT> void LazyObjFile::parse() {
1819 using Elf_Sym = typename ELFT::Sym;
1820
1821 // A lazy object file wraps either a bitcode file or an ELF file.
1822 if (isBitcode(this->mb)) {
1823 std::unique_ptr<lto::InputFile> obj =
1824 CHECK(lto::InputFile::create(this->mb), this)check2((lto::InputFile::create(this->mb)), [&] { return
toString(this); })
;
1825 for (const lto::InputFile::Symbol &sym : obj->symbols()) {
1826 if (sym.isUndefined())
1827 continue;
1828 symtab->addSymbol(LazyObject{*this, saver.save(sym.getName())});
1829 }
1830 return;
1831 }
1832
1833 if (getELFKind(this->mb, archiveName) != config->ekind) {
1834 error("incompatible file: " + this->mb.getBufferIdentifier());
1835 return;
1836 }
1837
1838 // Find a symbol table.
1839 ELFFile<ELFT> obj = check(ELFFile<ELFT>::create(mb.getBuffer()));
1840 ArrayRef<typename ELFT::Shdr> sections = CHECK(obj.sections(), this)check2((obj.sections()), [&] { return toString(this); });
1841
1842 for (const typename ELFT::Shdr &sec : sections) {
1843 if (sec.sh_type != SHT_SYMTAB)
1844 continue;
1845
1846 // A symbol table is found.
1847 ArrayRef<Elf_Sym> eSyms = CHECK(obj.symbols(&sec), this)check2((obj.symbols(&sec)), [&] { return toString(this
); })
;
1848 uint32_t firstGlobal = sec.sh_info;
1849 StringRef strtab = CHECK(obj.getStringTableForSymtab(sec, sections), this)check2((obj.getStringTableForSymtab(sec, sections)), [&] {
return toString(this); })
;
1850 this->symbols.resize(eSyms.size());
1851
1852 // Get existing symbols or insert placeholder symbols.
1853 for (size_t i = firstGlobal, end = eSyms.size(); i != end; ++i)
1854 if (eSyms[i].st_shndx != SHN_UNDEF)
1855 this->symbols[i] = symtab->insert(CHECK(eSyms[i].getName(strtab), this)check2((eSyms[i].getName(strtab)), [&] { return toString(
this); })
);
1856
1857 // Replace existing symbols with LazyObject symbols.
1858 //
1859 // resolve() may trigger this->fetch() if an existing symbol is an
1860 // undefined symbol. If that happens, this LazyObjFile has served
1861 // its purpose, and we can exit from the loop early.
1862 for (Symbol *sym : this->symbols) {
1863 if (!sym)
1864 continue;
1865 sym->resolve(LazyObject{*this, sym->getName()});
1866
1867 // If fetched, stop iterating because this->symbols has been transferred
1868 // to the instantiated ObjFile.
1869 if (fetched)
1870 return;
1871 }
1872 return;
1873 }
1874}
1875
1876bool LazyObjFile::shouldFetchForCommon(const StringRef &name) {
1877 if (isBitcode(mb))
1
Taking true branch
1878 return isBitcodeNonCommonDef(mb, name, archiveName);
2
Calling 'isBitcodeNonCommonDef'
1879
1880 return isNonCommonDef(mb, name, archiveName);
1881}
1882
1883std::string elf::replaceThinLTOSuffix(StringRef path) {
1884 StringRef suffix = config->thinLTOObjectSuffixReplace.first;
1885 StringRef repl = config->thinLTOObjectSuffixReplace.second;
1886
1887 if (path.consume_back(suffix))
1888 return (path + repl).str();
1889 return std::string(path);
1890}
1891
1892template void BitcodeFile::parse<ELF32LE>();
1893template void BitcodeFile::parse<ELF32BE>();
1894template void BitcodeFile::parse<ELF64LE>();
1895template void BitcodeFile::parse<ELF64BE>();
1896
1897template void LazyObjFile::parse<ELF32LE>();
1898template void LazyObjFile::parse<ELF32BE>();
1899template void LazyObjFile::parse<ELF64LE>();
1900template void LazyObjFile::parse<ELF64BE>();
1901
1902template class elf::ObjFile<ELF32LE>;
1903template class elf::ObjFile<ELF32BE>;
1904template class elf::ObjFile<ELF64LE>;
1905template class elf::ObjFile<ELF64BE>;
1906
1907template void SharedFile::parse<ELF32LE>();
1908template void SharedFile::parse<ELF32BE>();
1909template void SharedFile::parse<ELF64LE>();
1910template void SharedFile::parse<ELF64BE>();

/usr/src/gnu/usr.bin/clang/liblldELF/../../../llvm/llvm/include/llvm/Object/IRSymtab.h

1//===- IRSymtab.h - data definitions for IR symbol tables -------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file contains data definitions and a reader and builder for a symbol
10// table for LLVM IR. Its purpose is to allow linkers and other consumers of
11// bitcode files to efficiently read the symbol table for symbol resolution
12// purposes without needing to construct a module in memory.
13//
14// As with most object files the symbol table has two parts: the symbol table
15// itself and a string table which is referenced by the symbol table.
16//
17// A symbol table corresponds to a single bitcode file, which may consist of
18// multiple modules, so symbol tables may likewise contain symbols for multiple
19// modules.
20//
21//===----------------------------------------------------------------------===//
22
23#ifndef LLVM_OBJECT_IRSYMTAB_H
24#define LLVM_OBJECT_IRSYMTAB_H
25
26#include "llvm/ADT/ArrayRef.h"
27#include "llvm/ADT/StringRef.h"
28#include "llvm/ADT/iterator_range.h"
29#include "llvm/IR/Comdat.h"
30#include "llvm/IR/GlobalValue.h"
31#include "llvm/Object/SymbolicFile.h"
32#include "llvm/Support/Allocator.h"
33#include "llvm/Support/Endian.h"
34#include "llvm/Support/Error.h"
35#include <cassert>
36#include <cstdint>
37#include <vector>
38
39namespace llvm {
40
41struct BitcodeFileContents;
42class StringTableBuilder;
43
44namespace irsymtab {
45
46namespace storage {
47
48// The data structures in this namespace define the low-level serialization
49// format. Clients that just want to read a symbol table should use the
50// irsymtab::Reader class.
51
52using Word = support::ulittle32_t;
53
54/// A reference to a string in the string table.
55struct Str {
56 Word Offset, Size;
57
58 StringRef get(StringRef Strtab) const {
59 return {Strtab.data() + Offset, Size};
60 }
61};
62
63/// A reference to a range of objects in the symbol table.
64template <typename T> struct Range {
65 Word Offset, Size;
66
67 ArrayRef<T> get(StringRef Symtab) const {
68 return {reinterpret_cast<const T *>(Symtab.data() + Offset), Size};
69 }
70};
71
72/// Describes the range of a particular module's symbols within the symbol
73/// table.
74struct Module {
75 Word Begin, End;
76
77 /// The index of the first Uncommon for this Module.
78 Word UncBegin;
79};
80
81/// This is equivalent to an IR comdat.
82struct Comdat {
83 Str Name;
84
85 // llvm::Comdat::SelectionKind
86 Word SelectionKind;
87};
88
89/// Contains the information needed by linkers for symbol resolution, as well as
90/// by the LTO implementation itself.
91struct Symbol {
92 /// The mangled symbol name.
93 Str Name;
94
95 /// The unmangled symbol name, or the empty string if this is not an IR
96 /// symbol.
97 Str IRName;
98
99 /// The index into Header::Comdats, or -1 if not a comdat member.
100 Word ComdatIndex;
101
102 Word Flags;
103 enum FlagBits {
104 FB_visibility, // 2 bits
105 FB_has_uncommon = FB_visibility + 2,
106 FB_undefined,
107 FB_weak,
108 FB_common,
109 FB_indirect,
110 FB_used,
111 FB_tls,
112 FB_may_omit,
113 FB_global,
114 FB_format_specific,
115 FB_unnamed_addr,
116 FB_executable,
117 };
118};
119
120/// This data structure contains rarely used symbol fields and is optionally
121/// referenced by a Symbol.
122struct Uncommon {
123 Word CommonSize, CommonAlign;
124
125 /// COFF-specific: the name of the symbol that a weak external resolves to
126 /// if not defined.
127 Str COFFWeakExternFallbackName;
128
129 /// Specified section name, if any.
130 Str SectionName;
131};
132
133
134struct Header {
135 /// Version number of the symtab format. This number should be incremented
136 /// when the format changes, but it does not need to be incremented if a
137 /// change to LLVM would cause it to create a different symbol table.
138 Word Version;
139 enum { kCurrentVersion = 3 };
140
141 /// The producer's version string (LLVM_VERSION_STRING " " LLVM_REVISION).
142 /// Consumers should rebuild the symbol table from IR if the producer's
143 /// version does not match the consumer's version due to potential differences
144 /// in symbol table format, symbol enumeration order and so on.
145 Str Producer;
146
147 Range<Module> Modules;
148 Range<Comdat> Comdats;
149 Range<Symbol> Symbols;
150 Range<Uncommon> Uncommons;
151
152 Str TargetTriple, SourceFileName;
153
154 /// COFF-specific: linker directives.
155 Str COFFLinkerOpts;
156
157 /// Dependent Library Specifiers
158 Range<Str> DependentLibraries;
159};
160
161} // end namespace storage
162
163/// Fills in Symtab and StrtabBuilder with a valid symbol and string table for
164/// Mods.
165Error build(ArrayRef<Module *> Mods, SmallVector<char, 0> &Symtab,
166 StringTableBuilder &StrtabBuilder, BumpPtrAllocator &Alloc);
167
168/// This represents a symbol that has been read from a storage::Symbol and
169/// possibly a storage::Uncommon.
170struct Symbol {
171 // Copied from storage::Symbol.
172 StringRef Name, IRName;
173 int ComdatIndex;
174 uint32_t Flags;
175
176 // Copied from storage::Uncommon.
177 uint32_t CommonSize, CommonAlign;
178 StringRef COFFWeakExternFallbackName;
179 StringRef SectionName;
180
181 /// Returns the mangled symbol name.
182 StringRef getName() const { return Name; }
183
184 /// Returns the unmangled symbol name, or the empty string if this is not an
185 /// IR symbol.
186 StringRef getIRName() const { return IRName; }
187
188 /// Returns the index into the comdat table (see Reader::getComdatTable()), or
189 /// -1 if not a comdat member.
190 int getComdatIndex() const { return ComdatIndex; }
191
192 using S = storage::Symbol;
193
194 GlobalValue::VisibilityTypes getVisibility() const {
195 return GlobalValue::VisibilityTypes((Flags >> S::FB_visibility) & 3);
196 }
197
198 bool isUndefined() const { return (Flags >> S::FB_undefined) & 1; }
199 bool isWeak() const { return (Flags >> S::FB_weak) & 1; }
200 bool isCommon() const { return (Flags >> S::FB_common) & 1; }
201 bool isIndirect() const { return (Flags >> S::FB_indirect) & 1; }
202 bool isUsed() const { return (Flags >> S::FB_used) & 1; }
203 bool isTLS() const { return (Flags >> S::FB_tls) & 1; }
204
205 bool canBeOmittedFromSymbolTable() const {
206 return (Flags >> S::FB_may_omit) & 1;
207 }
208
209 bool isGlobal() const { return (Flags >> S::FB_global) & 1; }
210 bool isFormatSpecific() const { return (Flags >> S::FB_format_specific) & 1; }
211 bool isUnnamedAddr() const { return (Flags >> S::FB_unnamed_addr) & 1; }
212 bool isExecutable() const { return (Flags >> S::FB_executable) & 1; }
213
214 uint64_t getCommonSize() const {
215 assert(isCommon())((void)0);
216 return CommonSize;
217 }
218
219 uint32_t getCommonAlignment() const {
220 assert(isCommon())((void)0);
221 return CommonAlign;
222 }
223
224 /// COFF-specific: for weak externals, returns the name of the symbol that is
225 /// used as a fallback if the weak external remains undefined.
226 StringRef getCOFFWeakExternalFallback() const {
227 assert(isWeak() && isIndirect())((void)0);
228 return COFFWeakExternFallbackName;
229 }
230
231 StringRef getSectionName() const { return SectionName; }
232};
233
234/// This class can be used to read a Symtab and Strtab produced by
235/// irsymtab::build.
236class Reader {
237 StringRef Symtab, Strtab;
238
239 ArrayRef<storage::Module> Modules;
240 ArrayRef<storage::Comdat> Comdats;
241 ArrayRef<storage::Symbol> Symbols;
242 ArrayRef<storage::Uncommon> Uncommons;
243 ArrayRef<storage::Str> DependentLibraries;
244
245 StringRef str(storage::Str S) const { return S.get(Strtab); }
246
247 template <typename T> ArrayRef<T> range(storage::Range<T> R) const {
248 return R.get(Symtab);
249 }
250
251 const storage::Header &header() const {
252 return *reinterpret_cast<const storage::Header *>(Symtab.data());
253 }
254
255public:
256 class SymbolRef;
257
258 Reader() = default;
259 Reader(StringRef Symtab, StringRef Strtab) : Symtab(Symtab), Strtab(Strtab) {
260 Modules = range(header().Modules);
261 Comdats = range(header().Comdats);
262 Symbols = range(header().Symbols);
263 Uncommons = range(header().Uncommons);
264 DependentLibraries = range(header().DependentLibraries);
265 }
266
267 using symbol_range = iterator_range<object::content_iterator<SymbolRef>>;
268
269 /// Returns the symbol table for the entire bitcode file.
270 /// The symbols enumerated by this method are ephemeral, but they can be
271 /// copied into an irsymtab::Symbol object.
272 symbol_range symbols() const;
273
274 size_t getNumModules() const { return Modules.size(); }
275
276 /// Returns a slice of the symbol table for the I'th module in the file.
277 /// The symbols enumerated by this method are ephemeral, but they can be
278 /// copied into an irsymtab::Symbol object.
279 symbol_range module_symbols(unsigned I) const;
280
281 StringRef getTargetTriple() const { return str(header().TargetTriple); }
282
283 /// Returns the source file path specified at compile time.
284 StringRef getSourceFileName() const { return str(header().SourceFileName); }
285
286 /// Returns a table with all the comdats used by this file.
287 std::vector<std::pair<StringRef, llvm::Comdat::SelectionKind>>
288 getComdatTable() const {
289 std::vector<std::pair<StringRef, llvm::Comdat::SelectionKind>> ComdatTable;
290 ComdatTable.reserve(Comdats.size());
291 for (auto C : Comdats)
292 ComdatTable.push_back({str(C.Name), llvm::Comdat::SelectionKind(
293 uint32_t(C.SelectionKind))});
294 return ComdatTable;
295 }
296
297 /// COFF-specific: returns linker options specified in the input file.
298 StringRef getCOFFLinkerOpts() const { return str(header().COFFLinkerOpts); }
299
300 /// Returns dependent library specifiers
301 std::vector<StringRef> getDependentLibraries() const {
302 std::vector<StringRef> Specifiers;
303 Specifiers.reserve(DependentLibraries.size());
304 for (auto S : DependentLibraries) {
305 Specifiers.push_back(str(S));
306 }
307 return Specifiers;
308 }
309};
310
311/// Ephemeral symbols produced by Reader::symbols() and
312/// Reader::module_symbols().
313class Reader::SymbolRef : public Symbol {
314 const storage::Symbol *SymI, *SymE;
315 const storage::Uncommon *UncI;
316 const Reader *R;
317
318 void read() {
319 if (SymI == SymE)
8
Assuming field 'SymI' is not equal to field 'SymE'
9
Taking false branch
320 return;
321
322 Name = R->str(SymI->Name);
323 IRName = R->str(SymI->IRName);
324 ComdatIndex = SymI->ComdatIndex;
325 Flags = SymI->Flags;
326
327 if (Flags & (1 << storage::Symbol::FB_has_uncommon)) {
10
Assuming the condition is true
11
Taking true branch
328 CommonSize = UncI->CommonSize;
12
Called C++ object pointer is null
329 CommonAlign = UncI->CommonAlign;
330 COFFWeakExternFallbackName = R->str(UncI->COFFWeakExternFallbackName);
331 SectionName = R->str(UncI->SectionName);
332 } else
333 // Reset this field so it can be queried unconditionally for all symbols.
334 SectionName = "";
335 }
336
337public:
338 SymbolRef(const storage::Symbol *SymI, const storage::Symbol *SymE,
339 const storage::Uncommon *UncI, const Reader *R)
340 : SymI(SymI), SymE(SymE), UncI(UncI), R(R) {
6
Null pointer value stored to 'symb.UncI'
341 read();
7
Calling 'SymbolRef::read'
342 }
343
344 void moveNext() {
345 ++SymI;
346 if (Flags & (1 << storage::Symbol::FB_has_uncommon))
347 ++UncI;
348 read();
349 }
350
351 bool operator==(const SymbolRef &Other) const { return SymI == Other.SymI; }
352};
353
354inline Reader::symbol_range Reader::symbols() const {
355 return {SymbolRef(Symbols.begin(), Symbols.end(), Uncommons.begin(), this),
356 SymbolRef(Symbols.end(), Symbols.end(), nullptr, this)};
4
Passing null pointer value via 3rd parameter 'UncI'
5
Calling constructor for 'SymbolRef'
357}
358
359inline Reader::symbol_range Reader::module_symbols(unsigned I) const {
360 const storage::Module &M = Modules[I];
361 const storage::Symbol *MBegin = Symbols.begin() + M.Begin,
362 *MEnd = Symbols.begin() + M.End;
363 return {SymbolRef(MBegin, MEnd, Uncommons.begin() + M.UncBegin, this),
364 SymbolRef(MEnd, MEnd, nullptr, this)};
365}
366
367/// The contents of the irsymtab in a bitcode file. Any underlying data for the
368/// irsymtab are owned by Symtab and Strtab.
369struct FileContents {
370 SmallVector<char, 0> Symtab, Strtab;
371 Reader TheReader;
372};
373
374/// Reads the contents of a bitcode file, creating its irsymtab if necessary.
375Expected<FileContents> readBitcode(const BitcodeFileContents &BFC);
376
377} // end namespace irsymtab
378} // end namespace llvm
379
380#endif // LLVM_OBJECT_IRSYMTAB_H