[MemProf] Templatize CallStackRadixTreeBuilder (NFC) (#117014)
[llvm-project.git] / lld / MachO / InputSection.h
blob8e1f7ea0af01e788bc2e9fc8dfc757d4f8ec7f97
1 //===- InputSection.h -------------------------------------------*- 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 //===----------------------------------------------------------------------===//
9 #ifndef LLD_MACHO_INPUT_SECTION_H
10 #define LLD_MACHO_INPUT_SECTION_H
12 #include "Config.h"
13 #include "Relocations.h"
14 #include "Symbols.h"
16 #include "lld/Common/LLVM.h"
17 #include "lld/Common/Memory.h"
18 #include "llvm/ADT/ArrayRef.h"
19 #include "llvm/ADT/BitVector.h"
20 #include "llvm/ADT/CachedHashString.h"
21 #include "llvm/ADT/TinyPtrVector.h"
22 #include "llvm/BinaryFormat/MachO.h"
24 namespace lld {
25 namespace macho {
27 class InputFile;
28 class OutputSection;
30 class InputSection {
31 public:
32 enum Kind : uint8_t {
33 ConcatKind,
34 CStringLiteralKind,
35 WordLiteralKind,
38 Kind kind() const { return sectionKind; }
39 virtual ~InputSection() = default;
40 virtual uint64_t getSize() const { return data.size(); }
41 virtual bool empty() const { return data.empty(); }
42 InputFile *getFile() const { return section.file; }
43 StringRef getName() const { return section.name; }
44 StringRef getSegName() const { return section.segname; }
45 uint32_t getFlags() const { return section.flags; }
46 uint64_t getFileSize() const;
47 // Translates \p off -- an offset relative to this InputSection -- into an
48 // offset from the beginning of its parent OutputSection.
49 virtual uint64_t getOffset(uint64_t off) const = 0;
50 // The offset from the beginning of the file.
51 uint64_t getVA(uint64_t off) const;
52 // Return a user-friendly string for use in diagnostics.
53 // Format: /path/to/object.o:(symbol _func+0x123)
54 std::string getLocation(uint64_t off) const;
55 // Return the source line corresponding to an address, or the empty string.
56 // Format: Source.cpp:123 (/path/to/Source.cpp:123)
57 std::string getSourceLocation(uint64_t off) const;
58 // Return the relocation at \p off, if it exists. This does a linear search.
59 const Reloc *getRelocAt(uint32_t off) const;
60 // Whether the data at \p off in this InputSection is live.
61 virtual bool isLive(uint64_t off) const = 0;
62 virtual void markLive(uint64_t off) = 0;
63 virtual InputSection *canonical() { return this; }
64 virtual const InputSection *canonical() const { return this; }
66 protected:
67 InputSection(Kind kind, const Section &section, ArrayRef<uint8_t> data,
68 uint32_t align)
69 : sectionKind(kind), keepUnique(false), hasAltEntry(false), align(align),
70 data(data), section(section) {}
72 InputSection(const InputSection &rhs)
73 : sectionKind(rhs.sectionKind), keepUnique(false), hasAltEntry(false),
74 align(rhs.align), data(rhs.data), section(rhs.section) {}
76 Kind sectionKind;
78 public:
79 // is address assigned?
80 bool isFinal = false;
81 // keep the address of the symbol(s) in this section unique in the final
82 // binary ?
83 bool keepUnique : 1;
84 // Does this section have symbols at offsets other than zero? (NOTE: only
85 // applies to ConcatInputSections.)
86 bool hasAltEntry : 1;
87 uint32_t align = 1;
89 OutputSection *parent = nullptr;
90 ArrayRef<uint8_t> data;
91 std::vector<Reloc> relocs;
92 // The symbols that belong to this InputSection, sorted by value. With
93 // .subsections_via_symbols, there is typically only one element here.
94 llvm::TinyPtrVector<Defined *> symbols;
96 const Section &section;
98 protected:
99 const Defined *getContainingSymbol(uint64_t off) const;
102 // ConcatInputSections are combined into (Concat)OutputSections through simple
103 // concatenation, in contrast with literal sections which may have their
104 // contents merged before output.
105 class ConcatInputSection final : public InputSection {
106 public:
107 ConcatInputSection(const Section &section, ArrayRef<uint8_t> data,
108 uint32_t align = 1)
109 : InputSection(ConcatKind, section, data, align) {}
111 uint64_t getOffset(uint64_t off) const override { return outSecOff + off; }
112 uint64_t getVA() const { return InputSection::getVA(0); }
113 // ConcatInputSections are entirely live or dead, so the offset is irrelevant.
114 bool isLive(uint64_t off) const override { return live; }
115 void markLive(uint64_t off) override { live = true; }
116 bool isCoalescedWeak() const { return wasCoalesced && symbols.empty(); }
117 bool shouldOmitFromOutput() const { return !live || isCoalescedWeak(); }
118 void writeTo(uint8_t *buf);
120 void foldIdentical(ConcatInputSection *redundant,
121 Symbol::ICFFoldKind foldKind = Symbol::ICFFoldKind::Body);
122 ConcatInputSection *canonical() override {
123 return replacement ? replacement : this;
125 const InputSection *canonical() const override {
126 return replacement ? replacement : this;
129 static bool classof(const InputSection *isec) {
130 return isec->kind() == ConcatKind;
133 // Points to the surviving section after this one is folded by ICF
134 ConcatInputSection *replacement = nullptr;
135 // Equivalence-class ID for ICF
136 uint32_t icfEqClass[2] = {0, 0};
138 // With subsections_via_symbols, most symbols have their own InputSection,
139 // and for weak symbols (e.g. from inline functions), only the
140 // InputSection from one translation unit will make it to the output,
141 // while all copies in other translation units are coalesced into the
142 // first and not copied to the output.
143 bool wasCoalesced = false;
144 bool live = !config->deadStrip;
145 bool hasCallSites = false;
146 // This variable has two usages. Initially, it represents the input order.
147 // After assignAddresses is called, it represents the offset from the
148 // beginning of the output section this section was assigned to.
149 uint64_t outSecOff = 0;
152 // Initialize a fake InputSection that does not belong to any InputFile.
153 // The created ConcatInputSection will always have 'live=true'
154 ConcatInputSection *makeSyntheticInputSection(StringRef segName,
155 StringRef sectName,
156 uint32_t flags = 0,
157 ArrayRef<uint8_t> data = {},
158 uint32_t align = 1);
160 // Helper functions to make it easy to sprinkle asserts.
162 inline bool shouldOmitFromOutput(InputSection *isec) {
163 return isa<ConcatInputSection>(isec) &&
164 cast<ConcatInputSection>(isec)->shouldOmitFromOutput();
167 inline bool isCoalescedWeak(InputSection *isec) {
168 return isa<ConcatInputSection>(isec) &&
169 cast<ConcatInputSection>(isec)->isCoalescedWeak();
172 // We allocate a lot of these and binary search on them, so they should be as
173 // compact as possible. Hence the use of 31 rather than 64 bits for the hash.
174 struct StringPiece {
175 // Offset from the start of the containing input section.
176 uint32_t inSecOff;
177 uint32_t live : 1;
178 // Only set if deduplicating literals
179 uint32_t hash : 31;
180 // Offset from the start of the containing output section.
181 uint64_t outSecOff = 0;
183 StringPiece(uint64_t off, uint32_t hash)
184 : inSecOff(off), live(!config->deadStrip), hash(hash) {}
187 static_assert(sizeof(StringPiece) == 16, "StringPiece is too big!");
189 // CStringInputSections are composed of multiple null-terminated string
190 // literals, which we represent using StringPieces. These literals can be
191 // deduplicated and tail-merged, so translating offsets between the input and
192 // outputs sections is more complicated.
194 // NOTE: One significant difference between LLD and ld64 is that we merge all
195 // cstring literals, even those referenced directly by non-private symbols.
196 // ld64 is more conservative and does not do that. This was mostly done for
197 // implementation simplicity; if we find programs that need the more
198 // conservative behavior we can certainly implement that.
199 class CStringInputSection final : public InputSection {
200 public:
201 CStringInputSection(const Section &section, ArrayRef<uint8_t> data,
202 uint32_t align, bool dedupLiterals)
203 : InputSection(CStringLiteralKind, section, data, align),
204 deduplicateLiterals(dedupLiterals) {}
206 uint64_t getOffset(uint64_t off) const override;
207 bool isLive(uint64_t off) const override { return getStringPiece(off).live; }
208 void markLive(uint64_t off) override { getStringPiece(off).live = true; }
209 // Find the StringPiece that contains this offset.
210 StringPiece &getStringPiece(uint64_t off);
211 const StringPiece &getStringPiece(uint64_t off) const;
212 // Split at each null byte.
213 void splitIntoPieces();
215 LLVM_ATTRIBUTE_ALWAYS_INLINE
216 StringRef getStringRef(size_t i) const {
217 size_t begin = pieces[i].inSecOff;
218 // The endpoint should be *at* the null terminator, not after. This matches
219 // the behavior of StringRef(const char *Str).
220 size_t end =
221 ((pieces.size() - 1 == i) ? data.size() : pieces[i + 1].inSecOff) - 1;
222 return toStringRef(data.slice(begin, end - begin));
225 StringRef getStringRefAtOffset(uint64_t off) const {
226 return getStringRef(getStringPieceIndex(off));
229 // Returns i'th piece as a CachedHashStringRef. This function is very hot when
230 // string merging is enabled, so we want to inline.
231 LLVM_ATTRIBUTE_ALWAYS_INLINE
232 llvm::CachedHashStringRef getCachedHashStringRef(size_t i) const {
233 assert(deduplicateLiterals);
234 return {getStringRef(i), pieces[i].hash};
237 static bool classof(const InputSection *isec) {
238 return isec->kind() == CStringLiteralKind;
241 bool deduplicateLiterals = false;
242 std::vector<StringPiece> pieces;
244 private:
245 size_t getStringPieceIndex(uint64_t off) const;
248 class WordLiteralInputSection final : public InputSection {
249 public:
250 WordLiteralInputSection(const Section &section, ArrayRef<uint8_t> data,
251 uint32_t align);
252 uint64_t getOffset(uint64_t off) const override;
253 bool isLive(uint64_t off) const override {
254 return live[off >> power2LiteralSize];
256 void markLive(uint64_t off) override {
257 live[off >> power2LiteralSize] = true;
260 static bool classof(const InputSection *isec) {
261 return isec->kind() == WordLiteralKind;
264 private:
265 unsigned power2LiteralSize;
266 // The liveness of data[off] is tracked by live[off >> power2LiteralSize].
267 llvm::BitVector live;
270 inline uint8_t sectionType(uint32_t flags) {
271 return flags & llvm::MachO::SECTION_TYPE;
274 inline bool isZeroFill(uint32_t flags) {
275 return llvm::MachO::isVirtualSection(sectionType(flags));
278 inline bool isThreadLocalVariables(uint32_t flags) {
279 return sectionType(flags) == llvm::MachO::S_THREAD_LOCAL_VARIABLES;
282 // These sections contain the data for initializing thread-local variables.
283 inline bool isThreadLocalData(uint32_t flags) {
284 return sectionType(flags) == llvm::MachO::S_THREAD_LOCAL_REGULAR ||
285 sectionType(flags) == llvm::MachO::S_THREAD_LOCAL_ZEROFILL;
288 inline bool isDebugSection(uint32_t flags) {
289 return (flags & llvm::MachO::SECTION_ATTRIBUTES_USR) ==
290 llvm::MachO::S_ATTR_DEBUG;
293 inline bool isWordLiteralSection(uint32_t flags) {
294 return sectionType(flags) == llvm::MachO::S_4BYTE_LITERALS ||
295 sectionType(flags) == llvm::MachO::S_8BYTE_LITERALS ||
296 sectionType(flags) == llvm::MachO::S_16BYTE_LITERALS;
299 bool isCodeSection(const InputSection *);
300 bool isCfStringSection(const InputSection *);
301 bool isClassRefsSection(const InputSection *);
302 bool isSelRefsSection(const InputSection *);
303 bool isEhFrameSection(const InputSection *);
304 bool isGccExceptTabSection(const InputSection *);
306 extern std::vector<ConcatInputSection *> inputSections;
307 // This is used as a counter for specyfing input order for input sections
308 extern int inputSectionsOrder;
310 namespace section_names {
312 constexpr const char authGot[] = "__auth_got";
313 constexpr const char authPtr[] = "__auth_ptr";
314 constexpr const char binding[] = "__binding";
315 constexpr const char bitcodeBundle[] = "__bundle";
316 constexpr const char cString[] = "__cstring";
317 constexpr const char cfString[] = "__cfstring";
318 constexpr const char cgProfile[] = "__cg_profile";
319 constexpr const char chainFixups[] = "__chainfixups";
320 constexpr const char codeSignature[] = "__code_signature";
321 constexpr const char common[] = "__common";
322 constexpr const char compactUnwind[] = "__compact_unwind";
323 constexpr const char data[] = "__data";
324 constexpr const char debugAbbrev[] = "__debug_abbrev";
325 constexpr const char debugInfo[] = "__debug_info";
326 constexpr const char debugLine[] = "__debug_line";
327 constexpr const char debugStr[] = "__debug_str";
328 constexpr const char debugStrOffs[] = "__debug_str_offs";
329 constexpr const char ehFrame[] = "__eh_frame";
330 constexpr const char gccExceptTab[] = "__gcc_except_tab";
331 constexpr const char export_[] = "__export";
332 constexpr const char dataInCode[] = "__data_in_code";
333 constexpr const char functionStarts[] = "__func_starts";
334 constexpr const char got[] = "__got";
335 constexpr const char header[] = "__mach_header";
336 constexpr const char indirectSymbolTable[] = "__ind_sym_tab";
337 constexpr const char initOffsets[] = "__init_offsets";
338 constexpr const char const_[] = "__const";
339 constexpr const char lazySymbolPtr[] = "__la_symbol_ptr";
340 constexpr const char lazyBinding[] = "__lazy_binding";
341 constexpr const char literals[] = "__literals";
342 constexpr const char functionMap[] = "__llvm_merge";
343 constexpr const char moduleInitFunc[] = "__mod_init_func";
344 constexpr const char moduleTermFunc[] = "__mod_term_func";
345 constexpr const char nonLazySymbolPtr[] = "__nl_symbol_ptr";
346 constexpr const char objcCatList[] = "__objc_catlist";
347 constexpr const char objcClassList[] = "__objc_classlist";
348 constexpr const char objcMethList[] = "__objc_methlist";
349 constexpr const char objcClassRefs[] = "__objc_classrefs";
350 constexpr const char objcConst[] = "__objc_const";
351 constexpr const char objCImageInfo[] = "__objc_imageinfo";
352 constexpr const char objcStubs[] = "__objc_stubs";
353 constexpr const char objcSelrefs[] = "__objc_selrefs";
354 constexpr const char objcMethname[] = "__objc_methname";
355 constexpr const char objcNonLazyCatList[] = "__objc_nlcatlist";
356 constexpr const char objcNonLazyClassList[] = "__objc_nlclslist";
357 constexpr const char objcProtoList[] = "__objc_protolist";
358 constexpr const char outlinedHashTree[] = "__llvm_outline";
359 constexpr const char pageZero[] = "__pagezero";
360 constexpr const char pointers[] = "__pointers";
361 constexpr const char rebase[] = "__rebase";
362 constexpr const char staticInit[] = "__StaticInit";
363 constexpr const char stringTable[] = "__string_table";
364 constexpr const char stubHelper[] = "__stub_helper";
365 constexpr const char stubs[] = "__stubs";
366 constexpr const char swift[] = "__swift";
367 constexpr const char symbolTable[] = "__symbol_table";
368 constexpr const char textCoalNt[] = "__textcoal_nt";
369 constexpr const char text[] = "__text";
370 constexpr const char threadPtrs[] = "__thread_ptrs";
371 constexpr const char threadVars[] = "__thread_vars";
372 constexpr const char unwindInfo[] = "__unwind_info";
373 constexpr const char weakBinding[] = "__weak_binding";
374 constexpr const char zeroFill[] = "__zerofill";
375 constexpr const char addrSig[] = "__llvm_addrsig";
377 } // namespace section_names
379 void addInputSection(InputSection *inputSection);
380 } // namespace macho
382 std::string toString(const macho::InputSection *);
384 } // namespace lld
386 #endif