lld/COFF/Chunks.h

   1 //===- Chunks.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 //===----------------------------------------------------------------------===//
   8
   9 #ifndef LLD_COFF_CHUNKS_H
  10 #define LLD_COFF_CHUNKS_H
  11
  12 #include "Config.h"
  13 #include "InputFiles.h"
  14 #include "lld/Common/LLVM.h"
  15 #include "llvm/ADT/ArrayRef.h"
  16 #include "llvm/ADT/PointerIntPair.h"
  17 #include "llvm/ADT/iterator.h"
  18 #include "llvm/ADT/iterator_range.h"
  19 #include "llvm/MC/StringTableBuilder.h"
  20 #include "llvm/Object/COFF.h"
  21 #include "llvm/Object/WindowsMachineFlag.h"
  22 #include <utility>
  23 #include <vector>
  24
  25 namespace lld::coff {
  26
  27 using llvm::COFF::ImportDirectoryTableEntry;
  28 using llvm::object::chpe_range_type;
  29 using llvm::object::coff_relocation;
  30 using llvm::object::coff_section;
  31 using llvm::object::COFFSymbolRef;
  32 using llvm::object::SectionRef;
  33
  34 class Baserel;
  35 class Defined;
  36 class DefinedImportData;
  37 class DefinedRegular;
  38 class ObjFile;
  39 class OutputSection;
  40 class RuntimePseudoReloc;
  41 class Symbol;
  42
  43 // Mask for permissions (discardable, writable, readable, executable, etc).
  44 const uint32_t permMask = 0xFE000000;
  45
  46 // Mask for section types (code, data, bss).
  47 const uint32_t typeMask = 0x000000E0;
  48
  49 // The log base 2 of the largest section alignment, which is log2(8192), or 13.
  50 enum : unsigned { Log2MaxSectionAlignment = 13 };
  51
  52 // A Chunk represents a chunk of data that will occupy space in the
  53 // output (if the resolver chose that). It may or may not be backed by
  54 // a section of an input file. It could be linker-created data, or
  55 // doesn't even have actual data (if common or bss).
  56 class Chunk {
  57 public:
  58   enum Kind : uint8_t {
  59     SectionKind,
  60     SectionECKind,
  61     OtherKind,
  62     ImportThunkKind
  63   };
  64   Kind kind() const { return chunkKind; }
  65
  66   // Returns the size of this chunk (even if this is a common or BSS.)
  67   size_t getSize() const;
  68
  69   // Returns chunk alignment in power of two form. Value values are powers of
  70   // two from 1 to 8192.
  71   uint32_t getAlignment() const { return 1U << p2Align; }
  72
  73   // Update the chunk section alignment measured in bytes. Internally alignment
  74   // is stored in log2.
  75   void setAlignment(uint32_t align) {
  76     // Treat zero byte alignment as 1 byte alignment.
  77     align = align ? align : 1;
  78     assert(llvm::isPowerOf2_32(align) && "alignment is not a power of 2");
  79     p2Align = llvm::Log2_32(align);
  80     assert(p2Align <= Log2MaxSectionAlignment &&
  81            "impossible requested alignment");
  82   }
  83
  84   // Write this chunk to a mmap'ed file, assuming Buf is pointing to
  85   // beginning of the file. Because this function may use RVA values
  86   // of other chunks for relocations, you need to set them properly
  87   // before calling this function.
  88   void writeTo(uint8_t *buf) const;
  89
  90   // The writer sets and uses the addresses. In practice, PE images cannot be
  91   // larger than 2GB. Chunks are always laid as part of the image, so Chunk RVAs
  92   // can be stored with 32 bits.
  93   uint32_t getRVA() const { return rva; }
  94   void setRVA(uint64_t v) {
  95     // This may truncate. The writer checks for overflow later.
  96     rva = (uint32_t)v;
  97   }
  98
  99   // Returns readable/writable/executable bits.
 100   uint32_t getOutputCharacteristics() const;
 101
 102   // Returns the section name if this is a section chunk.
 103   // It is illegal to call this function on non-section chunks.
 104   StringRef getSectionName() const;
 105
 106   // An output section has pointers to chunks in the section, and each
 107   // chunk has a back pointer to an output section.
 108   void setOutputSectionIdx(uint16_t o) { osidx = o; }
 109   uint16_t getOutputSectionIdx() const { return osidx; }
 110
 111   // Windows-specific.
 112   // Collect all locations that contain absolute addresses for base relocations.
 113   void getBaserels(std::vector<Baserel> *res);
 114
 115   // Returns a human-readable name of this chunk. Chunks are unnamed chunks of
 116   // bytes, so this is used only for logging or debugging.
 117   StringRef getDebugName() const;
 118
 119   // Return true if this file has the hotpatch flag set to true in the
 120   // S_COMPILE3 record in codeview debug info. Also returns true for some thunks
 121   // synthesized by the linker.
 122   bool isHotPatchable() const;
 123
 124   MachineTypes getMachine() const;
 125   llvm::Triple::ArchType getArch() const;
 126   std::optional<chpe_range_type> getArm64ECRangeType() const;
 127
 128   // ARM64EC entry thunk associated with the chunk.
 129   Defined *getEntryThunk() const;
 130   void setEntryThunk(Defined *entryThunk);
 131
 132 protected:
 133   Chunk(Kind k = OtherKind) : chunkKind(k), hasData(true), p2Align(0) {}
 134
 135   const Kind chunkKind;
 136
 137 public:
 138   // Returns true if this has non-zero data. BSS chunks return
 139   // false. If false is returned, the space occupied by this chunk
 140   // will be filled with zeros. Corresponds to the
 141   // IMAGE_SCN_CNT_UNINITIALIZED_DATA section characteristic bit.
 142   uint8_t hasData : 1;
 143
 144 public:
 145   // The alignment of this chunk, stored in log2 form. The writer uses the
 146   // value.
 147   uint8_t p2Align : 7;
 148
 149   // The output section index for this chunk. The first valid section number is
 150   // one.
 151   uint16_t osidx = 0;
 152
 153   // The RVA of this chunk in the output. The writer sets a value.
 154   uint32_t rva = 0;
 155 };
 156
 157 class NonSectionChunk : public Chunk {
 158 public:
 159   virtual ~NonSectionChunk() = default;
 160
 161   // Returns the size of this chunk (even if this is a common or BSS.)
 162   virtual size_t getSize() const = 0;
 163
 164   virtual uint32_t getOutputCharacteristics() const { return 0; }
 165
 166   // Write this chunk to a mmap'ed file, assuming Buf is pointing to
 167   // beginning of the file. Because this function may use RVA values
 168   // of other chunks for relocations, you need to set them properly
 169   // before calling this function.
 170   virtual void writeTo(uint8_t *buf) const {}
 171
 172   // Returns the section name if this is a section chunk.
 173   // It is illegal to call this function on non-section chunks.
 174   virtual StringRef getSectionName() const {
 175     llvm_unreachable("unimplemented getSectionName");
 176   }
 177
 178   // Windows-specific.
 179   // Collect all locations that contain absolute addresses for base relocations.
 180   virtual void getBaserels(std::vector<Baserel> *res) {}
 181
 182   virtual MachineTypes getMachine() const { return IMAGE_FILE_MACHINE_UNKNOWN; }
 183
 184   // Returns a human-readable name of this chunk. Chunks are unnamed chunks of
 185   // bytes, so this is used only for logging or debugging.
 186   virtual StringRef getDebugName() const { return ""; }
 187
 188   static bool classof(const Chunk *c) { return c->kind() >= OtherKind; }
 189
 190 protected:
 191   NonSectionChunk(Kind k = OtherKind) : Chunk(k) {}
 192 };
 193
 194 class NonSectionCodeChunk : public NonSectionChunk {
 195 public:
 196   virtual uint32_t getOutputCharacteristics() const override {
 197     return llvm::COFF::IMAGE_SCN_MEM_READ | llvm::COFF::IMAGE_SCN_MEM_EXECUTE;
 198   }
 199
 200 protected:
 201   NonSectionCodeChunk(Kind k = OtherKind) : NonSectionChunk(k) {}
 202 };
 203
 204 // MinGW specific; information about one individual location in the image
 205 // that needs to be fixed up at runtime after loading. This represents
 206 // one individual element in the PseudoRelocTableChunk table.
 207 class RuntimePseudoReloc {
 208 public:
 209   RuntimePseudoReloc(Defined *sym, SectionChunk *target, uint32_t targetOffset,
 210                      int flags)
 211       : sym(sym), target(target), targetOffset(targetOffset), flags(flags) {}
 212
 213   Defined *sym;
 214   SectionChunk *target;
 215   uint32_t targetOffset;
 216   // The Flags field contains the size of the relocation, in bits. No other
 217   // flags are currently defined.
 218   int flags;
 219 };
 220
 221 // A chunk corresponding a section of an input file.
 222 class SectionChunk : public Chunk {
 223   // Identical COMDAT Folding feature accesses section internal data.
 224   friend class ICF;
 225
 226 public:
 227   class symbol_iterator : public llvm::iterator_adaptor_base<
 228                               symbol_iterator, const coff_relocation *,
 229                               std::random_access_iterator_tag, Symbol *> {
 230     friend SectionChunk;
 231
 232     ObjFile *file;
 233
 234     symbol_iterator(ObjFile *file, const coff_relocation *i)
 235         : symbol_iterator::iterator_adaptor_base(i), file(file) {}
 236
 237   public:
 238     symbol_iterator() = default;
 239
 240     Symbol *operator*() const { return file->getSymbol(I->SymbolTableIndex); }
 241   };
 242
 243   SectionChunk(ObjFile *file, const coff_section *header, Kind k = SectionKind);
 244   static bool classof(const Chunk *c) { return c->kind() <= SectionECKind; }
 245   size_t getSize() const { return header->SizeOfRawData; }
 246   ArrayRef<uint8_t> getContents() const;
 247   void writeTo(uint8_t *buf) const;
 248
 249   MachineTypes getMachine() const { return file->getMachineType(); }
 250
 251   // Defend against unsorted relocations. This may be overly conservative.
 252   void sortRelocations();
 253
 254   // Write and relocate a portion of the section. This is intended to be called
 255   // in a loop. Relocations must be sorted first.
 256   void writeAndRelocateSubsection(ArrayRef<uint8_t> sec,
 257                                   ArrayRef<uint8_t> subsec,
 258                                   uint32_t &nextRelocIndex, uint8_t *buf) const;
 259
 260   uint32_t getOutputCharacteristics() const {
 261     return header->Characteristics & (permMask | typeMask);
 262   }
 263   StringRef getSectionName() const {
 264     return StringRef(sectionNameData, sectionNameSize);
 265   }
 266   void getBaserels(std::vector<Baserel> *res);
 267   bool isCOMDAT() const;
 268   void applyRelocation(uint8_t *off, const coff_relocation &rel) const;
 269   void applyRelX64(uint8_t *off, uint16_t type, OutputSection *os, uint64_t s,
 270                    uint64_t p, uint64_t imageBase) const;
 271   void applyRelX86(uint8_t *off, uint16_t type, OutputSection *os, uint64_t s,
 272                    uint64_t p, uint64_t imageBase) const;
 273   void applyRelARM(uint8_t *off, uint16_t type, OutputSection *os, uint64_t s,
 274                    uint64_t p, uint64_t imageBase) const;
 275   void applyRelARM64(uint8_t *off, uint16_t type, OutputSection *os, uint64_t s,
 276                      uint64_t p, uint64_t imageBase) const;
 277
 278   void getRuntimePseudoRelocs(std::vector<RuntimePseudoReloc> &res);
 279
 280   // Called if the garbage collector decides to not include this chunk
 281   // in a final output. It's supposed to print out a log message to stdout.
 282   void printDiscardedMessage() const;
 283
 284   // Adds COMDAT associative sections to this COMDAT section. A chunk
 285   // and its children are treated as a group by the garbage collector.
 286   void addAssociative(SectionChunk *child);
 287
 288   StringRef getDebugName() const;
 289
 290   // True if this is a codeview debug info chunk. These will not be laid out in
 291   // the image. Instead they will end up in the PDB, if one is requested.
 292   bool isCodeView() const {
 293     return getSectionName() == ".debug" || getSectionName().starts_with(".debug$");
 294   }
 295
 296   // True if this is a DWARF debug info or exception handling chunk.
 297   bool isDWARF() const {
 298     return getSectionName().starts_with(".debug_") || getSectionName() == ".eh_frame";
 299   }
 300
 301   // Allow iteration over the bodies of this chunk's relocated symbols.
 302   llvm::iterator_range<symbol_iterator> symbols() const {
 303     return llvm::make_range(symbol_iterator(file, relocsData),
 304                             symbol_iterator(file, relocsData + relocsSize));
 305   }
 306
 307   ArrayRef<coff_relocation> getRelocs() const {
 308     return llvm::ArrayRef(relocsData, relocsSize);
 309   }
 310
 311   // Reloc setter used by ARM range extension thunk insertion.
 312   void setRelocs(ArrayRef<coff_relocation> newRelocs) {
 313     relocsData = newRelocs.data();
 314     relocsSize = newRelocs.size();
 315     assert(relocsSize == newRelocs.size() && "reloc size truncation");
 316   }
 317
 318   // Single linked list iterator for associated comdat children.
 319   class AssociatedIterator
 320       : public llvm::iterator_facade_base<
 321             AssociatedIterator, std::forward_iterator_tag, SectionChunk> {
 322   public:
 323     AssociatedIterator() = default;
 324     AssociatedIterator(SectionChunk *head) : cur(head) {}
 325     bool operator==(const AssociatedIterator &r) const { return cur == r.cur; }
 326     // FIXME: Wrong const-ness, but it makes filter ranges work.
 327     SectionChunk &operator*() const { return *cur; }
 328     SectionChunk &operator*() { return *cur; }
 329     AssociatedIterator &operator++() {
 330       cur = cur->assocChildren;
 331       return *this;
 332     }
 333
 334   private:
 335     SectionChunk *cur = nullptr;
 336   };
 337
 338   // Allow iteration over the associated child chunks for this section.
 339   llvm::iterator_range<AssociatedIterator> children() const {
 340     // Associated sections do not have children. The assocChildren field is
 341     // part of the parent's list of children.
 342     bool isAssoc = selection == llvm::COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE;
 343     return llvm::make_range(
 344         AssociatedIterator(isAssoc ? nullptr : assocChildren),
 345         AssociatedIterator(nullptr));
 346   }
 347
 348   // The section ID this chunk belongs to in its Obj.
 349   uint32_t getSectionNumber() const;
 350
 351   ArrayRef<uint8_t> consumeDebugMagic();
 352
 353   static ArrayRef<uint8_t> consumeDebugMagic(ArrayRef<uint8_t> data,
 354                                              StringRef sectionName);
 355
 356   static SectionChunk *findByName(ArrayRef<SectionChunk *> sections,
 357                                   StringRef name);
 358
 359   // The file that this chunk was created from.
 360   ObjFile *file;
 361
 362   // Pointer to the COFF section header in the input file.
 363   const coff_section *header;
 364
 365   // The COMDAT leader symbol if this is a COMDAT chunk.
 366   DefinedRegular *sym = nullptr;
 367
 368   // The CRC of the contents as described in the COFF spec 4.5.5.
 369   // Auxiliary Format 5: Section Definitions. Used for ICF.
 370   uint32_t checksum = 0;
 371
 372   // Used by the garbage collector.
 373   bool live;
 374
 375   // Whether this section needs to be kept distinct from other sections during
 376   // ICF. This is set by the driver using address-significance tables.
 377   bool keepUnique = false;
 378
 379   // The COMDAT selection if this is a COMDAT chunk.
 380   llvm::COFF::COMDATType selection = (llvm::COFF::COMDATType)0;
 381
 382   // A pointer pointing to a replacement for this chunk.
 383   // Initially it points to "this" object. If this chunk is merged
 384   // with other chunk by ICF, it points to another chunk,
 385   // and this chunk is considered as dead.
 386   SectionChunk *repl;
 387
 388 private:
 389   SectionChunk *assocChildren = nullptr;
 390
 391   // Used for ICF (Identical COMDAT Folding)
 392   void replace(SectionChunk *other);
 393   uint32_t eqClass[2] = {0, 0};
 394
 395   // Relocations for this section. Size is stored below.
 396   const coff_relocation *relocsData;
 397
 398   // Section name string. Size is stored below.
 399   const char *sectionNameData;
 400
 401   uint32_t relocsSize = 0;
 402   uint32_t sectionNameSize = 0;
 403 };
 404
 405 // A section chunk corresponding a section of an EC input file.
 406 class SectionChunkEC final : public SectionChunk {
 407 public:
 408   static bool classof(const Chunk *c) { return c->kind() == SectionECKind; }
 409
 410   SectionChunkEC(ObjFile *file, const coff_section *header)
 411       : SectionChunk(file, header, SectionECKind) {}
 412   Defined *entryThunk = nullptr;
 413 };
 414
 415 // Inline methods to implement faux-virtual dispatch for SectionChunk.
 416
 417 inline size_t Chunk::getSize() const {
 418   if (isa<SectionChunk>(this))
 419     return static_cast<const SectionChunk *>(this)->getSize();
 420   return static_cast<const NonSectionChunk *>(this)->getSize();
 421 }
 422
 423 inline uint32_t Chunk::getOutputCharacteristics() const {
 424   if (isa<SectionChunk>(this))
 425     return static_cast<const SectionChunk *>(this)->getOutputCharacteristics();
 426   return static_cast<const NonSectionChunk *>(this)->getOutputCharacteristics();
 427 }
 428
 429 inline void Chunk::writeTo(uint8_t *buf) const {
 430   if (isa<SectionChunk>(this))
 431     static_cast<const SectionChunk *>(this)->writeTo(buf);
 432   else
 433     static_cast<const NonSectionChunk *>(this)->writeTo(buf);
 434 }
 435
 436 inline StringRef Chunk::getSectionName() const {
 437   if (isa<SectionChunk>(this))
 438     return static_cast<const SectionChunk *>(this)->getSectionName();
 439   return static_cast<const NonSectionChunk *>(this)->getSectionName();
 440 }
 441
 442 inline void Chunk::getBaserels(std::vector<Baserel> *res) {
 443   if (isa<SectionChunk>(this))
 444     static_cast<SectionChunk *>(this)->getBaserels(res);
 445   else
 446     static_cast<NonSectionChunk *>(this)->getBaserels(res);
 447 }
 448
 449 inline StringRef Chunk::getDebugName() const {
 450   if (isa<SectionChunk>(this))
 451     return static_cast<const SectionChunk *>(this)->getDebugName();
 452   return static_cast<const NonSectionChunk *>(this)->getDebugName();
 453 }
 454
 455 inline MachineTypes Chunk::getMachine() const {
 456   if (isa<SectionChunk>(this))
 457     return static_cast<const SectionChunk *>(this)->getMachine();
 458   return static_cast<const NonSectionChunk *>(this)->getMachine();
 459 }
 460
 461 inline llvm::Triple::ArchType Chunk::getArch() const {
 462   return llvm::getMachineArchType(getMachine());
 463 }
 464
 465 inline std::optional<chpe_range_type> Chunk::getArm64ECRangeType() const {
 466   // Data sections don't need codemap entries.
 467   if (!(getOutputCharacteristics() & llvm::COFF::IMAGE_SCN_MEM_EXECUTE))
 468     return std::nullopt;
 469
 470   switch (getMachine()) {
 471   case AMD64:
 472     return chpe_range_type::Amd64;
 473   case ARM64EC:
 474     return chpe_range_type::Arm64EC;
 475   default:
 476     return chpe_range_type::Arm64;
 477   }
 478 }
 479
 480 // This class is used to implement an lld-specific feature (not implemented in
 481 // MSVC) that minimizes the output size by finding string literals sharing tail
 482 // parts and merging them.
 483 //
 484 // If string tail merging is enabled and a section is identified as containing a
 485 // string literal, it is added to a MergeChunk with an appropriate alignment.
 486 // The MergeChunk then tail merges the strings using the StringTableBuilder
 487 // class and assigns RVAs and section offsets to each of the member chunks based
 488 // on the offsets assigned by the StringTableBuilder.
 489 class MergeChunk : public NonSectionChunk {
 490 public:
 491   MergeChunk(uint32_t alignment);
 492   static void addSection(COFFLinkerContext &ctx, SectionChunk *c);
 493   void finalizeContents();
 494   void assignSubsectionRVAs();
 495
 496   uint32_t getOutputCharacteristics() const override;
 497   StringRef getSectionName() const override { return ".rdata"; }
 498   size_t getSize() const override;
 499   void writeTo(uint8_t *buf) const override;
 500
 501   std::vector<SectionChunk *> sections;
 502
 503 private:
 504   llvm::StringTableBuilder builder;
 505   bool finalized = false;
 506 };
 507
 508 // A chunk for common symbols. Common chunks don't have actual data.
 509 class CommonChunk : public NonSectionChunk {
 510 public:
 511   CommonChunk(const COFFSymbolRef sym);
 512   size_t getSize() const override { return sym.getValue(); }
 513   uint32_t getOutputCharacteristics() const override;
 514   StringRef getSectionName() const override { return ".bss"; }
 515
 516 private:
 517   const COFFSymbolRef sym;
 518 };
 519
 520 // A chunk for linker-created strings.
 521 class StringChunk : public NonSectionChunk {
 522 public:
 523   explicit StringChunk(StringRef s) : str(s) {}
 524   size_t getSize() const override { return str.size() + 1; }
 525   void writeTo(uint8_t *buf) const override;
 526
 527 private:
 528   StringRef str;
 529 };
 530
 531 static const uint8_t importThunkX86[] = {
 532     0xff, 0x25, 0x00, 0x00, 0x00, 0x00, // JMP *0x0
 533 };
 534
 535 static const uint8_t importThunkARM[] = {
 536     0x40, 0xf2, 0x00, 0x0c, // mov.w ip, #0
 537     0xc0, 0xf2, 0x00, 0x0c, // mov.t ip, #0
 538     0xdc, 0xf8, 0x00, 0xf0, // ldr.w pc, [ip]
 539 };
 540
 541 static const uint8_t importThunkARM64[] = {
 542     0x10, 0x00, 0x00, 0x90, // adrp x16, #0
 543     0x10, 0x02, 0x40, 0xf9, // ldr  x16, [x16]
 544     0x00, 0x02, 0x1f, 0xd6, // br   x16
 545 };
 546
 547 // Windows-specific.
 548 // A chunk for DLL import jump table entry. In a final output, its
 549 // contents will be a JMP instruction to some __imp_ symbol.
 550 class ImportThunkChunk : public NonSectionCodeChunk {
 551 public:
 552   ImportThunkChunk(COFFLinkerContext &ctx, Defined *s)
 553       : NonSectionCodeChunk(ImportThunkKind), impSymbol(s), ctx(ctx) {}
 554   static bool classof(const Chunk *c) { return c->kind() == ImportThunkKind; }
 555
 556 protected:
 557   Defined *impSymbol;
 558   COFFLinkerContext &ctx;
 559 };
 560
 561 class ImportThunkChunkX64 : public ImportThunkChunk {
 562 public:
 563   explicit ImportThunkChunkX64(COFFLinkerContext &ctx, Defined *s);
 564   size_t getSize() const override { return sizeof(importThunkX86); }
 565   void writeTo(uint8_t *buf) const override;
 566   MachineTypes getMachine() const override { return AMD64; }
 567 };
 568
 569 class ImportThunkChunkX86 : public ImportThunkChunk {
 570 public:
 571   explicit ImportThunkChunkX86(COFFLinkerContext &ctx, Defined *s)
 572       : ImportThunkChunk(ctx, s) {}
 573   size_t getSize() const override { return sizeof(importThunkX86); }
 574   void getBaserels(std::vector<Baserel> *res) override;
 575   void writeTo(uint8_t *buf) const override;
 576   MachineTypes getMachine() const override { return I386; }
 577 };
 578
 579 class ImportThunkChunkARM : public ImportThunkChunk {
 580 public:
 581   explicit ImportThunkChunkARM(COFFLinkerContext &ctx, Defined *s)
 582       : ImportThunkChunk(ctx, s) {
 583     setAlignment(2);
 584   }
 585   size_t getSize() const override { return sizeof(importThunkARM); }
 586   void getBaserels(std::vector<Baserel> *res) override;
 587   void writeTo(uint8_t *buf) const override;
 588   MachineTypes getMachine() const override { return ARMNT; }
 589 };
 590
 591 class ImportThunkChunkARM64 : public ImportThunkChunk {
 592 public:
 593   explicit ImportThunkChunkARM64(COFFLinkerContext &ctx, Defined *s)
 594       : ImportThunkChunk(ctx, s) {
 595     setAlignment(4);
 596   }
 597   size_t getSize() const override { return sizeof(importThunkARM64); }
 598   void writeTo(uint8_t *buf) const override;
 599   MachineTypes getMachine() const override { return ARM64; }
 600 };
 601
 602 class RangeExtensionThunkARM : public NonSectionCodeChunk {
 603 public:
 604   explicit RangeExtensionThunkARM(COFFLinkerContext &ctx, Defined *t)
 605       : target(t), ctx(ctx) {
 606     setAlignment(2);
 607   }
 608   size_t getSize() const override;
 609   void writeTo(uint8_t *buf) const override;
 610   MachineTypes getMachine() const override { return ARMNT; }
 611
 612   Defined *target;
 613
 614 private:
 615   COFFLinkerContext &ctx;
 616 };
 617
 618 class RangeExtensionThunkARM64 : public NonSectionCodeChunk {
 619 public:
 620   explicit RangeExtensionThunkARM64(COFFLinkerContext &ctx, Defined *t)
 621       : target(t), ctx(ctx) {
 622     setAlignment(4);
 623   }
 624   size_t getSize() const override;
 625   void writeTo(uint8_t *buf) const override;
 626   MachineTypes getMachine() const override { return ARM64; }
 627
 628   Defined *target;
 629
 630 private:
 631   COFFLinkerContext &ctx;
 632 };
 633
 634 // Windows-specific.
 635 // See comments for DefinedLocalImport class.
 636 class LocalImportChunk : public NonSectionChunk {
 637 public:
 638   explicit LocalImportChunk(COFFLinkerContext &ctx, Defined *s);
 639   size_t getSize() const override;
 640   void getBaserels(std::vector<Baserel> *res) override;
 641   void writeTo(uint8_t *buf) const override;
 642
 643 private:
 644   Defined *sym;
 645   COFFLinkerContext &ctx;
 646 };
 647
 648 // Duplicate RVAs are not allowed in RVA tables, so unique symbols by chunk and
 649 // offset into the chunk. Order does not matter as the RVA table will be sorted
 650 // later.
 651 struct ChunkAndOffset {
 652   Chunk *inputChunk;
 653   uint32_t offset;
 654
 655   struct DenseMapInfo {
 656     static ChunkAndOffset getEmptyKey() {
 657       return {llvm::DenseMapInfo<Chunk *>::getEmptyKey(), 0};
 658     }
 659     static ChunkAndOffset getTombstoneKey() {
 660       return {llvm::DenseMapInfo<Chunk *>::getTombstoneKey(), 0};
 661     }
 662     static unsigned getHashValue(const ChunkAndOffset &co) {
 663       return llvm::DenseMapInfo<std::pair<Chunk *, uint32_t>>::getHashValue(
 664           {co.inputChunk, co.offset});
 665     }
 666     static bool isEqual(const ChunkAndOffset &lhs, const ChunkAndOffset &rhs) {
 667       return lhs.inputChunk == rhs.inputChunk && lhs.offset == rhs.offset;
 668     }
 669   };
 670 };
 671
 672 using SymbolRVASet = llvm::DenseSet<ChunkAndOffset>;
 673
 674 // Table which contains symbol RVAs. Used for /safeseh and /guard:cf.
 675 class RVATableChunk : public NonSectionChunk {
 676 public:
 677   explicit RVATableChunk(SymbolRVASet s) : syms(std::move(s)) {}
 678   size_t getSize() const override { return syms.size() * 4; }
 679   void writeTo(uint8_t *buf) const override;
 680
 681 private:
 682   SymbolRVASet syms;
 683 };
 684
 685 // Table which contains symbol RVAs with flags. Used for /guard:ehcont.
 686 class RVAFlagTableChunk : public NonSectionChunk {
 687 public:
 688   explicit RVAFlagTableChunk(SymbolRVASet s) : syms(std::move(s)) {}
 689   size_t getSize() const override { return syms.size() * 5; }
 690   void writeTo(uint8_t *buf) const override;
 691
 692 private:
 693   SymbolRVASet syms;
 694 };
 695
 696 // Windows-specific.
 697 // This class represents a block in .reloc section.
 698 // See the PE/COFF spec 5.6 for details.
 699 class BaserelChunk : public NonSectionChunk {
 700 public:
 701   BaserelChunk(uint32_t page, Baserel *begin, Baserel *end);
 702   size_t getSize() const override { return data.size(); }
 703   void writeTo(uint8_t *buf) const override;
 704
 705 private:
 706   std::vector<uint8_t> data;
 707 };
 708
 709 class Baserel {
 710 public:
 711   Baserel(uint32_t v, uint8_t ty) : rva(v), type(ty) {}
 712   explicit Baserel(uint32_t v, llvm::COFF::MachineTypes machine)
 713       : Baserel(v, getDefaultType(machine)) {}
 714   uint8_t getDefaultType(llvm::COFF::MachineTypes machine);
 715
 716   uint32_t rva;
 717   uint8_t type;
 718 };
 719
 720 // This is a placeholder Chunk, to allow attaching a DefinedSynthetic to a
 721 // specific place in a section, without any data. This is used for the MinGW
 722 // specific symbol __RUNTIME_PSEUDO_RELOC_LIST_END__, even though the concept
 723 // of an empty chunk isn't MinGW specific.
 724 class EmptyChunk : public NonSectionChunk {
 725 public:
 726   EmptyChunk() {}
 727   size_t getSize() const override { return 0; }
 728   void writeTo(uint8_t *buf) const override {}
 729 };
 730
 731 class ECCodeMapEntry {
 732 public:
 733   ECCodeMapEntry(Chunk *first, Chunk *last, chpe_range_type type)
 734       : first(first), last(last), type(type) {}
 735   Chunk *first;
 736   Chunk *last;
 737   chpe_range_type type;
 738 };
 739
 740 // This is a chunk containing CHPE code map on EC targets. It's a table
 741 // of address ranges and their types.
 742 class ECCodeMapChunk : public NonSectionChunk {
 743 public:
 744   ECCodeMapChunk(std::vector<ECCodeMapEntry> &map) : map(map) {}
 745   size_t getSize() const override;
 746   void writeTo(uint8_t *buf) const override;
 747
 748 private:
 749   std::vector<ECCodeMapEntry> &map;
 750 };
 751
 752 // MinGW specific, for the "automatic import of variables from DLLs" feature.
 753 // This provides the table of runtime pseudo relocations, for variable
 754 // references that turned out to need to be imported from a DLL even though
 755 // the reference didn't use the dllimport attribute. The MinGW runtime will
 756 // process this table after loading, before handling control over to user
 757 // code.
 758 class PseudoRelocTableChunk : public NonSectionChunk {
 759 public:
 760   PseudoRelocTableChunk(std::vector<RuntimePseudoReloc> &relocs)
 761       : relocs(std::move(relocs)) {
 762     setAlignment(4);
 763   }
 764   size_t getSize() const override;
 765   void writeTo(uint8_t *buf) const override;
 766
 767 private:
 768   std::vector<RuntimePseudoReloc> relocs;
 769 };
 770
 771 // MinGW specific. A Chunk that contains one pointer-sized absolute value.
 772 class AbsolutePointerChunk : public NonSectionChunk {
 773 public:
 774   AbsolutePointerChunk(COFFLinkerContext &ctx, uint64_t value)
 775       : value(value), ctx(ctx) {
 776     setAlignment(getSize());
 777   }
 778   size_t getSize() const override;
 779   void writeTo(uint8_t *buf) const override;
 780
 781 private:
 782   uint64_t value;
 783   COFFLinkerContext &ctx;
 784 };
 785
 786 // Return true if this file has the hotpatch flag set to true in the S_COMPILE3
 787 // record in codeview debug info. Also returns true for some thunks synthesized
 788 // by the linker.
 789 inline bool Chunk::isHotPatchable() const {
 790   if (auto *sc = dyn_cast<SectionChunk>(this))
 791     return sc->file->hotPatchable;
 792   else if (isa<ImportThunkChunk>(this))
 793     return true;
 794   return false;
 795 }
 796
 797 inline Defined *Chunk::getEntryThunk() const {
 798   if (auto *c = dyn_cast<const SectionChunkEC>(this))
 799     return c->entryThunk;
 800   return nullptr;
 801 }
 802
 803 inline void Chunk::setEntryThunk(Defined *entryThunk) {
 804   if (auto c = dyn_cast<SectionChunkEC>(this))
 805     c->entryThunk = entryThunk;
 806 }
 807
 808 void applyMOV32T(uint8_t *off, uint32_t v);
 809 void applyBranch24T(uint8_t *off, int32_t v);
 810
 811 void applyArm64Addr(uint8_t *off, uint64_t s, uint64_t p, int shift);
 812 void applyArm64Imm(uint8_t *off, uint64_t imm, uint32_t rangeLimit);
 813 void applyArm64Branch26(uint8_t *off, int64_t v);
 814
 815 // Convenience class for initializing a coff_section with specific flags.
 816 class FakeSection {
 817 public:
 818   FakeSection(int c) { section.Characteristics = c; }
 819
 820   coff_section section;
 821 };
 822
 823 // Convenience class for initializing a SectionChunk with specific flags.
 824 class FakeSectionChunk {
 825 public:
 826   FakeSectionChunk(const coff_section *section) : chunk(nullptr, section) {
 827     // Comdats from LTO files can't be fully treated as regular comdats
 828     // at this point; we don't know what size or contents they are going to
 829     // have, so we can't do proper checking of such aspects of them.
 830     chunk.selection = llvm::COFF::IMAGE_COMDAT_SELECT_ANY;
 831   }
 832
 833   SectionChunk chunk;
 834 };
 835
 836 } // namespace lld::coff
 837
 838 namespace llvm {
 839 template <>
 840 struct DenseMapInfo<lld::coff::ChunkAndOffset>
 841     : lld::coff::ChunkAndOffset::DenseMapInfo {};
 842 }
 843
 844 #endif