Vendor import of lld trunk r256633:vendor/lld/lld-trunk-r256633

https://llvm.org/svn/llvm-project/lld/trunk@256633

1 files changed, 332 insertions, 0 deletions

diff --git a/COFF/Chunks.h b/COFF/Chunks.h
new file mode 100644
index 000000000000..60b8e76f8230
--- /dev/null
+++ b/COFF/Chunks.h
@@ -0,0 +1,332 @@
+//===- Chunks.h -------------------------------------------------*- C++ -*-===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLD_COFF_CHUNKS_H
+#define LLD_COFF_CHUNKS_H
+
+#include "Config.h"
+#include "InputFiles.h"
+#include "lld/Core/LLVM.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/iterator.h"
+#include "llvm/ADT/iterator_range.h"
+#include "llvm/Object/COFF.h"
+#include <atomic>
+#include <vector>
+
+namespace lld {
+namespace coff {
+
+using llvm::COFF::ImportDirectoryTableEntry;
+using llvm::object::COFFSymbolRef;
+using llvm::object::SectionRef;
+using llvm::object::coff_relocation;
+using llvm::object::coff_section;
+using llvm::sys::fs::file_magic;
+
+class Baserel;
+class Defined;
+class DefinedImportData;
+class DefinedRegular;
+class ObjectFile;
+class OutputSection;
+class SymbolBody;
+
+// Mask for section types (code, data, bss, disacardable, etc.)
+// and permissions (writable, readable or executable).
+const uint32_t PermMask = 0xFF0000F0;
+
+// A Chunk represents a chunk of data that will occupy space in the
+// output (if the resolver chose that). It may or may not be backed by
+// a section of an input file. It could be linker-created data, or
+// doesn't even have actual data (if common or bss).
+class Chunk {
+public:
+  enum Kind { SectionKind, OtherKind };
+  Kind kind() const { return ChunkKind; }
+  virtual ~Chunk() = default;
+
+  // Returns the size of this chunk (even if this is a common or BSS.)
+  virtual size_t getSize() const = 0;
+
+  // Write this chunk to a mmap'ed file, assuming Buf is pointing to
+  // beginning of the file. Because this function may use RVA values
+  // of other chunks for relocations, you need to set them properly
+  // before calling this function.
+  virtual void writeTo(uint8_t *Buf) const {}
+
+  // The writer sets and uses the addresses.
+  uint64_t getRVA() const { return RVA; }
+  uint32_t getAlign() const { return Align; }
+  void setRVA(uint64_t V) { RVA = V; }
+  void setOutputSectionOff(uint64_t V) { OutputSectionOff = V; }
+
+  // Returns true if this has non-zero data. BSS chunks return
+  // false. If false is returned, the space occupied by this chunk
+  // will be filled with zeros.
+  virtual bool hasData() const { return true; }
+
+  // Returns readable/writable/executable bits.
+  virtual uint32_t getPermissions() const { return 0; }
+
+  // Returns the section name if this is a section chunk.
+  // It is illegal to call this function on non-section chunks.
+  virtual StringRef getSectionName() const {
+    llvm_unreachable("unimplemented getSectionName");
+  }
+
+  // An output section has pointers to chunks in the section, and each
+  // chunk has a back pointer to an output section.
+  void setOutputSection(OutputSection *O) { Out = O; }
+  OutputSection *getOutputSection() { return Out; }
+
+  // Windows-specific.
+  // Collect all locations that contain absolute addresses for base relocations.
+  virtual void getBaserels(std::vector<Baserel> *Res) {}
+
+  // Returns a human-readable name of this chunk. Chunks are unnamed chunks of
+  // bytes, so this is used only for logging or debugging.
+  virtual StringRef getDebugName() { return ""; }
+
+protected:
+  Chunk(Kind K = OtherKind) : ChunkKind(K) {}
+  const Kind ChunkKind;
+
+  // The RVA of this chunk in the output. The writer sets a value.
+  uint64_t RVA = 0;
+
+  // The offset from beginning of the output section. The writer sets a value.
+  uint64_t OutputSectionOff = 0;
+
+  // The output section for this chunk.
+  OutputSection *Out = nullptr;
+
+  // The alignment of this chunk. The writer uses the value.
+  uint32_t Align = 1;
+};
+
+// A chunk corresponding a section of an input file.
+class SectionChunk : public Chunk {
+  // Identical COMDAT Folding feature accesses section internal data.
+  friend class ICF;
+
+public:
+  class symbol_iterator : public llvm::iterator_adaptor_base<
+                              symbol_iterator, const coff_relocation *,
+                              std::random_access_iterator_tag, SymbolBody *> {
+    friend SectionChunk;
+
+    ObjectFile *File;
+
+    symbol_iterator(ObjectFile *File, const coff_relocation *I)
+        : symbol_iterator::iterator_adaptor_base(I), File(File) {}
+
+  public:
+    symbol_iterator() = default;
+
+    SymbolBody *operator*() const {
+      return File->getSymbolBody(I->SymbolTableIndex);
+    }
+  };
+
+  SectionChunk(ObjectFile *File, const coff_section *Header);
+  static bool classof(const Chunk *C) { return C->kind() == SectionKind; }
+  size_t getSize() const override { return Header->SizeOfRawData; }
+  void writeTo(uint8_t *Buf) const override;
+  bool hasData() const override;
+  uint32_t getPermissions() const override;
+  StringRef getSectionName() const override { return SectionName; }
+  void getBaserels(std::vector<Baserel> *Res) override;
+  bool isCOMDAT() const;
+  void applyRelX64(uint8_t *Off, uint16_t Type, Defined *Sym, uint64_t P) const;
+  void applyRelX86(uint8_t *Off, uint16_t Type, Defined *Sym, uint64_t P) const;
+  void applyRelARM(uint8_t *Off, uint16_t Type, Defined *Sym, uint64_t P) const;
+
+  // Called if the garbage collector decides to not include this chunk
+  // in a final output. It's supposed to print out a log message to stdout.
+  void printDiscardedMessage() const;
+
+  // Adds COMDAT associative sections to this COMDAT section. A chunk
+  // and its children are treated as a group by the garbage collector.
+  void addAssociative(SectionChunk *Child);
+
+  StringRef getDebugName() override;
+  void setSymbol(DefinedRegular *S) { if (!Sym) Sym = S; }
+
+  // Used by the garbage collector.
+  bool isLive() { return !Config->DoGC || Live; }
+  void markLive() {
+    assert(!isLive() && "Cannot mark an already live section!");
+    Live = true;
+  }
+
+  // Allow iteration over the bodies of this chunk's relocated symbols.
+  llvm::iterator_range<symbol_iterator> symbols() const {
+    return llvm::make_range(symbol_iterator(File, Relocs.begin()),
+                            symbol_iterator(File, Relocs.end()));
+  }
+
+  // Allow iteration over the associated child chunks for this section.
+  ArrayRef<SectionChunk *> children() const { return AssocChildren; }
+
+  // A pointer pointing to a replacement for this chunk.
+  // Initially it points to "this" object. If this chunk is merged
+  // with other chunk by ICF, it points to another chunk,
+  // and this chunk is considrered as dead.
+  SectionChunk *Repl;
+
+  // The CRC of the contents as described in the COFF spec 4.5.5.
+  // Auxiliary Format 5: Section Definitions. Used for ICF.
+  uint32_t Checksum = 0;
+
+private:
+  ArrayRef<uint8_t> getContents() const;
+
+  // A file this chunk was created from.
+  ObjectFile *File;
+
+  const coff_section *Header;
+  StringRef SectionName;
+  std::vector<SectionChunk *> AssocChildren;
+  llvm::iterator_range<const coff_relocation *> Relocs;
+  size_t NumRelocs;
+
+  // Used by the garbage collector.
+  bool Live;
+
+  // Used for ICF (Identical COMDAT Folding)
+  void replace(SectionChunk *Other);
+  std::atomic<uint64_t> GroupID = { 0 };
+
+  // Sym points to a section symbol if this is a COMDAT chunk.
+  DefinedRegular *Sym = nullptr;
+};
+
+// A chunk for common symbols. Common chunks don't have actual data.
+class CommonChunk : public Chunk {
+public:
+  CommonChunk(const COFFSymbolRef Sym);
+  size_t getSize() const override { return Sym.getValue(); }
+  bool hasData() const override { return false; }
+  uint32_t getPermissions() const override;
+  StringRef getSectionName() const override { return ".bss"; }
+
+private:
+  const COFFSymbolRef Sym;
+};
+
+// A chunk for linker-created strings.
+class StringChunk : public Chunk {
+public:
+  explicit StringChunk(StringRef S) : Str(S) {}
+  size_t getSize() const override { return Str.size() + 1; }
+  void writeTo(uint8_t *Buf) const override;
+
+private:
+  StringRef Str;
+};
+
+static const uint8_t ImportThunkX86[] = {
+    0xff, 0x25, 0x00, 0x00, 0x00, 0x00, // JMP *0x0
+};
+
+static const uint8_t ImportThunkARM[] = {
+    0x40, 0xf2, 0x00, 0x0c, // mov.w ip, #0
+    0xc0, 0xf2, 0x00, 0x0c, // mov.t ip, #0
+    0xdc, 0xf8, 0x00, 0xf0, // ldr.w pc, [ip]
+};
+
+// Windows-specific.
+// A chunk for DLL import jump table entry. In a final output, it's
+// contents will be a JMP instruction to some __imp_ symbol.
+class ImportThunkChunkX64 : public Chunk {
+public:
+  explicit ImportThunkChunkX64(Defined *S);
+  size_t getSize() const override { return sizeof(ImportThunkX86); }
+  void writeTo(uint8_t *Buf) const override;
+
+private:
+  Defined *ImpSymbol;
+};
+
+class ImportThunkChunkX86 : public Chunk {
+public:
+  explicit ImportThunkChunkX86(Defined *S) : ImpSymbol(S) {}
+  size_t getSize() const override { return sizeof(ImportThunkX86); }
+  void getBaserels(std::vector<Baserel> *Res) override;
+  void writeTo(uint8_t *Buf) const override;
+
+private:
+  Defined *ImpSymbol;
+};
+
+class ImportThunkChunkARM : public Chunk {
+public:
+  explicit ImportThunkChunkARM(Defined *S) : ImpSymbol(S) {}
+  size_t getSize() const override { return sizeof(ImportThunkARM); }
+  void getBaserels(std::vector<Baserel> *Res) override;
+  void writeTo(uint8_t *Buf) const override;
+
+private:
+  Defined *ImpSymbol;
+};
+
+// Windows-specific.
+// See comments for DefinedLocalImport class.
+class LocalImportChunk : public Chunk {
+public:
+  explicit LocalImportChunk(Defined *S) : Sym(S) {}
+  size_t getSize() const override;
+  void getBaserels(std::vector<Baserel> *Res) override;
+  void writeTo(uint8_t *Buf) const override;
+
+private:
+  Defined *Sym;
+};
+
+// Windows-specific.
+// A chunk for SEH table which contains RVAs of safe exception handler
+// functions. x86-only.
+class SEHTableChunk : public Chunk {
+public:
+  explicit SEHTableChunk(std::set<Defined *> S) : Syms(S) {}
+  size_t getSize() const override { return Syms.size() * 4; }
+  void writeTo(uint8_t *Buf) const override;
+
+private:
+  std::set<Defined *> Syms;
+};
+
+// Windows-specific.
+// This class represents a block in .reloc section.
+// See the PE/COFF spec 5.6 for details.
+class BaserelChunk : public Chunk {
+public:
+  BaserelChunk(uint32_t Page, Baserel *Begin, Baserel *End);
+  size_t getSize() const override { return Data.size(); }
+  void writeTo(uint8_t *Buf) const override;
+
+private:
+  std::vector<uint8_t> Data;
+};
+
+class Baserel {
+public:
+  Baserel(uint32_t V, uint8_t Ty) : RVA(V), Type(Ty) {}
+  explicit Baserel(uint32_t V) : Baserel(V, getDefaultType()) {}
+  uint8_t getDefaultType();
+
+  uint32_t RVA;
+  uint8_t Type;
+};
+
+} // namespace coff
+} // namespace lld
+
+#endif