[yaml2obj][ELF] ELF Relocations Support.

The patch implements support for both relocation record formats: Elf_Rel
and Elf_Rela. It is possible to define relocation against symbol only.
Relocations against sections will be implemented later. Now yaml2obj
recognizes X86_64, MIPS and Hexagon relocation types.

Example of relocation section specification:
Sections:
- Name: .text
  Type: SHT_PROGBITS
  Content: "0000000000000000"
  AddressAlign: 16
  Flags: [SHF_ALLOC]

- Name: .rel.text
  Type: SHT_REL
  Info: .text
  AddressAlign: 4
  Relocations:
    - Offset: 0x1
      Symbol: glob1
      Type: R_MIPS_32
    - Offset: 0x2
      Symbol: glob2
      Type: R_MIPS_CALL16

The patch reviewed by Michael Spencer, Sean Silva, Shankar Easwaran.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206017 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 39 insertions, 5 deletions

diff --git a/include/llvm/Object/ELFYAML.h b/include/llvm/Object/ELFYAML.h
index 1eba660208..38707776ab 100644
--- a/include/llvm/Object/ELFYAML.h
+++ b/include/llvm/Object/ELFYAML.h
@@ -40,6 +40,7 @@ LLVM_YAML_STRONG_TYPEDEF(uint8_t, ELF_ELFOSABI)
 // Just use 64, since it can hold 32-bit values too.
 LLVM_YAML_STRONG_TYPEDEF(uint64_t, ELF_EF)
 LLVM_YAML_STRONG_TYPEDEF(uint32_t, ELF_SHT)
+LLVM_YAML_STRONG_TYPEDEF(uint8_t, ELF_REL)
 // Just use 64, since it can hold 32-bit values too.
 LLVM_YAML_STRONG_TYPEDEF(uint64_t, ELF_SHF)
 LLVM_YAML_STRONG_TYPEDEF(uint8_t, ELF_STT)
@@ -68,17 +69,40 @@ struct LocalGlobalWeakSymbols {
   std::vector<Symbol> Weak;
 };
 struct Section {
+  enum class SectionKind { RawContent, Relocation };
+  SectionKind Kind;
   StringRef Name;
   ELF_SHT Type;
   ELF_SHF Flags;
   llvm::yaml::Hex64 Address;
-  object::yaml::BinaryRef Content;
   StringRef Link;
+  StringRef Info;
   llvm::yaml::Hex64 AddressAlign;
+  Section(SectionKind Kind) : Kind(Kind) {}
+};
+struct RawContentSection : Section {
+  object::yaml::BinaryRef Content;
+  RawContentSection() : Section(SectionKind::RawContent) {}
+  static bool classof(const Section *S) {
+    return S->Kind == SectionKind::RawContent;
+  }
+};
+struct Relocation {
+  uint32_t Offset;
+  uint32_t Addend;
+  ELF_REL Type;
+  StringRef Symbol;
+};
+struct RelocationSection : Section {
+  std::vector<Relocation> Relocations;
+  RelocationSection() : Section(SectionKind::Relocation) {}
+  static bool classof(const Section *S) {
+    return S->Kind == SectionKind::Relocation;
+  }
 };
 struct Object {
   FileHeader Header;
-  std::vector<Section> Sections;
+  std::vector<std::unique_ptr<Section>> Sections;
   // Although in reality the symbols reside in a section, it is a lot
   // cleaner and nicer if we read them from the YAML as a separate
   // top-level key, which automatically ensures that invariants like there
@@ -89,8 +113,9 @@ struct Object {
 } // end namespace ELFYAML
 } // end namespace llvm
 
-LLVM_YAML_IS_SEQUENCE_VECTOR(llvm::ELFYAML::Section)
+LLVM_YAML_IS_SEQUENCE_VECTOR(std::unique_ptr<llvm::ELFYAML::Section>)
 LLVM_YAML_IS_SEQUENCE_VECTOR(llvm::ELFYAML::Symbol)
+LLVM_YAML_IS_SEQUENCE_VECTOR(llvm::ELFYAML::Relocation)
 
 namespace llvm {
 namespace yaml {
@@ -141,6 +166,11 @@ struct ScalarEnumerationTraits<ELFYAML::ELF_STT> {
 };
 
 template <>
+struct ScalarEnumerationTraits<ELFYAML::ELF_REL> {
+  static void enumeration(IO &IO, ELFYAML::ELF_REL &Value);
+};
+
+template <>
 struct MappingTraits<ELFYAML::FileHeader> {
   static void mapping(IO &IO, ELFYAML::FileHeader &FileHdr);
 };
@@ -155,9 +185,13 @@ struct MappingTraits<ELFYAML::LocalGlobalWeakSymbols> {
   static void mapping(IO &IO, ELFYAML::LocalGlobalWeakSymbols &Symbols);
 };
 
+template <> struct MappingTraits<ELFYAML::Relocation> {
+  static void mapping(IO &IO, ELFYAML::Relocation &Rel);
+};
+
 template <>
-struct MappingTraits<ELFYAML::Section> {
-  static void mapping(IO &IO, ELFYAML::Section &Section);
+struct MappingTraits<std::unique_ptr<ELFYAML::Section>> {
+  static void mapping(IO &IO, std::unique_ptr<ELFYAML::Section> &Section);
 };
 
 template <>