[yaml2obj] Initial ELF support.

Currently, only emitting the ELF header is supported (no sections or
segments).

The ELFYAML code organization is broadly similar to the COFFYAML code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183711 91177308-0d34-0410-b5e6-96231b3b80d8

tools/yaml2obj/CMakeLists.txt

@@ -3,6 +3,7 @@ set(LLVM_LINK_COMPONENTS object)
 add_llvm_utility(yaml2obj
   yaml2obj.cpp
   yaml2coff.cpp
+  yaml2elf.cpp
   )
 
 target_link_libraries(yaml2obj LLVMSupport)

tools/yaml2obj/yaml2elf.cpp

@@ -0,0 +1,78 @@
+//===- yaml2elf - Convert YAML to a ELF object file -----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief The ELF component of yaml2obj.
+///
+//===----------------------------------------------------------------------===//
+
+#include "yaml2obj.h"
+#include "llvm/Object/ELF.h"
+#include "llvm/Object/ELFYAML.h"
+#include "llvm/Support/ELF.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/YAMLTraits.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace llvm;
+
+template <class ELFT>
+static void writeELF(raw_ostream &OS, const ELFYAML::Object &Doc) {
+  const ELFYAML::Header &Hdr = Doc.Header;
+  using namespace llvm::ELF;
+  using namespace llvm::object;
+  typename ELFObjectFile<ELFT>::Elf_Ehdr Header;
+  memset(&Header, 0, sizeof(Header));
+  Header.e_ident[EI_MAG0] = 0x7f;
+  Header.e_ident[EI_MAG1] = 'E';
+  Header.e_ident[EI_MAG2] = 'L';
+  Header.e_ident[EI_MAG3] = 'F';
+  Header.e_ident[EI_CLASS] = ELFT::Is64Bits ? ELFCLASS64 : ELFCLASS32;
+  bool IsLittleEndian = ELFT::TargetEndianness == support::little;
+  Header.e_ident[EI_DATA] = IsLittleEndian ? ELFDATA2LSB : ELFDATA2MSB;
+
+  Header.e_ident[EI_VERSION] = EV_CURRENT;
+
+  // TODO: Implement ELF_ELFOSABI enum.
+  Header.e_ident[EI_OSABI] = ELFOSABI_NONE;
+  // TODO: Implement ELF_ABIVERSION enum.
+  Header.e_ident[EI_ABIVERSION] = 0;
+  Header.e_type = Hdr.Type;
+  Header.e_machine = Hdr.Machine;
+  Header.e_version = EV_CURRENT;
+  Header.e_entry = Hdr.Entry;
+  Header.e_ehsize = sizeof(Header);
+
+  // TODO: Section headers and program headers.
+
+  OS.write((const char *)&Header, sizeof(Header));
+}
+
+int yaml2elf(llvm::raw_ostream &Out, llvm::MemoryBuffer *Buf) {
+  yaml::Input YIn(Buf->getBuffer());
+  ELFYAML::Object Doc;
+  YIn >> Doc;
+  if (YIn.error()) {
+    errs() << "yaml2obj: Failed to parse YAML file!\n";
+    return 1;
+  }
+  if (Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64)) {
+    if (Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB))
+      writeELF<object::ELFType<support::little, 8, true> >(outs(), Doc);
+    else
+      writeELF<object::ELFType<support::big, 8, true> >(outs(), Doc);
+  } else {
+    if (Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB))
+      writeELF<object::ELFType<support::little, 4, false> >(outs(), Doc);
+    else
+      writeELF<object::ELFType<support::big, 4, false> >(outs(), Doc);
+  }
+
+  return 0;
+}

tools/yaml2obj/yaml2obj.cpp

@@ -38,7 +38,8 @@ static cl::opt<std::string>
 // them appropriately requires some work in the YAML parser and the YAMLIO
 // library.
 enum YAMLObjectFormat {
-  YOF_COFF
+  YOF_COFF,
+  YOF_ELF
 };
 
 cl::opt<YAMLObjectFormat> Format(
@@ -46,6 +47,7 @@ cl::opt<YAMLObjectFormat> Format(
   cl::desc("Interpret input as this type of object file"),
   cl::values(
     clEnumValN(YOF_COFF, "coff", "COFF object file format"),
+    clEnumValN(YOF_ELF, "elf", "ELF object file format"),
   clEnumValEnd));
 
 
@@ -60,6 +62,8 @@ int main(int argc, char **argv) {
     return 1;
   if (Format == YOF_COFF) {
     return yaml2coff(outs(), Buf.get());
+  } else if (Format == YOF_ELF) {
+    return yaml2elf(outs(), Buf.get());
   } else {
     errs() << "Not yet implemented\n";
     return 1;

tools/yaml2obj/yaml2obj.h

@@ -17,5 +17,6 @@ namespace llvm {
   class MemoryBuffer;
 }
 int yaml2coff(llvm::raw_ostream &Out, llvm::MemoryBuffer *Buf);
+int yaml2elf(llvm::raw_ostream &Out, llvm::MemoryBuffer *Buf);
 
 #endif