[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

14 files changed, 485 insertions, 1 deletions

diff --git a/include/llvm/Object/ELFYAML.h b/include/llvm/Object/ELFYAML.h
new file mode 100644
index 0000000000..18eacce707
--- /dev/null
+++ b/include/llvm/Object/ELFYAML.h
@@ -0,0 +1,92 @@
+//===- ELFYAML.h - ELF YAMLIO implementation --------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief This file declares classes for handling the YAML representation
+/// of ELF.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_OBJECT_ELFYAML_H
+#define LLVM_OBJECT_ELFYAML_H
+
+#include "llvm/Object/YAML.h"
+#include "llvm/Support/ELF.h"
+
+namespace llvm {
+namespace ELFYAML {
+
+// These types are invariant across 32/64-bit ELF, so for simplicity just
+// directly give them their exact sizes. We don't need to worry about
+// endianness because these are just the types in the YAMLIO structures,
+// and are appropriately converted to the necessary endianness when
+// reading/generating binary object files.
+// The naming of these types is intended to be ELF_PREFIX, where PREFIX is
+// the common prefix of the respective constants. E.g. ELF_EM corresponds
+// to the `e_machine` constants, like `EM_X86_64`.
+// In the future, these would probably be better suited by C++11 enum
+// class's with appropriate fixed underlying type.
+LLVM_YAML_STRONG_TYPEDEF(uint16_t, ELF_ET);
+LLVM_YAML_STRONG_TYPEDEF(uint32_t, ELF_EM);
+LLVM_YAML_STRONG_TYPEDEF(uint8_t, ELF_ELFCLASS);
+LLVM_YAML_STRONG_TYPEDEF(uint8_t, ELF_ELFDATA);
+
+// For now, hardcode 64 bits everywhere that 32 or 64 would be needed
+// since 64-bit can hold 32-bit values too.
+struct Header {
+  ELF_ELFCLASS Class;
+  ELF_ELFDATA Data;
+  ELF_ET Type;
+  ELF_EM Machine;
+  llvm::yaml::Hex64 Entry;
+};
+struct Object {
+  Header Header;
+};
+
+} // end namespace ELFYAML
+} // end namespace llvm
+
+namespace llvm {
+namespace yaml {
+
+template <>
+struct ScalarEnumerationTraits<ELFYAML::ELF_ET> {
+  static void enumeration(IO &IO, ELFYAML::ELF_ET &Value);
+};
+
+template <>
+struct ScalarEnumerationTraits<ELFYAML::ELF_EM> {
+  static void enumeration(IO &IO, ELFYAML::ELF_EM &Value);
+};
+
+template <>
+struct ScalarEnumerationTraits<ELFYAML::ELF_ELFCLASS> {
+  static void enumeration(IO &IO, ELFYAML::ELF_ELFCLASS &Value);
+};
+
+template <>
+struct ScalarEnumerationTraits<ELFYAML::ELF_ELFDATA> {
+  static void enumeration(IO &IO, ELFYAML::ELF_ELFDATA &Value);
+};
+
+template <>
+struct MappingTraits<ELFYAML::Header> {
+  static void mapping(IO &IO, ELFYAML::Header &Header);
+};
+
+template <>
+struct MappingTraits<ELFYAML::Object> {
+  static void mapping(IO &IO, ELFYAML::Object &Object);
+};
+
+} // end namespace yaml
+} // end namespace llvm
+
+#endif
diff --git a/lib/Object/CMakeLists.txt b/lib/Object/CMakeLists.txt
index e24f78a598..cec0e28337 100644
--- a/lib/Object/CMakeLists.txt
+++ b/lib/Object/CMakeLists.txt
@@ -4,6 +4,7 @@ add_llvm_library(LLVMObject
   COFFObjectFile.cpp
   COFFYAML.cpp
   ELFObjectFile.cpp
+  ELFYAML.cpp
   Error.cpp
   MachOObjectFile.cpp
   Object.cpp
diff --git a/lib/Object/ELFYAML.cpp b/lib/Object/ELFYAML.cpp
new file mode 100644
index 0000000000..c4f3fc187a
--- /dev/null
+++ b/lib/Object/ELFYAML.cpp
@@ -0,0 +1,228 @@
+//===- ELFYAML.cpp - ELF YAMLIO implementation ----------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines classes for handling the YAML representation of ELF.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Object/ELFYAML.h"
+
+namespace llvm {
+namespace yaml {
+
+void
+ScalarEnumerationTraits<ELFYAML::ELF_ET>::enumeration(IO &IO,
+                                                      ELFYAML::ELF_ET &Value) {
+#define ECase(X) IO.enumCase(Value, #X, ELF::X);
+  ECase(ET_NONE)
+  ECase(ET_REL)
+  ECase(ET_EXEC)
+  ECase(ET_DYN)
+  ECase(ET_CORE)
+#undef ECase
+}
+
+void
+ScalarEnumerationTraits<ELFYAML::ELF_EM>::enumeration(IO &IO,
+                                                      ELFYAML::ELF_EM &Value) {
+#define ECase(X) IO.enumCase(Value, #X, ELF::X);
+  ECase(EM_NONE)
+  ECase(EM_M32)
+  ECase(EM_SPARC)
+  ECase(EM_386)
+  ECase(EM_68K)
+  ECase(EM_88K)
+  ECase(EM_486)
+  ECase(EM_860)
+  ECase(EM_MIPS)
+  ECase(EM_S370)
+  ECase(EM_MIPS_RS3_LE)
+  ECase(EM_PARISC)
+  ECase(EM_VPP500)
+  ECase(EM_SPARC32PLUS)
+  ECase(EM_960)
+  ECase(EM_PPC)
+  ECase(EM_PPC64)
+  ECase(EM_S390)
+  ECase(EM_SPU)
+  ECase(EM_V800)
+  ECase(EM_FR20)
+  ECase(EM_RH32)
+  ECase(EM_RCE)
+  ECase(EM_ARM)
+  ECase(EM_ALPHA)
+  ECase(EM_SH)
+  ECase(EM_SPARCV9)
+  ECase(EM_TRICORE)
+  ECase(EM_ARC)
+  ECase(EM_H8_300)
+  ECase(EM_H8_300H)
+  ECase(EM_H8S)
+  ECase(EM_H8_500)
+  ECase(EM_IA_64)
+  ECase(EM_MIPS_X)
+  ECase(EM_COLDFIRE)
+  ECase(EM_68HC12)
+  ECase(EM_MMA)
+  ECase(EM_PCP)
+  ECase(EM_NCPU)
+  ECase(EM_NDR1)
+  ECase(EM_STARCORE)
+  ECase(EM_ME16)
+  ECase(EM_ST100)
+  ECase(EM_TINYJ)
+  ECase(EM_X86_64)
+  ECase(EM_PDSP)
+  ECase(EM_PDP10)
+  ECase(EM_PDP11)
+  ECase(EM_FX66)
+  ECase(EM_ST9PLUS)
+  ECase(EM_ST7)
+  ECase(EM_68HC16)
+  ECase(EM_68HC11)
+  ECase(EM_68HC08)
+  ECase(EM_68HC05)
+  ECase(EM_SVX)
+  ECase(EM_ST19)
+  ECase(EM_VAX)
+  ECase(EM_CRIS)
+  ECase(EM_JAVELIN)
+  ECase(EM_FIREPATH)
+  ECase(EM_ZSP)
+  ECase(EM_MMIX)
+  ECase(EM_HUANY)
+  ECase(EM_PRISM)
+  ECase(EM_AVR)
+  ECase(EM_FR30)
+  ECase(EM_D10V)
+  ECase(EM_D30V)
+  ECase(EM_V850)
+  ECase(EM_M32R)
+  ECase(EM_MN10300)
+  ECase(EM_MN10200)
+  ECase(EM_PJ)
+  ECase(EM_OPENRISC)
+  ECase(EM_ARC_COMPACT)
+  ECase(EM_XTENSA)
+  ECase(EM_VIDEOCORE)
+  ECase(EM_TMM_GPP)
+  ECase(EM_NS32K)
+  ECase(EM_TPC)
+  ECase(EM_SNP1K)
+  ECase(EM_ST200)
+  ECase(EM_IP2K)
+  ECase(EM_MAX)
+  ECase(EM_CR)
+  ECase(EM_F2MC16)
+  ECase(EM_MSP430)
+  ECase(EM_BLACKFIN)
+  ECase(EM_SE_C33)
+  ECase(EM_SEP)
+  ECase(EM_ARCA)
+  ECase(EM_UNICORE)
+  ECase(EM_EXCESS)
+  ECase(EM_DXP)
+  ECase(EM_ALTERA_NIOS2)
+  ECase(EM_CRX)
+  ECase(EM_XGATE)
+  ECase(EM_C166)
+  ECase(EM_M16C)
+  ECase(EM_DSPIC30F)
+  ECase(EM_CE)
+  ECase(EM_M32C)
+  ECase(EM_TSK3000)
+  ECase(EM_RS08)
+  ECase(EM_SHARC)
+  ECase(EM_ECOG2)
+  ECase(EM_SCORE7)
+  ECase(EM_DSP24)
+  ECase(EM_VIDEOCORE3)
+  ECase(EM_LATTICEMICO32)
+  ECase(EM_SE_C17)
+  ECase(EM_TI_C6000)
+  ECase(EM_TI_C2000)
+  ECase(EM_TI_C5500)
+  ECase(EM_MMDSP_PLUS)
+  ECase(EM_CYPRESS_M8C)
+  ECase(EM_R32C)
+  ECase(EM_TRIMEDIA)
+  ECase(EM_HEXAGON)
+  ECase(EM_8051)
+  ECase(EM_STXP7X)
+  ECase(EM_NDS32)
+  ECase(EM_ECOG1)
+  ECase(EM_ECOG1X)
+  ECase(EM_MAXQ30)
+  ECase(EM_XIMO16)
+  ECase(EM_MANIK)
+  ECase(EM_CRAYNV2)
+  ECase(EM_RX)
+  ECase(EM_METAG)
+  ECase(EM_MCST_ELBRUS)
+  ECase(EM_ECOG16)
+  ECase(EM_CR16)
+  ECase(EM_ETPU)
+  ECase(EM_SLE9X)
+  ECase(EM_L10M)
+  ECase(EM_K10M)
+  ECase(EM_AARCH64)
+  ECase(EM_AVR32)
+  ECase(EM_STM8)
+  ECase(EM_TILE64)
+  ECase(EM_TILEPRO)
+  ECase(EM_MICROBLAZE)
+  ECase(EM_CUDA)
+  ECase(EM_TILEGX)
+  ECase(EM_CLOUDSHIELD)
+  ECase(EM_COREA_1ST)
+  ECase(EM_COREA_2ND)
+  ECase(EM_ARC_COMPACT2)
+  ECase(EM_OPEN8)
+  ECase(EM_RL78)
+  ECase(EM_VIDEOCORE5)
+  ECase(EM_78KOR)
+  ECase(EM_56800EX)
+  ECase(EM_MBLAZE)
+#undef ECase
+}
+
+void ScalarEnumerationTraits<ELFYAML::ELF_ELFCLASS>::enumeration(
+    IO &IO, ELFYAML::ELF_ELFCLASS &Value) {
+#define ECase(X) IO.enumCase(Value, #X, ELF::X);
+  // Since the semantics of ELFCLASSNONE is "invalid", just don't accept it
+  // here.
+  ECase(ELFCLASS32)
+  ECase(ELFCLASS64)
+#undef ECase
+}
+
+void ScalarEnumerationTraits<ELFYAML::ELF_ELFDATA>::enumeration(
+    IO &IO, ELFYAML::ELF_ELFDATA &Value) {
+#define ECase(X) IO.enumCase(Value, #X, ELF::X);
+  // Since the semantics of ELFDATANONE is "invalid", just don't accept it
+  // here.
+  ECase(ELFDATA2LSB)
+  ECase(ELFDATA2MSB)
+#undef ECase
+}
+
+void MappingTraits<ELFYAML::Header>::mapping(IO &IO, ELFYAML::Header &Header) {
+  IO.mapRequired("Class", Header.Class);
+  IO.mapRequired("Data", Header.Data);
+  IO.mapRequired("Type", Header.Type);
+  IO.mapRequired("Machine", Header.Machine);
+  IO.mapOptional("Entry", Header.Entry, Hex64(0));
+}
+
+void MappingTraits<ELFYAML::Object>::mapping(IO &IO, ELFYAML::Object &Object) {
+  IO.mapRequired("Header", Object.Header);
+}
+
+} // end namespace yaml
+} // end namespace llvm
diff --git a/test/Object/Inputs/ELF/BE32.yaml b/test/Object/Inputs/ELF/BE32.yaml
new file mode 100644
index 0000000000..3709ff70cd
--- /dev/null
+++ b/test/Object/Inputs/ELF/BE32.yaml
@@ -0,0 +1,6 @@
+!ELF
+Header: !Header
+  Class: ELFCLASS32
+  Data: ELFDATA2MSB
+  Type: ET_EXEC
+  Machine: EM_PPC
diff --git a/test/Object/Inputs/ELF/BE64.yaml b/test/Object/Inputs/ELF/BE64.yaml
new file mode 100644
index 0000000000..d1c4401c0c
--- /dev/null
+++ b/test/Object/Inputs/ELF/BE64.yaml
@@ -0,0 +1,6 @@
+!ELF
+Header: !Header
+  Class: ELFCLASS64
+  Data: ELFDATA2MSB
+  Type: ET_EXEC
+  Machine: EM_PPC64
diff --git a/test/Object/Inputs/ELF/Header.yaml b/test/Object/Inputs/ELF/Header.yaml
new file mode 100644
index 0000000000..085b12077d
--- /dev/null
+++ b/test/Object/Inputs/ELF/Header.yaml
@@ -0,0 +1,7 @@
+!ELF
+Header: !Header
+  Class: ELFCLASS64
+  Data: ELFDATA2LSB
+  Type: ET_EXEC
+  Machine: EM_X86_64
+  Entry: 0x400000
diff --git a/test/Object/Inputs/ELF/LE32.yaml b/test/Object/Inputs/ELF/LE32.yaml
new file mode 100644
index 0000000000..a4f30fbb80
--- /dev/null
+++ b/test/Object/Inputs/ELF/LE32.yaml
@@ -0,0 +1,6 @@
+!ELF
+Header: !Header
+  Class: ELFCLASS32
+  Data: ELFDATA2LSB
+  Type: ET_EXEC
+  Machine: EM_386
diff --git a/test/Object/Inputs/ELF/LE64.yaml b/test/Object/Inputs/ELF/LE64.yaml
new file mode 100644
index 0000000000..cd0ca2545b
--- /dev/null
+++ b/test/Object/Inputs/ELF/LE64.yaml
@@ -0,0 +1,6 @@
+!ELF
+Header: !Header
+  Class: ELFCLASS64
+  Data: ELFDATA2LSB
+  Type: ET_EXEC
+  Machine: EM_X86_64
diff --git a/test/Object/yaml2obj-elf-basic.test b/test/Object/yaml2obj-elf-basic.test
new file mode 100644
index 0000000000..e97ad2013b
--- /dev/null
+++ b/test/Object/yaml2obj-elf-basic.test
@@ -0,0 +1,32 @@
+RUN: yaml2obj -format=elf %p/Inputs/ELF/Header.yaml | llvm-readobj -file-headers - | FileCheck %s
+
+// CHECK:      File: <stdin>
+// CHECK-NEXT: Format: ELF64-x86-64
+// CHECK-NEXT: Arch: x86_64
+// CHECK-NEXT: AddressSize: 64bit
+// CHECK-NEXT: LoadName:
+// CHECK-NEXT: ElfHeader {
+// CHECK-NEXT:   Ident {
+// CHECK-NEXT:     Magic: (7F 45 4C 46)
+// CHECK-NEXT:     Class: 64-bit (0x2)
+// CHECK-NEXT:     DataEncoding: LittleEndian (0x1)
+// CHECK-NEXT:     FileVersion: 1
+// CHECK-NEXT:     OS/ABI: SystemV (0x0)
+// CHECK-NEXT:     ABIVersion: 0
+// CHECK-NEXT:     Unused: (00 00 00 00 00 00 00)
+// CHECK-NEXT:   }
+// CHECK-NEXT:   Type: Executable (0x2)
+// CHECK-NEXT:   Machine: EM_X86_64 (0x3E)
+// CHECK-NEXT:   Version: 1
+// CHECK-NEXT:   Entry: 0x400000
+// CHECK-NEXT:   ProgramHeaderOffset: 0x0
+// CHECK-NEXT:   SectionHeaderOffset: 0x0
+// CHECK-NEXT:   Flags [ (0x0)
+// CHECK-NEXT:   ]
+// CHECK-NEXT:   HeaderSize: 64
+// CHECK-NEXT:   ProgramHeaderEntrySize: 0
+// CHECK-NEXT:   ProgramHeaderCount: 0
+// CHECK-NEXT:   SectionHeaderEntrySize: 0
+// CHECK-NEXT:   SectionHeaderCount: 0
+// CHECK-NEXT:   StringTableSectionIndex: 0
+// CHECK-NEXT: }
diff --git a/test/Object/yaml2obj-elf-bits-endian.test b/test/Object/yaml2obj-elf-bits-endian.test
new file mode 100644
index 0000000000..4be9a4465b
--- /dev/null
+++ b/test/Object/yaml2obj-elf-bits-endian.test
@@ -0,0 +1,16 @@
+RUN: yaml2obj -format=elf %p/Inputs/ELF/LE64.yaml | llvm-readobj -file-headers - | FileCheck %s --check-prefix LE64
+RUN: yaml2obj -format=elf %p/Inputs/ELF/BE64.yaml | llvm-readobj -file-headers - | FileCheck %s --check-prefix BE64
+RUN: yaml2obj -format=elf %p/Inputs/ELF/LE32.yaml | llvm-readobj -file-headers - | FileCheck %s --check-prefix LE32
+RUN: yaml2obj -format=elf %p/Inputs/ELF/BE32.yaml | llvm-readobj -file-headers - | FileCheck %s --check-prefix BE32
+
+LE64:      Class: 64-bit (0x2)
+LE64-NEXT: DataEncoding: LittleEndian (0x1)
+
+BE64:      Class: 64-bit (0x2)
+BE64-NEXT: DataEncoding: BigEndian (0x2)
+
+LE32:      Class: 32-bit (0x1)
+LE32-NEXT: DataEncoding: LittleEndian (0x1)
+
+BE32:      Class: 32-bit (0x1)
+BE32-NEXT: DataEncoding: BigEndian (0x2)
diff --git a/tools/yaml2obj/CMakeLists.txt b/tools/yaml2obj/CMakeLists.txt
index 5cccf9330e..8d9d652246 100644
--- a/tools/yaml2obj/CMakeLists.txt
+++ b/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)
diff --git a/tools/yaml2obj/yaml2elf.cpp b/tools/yaml2obj/yaml2elf.cpp
new file mode 100644
index 0000000000..d59594236f
--- /dev/null
+++ b/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;
+}
diff --git a/tools/yaml2obj/yaml2obj.cpp b/tools/yaml2obj/yaml2obj.cpp
index a9ac78bce4..6d1107c858 100644
--- a/tools/yaml2obj/yaml2obj.cpp
+++ b/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;
diff --git a/tools/yaml2obj/yaml2obj.h b/tools/yaml2obj/yaml2obj.h
index 7197410b26..095435c549 100644
--- a/tools/yaml2obj/yaml2obj.h
+++ b/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