[ELF] elfiamcu triple should imply e_machine == EM_IAMCU

[mkuper]

ping?

(To be honest, I'm not sure who'd be the right person to review this. Sorry if this is noise for you.)

[• rafael]

LGTM

include/llvm/Object/ELFObjectFile.h

 template <class ELFT>
 StringRef ELFObjectFile<ELFT>::getFileFormatName() const {
   bool IsLittleEndian = ELFT::TargetEndianness == support::little;
   switch (EF.getHeader()->e_ident[ELF::EI_CLASS]) {
   case ELF::ELFCLASS32:
     switch (EF.getHeader()->e_machine) {
     case ELF::EM_386:
       return "ELF32-i386";
+    case ELF::EM_IAMCU:
+      return "ELF32-iamcu";
     case ELF::EM_X86_64:
       return "ELF32-x86-64";
     case ELF::EM_ARM:
       return (IsLittleEndian ? "ELF32-arm-little" : "ELF32-arm-big");
     case ELF::EM_AVR:
       return "ELF32-avr";
     case ELF::EM_HEXAGON:
       return "ELF32-hexagon";
StringRef ELFObjectFile<ELFT>::getFileFormatName() const {
   }
 }
 
 template <class ELFT>
 unsigned ELFObjectFile<ELFT>::getArch() const {
   bool IsLittleEndian = ELFT::TargetEndianness == support::little;
   switch (EF.getHeader()->e_machine) {
   case ELF::EM_386:
+  case ELF::EM_IAMCU:
     return Triple::x86;
   case ELF::EM_X86_64:
     return Triple::x86_64;
   case ELF::EM_AARCH64:
     return Triple::aarch64;
   case ELF::EM_ARM:
     return Triple::arm;
   case ELF::EM_AVR:

lib/Object/ELF.cpp

StringRef getELFRelocationTypeName(uint32_t Machine, uint32_t Type) {
   case ELF::EM_X86_64:
     switch (Type) {
 #include "llvm/Support/ELFRelocs/x86_64.def"
     default:
       break;
     }
     break;
   case ELF::EM_386:
+  case ELF::EM_IAMCU:
     switch (Type) {
 #include "llvm/Support/ELFRelocs/i386.def"
     default:
       break;
     }
     break;
   case ELF::EM_MIPS:
     switch (Type) {

lib/Object/ELFYAML.cpp

#include "llvm/Support/ELFRelocs/x86_64.def"
     break;
   case ELF::EM_MIPS:
 #include "llvm/Support/ELFRelocs/Mips.def"
     break;
   case ELF::EM_HEXAGON:
 #include "llvm/Support/ELFRelocs/Hexagon.def"
     break;
   case ELF::EM_386:
+  case ELF::EM_IAMCU:
 #include "llvm/Support/ELFRelocs/i386.def"
     break;
   case ELF::EM_AARCH64:
 #include "llvm/Support/ELFRelocs/AArch64.def"
     break;
   case ELF::EM_ARM:
 #include "llvm/Support/ELFRelocs/ARM.def"
     break;

lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp

ELFX86_X32AsmBackend(const Target &T, uint8_t OSABI, StringRef CPU)
       : ELFX86AsmBackend(T, OSABI, CPU) {}
 
   MCObjectWriter *createObjectWriter(raw_pwrite_stream &OS) const override {
     return createX86ELFObjectWriter(OS, /*IsELF64*/ false, OSABI,
                                     ELF::EM_X86_64);
   }
 };
 
+class ELFX86_IAMCUAsmBackend : public ELFX86AsmBackend {
+public:
+  ELFX86_IAMCUAsmBackend(const Target &T, uint8_t OSABI, StringRef CPU)
+      : ELFX86AsmBackend(T, OSABI, CPU) {}
+
+  MCObjectWriter *createObjectWriter(raw_pwrite_stream &OS) const override {
+    return createX86ELFObjectWriter(OS, /*IsELF64*/ false, OSABI,
+                                    ELF::EM_IAMCU);
+  }
+};
+
 class ELFX86_64AsmBackend : public ELFX86AsmBackend {
 public:
   ELFX86_64AsmBackend(const Target &T, uint8_t OSABI, StringRef CPU)
     : ELFX86AsmBackend(T, OSABI, CPU) {}
 
   MCObjectWriter *createObjectWriter(raw_pwrite_stream &OS) const override {
     return createX86ELFObjectWriter(OS, /*IsELF64*/ true, OSABI, ELF::EM_X86_64);
   }
MCAsmBackend *llvm::createX86_32AsmBackend(const Target &T,
                                            StringRef CPU) {
   if (TheTriple.isOSBinFormatMachO())
     return new DarwinX86_32AsmBackend(T, MRI, CPU);
 
   if (TheTriple.isOSWindows() && !TheTriple.isOSBinFormatELF())
     return new WindowsX86AsmBackend(T, false, CPU);
 
   uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(TheTriple.getOS());
+
+  if (TheTriple.isOSIAMCU())
+    return new ELFX86_IAMCUAsmBackend(T, OSABI, CPU);
+
   return new ELFX86_32AsmBackend(T, OSABI, CPU);
 }
 
 MCAsmBackend *llvm::createX86_64AsmBackend(const Target &T,
                                            const MCRegisterInfo &MRI,
                                            const Triple &TheTriple,
                                            StringRef CPU) {
   if (TheTriple.isOSBinFormatMachO()) {

lib/Target/X86/MCTargetDesc/X86ELFObjectWriter.cpp

namespace {
   protected:
     unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
                           bool IsPCRel) const override;
   };
 }
 
 X86ELFObjectWriter::X86ELFObjectWriter(bool IsELF64, uint8_t OSABI,
                                        uint16_t EMachine)
     : MCELFObjectTargetWriter(IsELF64, OSABI, EMachine,
-                            // Only i386 uses Rel instead of RelA.
-                            /*HasRelocationAddend*/ EMachine != ELF::EM_386) {}
+                              // Only i386 and IAMCU use Rel instead of RelA.
+                              /*HasRelocationAddend*/
+                              (EMachine != ELF::EM_386) &&
+                                  (EMachine != ELF::EM_IAMCU)) {}
 
 X86ELFObjectWriter::~X86ELFObjectWriter()
 {}
 
 enum X86_64RelType { RT64_64, RT64_32, RT64_32S, RT64_16, RT64_8 };
 
 static X86_64RelType getType64(unsigned Kind,
                                MCSymbolRefExpr::VariantKind &Modifier,

 unsigned X86ELFObjectWriter::GetRelocType(const MCValue &Target,
                                           const MCFixup &Fixup,
                                           bool IsPCRel) const {
   MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();
   X86_64RelType Type = getType64(Fixup.getKind(), Modifier, IsPCRel);
   if (getEMachine() == ELF::EM_X86_64)
     return getRelocType64(Modifier, Type, IsPCRel);
 
-  assert(getEMachine() == ELF::EM_386 && "Unsupported ELF machine type.");
+  assert((getEMachine() == ELF::EM_386 || getEMachine() == ELF::EM_IAMCU) &&
+         "Unsupported ELF machine type.");
   return getRelocType32(Modifier, getType32(Type), IsPCRel);
 }
 
 MCObjectWriter *llvm::createX86ELFObjectWriter(raw_pwrite_stream &OS,
                                                bool IsELF64, uint8_t OSABI,
                                                uint16_t EMachine) {
   MCELFObjectTargetWriter *MOTW =
     new X86ELFObjectWriter(IsELF64, OSABI, EMachine);
   return createELFObjectWriter(MOTW, OS,  /*IsLittleEndian=*/true);
 }

test/MC/ELF/relocation-386.s

-// RUN: llvm-mc -filetype=obj -triple i386-pc-linux-gnu %s -o - | llvm-readobj -r  | FileCheck  %s
+// RUN: llvm-mc -filetype=obj -triple i386-pc-linux-gnu %s -o - | llvm-readobj -r  | FileCheck  %s --check-prefix=CHECK --check-prefix=I386 
+// RUN: llvm-mc -filetype=obj -triple i386-pc-elfiamcu %s -o - | llvm-readobj -r  | FileCheck  %s --check-prefix=CHECK --check-prefix=IAMCU
 
 // Test that we produce the correct relocation types and that the relocations
 // correctly point to the section or the symbol.
 
+// IAMCU: Format: ELF32-iamcu
+// I386: Format: ELF32-i386
 // CHECK:      Relocations [
 // CHECK-NEXT:   Section {{.*}} .rel.text {
 // CHECK-NEXT:     0x2          R_386_GOTOFF     .Lfoo 0x0
 // CHECK-NEXT:     0x{{[^ ]+}}  R_386_PLT32      bar2 0x0
 // CHECK-NEXT:     0x{{[^ ]+}}  R_386_GOTPC      _GLOBAL_OFFSET_TABLE_ 0x0
 // Relocation 3 (bar3@GOTOFF) is done with symbol 7 (bss)
 // CHECK-NEXT:     0x{{[^ ]+}}  R_386_GOTOFF     .bss 0x0
 // Relocation 4 (bar2@GOT) is of type R_386_GOT32

tools/llvm-objdump/llvm-objdump.cpp

case ELF::EM_AARCH64: {
     fmt << Target;
     if (addend != 0)
       fmt << (addend < 0 ? "" : "+") << addend;
     fmt.flush();
     Result.append(fmtbuf.begin(), fmtbuf.end());
     break;
   }
   case ELF::EM_386:
+  case ELF::EM_IAMCU:
   case ELF::EM_ARM:
   case ELF::EM_HEXAGON:
   case ELF::EM_MIPS:
     res = Target;
     break;
   default:
     res = "Unknown";
   }