lld: Add EM_IAMCU support

[hjl.tools]

Summary

This patch adds "-m elf_iamcu" to ldd for IAMCU psABI:

https://github.com/hjl-tools/x86-psABI/wiki/X86-psABI

[ruiu]

LGTM

So this is this one right? https://groups.google.com/forum/#!topic/ia32-abi/cn7TM6J_TIg

Is this all you have to do to the linker ot support Intel MCU ABI?

[hjl.tools]

In D23126#504970, @ruiu wrote:

LGTM

Please check it in for me. Thanks.

So this is this one right? https://groups.google.com/forum/#!topic/ia32-abi/cn7TM6J_TIg

Is this all you have to do to the linker ot support Intel MCU ABI?

That is correct. In terms of linker, the only difference is EM_386 vs
EM_IAMCU. But IAMCU psABI has a different calling convention.

[Eugene.Zelenko]

Committed in r277643.

ELF/Driver.cpp

std::pair<ELFKind, uint16_t> Ret =
           .Case("elf32_x86_64", {ELF32LEKind, EM_X86_64})
           .Case("elf32btsmip", {ELF32BEKind, EM_MIPS})
           .Case("elf32ltsmip", {ELF32LEKind, EM_MIPS})
           .Case("elf32ppc", {ELF32BEKind, EM_PPC})
           .Case("elf64btsmip", {ELF64BEKind, EM_MIPS})
           .Case("elf64ltsmip", {ELF64LEKind, EM_MIPS})
           .Case("elf64ppc", {ELF64BEKind, EM_PPC64})
           .Case("elf_i386", {ELF32LEKind, EM_386})
+          .Case("elf_iamcu", {ELF32LEKind, EM_IAMCU})
           .Case("elf_x86_64", {ELF64LEKind, EM_X86_64})
           .Default({ELFNoneKind, EM_NONE});
 
   if (Ret.first == ELFNoneKind) {
     if (S == "i386pe" || S == "i386pep" || S == "thumb2pe")
       error("Windows targets are not supported on the ELF frontend: " + S);
     else
       error("unknown emulation: " + S);

ELF/InputFiles.cpp

static uint8_t getMachineKind(MemoryBufferRef MB) {
   case Triple::mips64:
   case Triple::mips64el:
     return EM_MIPS;
   case Triple::ppc:
     return EM_PPC;
   case Triple::ppc64:
     return EM_PPC64;
   case Triple::x86:
-    return EM_386;
+    return Triple(TripleStr).isOSIAMCU() ? EM_IAMCU : EM_386;
   case Triple::x86_64:
     return EM_X86_64;
   default:
     fatal(MB.getBufferIdentifier() +
           ": could not infer e_machine from bitcode target triple " +
           TripleStr);
   }
 }

ELF/Target.cpp

public:
   void relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const override;
   bool usesOnlyLowPageBits(uint32_t Type) const override;
 };
 } // anonymous namespace
 
 TargetInfo *createTarget() {
   switch (Config->EMachine) {
   case EM_386:
+  case EM_IAMCU:
     return new X86TargetInfo();
   case EM_AARCH64:
     return new AArch64TargetInfo();
   case EM_AMDGPU:
     return new AMDGPUTargetInfo();
   case EM_ARM:
     return new ARMTargetInfo();
   case EM_MIPS:

test/ELF/emulation.s

 # X86FBSD-NEXT:   HeaderSize: 52
 # X86FBSD-NEXT:   ProgramHeaderEntrySize: 32
 # X86FBSD-NEXT:   ProgramHeaderCount:
 # X86FBSD-NEXT:   SectionHeaderEntrySize: 40
 # X86FBSD-NEXT:   SectionHeaderCount:
 # X86FBSD-NEXT:   StringTableSectionIndex:
 # X86FBSD-NEXT: }
 
+# RUN: llvm-mc -filetype=obj -triple=i586-intel-elfiamcu %s -o %tiamcu
+# RUN: ld.lld -m elf_iamcu %tiamcu -o %t2iamcu
+# RUN: llvm-readobj -file-headers %t2iamcu | FileCheck --check-prefix=IAMCU %s
+# RUN: ld.lld %tiamcu -o %t3iamcu
+# RUN: llvm-readobj -file-headers %t3iamcu | FileCheck --check-prefix=IAMCU %s
+# IAMCU:      ElfHeader {
+# IAMCU-NEXT:   Ident {
+# IAMCU-NEXT:     Magic: (7F 45 4C 46)
+# IAMCU-NEXT:     Class: 32-bit (0x1)
+# IAMCU-NEXT:     DataEncoding: LittleEndian (0x1)
+# IAMCU-NEXT:     FileVersion: 1
+# IAMCU-NEXT:     OS/ABI: SystemV (0x0)
+# IAMCU-NEXT:     ABIVersion: 0
+# IAMCU-NEXT:     Unused: (00 00 00 00 00 00 00)
+# IAMCU-NEXT:   }
+# IAMCU-NEXT:   Type: Executable (0x2)
+# IAMCU-NEXT:   Machine: EM_IAMCU (0x6)
+# IAMCU-NEXT:   Version: 1
+# IAMCU-NEXT:   Entry:
+# IAMCU-NEXT:   ProgramHeaderOffset: 0x34
+# IAMCU-NEXT:   SectionHeaderOffset:
+# IAMCU-NEXT:   Flags [ (0x0)
+# IAMCU-NEXT:   ]
+# IAMCU-NEXT:   HeaderSize: 52
+# IAMCU-NEXT:   ProgramHeaderEntrySize: 32
+# IAMCU-NEXT:   ProgramHeaderCount:
+# IAMCU-NEXT:   SectionHeaderEntrySize: 40
+# IAMCU-NEXT:   SectionHeaderCount:
+# IAMCU-NEXT:   StringTableSectionIndex:
+# IAMCU-NEXT: }
+
 # RUN: llvm-mc -filetype=obj -triple=powerpc64-unknown-linux %s -o %tppc64
 # RUN: ld.lld -m elf64ppc %tppc64 -o %t2ppc64
 # RUN: llvm-readobj -file-headers %t2ppc64 | FileCheck --check-prefix=PPC64 %s
 # RUN: ld.lld %tppc64 -o %t3ppc64
 # RUN: llvm-readobj -file-headers %t3ppc64 | FileCheck --check-prefix=PPC64 %s
 # PPC64:      ElfHeader {
 # PPC64-NEXT:   Ident {
 # PPC64-NEXT:     Magic: (7F 45 4C 46)