[ELF/AArch64] Accept -m aarch64linux.

[ikudrin]

Summary

This option is passed by clang driver if the target triple is aarch64-unknown-linux.

[ruiu]

Do you know why the flag is so inconsistent? (Naturally I expected something like elf_aarch64.)

[ikudrin]

$ aarch64-linux-gnu-ld -V
GNU ld (GNU Binutils for Ubuntu) 2.25
  Supported emulations:
   aarch64linux
   aarch64elf
   aarch64elf32
   aarch64elf32b
   aarch64elfb
   armelf
   armelfb
   aarch64linuxb
   aarch64linux32
   aarch64linux32b
   armelfb_linux_eabi
   armelf_linux_eabi

As far as I know, "aarch64linux" is the only variant sent by clang. And if the triple is "aarch64-pc-freebsd" it doesn't pass "-m" switch at all.

[ruiu]

LGTM with a nti.

test/ELF/emulation.s

167–173 ↗

(On Diff #40674)

Remove these lines as the other test cases doesn't test these fields.

[ikudrin]

test/ELF/emulation.s

167–173 ↗

(On Diff #40674)

As far as I can see, both X86-64 and PPC64 have the same lines, X86 has similar lines and only MIPS and MIPSEL miss them.

[ruiu]

test/ELF/emulation.s

167–173 ↗

(On Diff #40674)

Then maybe we should remove from them too? I think the purpose of this test is to test is Machine field, so checking values of miscellaneous Size fields seem excessive.

[ikudrin]

test/ELF/emulation.s

167–173 ↗

(On Diff #40674)

OK, but I don't think that cleaning the other cases is relevant to this patch.

[ruiu]

test/ELF/emulation.s

167–173 ↗

(On Diff #40674)

Agreed. This should be done in another patch.

lld/trunk/ELF/Driver.cpp

static std::pair<ELFKind, uint16_t> parseEmulation(StringRef S) {
   if (S == "elf32ppc")
     return {ELF32BEKind, EM_PPC};
   if (S == "elf64ppc")
     return {ELF64BEKind, EM_PPC64};
   if (S == "elf_i386")
     return {ELF32LEKind, EM_386};
   if (S == "elf_x86_64")
     return {ELF64LEKind, EM_X86_64};
+  if (S == "aarch64linux")
+    return {ELF64LEKind, EM_AARCH64};
   error("Unknown emulation: " + S);
 }
 
 // Opens and parses a file. Path has to be resolved already.
 // Newly created memory buffers are owned by this driver.
 void LinkerDriver::addFile(StringRef Path) {
   using namespace llvm::sys::fs;
   if (Config->Verbose)

lld/trunk/test/ELF/emulation.s

 # MIPSEL-NEXT:   Machine: EM_MIPS (0x8)
 # MIPSEL-NEXT:   Version: 1
 # MIPSEL-NEXT:   Entry:
 # MIPSEL-NEXT:   ProgramHeaderOffset: 0x34
 # MIPSEL-NEXT:   SectionHeaderOffset:
 # MIPSEL-NEXT:   Flags [ (0x0)
 # MIPSEL-NEXT:   ]
 
-# REQUIRES: x86,ppc,mips
+# RUN: llvm-mc -filetype=obj -triple=aarch64-unknown-linux %s -o %taarch64
+# RUN: ld.lld -m aarch64linux %taarch64 -o %t2aarch64
+# RUN: llvm-readobj -file-headers %t2aarch64 | FileCheck --check-prefix=AARCH64 %s
+# RUN: ld.lld %taarch64 -o %t3aarch64
+# RUN: llvm-readobj -file-headers %t3aarch64 | FileCheck --check-prefix=AARCH64 %s
+# AARCH64:      ElfHeader {
+# AARCH64-NEXT:   Ident {
+# AARCH64-NEXT:     Magic: (7F 45 4C 46)
+# AARCH64-NEXT:     Class: 64-bit (0x2)
+# AARCH64-NEXT:     DataEncoding: LittleEndian (0x1)
+# AARCH64-NEXT:     FileVersion: 1
+# AARCH64-NEXT:     OS/ABI: SystemV (0x0)
+# AARCH64-NEXT:     ABIVersion: 0
+# AARCH64-NEXT:     Unused: (00 00 00 00 00 00 00)
+# AARCH64-NEXT:   }
+# AARCH64-NEXT:   Type: Executable (0x2)
+# AARCH64-NEXT:   Machine: EM_AARCH64 (0xB7)
+# AARCH64-NEXT:   Version: 1
+# AARCH64-NEXT:   Entry:
+# AARCH64-NEXT:   ProgramHeaderOffset: 0x40
+# AARCH64-NEXT:   SectionHeaderOffset:
+# AARCH64-NEXT:   Flags [ (0x0)
+# AARCH64-NEXT:   ]
+
+# REQUIRES: x86,ppc,mips,aarch64
 
 .globl _start;
 _start: