AArch64: remove arm64 triple enumerator.

Having both Triple::arm64 and Triple::aarch64 is extremely confusing, and
invites bugs where only one is checked. In reality, the only legitimate
difference between the two (arm64 usually means iOS) is also present in the OS
part of the triple and that's what should be checked.

We still parse the "arm64" triple, just canonicalise it to Triple::aarch64, so
there aren't any LLVM-side test changes.

llvm-svn: 213743
diff --git a/llvm/lib/MC/MCObjectFileInfo.cpp b/llvm/lib/MC/MCObjectFileInfo.cpp
index d490ef3..990938e 100644
--- a/llvm/lib/MC/MCObjectFileInfo.cpp
+++ b/llvm/lib/MC/MCObjectFileInfo.cpp
@@ -24,7 +24,7 @@
     return false;
 
   // aarch64 always has it.
-  if (T.getArch() == Triple::arm64 || T.getArch() == Triple::aarch64)
+  if (T.getArch() == Triple::aarch64)
     return true;
 
   // Use it on newer version of OS X.
@@ -43,8 +43,7 @@
   // MachO
   SupportsWeakOmittedEHFrame = false;
 
-  if (T.isOSDarwin() &&
-      (T.getArch() == Triple::arm64 || T.getArch() == Triple::aarch64))
+  if (T.isOSDarwin() && T.getArch() == Triple::aarch64)
     SupportsCompactUnwindWithoutEHFrame = true;
 
   PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel
@@ -178,7 +177,7 @@
 
     if (T.getArch() == Triple::x86_64 || T.getArch() == Triple::x86)
       CompactUnwindDwarfEHFrameOnly = 0x04000000;
-    else if (T.getArch() == Triple::arm64 || T.getArch() == Triple::aarch64)
+    else if (T.getArch() == Triple::aarch64)
       CompactUnwindDwarfEHFrameOnly = 0x03000000;
   }
 
@@ -321,8 +320,6 @@
     break;
   case Triple::aarch64:
   case Triple::aarch64_be:
-  case Triple::arm64:
-  case Triple::arm64_be:
     // The small model guarantees static code/data size < 4GB, but not where it
     // will be in memory. Most of these could end up >2GB away so even a signed
     // pc-relative 32-bit address is insufficient, theoretically.
@@ -827,7 +824,7 @@
   // cellspu-apple-darwin. Perhaps we should fix in Triple?
   if ((Arch == Triple::x86 || Arch == Triple::x86_64 ||
        Arch == Triple::arm || Arch == Triple::thumb ||
-       Arch == Triple::arm64 || Arch == Triple::aarch64 ||
+       Arch == Triple::aarch64 ||
        Arch == Triple::ppc || Arch == Triple::ppc64 ||
        Arch == Triple::UnknownArch) &&
       (TT.isOSDarwin() || TT.isOSBinFormatMachO())) {