[lld-macho] Switch default to new Darwin backend

The new Darwin backend for LLD is now able to link reasonably large
real-world programs on x86_64. For instance, we have achieved
self-hosting for the X86_64 target, where all LLD tests pass when
building lld with itself on macOS. As such, we would like to make it the
default back-end.

The new port is now named `ld64.lld`, and the old port remains
accessible as `ld64.lld.darwinold`

This [annoucement email][1] has some context. (But note that, unlike
what the email says, we are no longer doing this as part of the LLVM 12
branch cut -- instead we will go into LLVM 13.)

Numerous mechanical test changes were required to make this change; in
the interest of creating something that's reviewable on Phabricator,
I've split out the boring changes into a separate diff (D95905). I plan to
merge its contents with those in this diff before landing.

(@gkm made the original draft of this diff, and he has agreed to let me
take over.)

[1]: https://lists.llvm.org/pipermail/llvm-dev/2021-January/147665.html

Reviewed By: #lld-macho, thakis

Differential Revision: https://reviews.llvm.org/D95204

2 files changed, 7 insertions, 6 deletions

diff --git a/lld/tools/lld/CMakeLists.txt b/lld/tools/lld/CMakeLists.txt
index 5cff736..e77b216 100644
--- a/lld/tools/lld/CMakeLists.txt
+++ b/lld/tools/lld/CMakeLists.txt
@@ -25,7 +25,7 @@ install(TARGETS lld
 
 if(NOT LLD_SYMLINKS_TO_CREATE)
   set(LLD_SYMLINKS_TO_CREATE
-      lld-link ld.lld ld64.lld ld64.lld.darwinnew wasm-ld)
+      lld-link ld.lld ld64.lld ld64.lld.darwinnew ld64.lld.darwinold wasm-ld)
 endif()
 
 foreach(link ${LLD_SYMLINKS_TO_CREATE})
diff --git a/lld/tools/lld/lld.cpp b/lld/tools/lld/lld.cpp
index 77d7792..01605bc 100644
--- a/lld/tools/lld/lld.cpp
+++ b/lld/tools/lld/lld.cpp
@@ -56,7 +56,7 @@ enum Flavor {
   Gnu,       // -flavor gnu
   WinLink,   // -flavor link
   Darwin,    // -flavor darwin
-  DarwinNew, // -flavor darwinnew
+  DarwinOld, // -flavor darwinold
   Wasm,      // -flavor wasm
 };
 
@@ -70,8 +70,9 @@ static Flavor getFlavor(StringRef s) {
       .CasesLower("ld", "ld.lld", "gnu", Gnu)
       .CasesLower("wasm", "ld-wasm", Wasm)
       .CaseLower("link", WinLink)
-      .CasesLower("ld64", "ld64.lld", "darwin", Darwin)
-      .CasesLower("darwinnew", "ld64.lld.darwinnew", DarwinNew)
+      .CasesLower("ld64", "ld64.lld", "darwin", "darwinnew",
+                  "ld64.lld.darwinnew", Darwin)
+      .CasesLower("darwinold", "ld64.lld.darwinold", DarwinOld)
       .Default(Invalid);
 }
 
@@ -154,9 +155,9 @@ static int lldMain(int argc, const char **argv, llvm::raw_ostream &stdoutOS,
   case WinLink:
     return !coff::link(args, exitEarly, stdoutOS, stderrOS);
   case Darwin:
-    return !mach_o::link(args, exitEarly, stdoutOS, stderrOS);
-  case DarwinNew:
     return !macho::link(args, exitEarly, stdoutOS, stderrOS);
+  case DarwinOld:
+    return !mach_o::link(args, exitEarly, stdoutOS, stderrOS);
   case Wasm:
     return !lld::wasm::link(args, exitEarly, stdoutOS, stderrOS);
   default: