If lld binary is named 'ld' on darwin, use darwin driver mode

[kledzik]

Summary

Based on feedback from Joerg, change check so full tool name has to be "ld". Previously, an lld tool named "x86_86-netbsd-ld" on MacOSX would also be forced into using the darwin driver.

I've now generalized this patch so, if lld is built on an ELF system and named "ld", it will behave as the gnu linker. There is two new test cases where lld is copied to "ld". One on Linux and one on Darwin. If other non-linux ELF system want the test to run, they'll need to update test/lit.cfg.

[ruiu]

lib/Driver/UniversalDriver.cpp

162

argv[0] == "ld" means "the default linker driver" only on Darwin? On other platforms it should also mean the default linker, which is gnu ld driver, for the sake of consistency.

[kledzik]

Adding support for "ld" on *nix meaning use-gnu-driver is reasonable, but it is an additional feature (which I have no way to test).

What would be the correct way to test for that?

#if LLVM_ON_UNIX && !__APPLE_

[ruiu]

It's a small feature. You can write it and the buildbots will tell you you did it right :)

I'm not an expert of lit tests. I'd probably write it using shell and uname command with "REQUIRES: shell", but I'm not sure if it's the correct way.

[ruiu]

LGTM

[kledzik]

committed as r217566

lib/Driver/UniversalDriver.cpp

 static Flavor strToFlavor(StringRef str) {
   return llvm::StringSwitch<Flavor>(str)
       .Case("gnu", Flavor::gnu_ld)
       .Case("link", Flavor::win_link)
       .Case("lld-link", Flavor::win_link)
       .Case("darwin", Flavor::darwin_ld)
       .Case("core", Flavor::core)
-#if __APPLE__
-      // On a Darwin systems, if linker binary is named "ld", use Darwin driver.
-      .Case("ld", Flavor::darwin_ld)
-#else
-      // On other *nix systems, if linker binary is named "ld", use gnu driver.
       .Case("ld", Flavor::gnu_ld)
-#endif
       .Default(Flavor::invalid);
 }
 

 bool UniversalDriver::link(int argc, const char *argv[],
                            raw_ostream &diagnostics) {
   // Parse command line options using GnuLdOptions.td
   std::unique_ptr<llvm::opt::InputArgList> parsedArgs;
   UniversalDriverOptTable table;

   // Handle --help
   if (parsedArgs->getLastArg(OPT_help)) {
     table.PrintHelp(llvm::outs(), argv[0], "LLVM Linker", false);
     return true;
   }
 
   Flavor flavor;
 
+#if LLVM_ON_UNIX
+  if (llvm::sys::path::filename(argv[0]).equals("ld")) {
+#if __APPLE__
+    // On a Darwin systems, if linker binary is named "ld", use Darwin driver.
+    flavor = Flavor::darwin_ld;
+#else
+    // On a ELF based systems, if linker binary is named "ld", use gnu driver.
+    flavor = Flavor::gnu_ld;
+#endif
+  } else
+#endif
   if (parsedArgs->getLastArg(OPT_core)) {
     flavor = Flavor::core;
     argv++;
     argc--;
   } else if (llvm::opt::Arg *argFlavor = parsedArgs->getLastArg(OPT_flavor)) {
     flavor = strToFlavor(argFlavor->getValue());
     argv += 2;
     argc -= 2;

test/elf/linker-as-ld.test

+REQUIRES: system-linker-elf
+
+RUN: mkdir -p %t.dir && cp `which lld` %t.dir/ld
+RUN: %t.dir/ld -target x86_64-linux -o %t %p/Inputs/relocs.x86-64 \
+RUN:  -e _start -static
+RUN: llvm-readobj -t %t | FileCheck %s
+
+# Test linker run as "ld" on elf based system works like gnu linker.
+
+
+CHECK:        Symbol {
+CHECK:          Name: i
+CHECK-NEXT:     Value:
+CHECK-NEXT:     Size:
+CHECK-NEXT:     Binding:
+CHECK-NEXT:     Type: Object

test/lit.cfg

 if platform.system() not in ['Windows'] or lit_config.getBashPath() != '':
     config.available_features.add('shell')
 
+# Running on Darwin OS
+if platform.system() in ['Darwin']:
+    config.available_features.add('system-linker-mach-o')
+
+# Running on ELF based *nix
+if platform.system() in ['Linux']:
+    config.available_features.add('system-linker-elf')
+
 # llvm-config knows whether it is compiled with asserts (and)
 # whether we are operating in release/debug mode.
 import subprocess

test/mach-o/linker-as-ld.yaml

+# REQUIRES: system-linker-mach-o
+#
+# RUN: mkdir -p %t.dir && cp `which lld` %t.dir/ld \
+# RUN:  && %t.dir/ld -arch x86_64 -macosx_version_min 10.8 %s -o %t \
+# RUN:  && llvm-nm %t | FileCheck %s
+#
+# Test linker run as "ld" on darwin works as darwin linker.
+#
+
+--- !mach-o
+arch:            x86_64
+file-type:       MH_OBJECT
+flags:           [ MH_SUBSECTIONS_VIA_SYMBOLS ]
+has-UUID:        false
+OS:              unknown
+sections:
+  - segment:         __TEXT
+    section:         __text
+    type:            S_REGULAR
+    attributes:      [ S_ATTR_PURE_INSTRUCTIONS, S_ATTR_SOME_INSTRUCTIONS ]
+    address:         0x0000000000000000
+    content:         [ 0xC3 ]
+global-symbols:
+  - name:            _main
+    type:            N_SECT
+    scope:           [ N_EXT ]
+    sect:            1
+    value:           0x0000000000000000
+
+--- !mach-o
+arch:            x86_64
+file-type:       MH_DYLIB
+install-name:    /usr/lib/libSystem.B.dylib
+exports:
+  - name:            dyld_stub_binder
+
+...
+
+# CHECK:            T _main