Merge pull request #74046 from al45tair/eng/PR-129053233

[6.0][lld] Allow opt-out from building lld via --skip-build-lld

Author: al45tair

utils/build_swift/build_swift/driver_arguments.py

@@ -841,8 +841,10 @@ def create_argument_parser():
     option('--build-ninja', toggle_true,
            help='build the Ninja tool')
 
-    option(['--build-lld'], toggle_true('build_lld'),
+    option(['--build-lld'], toggle_true('build_lld'), default=True,
            help='build lld as part of llvm')
+    option(['--skip-build-lld'], toggle_false('build_lld'),
+           help='skip building lld as part of llvm')
 
     option('--skip-build-clang-tools-extra',
            toggle_false('build_clang_tools_extra'),

utils/build_swift/tests/expected_options.py

@@ -74,7 +74,7 @@
     'build_libcxx': False,
     'build_linux_static': False,
     'build_ninja': False,
-    'build_lld': False,
+    'build_lld': True,
     'build_osx': True,
     'build_playgroundsupport': False,
     'build_runtime_with_host_compiler': False,
@@ -758,6 +758,7 @@ class BuildScriptImplOption(_BaseOption):
     DisableOption('--skip-build-zlib', dest='build_zlib'),
     DisableOption('--skip-build-curl', dest='build_curl'),
     DisableOption('--skip-build-compiler-rt', dest='build_compiler_rt'),
+    DisableOption('--skip-build-lld', dest='build_lld'),
 
     ChoicesOption('--compiler-vendor',
                   choices=['none', 'apple']),

utils/swift_build_support/swift_build_support/build_script_invocation.py

@@ -465,16 +465,7 @@ def convert_to_impl_arguments(self):
                 "--llvm-install-components=%s" % args.llvm_install_components
             ]
 
-        # On non-Darwin platforms, build lld so we can always have a
-        # linker that is compatible with the swift we are using to
-        # compile the stdlib.
-        #
-        # This makes it easier to build target stdlibs on systems that
-        # have old toolchains without more modern linker features.
-        #
-        # On Darwin, only build lld if explicitly requested using --build-lld.
-        should_build_lld = (platform.system() != 'Darwin' or args.build_lld)
-        if not should_build_lld:
+        if not args.build_lld:
             impl_args += [
                 "--skip-build-lld"
             ]

utils/swift_build_support/swift_build_support/products/llvm.py

@@ -295,13 +295,14 @@ def build(self, host_target):
         if self.args.build_clang_tools_extra:
             llvm_enable_projects.append('clang-tools-extra')
 
-        # Always build lld -- on non-Darwin so we can always have a
+        # Building lld is on by default -- on non-Darwin so we can always have a
         # linker that is compatible with the swift we are using to
         # compile the stdlib, but on Darwin too for Embedded Swift use cases.
         #
         # This makes it easier to build target stdlibs on systems that
         # have old toolchains without more modern linker features.
-        llvm_enable_projects.append('lld')
+        if self.args.build_lld:
+            llvm_enable_projects.append('lld')
 
         llvm_cmake_options.define('LLVM_ENABLE_PROJECTS',
                                   ';'.join(llvm_enable_projects))