[lldb] Support Darwin cross compilation for remote Linux test suite runs (#151403)

Fix cross-compilation of test inferiors on Darwin, targeting remote
Linux. This requires specifying the target triple and using LLD for
linking.

Fixes #150806

Author: JDevlieghere

lldb/packages/Python/lldbsuite/test/builders/builder.py

@@ -26,7 +26,7 @@ def getCompiler(self):
 
     def getTriple(self, arch):
         """Returns the triple for the given architecture or None."""
-        return None
+        return configuration.triple
 
     def getExtraMakeArgs(self):
         """
@@ -37,6 +37,9 @@ def getExtraMakeArgs(self):
 
     def getArchCFlags(self, architecture):
         """Returns the ARCH_CFLAGS for the make system."""
+        triple = self.getTriple(architecture)
+        if triple:
+            return ["ARCH_CFLAGS=-target {}".format(triple)]
         return []
 
     def getMake(self, test_subdir, test_name):

lldb/packages/Python/lldbsuite/test/configuration.py

@@ -45,6 +45,9 @@
 sdkroot = None
 make_path = None
 
+# Allow specifying a triple for cross compilation.
+triple = None
+
 # The overriden dwarf verison.
 # Don't use this to test the current compiler's
 # DWARF version, as this won't be set if the
@@ -141,6 +144,7 @@
 # Typical values include Debug, Release, RelWithDebInfo and MinSizeRel
 cmake_build_type = None
 
+
 def shouldSkipBecauseOfCategories(test_categories):
     if use_categories:
         if (

lldb/packages/Python/lldbsuite/test/dotest.py

@@ -321,8 +321,13 @@ def parseOptionsAndInitTestdirs():
             logging.error("No SDK found with the name %s; aborting...", args.apple_sdk)
             sys.exit(-1)
 
+    if args.triple:
+        configuration.triple = args.triple
+
     if args.arch:
         configuration.arch = args.arch
+    elif args.triple:
+        configuration.arch = args.triple.split("-")[0]
     else:
         configuration.arch = platform_machine
 

lldb/packages/Python/lldbsuite/test/dotest_args.py

@@ -58,6 +58,14 @@ def create_parser():
             """Specify the path to sysroot. This overrides apple_sdk sysroot."""
         ),
     )
+    group.add_argument(
+        "--triple",
+        metavar="triple",
+        dest="triple",
+        help=textwrap.dedent(
+            """Specify the target triple. Used for cross compilation."""
+        ),
+    )
     if sys.platform == "darwin":
         group.add_argument(
             "--apple-sdk",

lldb/packages/Python/lldbsuite/test/make/Makefile.rules

@@ -148,6 +148,16 @@ else
     endif
 endif
 
+#----------------------------------------------------------------------
+# Use LLD when cross compiling on Darwin.
+#----------------------------------------------------------------------
+ifeq "$(HOST_OS)" "Darwin"
+	ifneq (,$(filter $(OS), Android FreeBSD Linux NetBSD Windows_NT))
+		LDFLAGS += -fuse-ld=lld
+	endif
+endif
+
+
 #----------------------------------------------------------------------
 # ARCHFLAG is the flag used to tell the compiler which architecture
 # to compile for. The default is the flag that clang accepts.