pick up logic to use ld.gold when available from experimental/foundation

Author: dgrove-oss

configure.ac

@@ -108,6 +108,14 @@ AC_ARG_WITH([swift-toolchain],
 AM_CONDITIONAL(HAVE_SWIFT, $have_swift)
 AC_SUBST([SWIFTC])
 
+#
+# Enable use of gold linker when building the Swift overlay
+# to avoid a symbol relocation issue.
+# Ultimately the request to use gold should be passed in as an arg
+#
+AC_CHECK_PROG(use_gold_linker, ld.gold, true, false)
+AM_CONDITIONAL(USE_GOLD_LINKER, $use_gold_linker)
+
 #
 # Enable __thread based TSD on platforms where it is efficient
 # Allow override based on command line argument to configure

src/Makefile.am

@@ -83,6 +83,10 @@ libdispatch_la_LDFLAGS+=-Wl,-compatibility_version,1 \
 	-Wl,-alias_list,$(top_srcdir)/xcodeconfig/libdispatch.aliases
 endif
 
+if USE_GOLD_LINKER
+libdispatch_la_LDFLAGS+=-Xcompiler -fuse-ld=gold
+endif
+
 if USE_OBJC
 libdispatch_la_SOURCES+=block.cpp data.m object.m
 libdispatch_la_OBJCFLAGS=$(AM_OBJCFLAGS) -Wno-switch -fobjc-gc
@@ -159,12 +163,10 @@ $(abs_builddir)/swift/Dispatch.swiftmodule: $(SWIFT_ABS_SRC_FILES)
 	$(SWIFTC_FLAGS) -module-cache-path $(top_builddir) -module-link-name dispatch \
 	-o $@ -emit-module-doc-path $(@:%.swiftmodule=%.swiftdoc)
 
-if HAVE_SWIFT
 swiftmoddir=${prefix}/lib/swift/linux/${build_cpu}
 swiftmod_HEADERS=\
 	$(abs_builddir)/swift/Dispatch.swiftmodule \
 	$(abs_builddir)/swift/Dispatch.swiftdoc
-endif
 
 endif