Enable LTO on the stdlib for the 'minimal' preset

test/lit.cfg

@@ -965,6 +965,8 @@ if run_vendor == 'apple':
     # it by explicitly -l linking all libraries needed in tests.
     if "stdlib_lto" in config.available_features:
         for library in ["swiftCore", "swiftStdlibUnittest",
+                        "swiftStdlibUnicodeUnittest",
+                        "swiftStdlibCollectionUnittest",
                         "swiftSwiftPrivateLibcExtras", "swiftSwiftPrivate",
                         "swiftDarwin", "swiftSwiftPrivateThreadExtras",
                         "swiftSwiftOnoneSupport"]:

utils/build-presets.ini

@@ -2469,6 +2469,7 @@ swift-stdlib-has-stdin=0
 swift-runtime-static-image-inspection=1
 swift-stdlib-single-threaded-runtime=1
 swift-stdlib-os-versioning=0
+swift-stdlib-lto=full
 extra-cmake-options=
     -DSWIFT_ENABLE_DISPATCH:BOOL=FALSE
     -DSWIFT_IMPLICIT_CONCURRENCY_IMPORT:BOOL=FALSE

utils/build-script-impl

@@ -213,6 +213,7 @@ KNOWN_SETTINGS=(
     swift-stdlib-stable-abi                       ""                "should stdlib be built with stable ABI, if not set defaults to true on Darwin, false otherwise"
     swift-stdlib-has-darwin-libmalloc             "1"               "whether the Darwin build of stdlib can use extended libmalloc APIs"
     swift-stdlib-has-stdin                        "1"               "whether to build stdlib assuming the platform supports stdin and getline API"
+    swift-stdlib-lto                              ""                "enable LLVM LTO on the stdlib, valid values are empty string (no LTO), 'full' and 'thin'"
     swift-disable-dead-stripping                  "0"               "turns off Darwin-specific dead stripping for Swift host tools"
     common-swift-flags                            ""                "Flags used for Swift targets other than the stdlib, like the corelibs"
 
@@ -1988,6 +1989,7 @@ for host in "${ALL_HOSTS[@]}"; do
                     -DSWIFT_STDLIB_OS_VERSIONING:BOOL=$(true_false "${SWIFT_STDLIB_OS_VERSIONING}")
                     -DSWIFT_STDLIB_HAS_DARWIN_LIBMALLOC:BOOL=$(true_false "${SWIFT_STDLIB_HAS_DARWIN_LIBMALLOC}")
                     -DSWIFT_STDLIB_HAS_STDIN:BOOL=$(true_false "${SWIFT_STDLIB_HAS_STDIN}")
+                    -DSWIFT_STDLIB_ENABLE_LTO:STRING="${SWIFT_STDLIB_LTO}"
                     -DSWIFT_NATIVE_LLVM_TOOLS_PATH:STRING="${native_llvm_tools_path}"
                     -DSWIFT_NATIVE_CLANG_TOOLS_PATH:STRING="${native_clang_tools_path}"
                     -DSWIFT_NATIVE_SWIFT_TOOLS_PATH:STRING="${native_swift_tools_path}"

validation-test/lit.site.cfg.in

@@ -68,6 +68,9 @@ if "@SWIFT_TOOLS_ENABLE_LTO@".lower() in ["full", "thin"]:
 else:
    config.available_features.add("no_lto")
 
+if '@SWIFT_STDLIB_ENABLE_LTO@'.lower() in ['full', 'thin']:
+    config.available_features.add('stdlib_lto')
+
 if "@LLVM_ENABLE_ASSERTIONS@" == "TRUE":
     config.available_features.add('asserts')
 else: