Move stdlib-deployment-targets calculation into build-script

* Demux uname info into a list of stdlib_deployment_targets in python
* Generate list of allowed stdlib_cross_targets based on host info

Author: Tom Birch

utils/build-script

@@ -888,11 +888,55 @@ the number of parallel build jobs to use""",
             "--skip-build-benchmarks",
         ]
 
-    if platform.system() == 'Darwin':
+    system = platform.system()
+    machine = platform.machine()
+
+    if system == 'Darwin':
         build_script_impl_inferred_args += [
             "--toolchain-prefix",
             swift_build_support.targets.darwin_toolchain_prefix(args.install_prefix),
         ]
+        stdlib_deployment_targets = [
+            "macosx-x86_64",
+            "iphonesimulator-i386",
+            "iphonesimulator-x86_64",
+            "appletvsimulator-x86_64",
+            "watchsimulator-i386",
+
+            # Put iOS native targets last so that we test them last (it takes a
+            # long time).
+            "iphoneos-arm64",
+            "iphoneos-armv7",
+            "appletvos-arm64",
+            "watchos-armv7k"
+        ]
+        stdlib_cross_targets = [
+            "linux-armv7"
+        ]
+    elif system == 'Linux':
+        arch_mapping = [
+            ('x86_64' , 'x86_64'),
+            ('armv6' , 'armv6'),
+            ('armv7' , 'armv7'),
+            ('aarch64' , 'aarch64'),
+            ('ppc64' , 'powerpc64'),
+            ('ppc64le' , 'powerpc64le')
+        ]
+        arch_mapping = [(x, 'linux-'+y) for (x,y) in arch_mapping]
+
+        host_target = next(t for (s,t) in arch_mapping if machine.startswith(s))
+        stdlib_deployment_targets = [host_target]
+
+        # All other linux-* targets
+        stdlib_cross_targets = [t for (_,t) in arch_mapping]
+        stdlib_cross_targets.remove(host_target)
+    elif system == 'FreeBSD' and machine == 'amd64':
+        stdlib_deployment_targets = ["freebsd-x86_64"]
+    elif system == 'CYGWIN_NT-10' and machine == 'x86_64':
+        stdlib_deployment_targets = ["cygwin-x86_64"]
+    else:
+        print_with_argv0("Unknown operating system")
+        return 1
 
     if args.build_subdir is None:
         # Create a name for the build directory.
@@ -1043,16 +1087,15 @@ the number of parallel build jobs to use""",
             'watchsimulator',
         ])
 
-    host_build_script_impl_args = []
-
-    if platform.system() != 'Linux':
-        host_build_script_impl_args += [
-            "--skip-build-linux"
+    host_build_script_impl_args = [
+        "--stdlib-deployment-targets=" + " ".join(stdlib_deployment_targets)
         ]
 
     check_call(build_script_impl_args + host_build_script_impl_args)
 
     if args.cross_compile_stdlib_targets:
+        # Filter cross_compile_stdlib_targets by those supported for this host
+        stdlib_cross_targets = set(stdlib_cross_targets).intersection(args.cross_compile_stdlib_targets)
         # Currently only cross-compiling the swift libraries is supported.
         # Building the swift compiler would require building llvm too.
         llvm_path = os.path.join(build_dir, "llvm-"+args.host_target, 'bin')
@@ -1067,9 +1110,10 @@ the number of parallel build jobs to use""",
             "--build-swift-tools=0"
             ]
 
-        for target in args.cross_compile_stdlib_targets:
+        for target in stdlib_cross_targets:
             check_call(build_script_impl_args +
-                    ["--cross-compile-deployment-targets=" + target])
+                    ["--cross-compile-deployment-targets=" + target,
+                     "--stdlib-deployment-targets=" + target])
 
     if args.symbols_package:
         print('--- Creating symbols package ---')

utils/build-script-impl

@@ -181,6 +181,7 @@ KNOWN_SETTINGS=(
     install-libdispatch         ""               "whether to install libdispatch"
     darwin-install-extract-symbols ""            "whether to extract symbols with dsymutil during installations"
     host-target                 ""               "The host target. LLVM, Clang, and Swift will be built for this target. The built LLVM and Clang will be used to compile Swift for the cross-compilation targets. **This argument is required**"
+    stdlib-deployment-targets   ""               "The space separated list of stdlib targets to build"
     cross-compile-deployment-targets ""          "space-separated list of targets to cross-compile Swift for"
     cross-compile-sysroot       ""               "sysroot to use when cross-compiling"
     cross-compile-toolchain-bin ""               "toolchain binary dir to use when cross-compiling"
@@ -816,76 +817,6 @@ function is_cross_tools_deployment_target() {
     done
 }
 
-# A list of deployment targets that we compile or cross-compile the
-# Swift standard library for.
-STDLIB_DEPLOYMENT_TARGETS=()
-case "$(uname -s -m)" in
-    Linux\ x86_64)
-        STDLIB_DEPLOYMENT_TARGETS=(
-            "linux-x86_64"
-        )
-        ;;
-    Linux\ armv6*)
-        STDLIB_DEPLOYMENT_TARGETS=(
-            "linux-armv6"
-        )
-        ;;
-    Linux\ armv7*)
-        STDLIB_DEPLOYMENT_TARGETS=(
-            "linux-armv7"
-        )
-        ;;
-    Linux\ aarch64)
-        STDLIB_DEPLOYMENT_TARGETS=(
-            "linux-aarch64"
-        )
-        ;;
-    Linux\ ppc64)
-        STDLIB_DEPLOYMENT_TARGETS=(
-            "linux-powerpc64"
-        )
-        ;;
-    Linux\ ppc64le)
-        STDLIB_DEPLOYMENT_TARGETS=(
-            "linux-powerpc64le"
-        )
-        ;;
-    Darwin\ x86_64)
-        STDLIB_DEPLOYMENT_TARGETS=(
-            "macosx-x86_64"
-            "iphonesimulator-i386"
-            "iphonesimulator-x86_64"
-            "appletvsimulator-x86_64"
-            "watchsimulator-i386"
-
-            # Put iOS native targets last so that we test them last (it takes a
-            # long time).
-            "iphoneos-arm64"
-            "iphoneos-armv7"
-            "appletvos-arm64"
-            "watchos-armv7k"
-            "linux-armv7"
-        )
-        ;;
-
-    FreeBSD\ amd64)
-        STDLIB_DEPLOYMENT_TARGETS=(
-            "freebsd-x86_64"
-        )
-        ;;
-
-    CYGWIN_NT-10.0\ x86_64)
-        STDLIB_DEPLOYMENT_TARGETS=(
-            "cygwin-x86_64"
-        )
-        ;;
-
-    *)
-        echo "Unknown operating system"
-        exit 1
-        ;;
-esac
-
 #
 # Calculate source directories for each product.
 #
@@ -978,6 +909,7 @@ SWIFT_STDLIB_TARGETS=()
 SWIFT_BENCHMARK_TARGETS=()
 SWIFT_RUN_BENCHMARK_TARGETS=()
 SWIFT_TEST_TARGETS=()
+STDLIB_DEPLOYMENT_TARGETS=($STDLIB_DEPLOYMENT_TARGETS)
 for deployment_target in "${STDLIB_DEPLOYMENT_TARGETS[@]}"; do
     build_for_this_target=1
     test_this_target=1