Add gen_snapshot binaries, producing Linux ARM64/x64 snapshots

Inspired by `//runtime/bin:gen_snapshot_fuchsia`, required for go/dart-cross-compile.

TEST=ci, build only

Change-Id: Ie521c984a8f44d25f3f78d946af9416582a572dc
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/410402
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Ivan Inozemtsev <iinozemtsev@google.com>

runtime/BUILD.gn

@@ -128,6 +128,26 @@ config("dart_os_fuchsia_config") {
   defines = [ "DART_TARGET_OS_FUCHSIA" ]
 }
 
+# We need to build gen_snapshot targeting Linux ARM64 during a build
+# of the SDK. This configuration is used to unconditionally target
+# Linux ARM64. It should not be combined with dart_os_config and dart_arch_config.
+config("dart_linux_arm64_config") {
+  defines = [
+    "DART_TARGET_OS_LINUX",
+    "TARGET_ARCH_ARM64",
+  ]
+}
+
+# We need to build gen_snapshot targeting Linux ARM64 during a build
+# of the SDK. This configuration is used to unconditionally target
+# Linux ARM64. It should not be combined with dart_os_config and dart_arch_config.
+config("dart_linux_x64_config") {
+  defines = [
+    "DART_TARGET_OS_LINUX",
+    "TARGET_ARCH_X64",
+  ]
+}
+
 config("dart_arch_config") {
   defines = []
 

runtime/bin/BUILD.gn

@@ -107,6 +107,20 @@ build_libdart_builtin("libdart_builtin_product_host_targeting_host") {
   extra_configs = [ "..:dart_product_config" ]
 }
 
+build_libdart_builtin("libdart_builtin_product_linux_x64") {
+  extra_configs = [
+    "..:dart_product_config",
+    "..:dart_linux_x64_config",
+  ]
+}
+
+build_libdart_builtin("libdart_builtin_product_linux_arm64") {
+  extra_configs = [
+    "..:dart_product_config",
+    "..:dart_linux_arm64_config",
+  ]
+}
+
 template("build_native_assets_api") {
   extra_configs = []
   if (defined(invoker.extra_configs)) {
@@ -330,6 +344,31 @@ build_gen_snapshot("gen_snapshot_product_fuchsia") {
   ]
 }
 
+build_gen_snapshot("gen_snapshot_product_linux_x64") {
+  extra_configs = [
+    "..:dart_product_config",
+    "..:dart_linux_x64_config",
+  ]
+  extra_deps = [
+    ":gen_snapshot_dart_io_product_linux_x64",
+    ":libdart_builtin_product_linux_x64",
+    "..:libdart_precompiler_product_linux_x64",
+    "../platform:libdart_platform_precompiler_product_linux_x64",
+  ]
+}
+
+build_gen_snapshot("gen_snapshot_product_linux_arm64") {
+  extra_configs = [
+    "..:dart_product_config",
+    "..:dart_linux_arm64_config",
+  ]
+  extra_deps = [
+    ":gen_snapshot_dart_io_product_linux_arm64",
+    ":libdart_builtin_product_linux_arm64",
+    "..:libdart_precompiler_product_linux_arm64",
+    "../platform:libdart_platform_precompiler_product_linux_arm64",
+  ]
+}
 build_gen_snapshot("gen_snapshot_host_targeting_host") {
   extra_configs = [ "..:dart_maybe_product_config" ]
   extra_deps = [
@@ -434,6 +473,20 @@ build_gen_snapshot_dart_io("gen_snapshot_dart_io_product_fuchsia") {
   ]
 }
 
+build_gen_snapshot_dart_io("gen_snapshot_dart_io_product_linux_x64") {
+  extra_configs = [
+    "..:dart_product_config",
+    "..:dart_linux_x64_config",
+  ]
+}
+
+build_gen_snapshot_dart_io("gen_snapshot_dart_io_product_linux_arm64") {
+  extra_configs = [
+    "..:dart_product_config",
+    "..:dart_linux_arm64_config",
+  ]
+}
+
 # A source set for the implementation of 'dart:io' library.
 template("dart_io") {
   extra_configs = []

runtime/configs.gni

@@ -63,6 +63,18 @@ _precompiler_host_targeting_host_config =
 _precompiler_product_host_targeting_host_config =
     _base_host_targeting_host_config + _precompiler_base + _product
 
+_precompiler_product_linux_x64_config =
+    [
+      "$_dart_runtime:dart_config",
+      "$_dart_runtime:dart_linux_x64_config",
+    ] + _product + _precompiler_base
+
+_precompiler_product_linux_arm64_config =
+    [
+      "$_dart_runtime:dart_config",
+      "$_dart_runtime:dart_linux_arm64_config",
+    ] + _product + _precompiler_base
+
 _all_configs = [
   {
     suffix = "_jit"
@@ -148,6 +160,20 @@ _all_configs = [
     compiler = true
     is_product = false
   },
+  {
+    suffix = "_precompiler_product_linux_x64"
+    configs = _precompiler_product_linux_x64_config
+    snapshot = false
+    compiler = true
+    is_product = true
+  },
+  {
+    suffix = "_precompiler_product_linux_arm64"
+    configs = _precompiler_product_linux_arm64_config
+    snapshot = false
+    compiler = true
+    is_product = true
+  },
 ]
 
 # This template creates a target for each of the configurations listed above.

sdk/BUILD.gn

@@ -860,6 +860,13 @@ group("create_full_sdk") {
     if (dart_include_wasm_opt) {
       public_deps += [ ":copy_wasm_opt" ]
     }
+
+    # Do not include gen_snapshot binaries for cross-compilation into
+    # SDK, but add them as a dependency, so that they are built.
+    public_deps += [
+      "../runtime/bin:gen_snapshot_product_linux_arm64",
+      "../runtime/bin:gen_snapshot_product_linux_x64",
+    ]
   }
 }