[build] Don't make kernel generating depend on training run inputs.

Shortens the critial path when building the SDK by ~10 seconds.

Change-Id: I87bb31646c6468fe974da9fbc4ca2e09af39802b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/361760
Reviewed-by: Jonas Termansen <sortie@google.com>
Commit-Queue: Jonas Termansen <sortie@google.com>

utils/application_snapshot.gni

@@ -27,6 +27,12 @@ declare_args() {
 #  training_args (required):
 #    Arguments to pass to the Dart application for the training run.
 #
+#  training_deps (optional):
+#    Deps needed for the training run.
+#
+#  training_inputs (optional):
+#    Inputs needed for the training run.
+#
 #  vm_args (optional):
 #    Additional arguments to the Dart VM.
 #
@@ -57,6 +63,14 @@ template("application_snapshot") {
   }
   main_dart = invoker.main_dart
   training_args = invoker.training_args
+  training_deps = []
+  if (defined(invoker.training_deps)) {
+    training_deps += invoker.training_deps
+  }
+  training_inputs = []
+  if (defined(invoker.training_inputs)) {
+    training_inputs += invoker.training_inputs
+  }
   name = target_name
   if (defined(invoker.name)) {
     name = invoker.name
@@ -149,18 +163,20 @@ template("application_snapshot") {
 
       assert(snapshot_vm_args != "", "Ignoring unused argument")
       assert(training_args != "", "Ignoring unused argument")
+      assert(training_inputs != "", "Ignoring unused argument")
+      assert(training_deps != "", "Ignoring unused argument")
     }
   } else {
     dart_action(target_name) {
       if (defined(invoker.pool)) {
         pool = invoker.pool
       }
-      deps = extra_deps + [ ":${target_name}_dill" ]
+      deps = extra_deps + [ ":${target_name}_dill" ] + training_deps
       depfile = "$output.d"
 
       script = "$target_gen_dir/$name.dart.dill"
 
-      inputs = extra_inputs
+      inputs = extra_inputs + training_inputs
 
       outputs = [ output ]
 

utils/compiler/BUILD.gn

@@ -53,18 +53,17 @@ prebuilt_dart_action("dart2js_create_snapshot_entry") {
 sdk_root = "../../sdk"
 
 application_snapshot("dart2js") {
-  deps = [
+  deps = [ ":dart2js_create_snapshot_entry" ]
+  training_deps = [
     ":compile_dart2js_platform",
     ":compile_dart2js_platform_unsound",
-    ":dart2js_create_snapshot_entry",
   ]
-  inputs = [
+  training_inputs = [
     "$root_out_dir/dart2js_platform.dill",
     "$root_out_dir/dart2js_platform_unsound.dill",
     "$root_out_dir/dart2js_outline.dill",
     "$root_out_dir/dart2js_outline_unsound.dill",
   ]
-  vm_args = []
   main_dart = "$target_gen_dir/dart2js.dart"
   training_args = [
     "--invoker=gn_build",

utils/ddc/BUILD.gn

@@ -26,8 +26,8 @@ application_snapshot("dartdevc") {
     rebase_path("../../pkg/dev_compiler/bin/dartdevc.dart"),
   ]
 
-  deps = [ ":ddc_platform" ]
-  inputs = [ sdk_outline_dill ]
+  training_deps = [ ":ddc_platform" ]
+  training_inputs = [ sdk_outline_dill ]
 }
 
 template("dart2js_compile") {