[build] Set mnemonics.

Change-Id: Ib8729ebde2ae58c20afdc879336c3ad2a4a67b38
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/506282
Reviewed-by: Alexander Aprelev <aam@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>

utils/aot_snapshot.gni

@@ -52,6 +52,7 @@ template("aot_snapshot") {
   # simulator builds.
   kernel_label = target_name + "_dill"
   prebuilt_dart_action(kernel_label) {
+    mnemonic = "GEN_KERNEL"
     if (defined(invoker.pool)) {
       pool = invoker.pool
     }
@@ -148,8 +149,9 @@ template("aot_snapshot") {
 
   if (is_mac && codesigning_identity != "") {
     action(target_name) {
-      deps = [ ":$gen_snapshot_label" ]
+      mnemonic = "CODESIGN"
 
+      deps = [ ":$gen_snapshot_label" ]
       inputs = [ unsigned_snapshot ]
       outputs = [ signed_snapshot ]
 

utils/application_snapshot.gni

@@ -120,6 +120,7 @@ template("application_snapshot") {
   # Build the kernel file using the prebuilt VM to speed up the debug and
   # simulator builds.
   prebuilt_dart_action(target_name + "_dill") {
+    mnemonic = "GEN_KERNEL"
     if (defined(invoker.pool)) {
       pool = invoker.pool
     }
@@ -145,7 +146,8 @@ template("application_snapshot") {
     depfile = "$output.d"
 
     vm_args = [
-      # Ensure gen_kernel.dart will use this SDK hash when consuming/producing kernel.
+      # Ensure gen_kernel.dart will use this SDK hash when consuming/producing
+      # kernel.
       "-Dsdk_hash=$sdk_hash",
     ]
 
@@ -190,6 +192,7 @@ template("application_snapshot") {
     }
   } else {
     dart_action(target_name) {
+      mnemonic = "APP_JIT"
       if (defined(invoker.pool)) {
         pool = invoker.pool
       }
@@ -202,8 +205,8 @@ template("application_snapshot") {
 
       outputs = [ output ]
 
-      # Explicitly set DFE so Dart doesn't implicitly depend on the kernel service
-      # snapshot (creating a circular dep. for kernel-service_snapshot).
+      # Explicitly set DFE so Dart doesn't implicitly depend on the kernel
+      # service snapshot (creating a circular dep. for kernel-service_snapshot).
       dfe = "NEVER_LOADED"
 
       vm_args = [

utils/ddc/BUILD.gn

@@ -62,6 +62,7 @@ template("dart2js_compile") {
   rebased_output = rebase_path(out, root_build_dir)
 
   prebuilt_dart_action(target_name) {
+    mnemonic = "DART2JS"
     deps = invoker.deps + [ "../compiler:compile_dart2js_platform" ]
 
     inputs = [
@@ -201,6 +202,7 @@ template("ddc_compile") {
   #   * args: additional args to pass to dartdevc
 
   prebuilt_dart_action(target_name) {
+    mnemonic = "DDC"
     script = "../../pkg/dev_compiler/bin/dartdevc.dart"
     package_name = invoker.package
     out_dir = rebase_path("$js_gen_dir")
@@ -439,6 +441,7 @@ template("ddc_compile_sdk") {
   }
 
   prebuilt_dart_action(target_name) {
+    mnemonic = "DDC"
     deps = [
       ":ddc_files_stamp",
       ":ddc_platform",