[serializer] Add API to warm up startup snapshot with an additional script.

src/snapshot/mksnapshot.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <errno.h>
 #include <signal.h>
 #include <stdio.h>
 
 #include "include/libplatform/libplatform.h"
 #include "src/assembler.h"
@@ skipping 91 matching lines @@
       i::PrintF("Unable to open file \"%s\" for writing.\n", filename);
       exit(1);
     }
     return fp;
   }
 
   FILE* fp_;
   FILE* startup_blob_file_;
 };
 
-
-char* GetExtraCode(char* filename) {
+char* GetExtraCode(char* filename, const char* description) {
   if (filename == NULL || strlen(filename) == 0) return NULL;
-  ::printf("Embedding extra script: %s\n", filename);
+  if (strcmp(filename, "-") == 0) return NULL;
+  ::printf("Loading script for %s: %s\n", description, filename);
   FILE* file = base::OS::FOpen(filename, "rb");
   if (file == NULL) {
     fprintf(stderr, "Failed to open '%s': errno %d\n", filename, errno);
     exit(1);
   }
   fseek(file, 0, SEEK_END);
   size_t size = ftell(file);
   rewind(file);
   char* chars = new char[size + 1];
   chars[size] = '\0';
@@ skipping 11 matching lines @@
 
 
 int main(int argc, char** argv) {
   // By default, log code create information in the snapshot.
   i::FLAG_log_code = true;
   i::FLAG_logfile_per_isolate = false;
 
   // Print the usage if an error occurs when parsing the command line
   // flags or if the help flag is set.
   int result = i::FlagList::SetFlagsFromCommandLine(&argc, argv, true);
-  if (result > 0 || (argc != 1 && argc != 2) || i::FLAG_help) {
+  if (result > 0 || (argc > 3) || i::FLAG_help) {
     ::printf("Usage: %s --startup_src=... --startup_blob=... [extras]\n",
              argv[0]);
     i::FlagList::PrintHelp();
     return !i::FLAG_help;
   }
 
   i::CpuFeatures::Probe(true);
   V8::InitializeICU();
   v8::Platform* platform = v8::platform::CreateDefaultPlatform();
   v8::V8::InitializePlatform(platform);
   v8::V8::Initialize();
 
   {
     SnapshotWriter writer;
     if (i::FLAG_startup_src) writer.SetSnapshotFile(i::FLAG_startup_src);
     if (i::FLAG_startup_blob) writer.SetStartupBlobFile(i::FLAG_startup_blob);
-    char* extra_code = GetExtraCode(argc == 2 ? argv[1] : NULL);
-    StartupData blob = v8::V8::CreateSnapshotDataBlob(extra_code);
+
+    char* embed_script = GetExtraCode(argc >= 2 ? argv[1] : NULL, "embedding");
+    StartupData blob = v8::V8::CreateSnapshotDataBlob(embed_script);
+    delete[] embed_script;
+
+    char* warmup_script = GetExtraCode(argc >= 3 ? argv[2] : NULL, "warm up");
+    if (warmup_script) {
+      StartupData cold = blob;
+      blob = v8::V8::WarmUpSnapshotDataBlob(cold, warmup_script);
+      delete[] cold.data;
+      delete[] warmup_script;
+    }
+
     CHECK(blob.data);
     writer.WriteSnapshot(blob);
-    delete[] extra_code;
     delete[] blob.data;
   }
 
   V8::Dispose();
   V8::ShutdownPlatform();
   delete platform;
   return 0;
 }