Optimize compile time by using asm.

Switches to using asm incbin to embed the V8 snapshot instead of
outputing C code and then compiling it.

Compile time for from_snapshot.o goes from 44s to 1s.

BUILD.gn

@@ -107,6 +107,12 @@ static_library("libdeno") {
   sources = [
     "src/from_snapshot.cc",
   ]
+  data = [
+    "$target_gen_dir/snapshot_deno.bin",
+  ]
+  data_deps = [
+    ":bundle",
+  ]
   deps = [
     ":create_snapshot_deno",
     ":deno_bindings",
@@ -139,6 +145,9 @@ v8_source_set("deno_base_test") {
     "src/from_snapshot.cc",
     "src/mock_runtime_test.cc",
   ]
+  data = [
+    "$target_gen_dir/snapshot_mock_runtime.bin",
+  ]
   deps = [
     ":create_snapshot_mock_runtime",
     ":deno_base",

build_extra/deno.gni

@@ -28,15 +28,15 @@ template("create_snapshot") {
                            ])
     tool = ":snapshot_creator"
     visibility = [ ":*" ]  # Only targets in this file can depend on this.
-    snapshot_out_cc = "$target_gen_dir/snapshot_$name.cc"
+    snapshot_out_bin = "$target_gen_dir/snapshot_$name.bin"
     inputs = [
       invoker.js,
     ]
     outputs = [
-      snapshot_out_cc,
+      snapshot_out_bin,
     ]
     args = [
-      rebase_path(snapshot_out_cc, root_build_dir),
+      rebase_path(snapshot_out_bin, root_build_dir),
       rebase_path(invoker.js, root_build_dir),
     ]
 

src/file_util.cc

@@ -9,28 +9,6 @@
 
 namespace deno {
 
-std::string BinaryContentAsC(const char* name, const std::string& data) {
-  char b[512];
-  std::string output;
-  // Write prefix.
-  snprintf(b, sizeof(b), "static const char %s_data[] = {\n", name);
-  output.append(b);
-  // Write actual data.
-  for (size_t i = 0; i < data.size(); ++i) {
-    if ((i & 0x1F) == 0x1F) output.append("\n");
-    if (i > 0) output.append(",");
-    snprintf(b, sizeof(b), "%hhu", static_cast<unsigned char>(data.at(i)));
-    output.append(b);
-  }
-  output.append("\n");
-  // Write suffix.
-  output.append("};\n");
-  snprintf(b, sizeof(b), "static const int %s_size = %" PRId64 ";\n", name,
-           static_cast<uint64_t>(data.size()));
-  output.append(b);
-  return output;
-}
-
 bool ReadFileToString(const char* fn, std::string* contents) {
   std::ifstream file(fn, std::ios::binary);
   if (file.fail()) {

src/file_util.h

@@ -7,7 +7,6 @@
 namespace deno {
 bool ReadFileToString(const char* fn, std::string* contents);
 std::string Basename(std::string const& filename);
-std::string BinaryContentAsC(const char* name, const std::string& data);
 }  // namespace deno
 
 #endif  // FILE_UTIL_H_

src/file_util_test.cc

@@ -17,12 +17,5 @@ TEST(FileUtilTest, Basename) {
   EXPECT_EQ("foo.txt", deno::Basename("C:\\home\\ryan\\foo.txt"));
 }
 
-TEST(FileUtilTest, BinaryContentAsC) {
-  auto c_code = deno::BinaryContentAsC("aaa", std::string("bbb"));
-  EXPECT_TRUE(c_code.find("static const char aaa_data[]") != std::string::npos);
-  EXPECT_TRUE(c_code.find("static const int aaa_size = 3;") !=
-              std::string::npos);
-}
-
 // TODO(ry) success unit test. Needs a tempfile or fixture.
 // TEST(FileUtilTest, ReadFileToStringSuccess) { }

src/from_snapshot.cc

@@ -10,11 +10,21 @@
 #include "deno.h"
 #include "internal.h"
 
+extern const char deno_snapshot_start asm("deno_snapshot_start");
+extern const char deno_snapshot_end asm("deno_snapshot_end");
 #ifdef DENO_MOCK_RUNTIME
-#include "snapshot_mock_runtime.cc"
+asm(".data\n"
+    "deno_snapshot_start: .incbin \"gen/snapshot_mock_runtime.bin\"\n"
+    "deno_snapshot_end:\n"
+    ".globl deno_snapshot_start;\n"
+    ".globl deno_snapshot_end;");
 #else
-#include "snapshot_deno.cc"
-#endif
+asm(".data\n"
+    "deno_snapshot_start: .incbin \"gen/snapshot_deno.bin\"\n"
+    "deno_snapshot_end:\n"
+    ".globl deno_snapshot_start;\n"
+    ".globl deno_snapshot_end;");
+#endif  // DENO_MOCK_RUNTIME
 
 namespace deno {
 
@@ -42,7 +52,13 @@ Deno* NewFromSnapshot(void* data, deno_recv_cb cb) {
   params.array_buffer_allocator =
       v8::ArrayBuffer::Allocator::NewDefaultAllocator();
   params.external_references = external_references;
-  params.snapshot_blob = StartupBlob_snapshot();
+
+  CHECK_NE(&deno_snapshot_start, nullptr);
+  int snapshot_len =
+      static_cast<int>(&deno_snapshot_end - &deno_snapshot_start);
+  static v8::StartupData snapshot = {&deno_snapshot_start, snapshot_len};
+  params.snapshot_blob = &snapshot;
+
   v8::Isolate* isolate = v8::Isolate::New(params);
   AddIsolate(d, isolate);
 

src/snapshot_creator.cc

@@ -40,72 +40,17 @@ v8::StartupData MakeSnapshot(const char* js_filename, const char* js_source) {
   return snapshot_blob;
 }
 
-class StartupDataCppWriter {
- public:
-  StartupDataCppWriter(const char* name, const char* filename,
-                       const std::string& data)
-      : name_(name),
-        filename_(filename),
-        data_(data),
-        file_(filename_, std::ios::binary) {}
-
-  bool Write() {
-    if (file_.bad()) {
-      return false;
-    }
-    WritePrefix();
-    WriteData();
-    WriteSuffix();
-
-    file_.close();
-    // printf("Wrote %s %d %s \n", name_, data_.size(), filename_);
-    return !file_.bad();
-  }
-
- private:
-  void WritePrefix() {
-    file_ << "// Autogenerated snapshot file. Do not edit.\n\n";
-    file_ << "#include \"third_party/v8/include/v8.h\"\n\n";
-    file_ << "namespace deno { \n\n";
-  }
-
-  void WriteSuffix() {
-    char buffer[500];
-    snprintf(buffer, sizeof(buffer), "v8::StartupData* StartupBlob_%s() {\n",
-             name_);
-    file_ << buffer;
-    snprintf(buffer, sizeof(buffer), "  return &%s_blob;\n", name_);
-    file_ << buffer;
-    file_ << "}\n\n";
-    file_ << "}  // namespace deno\n\n";
-  }
-
-  void WriteData() {
-    char buffer[500];
-    file_ << BinaryContentAsC(name_, data_);
-    snprintf(buffer, sizeof(buffer),
-             "static v8::StartupData %s_blob = { %s_data, %s_size };\n", name_,
-             name_, name_);
-    file_ << buffer;
-  }
-
-  const char* name_;
-  const char* filename_;
-  std::string data_;
-  std::ofstream file_;
-};
-
 }  // namespace deno
 
 int main(int argc, char** argv) {
-  const char* snapshot_out_cc = argv[1];
+  const char* snapshot_out_bin = argv[1];
   const char* js_fn = argv[2];
 
   v8::V8::SetFlagsFromCommandLine(&argc, argv, true);
 
   CHECK_EQ(argc, 3);
   CHECK_NE(js_fn, nullptr);
-  CHECK_NE(snapshot_out_cc, nullptr);
+  CHECK_NE(snapshot_out_bin, nullptr);
 
   std::string js_source;
   CHECK(deno::ReadFileToString(js_fn, &js_source));
@@ -114,6 +59,8 @@ int main(int argc, char** argv) {
   auto snapshot_blob = deno::MakeSnapshot(js_fn, js_source.c_str());
   std::string snapshot_str(snapshot_blob.data, snapshot_blob.raw_size);
 
-  deno::StartupDataCppWriter writer("snapshot", snapshot_out_cc, snapshot_str);
-  CHECK(writer.Write());
+  std::ofstream file_(snapshot_out_bin, std::ios::binary);
+  file_ << snapshot_str;
+  file_.close();
+  return file_.bad();
 }