Revert "[build] Make separate snapshot for trusted variant"

This reverts commit 40d66d8bf8.

Reason for revert:
https://build.chromium.org/p/client.v8/builders/V8%20Mac64/builds/20910

Original change's description:
> [build] Make separate snapshot for trusted variant
> 
> This enables side-by-side snapshots with and without untrusted-code
> mitigations. It'll be the default in all V8 stand-alone builds
> with external startup data. Internal snapshots are not supported.
> 
> The files snapshot_blob.bin and snapshot_blob_trusted.bin will be
> bundled with V8 on swarming and the correct file is loaded dependent
> on the --untrusted-code-mitigations runtime flag.
> 
> Likewise we embed two snapshots for builtins.
> 
> Side-by-side snapshots won't be supported in Chromium.
> 
> Bug: v8:7441
> Change-Id: I2949ddfd5773649946b1c8e74751d48ad1d9c524
> Reviewed-on: https://chromium-review.googlesource.com/960004
> Commit-Queue: Michael Achenbach <machenbach@chromium.org>
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#52028}

TBR=rmcilroy@chromium.org,machenbach@chromium.org,yangguo@chromium.org,mstarzinger@chromium.org,jgruber@chromium.org

Change-Id: I5b18f7aff7c05a17842fc68d785bb617eeca4a41
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:7441
Reviewed-on: https://chromium-review.googlesource.com/968622
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52029}

BUILD.gn

@@ -9,7 +9,6 @@ import("//build/config/host_byteorder.gni")
 import("//build/config/jumbo.gni")
 import("//build/config/mips.gni")
 import("//build/config/sanitizers/sanitizers.gni")
-import("//build_overrides/build.gni")
 
 if (is_android) {
   import("//build/config/android/rules.gni")
@@ -327,9 +326,6 @@ config("features") {
   if (v8_enable_embedded_builtins) {
     defines += [ "V8_EMBEDDED_BUILTINS" ]
   }
-  if (v8_use_multi_snapshots) {
-    defines += [ "V8_MULTI_SNAPSHOTS" ]
-  }
 }
 
 config("toolchain") {
@@ -722,8 +718,6 @@ action("d8_js2c") {
 if (is_android && enable_java_templates) {
   android_assets("v8_external_startup_data_assets") {
     if (v8_use_external_startup_data) {
-      # We don't support side-by-side snapshots on Android within Chromium.
-      assert(!v8_use_multi_snapshots)
       deps = [
         "//v8",
       ]
@@ -811,24 +805,8 @@ action("postmortem-metadata") {
          rebase_path(sources, root_build_dir)
 }
 
-# Template to generate different V8 snapshots based on different runtime flags.
+if (v8_use_snapshot) {
-# Can be invoked with run_mksnapshot(<name>). The target will resolve to
+  action("run_mksnapshot") {
-# run_mksnapshot_<name>. If <name> is "default", no file suffixes will be used.
-# Otherwise files are suffixed, e.g. embedded_<name>.cc and
-# snapshot_blob_<name>.bin.
-#
-# The template exposes the variables:
-#   args: additional flags for mksnapshots
-#   embedded_suffix: a camel case suffix for method names in the embedded
-#       snapshot.
-template("run_mksnapshot") {
-  name = target_name
-  if (name == "default") {
-    suffix = ""
-  } else {
-    suffix = "_$name"
-  }
-  action("run_mksnapshot_" + name) {
     visibility = [ ":*" ]  # Only targets in this file can depend on this.
 
     deps = [
@@ -848,20 +826,12 @@ template("run_mksnapshot") {
       "--turbo_instruction_scheduling",
     ]
 
-    args += invoker.args
-
     if (v8_enable_embedded_builtins) {
-      outputs += [ "$target_gen_dir/embedded${suffix}.cc" ]
+      outputs += [ "$target_gen_dir/embedded.cc" ]
       args += [
         "--embedded_src",
-        rebase_path("$target_gen_dir/embedded${suffix}.cc", root_build_dir),
+        rebase_path("$target_gen_dir/embedded.cc", root_build_dir),
       ]
-      if (invoker.embedded_suffix != "") {
-        args += [
-          "--embedded_suffix",
-          invoker.embedded_suffix,
-        ]
-      }
     }
 
     if (v8_random_seed != "0") {
@@ -883,16 +853,16 @@ template("run_mksnapshot") {
     }
 
     if (v8_use_external_startup_data) {
-      outputs += [ "$root_out_dir/snapshot_blob${suffix}.bin" ]
+      outputs += [ "$root_out_dir/snapshot_blob.bin" ]
       args += [
         "--startup_blob",
-        rebase_path("$root_out_dir/snapshot_blob${suffix}.bin", root_build_dir),
+        rebase_path("$root_out_dir/snapshot_blob.bin", root_build_dir),
       ]
     } else {
-      outputs += [ "$target_gen_dir/snapshot${suffix}.cc" ]
+      outputs += [ "$target_gen_dir/snapshot.cc" ]
       args += [
         "--startup_src",
-        rebase_path("$target_gen_dir/snapshot${suffix}.cc", root_build_dir),
+        rebase_path("$target_gen_dir/snapshot.cc", root_build_dir),
       ]
     }
 
@@ -910,23 +880,6 @@ template("run_mksnapshot") {
   }
 }
 
-if (v8_use_snapshot) {
-  run_mksnapshot("default") {
-    args = []
-    if (v8_enable_embedded_builtins) {
-      embedded_suffix = ""
-    }
-  }
-  if (v8_use_multi_snapshots) {
-    run_mksnapshot("trusted") {
-      args = [ "--no-untrusted-code-mitigations" ]
-      if (v8_enable_embedded_builtins) {
-        embedded_suffix = "Trusted"
-      }
-    }
-  }
-}
-
 action("v8_dump_build_config") {
   script = "tools/testrunner/utils/dump_build_config.py"
   outputs = [
@@ -1032,7 +985,7 @@ if (v8_use_snapshot && !v8_use_external_startup_data) {
     public_deps = [
       # This should be public so downstream targets can declare the snapshot
       # output file as their inputs.
-      ":run_mksnapshot_default",
+      ":run_mksnapshot",
     ]
 
     sources = [
@@ -1072,13 +1025,9 @@ if (v8_use_snapshot && v8_use_external_startup_data) {
     ]
     public_deps = [
       ":natives_blob",
-      ":run_mksnapshot_default",
+      ":run_mksnapshot",
     ]
 
-    if (v8_use_multi_snapshots) {
-      public_deps += [ ":run_mksnapshot_trusted" ]
-    }
-
     sources = [
       "src/setup-isolate-deserialize.cc",
       "src/snapshot/natives-external.cc",
@@ -1087,9 +1036,6 @@ if (v8_use_snapshot && v8_use_external_startup_data) {
 
     if (v8_enable_embedded_builtins) {
       sources += [ "$target_gen_dir/embedded.cc" ]
-      if (v8_use_multi_snapshots) {
-        sources += [ "$target_gen_dir/embedded_trusted.cc" ]
-      }
     }
 
     configs = [ ":internal_config" ]

gni/isolate.gni

@@ -116,11 +116,6 @@ template("v8_isolate_run") {
       } else {
         use_snapshot = "false"
       }
-      if (v8_use_multi_snapshots) {
-        multi_snapshots = "1"
-      } else {
-        multi_snapshots = "0"
-      }
       if (v8_has_valgrind) {
         has_valgrind = "1"
       } else {
@@ -180,8 +175,6 @@ template("v8_isolate_run") {
         "--config-variable",
         "ubsan_vptr=$ubsan_vptr",
         "--config-variable",
-        "v8_use_multi_snapshots=$multi_snapshots",
-        "--config-variable",
         "v8_use_external_startup_data=$use_external_startup_data",
         "--config-variable",
         "v8_use_snapshot=$use_snapshot",

gni/v8.gni

@@ -37,9 +37,6 @@ declare_args() {
   # https://803591
   v8_use_snapshot = !(is_win && host_os != "win" && target_cpu == "x64")
 
-  # Enable several snapshots side-by-side (e.g. default and for trusted code).
-  v8_use_multi_snapshots = ""
-
   # Use external files for startup data blobs:
   # the JS builtins sources and the start snapshot.
   v8_use_external_startup_data = ""
@@ -61,10 +58,6 @@ if (v8_use_external_startup_data == "") {
   v8_use_external_startup_data = v8_use_snapshot && !is_ios
 }
 
-if (v8_use_multi_snapshots == "") {
-  v8_use_multi_snapshots = v8_use_external_startup_data && !build_with_chromium
-}
-
 if (v8_enable_backtrace == "") {
   v8_enable_backtrace = is_debug && !v8_optimized_debug
 }

src/base.isolate

@@ -17,13 +17,6 @@
         ],
       },
     }],
-    ['v8_use_snapshot=="true" and v8_use_external_startup_data==1 and v8_use_multi_snapshots==1', {
-      'variables': {
-        'files': [
-          '<(PRODUCT_DIR)/snapshot_blob_trusted.bin',
-        ],
-      },
-    }],
     ['tsan==1', {
       'variables': {
         'files': [

src/flag-definitions.h

@@ -1067,8 +1067,6 @@ DEFINE_INT(testing_prng_seed, 42, "Seed used for threading test randomness")
 // mksnapshot.cc
 DEFINE_STRING(embedded_src, nullptr,
               "Path for the generated embedded data file. (mksnapshot only)")
-DEFINE_STRING(embedded_suffix, nullptr,
-              "Symbol suffix in embedded data file. (mksnapshot only)")
 DEFINE_STRING(startup_src, nullptr,
               "Write V8 startup as C++ src. (mksnapshot only)")
 DEFINE_STRING(startup_blob, nullptr,

src/isolate.cc

@@ -70,11 +70,6 @@ base::Atomic32 ThreadId::highest_thread_id_ = 0;
 extern const uint8_t* DefaultEmbeddedBlob();
 extern uint32_t DefaultEmbeddedBlobSize();
 
-#ifdef V8_MULTI_SNAPSHOTS
-extern const uint8_t* DefaultEmbeddedBlobTrusted();
-extern uint32_t DefaultEmbeddedBlobSizeTrusted();
-#endif
-
 const uint8_t* Isolate::embedded_blob() const { return embedded_blob_; }
 uint32_t Isolate::embedded_blob_size() const { return embedded_blob_size_; }
 #endif
@@ -2944,18 +2939,8 @@ bool Isolate::Init(StartupDeserializer* des) {
       new CompilerDispatcher(this, V8::GetCurrentPlatform(), FLAG_stack_size);
 
 #ifdef V8_EMBEDDED_BUILTINS
-#ifdef V8_MULTI_SNAPSHOTS
-  if (FLAG_untrusted_code_mitigations) {
-    embedded_blob_ = DefaultEmbeddedBlob();
-    embedded_blob_size_ = DefaultEmbeddedBlobSize();
-  } else {
-    embedded_blob_ = DefaultEmbeddedBlobTrusted();
-    embedded_blob_size_ = DefaultEmbeddedBlobSizeTrusted();
-  }
-#else
   embedded_blob_ = DefaultEmbeddedBlob();
   embedded_blob_size_ = DefaultEmbeddedBlobSize();
-#endif
 #endif
 
   // Enable logging before setting up the heap

src/snapshot/embedded-empty.cc

@@ -12,12 +12,6 @@ namespace internal {
 #ifdef V8_EMBEDDED_BUILTINS
 const uint8_t* DefaultEmbeddedBlob() { return nullptr; }
 uint32_t DefaultEmbeddedBlobSize() { return 0; }
-
-#ifdef V8_MULTI_SNAPSHOTS
-const uint8_t* DefaultEmbeddedBlobTrusted() { return nullptr; }
-uint32_t DefaultEmbeddedBlobSizeTrusted() { return 0; }
-#endif
-
 #endif
 
 }  // namespace internal

src/snapshot/mksnapshot.cc

@@ -26,10 +26,6 @@ class SnapshotWriter {
   void SetEmbeddedFile(const char* embedded_cpp_file) {
     embedded_cpp_path_ = embedded_cpp_file;
   }
-
-  void SetEmbeddedSuffix(const char* embedded_suffix) {
-    embedded_suffix_ = embedded_suffix;
-  }
 #endif
 
   void SetSnapshotFile(const char* snapshot_cpp_file) {
@@ -128,7 +124,7 @@ class SnapshotWriter {
 
     WriteEmbeddedFilePrefix(fp);
     WriteEmbeddedFileData(fp, blob);
-    WriteEmbeddedFileSuffix(fp, embedded_suffix_);
+    WriteEmbeddedFileSuffix(fp);
 
     fclose(fp);
   }
@@ -142,16 +138,14 @@ class SnapshotWriter {
     fprintf(fp, "namespace {\n\n");
   }
 
-  static void WriteEmbeddedFileSuffix(FILE* fp, const char* symbol_suffix) {
+  static void WriteEmbeddedFileSuffix(FILE* fp) {
     fprintf(fp, "}  // namespace\n\n");
+    fprintf(
+        fp,
+        "const uint8_t* DefaultEmbeddedBlob() { return v8_embedded_blob_; }\n");
     fprintf(fp,
-            "const uint8_t* DefaultEmbeddedBlob%s() { return "
+            "uint32_t DefaultEmbeddedBlobSize() { return "
-            "v8_embedded_blob_; }\n",
+            "v8_embedded_blob_size_; }\n\n");
-            symbol_suffix);
-    fprintf(fp,
-            "uint32_t DefaultEmbeddedBlobSize%s() { return "
-            "v8_embedded_blob_size_; }\n\n",
-            symbol_suffix);
     fprintf(fp, "}  // namespace internal\n");
     fprintf(fp, "}  // namespace v8\n");
   }
@@ -217,7 +211,6 @@ class SnapshotWriter {
 
 #ifdef V8_EMBEDDED_BUILTINS
   const char* embedded_cpp_path_ = nullptr;
-  const char* embedded_suffix_ = "";
 #endif
   const char* snapshot_cpp_path_;
   const char* snapshot_blob_path_;
@@ -383,8 +376,6 @@ int main(int argc, char** argv) {
     if (i::FLAG_startup_blob) writer.SetStartupBlobFile(i::FLAG_startup_blob);
 #ifdef V8_EMBEDDED_BUILTINS
     if (i::FLAG_embedded_src) writer.SetEmbeddedFile(i::FLAG_embedded_src);
-    if (i::FLAG_embedded_suffix)
-      writer.SetEmbeddedSuffix(i::FLAG_embedded_suffix);
 #endif
 
     std::unique_ptr<char> embed_script(

src/startup-data-util.cc

@@ -10,7 +10,6 @@
 #include "src/base/file-utils.h"
 #include "src/base/logging.h"
 #include "src/base/platform/platform.h"
-#include "src/flags.h"
 #include "src/utils.h"
 
 
@@ -87,15 +86,9 @@ void InitializeExternalStartupData(const char* directory_path) {
 #ifdef V8_USE_EXTERNAL_STARTUP_DATA
   char* natives;
   char* snapshot;
-  const char* snapshot_name = "snapshot_blob.bin";
-#ifdef V8_MULTI_SNAPSHOTS
-  if (!FLAG_untrusted_code_mitigations) {
-    snapshot_name = "snapshot_blob_trusted.bin";
-  }
-#endif
   LoadFromFiles(
       base::RelativePath(&natives, directory_path, "natives_blob.bin"),
-      base::RelativePath(&snapshot, directory_path, snapshot_name));
+      base::RelativePath(&snapshot, directory_path, "snapshot_blob.bin"));
   free(natives);
   free(snapshot);
 #endif  // V8_USE_EXTERNAL_STARTUP_DATA

tools/run_perf.py

@@ -793,12 +793,6 @@ class AndroidPlatform(Platform):  # pragma: no cover
         target_dir,
         skip_if_missing=True,
     )
-    self._PushFile(
-        shell_dir,
-        "snapshot_blob_trusted.bin",
-        target_dir,
-        skip_if_missing=True,
-    )
     self._PushFile(
         shell_dir,
         "icudtl.dat",