Reapply "Save and restore feedback from JIT."

runtime/bin/main.cc

Index: runtime/bin/main.cc
diff --git a/runtime/bin/main.cc b/runtime/bin/main.cc
index 28804f4a1b6deccf32c39e52e95fbbe3a5cd4882..5b90c03f2994f898263fdf56b4e865987a2f4fb4 100644
--- a/runtime/bin/main.cc
+++ b/runtime/bin/main.cc
@@ -65,6 +65,16 @@ static bool use_dart_frontend = false;
 
 static const char* frontend_filename = NULL;
 
+// Value of the --save-feedback flag.
+// (This pointer points into an argv buffer and does not need to be
+// free'd.)
+static const char* save_feedback_filename = NULL;
+
+// Value of the --load-feedback flag.
+// (This pointer points into an argv buffer and does not need to be
+// free'd.)
+static const char* load_feedback_filename = NULL;
+
 // Value of the --package-root flag.
 // (This pointer points into an argv buffer and does not need to be
 // free'd.)
@@ -221,6 +231,28 @@ static bool ProcessPackagesOption(const char* arg,
 }
 
 
+static bool ProcessSaveFeedbackOption(const char* arg,
+                                      CommandLineOptions* vm_options) {
+  ASSERT(arg != NULL);
+  if (*arg == '-') {
+    return false;
+  }
+  save_feedback_filename = arg;
+  return true;
+}
+
+
+static bool ProcessLoadFeedbackOption(const char* arg,
+                                      CommandLineOptions* vm_options) {
+  ASSERT(arg != NULL);
+  if (*arg == '-') {
+    return false;
+  }
+  load_feedback_filename = arg;
+  return true;
+}
+
+
 static void* GetHashmapKeyFromString(char* key) {
   return reinterpret_cast<void*>(key);
 }
@@ -564,6 +596,8 @@ static struct {
     {"--snapshot=", ProcessSnapshotFilenameOption},
     {"--snapshot-kind=", ProcessSnapshotKindOption},
     {"--use-blobs", ProcessUseBlobsOption},
+    {"--save-feedback=", ProcessSaveFeedbackOption},
+    {"--load-feedback=", ProcessLoadFeedbackOption},
     {"--trace-loading", ProcessTraceLoadingOption},
     {"--hot-reload-test-mode", ProcessHotReloadTestModeOption},
     {"--hot-reload-rollback-test-mode", ProcessHotReloadRollbackTestModeOption},
@@ -1497,7 +1531,7 @@ static void GeneratePrecompiledSnapshot() {
 
 
 #if defined(TARGET_ARCH_X64)
-static void GeneratePrecompiledJITSnapshot() {
+static void GenerateAppJITSnapshot() {
   uint8_t* vm_isolate_buffer = NULL;
   intptr_t vm_isolate_size = 0;
   uint8_t* isolate_buffer = NULL;
@@ -1528,7 +1562,7 @@ static void GenerateAppSnapshot() {
   if (Dart_IsError(result)) {
     ErrorExit(kErrorExitCode, "%s\n", Dart_GetError(result));
   }
-  GeneratePrecompiledJITSnapshot();
+  GenerateAppJITSnapshot();
 #else
   // Create an application snapshot of the script.
   uint8_t* vm_isolate_buffer = NULL;
@@ -1687,8 +1721,27 @@ bool RunMainIsolate(const char* script_name, CommandLineOptions* dart_options) {
           {NULL, NULL, NULL}  // Must be terminated with NULL entries.
       };
 
+      uint8_t* feedback_buffer = NULL;
+      intptr_t feedback_length = 0;
+      if (load_feedback_filename != NULL) {
+        File* file = File::Open(load_feedback_filename, File::kRead);
+        if (file == NULL) {
+          ErrorExit(kErrorExitCode, "Failed to read JIT feedback.\n");
+        }
+        feedback_length = file->Length();
+        feedback_buffer = reinterpret_cast<uint8_t*>(malloc(feedback_length));
+        if (!file->ReadFully(feedback_buffer, feedback_length)) {
+          ErrorExit(kErrorExitCode, "Failed to read JIT feedback.\n");
+        }
+        file->Release();
+      }
+
       const bool reset_fields = gen_snapshot_kind == kAppAOT;
-      result = Dart_Precompile(standalone_entry_points, reset_fields);
+      result = Dart_Precompile(standalone_entry_points, reset_fields,
+                               feedback_buffer, feedback_length);
+      if (feedback_buffer != NULL) {
+        free(feedback_buffer);
+      }
       CHECK_RESULT(result);
     }
 
@@ -1732,6 +1785,16 @@ bool RunMainIsolate(const char* script_name, CommandLineOptions* dart_options) {
         }
       }
       CHECK_RESULT(result);
+
+      if (save_feedback_filename != NULL) {
+        uint8_t* buffer = NULL;
+        intptr_t size = 0;
+        result = Dart_SaveJITFeedback(&buffer, &size);
+        if (Dart_IsError(result)) {
+          ErrorExit(kErrorExitCode, "%s\n", Dart_GetError(result));
+        }
+        WriteSnapshotFile(save_feedback_filename, false, buffer, size);
+      }
     }
   }