From c1eff30f1f34757c6c948de3b80617934c26ab10 Mon Sep 17 00:00:00 2001
From: "yangguo@chromium.org"
 <yangguo@chromium.org@ce2b1a6d-e550-0410-aec6-3dcde31c8c00>
Date: Wed, 21 May 2014 15:00:32 +0000
Subject: [PATCH] Move promises recorded for debugging to thread local data.

R=rossberg@chromium.org

Review URL: https://codereview.chromium.org/296693005

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21413 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
---
 src/debug.cc | 42 +++++++++++++++++++++++++++---------------
 src/debug.h  | 29 ++++++++++++++++++++++-------
 2 files changed, 49 insertions(+), 22 deletions(-)

diff --git a/src/debug.cc b/src/debug.cc
index b13a163157..6cfc5001ae 100644
--- a/src/debug.cc
+++ b/src/debug.cc
@@ -37,8 +37,6 @@ Debug::Debug(Isolate* isolate)
       disable_break_(false),
       break_on_exception_(false),
       break_on_uncaught_exception_(false),
-      promise_catch_handlers_(0),
-      promise_getters_(0),
       isolate_(isolate) {
   ThreadInit();
 }
@@ -511,6 +509,7 @@ void Debug::ThreadInit() {
   thread_local_.debugger_entry_ = NULL;
   thread_local_.has_pending_interrupt_ = false;
   thread_local_.restarter_frame_function_pointer_ = NULL;
+  thread_local_.promise_on_stack_ = NULL;
 }
 
 
@@ -1249,29 +1248,42 @@ bool Debug::IsBreakOnException(ExceptionBreakType type) {
 }
 
 
+Debug::PromiseOnStack::PromiseOnStack(Isolate* isolate,
+                                      PromiseOnStack* prev,
+                                      Handle<JSFunction> getter)
+    : isolate_(isolate), prev_(prev) {
+  handler_ = StackHandler::FromAddress(
+      Isolate::handler(isolate->thread_local_top()));
+  getter_ = Handle<JSFunction>::cast(
+      isolate->global_handles()->Create(*getter));
+}
+
+
+Debug::PromiseOnStack::~PromiseOnStack() {
+  isolate_->global_handles()->Destroy(Handle<Object>::cast(getter_).location());
+}
+
+
 void Debug::PromiseHandlePrologue(Handle<JSFunction> promise_getter) {
-  Handle<JSFunction> promise_getter_global = Handle<JSFunction>::cast(
-      isolate_->global_handles()->Create(*promise_getter));
-  StackHandler* handler =
-      StackHandler::FromAddress(Isolate::handler(isolate_->thread_local_top()));
-  promise_getters_.Add(promise_getter_global);
-  promise_catch_handlers_.Add(handler);
+  PromiseOnStack* prev = thread_local_.promise_on_stack_;
+  thread_local_.promise_on_stack_ =
+      new PromiseOnStack(isolate_, prev, promise_getter);
 }
 
 
 void Debug::PromiseHandleEpilogue() {
-  if (promise_catch_handlers_.length() == 0) return;
-  promise_catch_handlers_.RemoveLast();
-  Handle<Object> promise_getter = promise_getters_.RemoveLast();
-  isolate_->global_handles()->Destroy(promise_getter.location());
+  if (thread_local_.promise_on_stack_ == NULL) return;
+  PromiseOnStack* prev = thread_local_.promise_on_stack_->prev();
+  delete thread_local_.promise_on_stack_;
+  thread_local_.promise_on_stack_ = prev;
 }
 
 
 Handle<Object> Debug::GetPromiseForUncaughtException() {
   Handle<Object> undefined = isolate_->factory()->undefined_value();
-  if (promise_getters_.length() == 0) return undefined;
-  Handle<JSFunction> promise_getter = promise_getters_.last();
-  StackHandler* promise_catch = promise_catch_handlers_.last();
+  if (thread_local_.promise_on_stack_ == NULL) return undefined;
+  Handle<JSFunction> promise_getter = thread_local_.promise_on_stack_->getter();
+  StackHandler* promise_catch = thread_local_.promise_on_stack_->handler();
   // Find the top-most try-catch handler.
   StackHandler* handler = StackHandler::FromAddress(
       Isolate::handler(isolate_->thread_local_top()));
diff --git a/src/debug.h b/src/debug.h
index 9a110475dc..7956237045 100644
--- a/src/debug.h
+++ b/src/debug.h
@@ -519,13 +519,21 @@ class Debug {
   bool break_on_exception_;
   bool break_on_uncaught_exception_;
 
-  // When a promise is being resolved, we may want to trigger a debug event for
-  // the case we catch a throw.  For this purpose we remember the try-catch
-  // handler address that would catch the exception.  We also hold onto a
-  // closure that returns a promise if the exception is considered uncaught.
-  // Due to the possibility of reentry we use a list to form a stack.
-  List<StackHandler*> promise_catch_handlers_;
-  List<Handle<JSFunction> > promise_getters_;
+  class PromiseOnStack {
+   public:
+    PromiseOnStack(Isolate* isolate,
+                   PromiseOnStack* prev,
+                   Handle<JSFunction> getter);
+    ~PromiseOnStack();
+    StackHandler* handler() { return handler_; }
+    Handle<JSFunction> getter() { return getter_; }
+    PromiseOnStack* prev() { return prev_; }
+   private:
+    Isolate* isolate_;
+    StackHandler* handler_;
+    Handle<JSFunction> getter_;
+    PromiseOnStack* prev_;
+  };
 
   // Per-thread data.
   class ThreadLocal {
@@ -578,6 +586,13 @@ class Debug {
     // of the pointer to function being restarted. Otherwise (most of the time)
     // stores NULL. This pointer is used with 'step in' implementation.
     Object** restarter_frame_function_pointer_;
+
+    // When a promise is being resolved, we may want to trigger a debug event
+    // if we catch a throw.  For this purpose we remember the try-catch
+    // handler address that would catch the exception.  We also hold onto a
+    // closure that returns a promise if the exception is considered uncaught.
+    // Due to the possibility of reentry we use a linked list.
+    PromiseOnStack* promise_on_stack_;
   };
 
   // Storage location for registers when handling debug break calls