From 1146835d77a99155e84105a8c71b1b5869c3ea10 Mon Sep 17 00:00:00 2001
From: Marco Castelluccio <mcastelluccio@mozilla.com>
Date: Tue, 30 Sep 2014 17:23:24 -0700
Subject: [PATCH] Don't create a fake caller frame for synthetic methods

---
 context.js | 15 +++++++++------
 frame.js   | 12 +++++-------
 jvm.js     | 37 ++++++++++++++++---------------------
 native.js  | 10 +++++-----
 4 files changed, 35 insertions(+), 39 deletions(-)

diff --git a/context.js b/context.js
index b716df77..f09edb82 100644
--- a/context.js
+++ b/context.js
@@ -115,7 +115,7 @@ Context.prototype.raiseExceptionAndYield = function(className, message) {
 
 Context.prototype.execute = function(stopFrame) {
   Instrument.callResumeHooks(this.current());
-  while (this.current() !== stopFrame) {
+  do {
     try {
       VM.execute(this);
     } catch (e) {
@@ -130,16 +130,13 @@ Context.prototype.execute = function(stopFrame) {
         throw e;
       }
     }
-  }
+  } while (this.current() !== stopFrame);
 }
 
 Context.prototype.start = function(stopFrame) {
-  if (this.current() === stopFrame) {
-    this.kill();
-    return;
-  }
   var ctx = this;
   ctx.stopFrame = stopFrame;
+
   window.setZeroTimeout(function() {
     Instrument.callResumeHooks(ctx.current());
     try {
@@ -157,6 +154,12 @@ Context.prototype.start = function(stopFrame) {
       }
     }
     Instrument.callPauseHooks(ctx.current());
+
+    if (ctx.current() === stopFrame) {
+      ctx.kill();
+      return;
+    }
+
     ctx.start(stopFrame);
   });
 }
diff --git a/frame.js b/frame.js
index 00185418..6404b30b 100644
--- a/frame.js
+++ b/frame.js
@@ -33,12 +33,10 @@ Array.prototype.popType = function(signature) {
 }
 
 var Frame = function(methodInfo, locals, localsBase) {
-    if (methodInfo) {
-        this.methodInfo = methodInfo;
-        this.cp = methodInfo.classInfo.constant_pool;
-        this.code = methodInfo.code;
-        this.ip = 0;
-    }
+    this.methodInfo = methodInfo;
+    this.cp = methodInfo.classInfo.constant_pool;
+    this.code = methodInfo.code;
+    this.ip = 0;
     this.stack = [];
     this.locals = locals;
     this.localsBase = localsBase;
@@ -50,7 +48,7 @@ var Frame = function(methodInfo, locals, localsBase) {
     // on the stack, while stack.read(2) returns the one underneath it.
     this.stack.read = function(i) { return this[this.length - i] };
 
-    Object.seal(this)
+    Object.seal(this);
 }
 
 Frame.prototype.getLocal = function(idx) {
diff --git a/jvm.js b/jvm.js
index 68d166d1..27e90942 100644
--- a/jvm.js
+++ b/jvm.js
@@ -34,22 +34,18 @@ JVM.prototype.startIsolate0 = function(className, args) {
     var isolate = ctx.newObject(com_sun_cldc_isolate_Isolate);
     isolate.id = util.id();
 
-    var caller = new Frame();
-    ctx.frames.push(caller);
-
     var array = ctx.newArray("[Ljava/lang/String;", args.length);
     for (var n = 0; n < args.length; ++n)
         array[n] = args[n] ? ctx.newString(args[n]) : null;
 
-    caller.stack.push(isolate);
-    caller.stack.push(ctx.newString(className.replace(/\./g, "/")));
-    caller.stack.push(array);
-    ctx.pushFrame(CLASSES.getMethod(com_sun_cldc_isolate_Isolate, "I.<init>.(Ljava/lang/String;[Ljava/lang/String;)V"), 3);
-    ctx.execute(caller);
+    var synthFrame1 = new Frame(CLASSES.getMethod(com_sun_cldc_isolate_Isolate, "I.<init>.(Ljava/lang/String;[Ljava/lang/String;)V"),
+                                [ isolate, ctx.newString(className.replace(/\./g, "/")), array ], 0);
+    ctx.frames.push(synthFrame1);
+    ctx.execute(synthFrame1);
 
-    caller.stack.push(isolate);
-    ctx.pushFrame(CLASSES.getMethod(com_sun_cldc_isolate_Isolate, "I.start.()V"), 1);
-    ctx.start(caller);
+    var synthFrame2 = new Frame(CLASSES.getMethod(com_sun_cldc_isolate_Isolate, "I.start.()V"), [ isolate ], 0);
+    ctx.frames.push(synthFrame2);
+    ctx.start(synthFrame2);
 }
 
 JVM.prototype.startIsolate = function(isolate) {
@@ -75,21 +71,20 @@ JVM.prototype.startIsolate = function(isolate) {
     if (!entryPoint)
         throw new Error("Could not find main method in class " + mainName);
 
-    var caller = new Frame();
-    ctx.frames.push(caller);
-
     ctx.thread = runtime.mainThread = ctx.newObject(CLASSES.java_lang_Thread);
     ctx.thread.pid = util.id();
     ctx.thread.alive = true;
-    caller.stack.push(runtime.mainThread);
-    caller.stack.push(ctx.newString("main"));
-    ctx.pushFrame(CLASSES.getMethod(CLASSES.java_lang_Thread, "I.<init>.(Ljava/lang/String;)V"), 2);
-    ctx.execute(caller);
+
+    var synthFrame1 = new Frame(CLASSES.getMethod(CLASSES.java_lang_Thread, "I.<init>.(Ljava/lang/String;)V"),
+                                [ runtime.mainThread, ctx.newString("main") ], 0);
+    ctx.frames.push(synthFrame1);
+    ctx.execute(synthFrame1);
 
     var args = ctx.newArray("[Ljava/lang/String;", mainArgs.length);
     for (var n = 0; n < mainArgs.length; ++n)
         args[n] = mainArgs[n] ? ctx.newString(mainArgs[n]) : null;
-    caller.stack.push(args);
-    ctx.pushFrame(entryPoint, 1);
-    ctx.start(caller);
+
+    var synthFrame2 = new Frame(entryPoint, [ args ], 0);
+    ctx.frames.push(synthFrame2);
+    ctx.start(synthFrame2);
 }
diff --git a/native.js b/native.js
index c9840ce1..c98482e8 100644
--- a/native.js
+++ b/native.js
@@ -501,9 +501,7 @@ Native["java/lang/Thread.start0.()V"] = function(ctx, stack) {
     // Create a context for the thread and start it.
     var ctx = new Context(ctx.runtime);
     ctx.thread = thread;
-    var caller = new Frame();
-    ctx.frames.push(caller);
-    caller.stack.push(thread);
+
     var syntheticMethod = {
       syntheticKey: "ThreadStart0Synthetic:" + thread.class.className + "." + run.name + "." + run.signature,
       classInfo: {
@@ -532,8 +530,10 @@ Native["java/lang/Thread.start0.()V"] = function(ctx, stack) {
       ],
       exception_table: [],
     };
-    ctx.pushFrame(syntheticMethod, 1);
-    ctx.start(caller);
+
+    var synthFrame = new Frame(syntheticMethod, [ thread ], 0)
+    ctx.frames.push(synthFrame);
+    ctx.start(synthFrame);
 }
 
 Native["java/lang/Thread.internalExit.()V"] = function(ctx, stack) {