diff --git a/js/src/js.msg b/js/src/js.msg
index fd9b0c20acc..078273d5cf0 100644
--- a/js/src/js.msg
+++ b/js/src/js.msg
@@ -330,4 +330,3 @@ MSG_DEF(JSMSG_CSP_BLOCKED_FUNCTION,   247, 0, JSEXN_ERR, "call to Function() blo
 MSG_DEF(JSMSG_BAD_GET_SET_FIELD,      248, 1, JSEXN_TYPEERR, "property descriptor's {0} field is neither undefined nor a function")
 MSG_DEF(JSMSG_BAD_PROXY_FIX,          249, 0, JSEXN_TYPEERR, "proxy was fixed while executing the handler")
 MSG_DEF(JSMSG_INVALID_EVAL_SCOPE_ARG, 250, 0, JSEXN_EVALERR, "invalid eval scope argument")
-MSG_DEF(JSMSG_NEED_DEBUG_MODE,        251, 0, JSEXN_ERR, "function can only be called in debug mode")
diff --git a/js/src/jsapi-tests/testTrap.cpp b/js/src/jsapi-tests/testTrap.cpp
index 4fb61d1cecc..8026e52ac4a 100644
--- a/js/src/jsapi-tests/testTrap.cpp
+++ b/js/src/jsapi-tests/testTrap.cpp
@@ -45,9 +45,6 @@ BEGIN_TEST(testTrap_gc)
     // Disable JIT for debugging
     JS_SetOptions(cx, JS_GetOptions(cx) & ~JSOPTION_JIT);
 
-    // Enable debug mode
-    CHECK(JS_SetDebugMode(cx, JS_TRUE));
-
     jsbytecode *line2 = JS_LineNumberToPC(cx, script, 1);
     CHECK(line2);
 
diff --git a/js/src/jscntxt.cpp b/js/src/jscntxt.cpp
index d16161c7a8e..8a45109bae6 100644
--- a/js/src/jscntxt.cpp
+++ b/js/src/jscntxt.cpp
@@ -513,25 +513,6 @@ FrameRegsIter::operator++()
     return *this;
 }
 
-AllFramesIter::AllFramesIter(JSContext *cx)
-  : curcs(cx->stack().getCurrentSegment()),
-    curfp(curcs ? curcs->getCurrentFrame() : NULL)
-{
-}
-
-AllFramesIter&
-AllFramesIter::operator++()
-{
-    JS_ASSERT(!done());
-    if (curfp == curcs->getInitialFrame()) {
-        curcs = curcs->getPreviousInMemory();
-        curfp = curcs ? curcs->getCurrentFrame() : NULL;
-    } else {
-        curfp = curfp->down;
-    }
-    return *this;
-}
-
 bool
 JSThreadData::init()
 {
@@ -609,6 +590,9 @@ JSThreadData::purge(JSContext *cx)
     if (cx->runtime->gcRegenShapes)
         traceMonitor.needFlush = JS_TRUE;
 #endif
+#ifdef JS_METHODJIT
+    jmData.purge(cx);
+#endif
 
     /* Destroy eval'ed scripts. */
     js_DestroyScriptsToGC(cx, this);
@@ -2284,10 +2268,9 @@ void
 JSContext::purge()
 {
     FreeOldArenas(runtime, &regexpPool);
-    /* :XXX: Is this the right place for this? */
-    compartment->purge(this);
 }
 
+
 namespace js {
 
 void
diff --git a/js/src/jscntxt.h b/js/src/jscntxt.h
index 79371d226b3..c693f1e8f31 100644
--- a/js/src/jscntxt.h
+++ b/js/src/jscntxt.h
@@ -237,6 +237,10 @@ namespace mjit {
     {
         JSC::ExecutableAllocator *execPool;
 
+        // Scripts that have had PICs patched or PIC stubs generated.
+        typedef js::HashSet<JSScript*, DefaultHasher<JSScript*>, js::SystemAllocPolicy> ScriptSet;
+        ScriptSet picScripts;
+
         // Trampolines for JIT code.
         Trampolines trampolines;
 
@@ -244,6 +248,10 @@ namespace mjit {
 
         bool Initialize();
         void Finish();
+
+        bool addScript(JSScript *script);
+        void removeScript(JSScript *script);
+        void purge(JSContext *cx);
     };
 }
 #endif /* JS_METHODJIT */
@@ -815,24 +823,6 @@ class FrameRegsIter
     jsbytecode *pc() const { return curpc; }
 };
 
-/*
- * Utility class for iteration over all active stack frames.
- */
-class AllFramesIter
-{
-public:
-    AllFramesIter(JSContext *cx);
-
-    bool done() const { return curfp == NULL; }
-    AllFramesIter& operator++();
-
-    JSStackFrame *fp() const { return curfp; }
-
-private:
-    CallStackSegment *curcs;
-    JSStackFrame *curfp;
-};
-
 /* Holds the number of recording attemps for an address. */
 typedef HashMap<jsbytecode*,
                 size_t,
@@ -1241,7 +1231,6 @@ struct WrapperHasher
 };
 
 typedef HashMap<Value, Value, WrapperHasher, SystemAllocPolicy> WrapperMap;
-typedef HashSet<JSScript *, DefaultHasher<JSScript *>, SystemAllocPolicy> ScriptSet;
 
 class AutoValueVector;
 class AutoIdVector;
@@ -1254,15 +1243,6 @@ struct JSCompartment {
     void *data;
     bool marked;
     js::WrapperMap crossCompartmentWrappers;
-    bool debugMode;
-
-#ifdef JS_METHODJIT
-    /* Executable allocator for PIC buffers. */
-    JSC::ExecutableAllocator *execPool;
-
-    /* Needed to re-JIT scripts for debug mode and so we can flush PICs. */
-    js::ScriptSet jitScripts;
-#endif
 
     JSCompartment(JSRuntime *cx);
     ~JSCompartment();
@@ -1279,12 +1259,6 @@ struct JSCompartment {
     bool wrapException(JSContext *cx);
 
     void sweep(JSContext *cx);
-
-#ifdef JS_METHODJIT
-    bool addScript(JSContext *cx, JSScript *script);
-    void removeScript(JSScript *script);
-#endif
-    void purge(JSContext *cx);
 };
 
 struct JSRuntime {
diff --git a/js/src/jsdbgapi.cpp b/js/src/jsdbgapi.cpp
index ea2c3e7f1aa..2a21aa6b81b 100644
--- a/js/src/jsdbgapi.cpp
+++ b/js/src/jsdbgapi.cpp
@@ -69,8 +69,10 @@
 
 #include "jsautooplen.h"
 
-#include "methodjit/MethodJIT.h"
-#include "methodjit/Retcon.h"
+#ifdef JS_METHODJIT
+# include "methodjit/MethodJIT.h"
+# include "methodjit/Retcon.h"
+#endif
 
 using namespace js;
 
@@ -87,79 +89,6 @@ typedef struct JSTrap {
 #define DBG_UNLOCK(rt)          JS_RELEASE_LOCK((rt)->debuggerLock)
 #define DBG_LOCK_EVAL(rt,expr)  (DBG_LOCK(rt), (expr), DBG_UNLOCK(rt))
 
-JS_PUBLIC_API(JSBool)
-JS_GetDebugMode(JSContext *cx)
-{
-    return cx->compartment->debugMode;
-}
-
-static bool
-IsScriptLive(JSContext *cx, JSScript *script)
-{
-    for (AllFramesIter i(cx); !i.done(); ++i) {
-        if (i.fp()->script == script)
-            return true;
-    }
-    return false;
-}
-
-JS_FRIEND_API(JSBool)
-js_SetDebugMode(JSContext *cx, JSBool debug)
-{
-    cx->compartment->debugMode = debug;
-#ifdef JS_METHODJIT
-    for (ScriptSet::Range r = cx->compartment->jitScripts.all();
-         !r.empty();
-         r.popFront()) {
-        JSScript *script = r.front();
-        if (script->debugMode != debug &&
-            script->ncode &&
-            script->ncode != JS_UNJITTABLE_METHOD &&
-            !IsScriptLive(cx, script)) {
-            /*
-             * In the event that this fails, debug mode is left partially on,
-             * leading to a small performance overhead but no loss of
-             * correctness. We set the debug flag to false so that the caller
-             * will not later attempt to use debugging features.
-             */
-            mjit::Recompiler recompiler(cx, script);
-            if (!recompiler.recompile()) {
-                cx->compartment->debugMode = JS_FALSE;
-                return JS_FALSE;
-            }
-        }
-    }
-#endif
-    return JS_TRUE;
-}
-
-JS_PUBLIC_API(JSBool)
-JS_SetDebugMode(JSContext *cx, JSBool debug)
-{
-#ifdef DEBUG
-    for (AllFramesIter i(cx); !i.done(); ++i)
-        JS_ASSERT(JS_IsNativeFrame(cx, i.fp()));
-#endif
-
-    return js_SetDebugMode(cx, debug);
-}
-
-static JSBool
-CheckDebugMode(JSContext *cx)
-{
-    JSBool debugMode = JS_GetDebugMode(cx);
-    /*
-     * :TODO:
-     * This probably should be an assertion, since it's indicative of a severe
-     * API misuse.
-     */
-    if (!debugMode) {
-        JS_ReportErrorFlagsAndNumber(cx, JSREPORT_ERROR, js_GetErrorMessage,
-                                     NULL, JSMSG_NEED_DEBUG_MODE);
-    }
-    return debugMode;
-}
-
 /*
  * NB: FindTrap must be called with rt->debuggerLock acquired.
  */
@@ -224,9 +153,6 @@ JS_SetTrap(JSContext *cx, JSScript *script, jsbytecode *pc,
     JSRuntime *rt;
     uint32 sample;
 
-    if (!CheckDebugMode(cx))
-        return JS_FALSE;
-
     if (script == JSScript::emptyScript()) {
         JS_ReportErrorFlagsAndNumber(cx, JSREPORT_ERROR, js_GetErrorMessage,
                                      NULL, JSMSG_READ_ONLY, "empty script");
@@ -311,7 +237,7 @@ JS_ClearTrap(JSContext *cx, JSScript *script, jsbytecode *pc,
              JSTrapHandler *handlerp, jsval *closurep)
 {
     JSTrap *trap;
-    
+
     DBG_LOCK(cx->runtime);
     trap = FindTrap(cx->runtime, script, pc);
     if (handlerp)
@@ -1447,9 +1373,6 @@ JS_EvaluateUCInStackFrame(JSContext *cx, JSStackFrame *fp,
 {
     JS_ASSERT_NOT_ON_TRACE(cx);
 
-    if (!CheckDebugMode(cx))
-        return JS_FALSE;
-
     JSObject *scobj = JS_GetFrameScopeChain(cx, fp);
     if (!scobj)
         return false;
@@ -1483,9 +1406,6 @@ JS_EvaluateInStackFrame(JSContext *cx, JSStackFrame *fp,
     jschar *chars;
     JSBool ok;
     size_t len = length;
-    
-    if (!CheckDebugMode(cx))
-        return JS_FALSE;
 
     chars = js_InflateString(cx, bytes, &len);
     if (!chars)
diff --git a/js/src/jsdbgapi.h b/js/src/jsdbgapi.h
index 846e0346889..56416bba234 100644
--- a/js/src/jsdbgapi.h
+++ b/js/src/jsdbgapi.h
@@ -49,28 +49,6 @@
 
 JS_BEGIN_EXTERN_C
 
-/*
- * Debug mode is a compartment-wide mode that enables a debugger to attach
- * to and interact with running methodjit-ed frames. In particular, it causes
- * every function to be compiled as if an eval was present (so eval-in-frame)
- * can work, and it ensures that functions can be re-JITed for other debug
- * features. In general, it is not safe to interact with frames that were live
- * before debug mode was enabled. For this reason, it is also not safe to
- * enable debug mode while frames are live.
- */
-
-/* Get current state of debugging mode. */
-extern JS_PUBLIC_API(JSBool)
-JS_GetDebugMode(JSContext *cx);
-
-/* Turn on debugging mode, ignoring the presence of live frames. */
-extern JS_FRIEND_API(JSBool)
-js_SetDebugMode(JSContext *cx, JSBool debug);
-
-/* Turn on debugging mode. */
-extern JS_PUBLIC_API(JSBool)
-JS_SetDebugMode(JSContext *cx, JSBool debug);
-
 /*
  * Unexported library-private helper used to unpatch all traps in a script.
  * Returns script->code if script has no traps, else a JS_malloc'ed copy of
diff --git a/js/src/jsscript.cpp b/js/src/jsscript.cpp
index c150cea9b21..91156f86774 100644
--- a/js/src/jsscript.cpp
+++ b/js/src/jsscript.cpp
@@ -76,12 +76,7 @@ static const jsbytecode emptyScriptCode[] = {JSOP_STOP, SRC_NULL};
 /* static */ const JSScript JSScript::emptyScriptConst = {
     const_cast<jsbytecode*>(emptyScriptCode),
     1, JSVERSION_DEFAULT, 0, 0, 0, 0, 0, 0, 0, true, false, false, false, false,
-    false, true, 
-#ifdef JS_METHODJIT
-    /* debugMode */
-    false,
-#endif
-    const_cast<jsbytecode*>(emptyScriptCode),
+    false, true, const_cast<jsbytecode*>(emptyScriptCode),
     {0, NULL}, NULL, 0, 0, 0, NULL, {NULL},
 #ifdef CHECK_SCRIPT_OWNER
     reinterpret_cast<JSThread*>(1)
@@ -876,7 +871,6 @@ js_NewScript(JSContext *cx, uint32 length, uint32 nsrcnotes, uint32 natoms,
     script = (JSScript *) cx->malloc(size);
     if (!script)
         return NULL;
-
     PodZero(script);
     script->length = length;
     script->version = cx->version;
diff --git a/js/src/jsscript.h b/js/src/jsscript.h
index a0663dd2eda..7a5f597bb22 100644
--- a/js/src/jsscript.h
+++ b/js/src/jsscript.h
@@ -212,9 +212,6 @@ struct JSScript {
     bool            warnedAboutTwoArgumentEval:1; /* have warned about use of
                                                      obsolete eval(s, o) in
                                                      this script */
-#ifdef JS_METHODJIT
-    bool            debugMode:1;      /* script was compiled in debug mode */
-#endif
 
     jsbytecode      *main;      /* main entry point, after predef'ing prolog */
     JSAtomMap       atomMap;    /* maps immediate index to literal struct */
diff --git a/js/src/jswrapper.cpp b/js/src/jswrapper.cpp
index 972a7b7556f..063b42d1f15 100644
--- a/js/src/jswrapper.cpp
+++ b/js/src/jswrapper.cpp
@@ -45,8 +45,6 @@
 #include "jsnum.h"
 #include "jsregexp.h"
 #include "jswrapper.h"
-#include "methodjit/PolyIC.h"
-#include "assembler/jit/ExecutableAllocator.h"
 
 #include "jsobjinlines.h"
 
@@ -291,26 +289,17 @@ TransparentObjectWrapper(JSContext *cx, JSObject *obj, JSObject *wrappedProto, u
 }
 
 JSCompartment::JSCompartment(JSRuntime *rt)
-  : rt(rt), principals(NULL), data(NULL), marked(false), debugMode(false)
+  : rt(rt), principals(NULL), data(NULL), marked(false)
 {
 }
 
 JSCompartment::~JSCompartment()
 {
-    delete execPool;
 }
 
 bool
 JSCompartment::init()
 {
-#ifdef JS_METHODJIT
-    execPool = new JSC::ExecutableAllocator();
-    if (!execPool)
-        return false;
-
-    if (!jitScripts.init())
-        return false;
-#endif
     return crossCompartmentWrappers.init();
 }
 
@@ -485,48 +474,6 @@ JSCompartment::sweep(JSContext *cx)
     }
 }
 
-#ifdef JS_METHODJIT
-bool
-JSCompartment::addScript(JSContext *cx, JSScript *script)
-{
-    ScriptSet::AddPtr ptr = jitScripts.lookupForAdd(script);
-    if (!ptr.found()) {
-        bool ok = jitScripts.add(ptr, script);
-        if (!ok)
-            JS_ReportOutOfMemory(cx);
-        return ok;
-    }
-    return true;
-}
-
-void
-JSCompartment::removeScript(JSScript *script)
-{
-    ScriptSet::Ptr ptr = jitScripts.lookup(script);
-    if (ptr.found())
-        jitScripts.remove(ptr);
-}
-#endif
-
-void
-JSCompartment::purge(JSContext *cx)
-{
-#ifdef JS_METHODJIT
-    if (!cx->runtime->gcRegenShapes)
-        return;
-
-    for (ScriptSet::Enum e(jitScripts); !e.empty(); e.popFront()) {
-# if defined JS_POLYIC
-        JSScript *script = e.front();
-        mjit::ic::PurgePICs(cx, script);
-# endif
-# if defined JS_MONOIC
-        //mjit::ic::PurgeMICs(cx, script);
-# endif
-    }
-#endif
-}
-
 static bool
 SetupFakeFrame(JSContext *cx, ExecuteFrameGuard &frame, JSFrameRegs &regs, JSObject *obj)
 {
diff --git a/js/src/methodjit/Compiler.cpp b/js/src/methodjit/Compiler.cpp
index 7843e704845..8839f966671 100644
--- a/js/src/methodjit/Compiler.cpp
+++ b/js/src/methodjit/Compiler.cpp
@@ -167,12 +167,8 @@ mjit::TryCompile(JSContext *cx, JSScript *script, JSFunction *fun, JSObject *sco
     JS_ASSERT(!script->isEmpty());
 
     CompileStatus status = cc.Compile();
-    if (status == Compile_Okay) {
-        if (!cx->compartment->addScript(cx, script))
-            status = Compile_Abort;
-    } else {
+    if (status != Compile_Okay)
         script->ncode = JS_UNJITTABLE_METHOD;
-    }
 
     return status;
 }
@@ -418,10 +414,6 @@ mjit::Compiler::finishThisUp()
     }
     script->callSites = callSiteList;
 
-#ifdef JS_METHODJIT
-    script->debugMode = cx->compartment->debugMode;
-#endif
-
     return Compile_Okay;
 }
 
diff --git a/js/src/methodjit/FrameState.cpp b/js/src/methodjit/FrameState.cpp
index 7ef2b9c3d68..83970834473 100644
--- a/js/src/methodjit/FrameState.cpp
+++ b/js/src/methodjit/FrameState.cpp
@@ -69,7 +69,7 @@ FrameState::init(uint32 nargs)
     }
 
     uint32 nlocals = script->nslots;
-    if ((eval = script->usesEval || cx->compartment->debugMode))
+    if ((eval = script->usesEval))
         nlocals = 0;
 
     uint8 *cursor = (uint8 *)cx->malloc(sizeof(FrameEntry) * nslots +       // entries[]
diff --git a/js/src/methodjit/MethodJIT.cpp b/js/src/methodjit/MethodJIT.cpp
index 402845249a5..265516d4e01 100644
--- a/js/src/methodjit/MethodJIT.cpp
+++ b/js/src/methodjit/MethodJIT.cpp
@@ -578,6 +578,11 @@ ThreadData::Initialize()
         return false;
     }
 
+    if (!picScripts.init()) {
+        delete execPool;
+        return false;
+    }
+
 #ifdef JS_METHODJIT_PROFILE_STUBS
     for (size_t i = 0; i < STUB_CALLS_FOR_OP_COUNT; ++i)
         StubCallsForOp[i] = 0;
@@ -603,6 +608,43 @@ ThreadData::Finish()
 #endif
 }
 
+bool
+ThreadData::addScript(JSScript *script)
+{
+    ScriptSet::AddPtr p = picScripts.lookupForAdd(script);
+    if (p)
+        return true;
+    return picScripts.add(p, script);
+}
+
+void
+ThreadData::removeScript(JSScript *script)
+{
+    ScriptSet::Ptr p = picScripts.lookup(script);
+    if (p)
+        picScripts.remove(p);
+}
+
+void
+ThreadData::purge(JSContext *cx)
+{
+    if (!cx->runtime->gcRegenShapes)
+        return;
+
+    for (ThreadData::ScriptSet::Enum e(picScripts); !e.empty(); e.popFront()) {
+#if defined JS_POLYIC
+        JSScript *script = e.front();
+        ic::PurgePICs(cx, script);
+#endif
+#if defined JS_MONOIC
+        //PurgeMICs(cs, script);
+#endif
+    }
+
+    picScripts.clear();
+}
+
+
 extern "C" JSBool JaegerTrampoline(JSContext *cx, JSStackFrame *fp, void *code,
                                    uintptr_t inlineCallCount);
 
@@ -682,8 +724,7 @@ mjit::ReleaseScriptCode(JSContext *cx, JSScript *script)
         script->ncode = NULL;
         script->inlineLength = 0;
         script->outOfLineLength = 0;
-
-        cx->compartment->removeScript(script);
+        
 #if defined JS_POLYIC
         if (script->pics) {
             uint32 npics = script->numPICs();
@@ -691,6 +732,7 @@ mjit::ReleaseScriptCode(JSContext *cx, JSScript *script)
                 script->pics[i].releasePools();
                 Destroy(script->pics[i].execPools);
             }
+            JS_METHODJIT_DATA(cx).removeScript(script);
             cx->free((uint8*)script->pics - sizeof(uint32));
         }
 #endif
diff --git a/js/src/methodjit/PolyIC.cpp b/js/src/methodjit/PolyIC.cpp
index 0410defda4d..e469b4c6efb 100644
--- a/js/src/methodjit/PolyIC.cpp
+++ b/js/src/methodjit/PolyIC.cpp
@@ -131,7 +131,8 @@ class PICStubCompiler
 
     JSC::ExecutablePool *getExecPool(size_t size)
     {
-        return f.cx->compartment->execPool->poolForSize(size);
+        mjit::ThreadData *jd = &JS_METHODJIT_DATA(f.cx);
+        return jd->execPool->poolForSize(size);
     }
 
   protected:
@@ -685,6 +686,12 @@ class GetPropCompiler : public PICStubCompiler
         if (!f.fp->script->compileAndGo)
             return disable("String.prototype without compile-and-go");
 
+        mjit::ThreadData &jm = JS_METHODJIT_DATA(f.cx);
+        if (!jm.addScript(script)) {
+            js_ReportOutOfMemory(f.cx);
+            return false;
+        }
+
         JSObject *holder;
         JSProperty *prop;
         if (!obj->lookupProperty(f.cx, ATOM_TO_JSID(atom), &holder, &prop))
@@ -807,6 +814,12 @@ class GetPropCompiler : public PICStubCompiler
         spew("patch", "inline");
         PICRepatchBuffer repatcher(pic, pic.fastPathStart);
 
+        mjit::ThreadData &jm = JS_METHODJIT_DATA(f.cx);
+        if (!jm.addScript(script)) {
+            js_ReportOutOfMemory(f.cx);
+            return false;
+        }
+
         int32 offset;
         if (sprop->slot < JS_INITIAL_NSLOTS) {
             JSC::CodeLocationInstruction istr;
diff --git a/js/src/methodjit/Retcon.cpp b/js/src/methodjit/Retcon.cpp
index b9ca138335e..093a4fa4d29 100644
--- a/js/src/methodjit/Retcon.cpp
+++ b/js/src/methodjit/Retcon.cpp
@@ -96,8 +96,7 @@ Recompiler::applyPatch(Compiler& c, PatchableAddress& toPatch)
     *toPatch.location = result;
 }
 
-Recompiler::Recompiler(JSContext *cx, JSScript *script)
-  : cx(cx), script(script)
+Recompiler::Recompiler(JSContext *cx, JSScript *script) : cx(cx), script(script)
 {    
 }
 
@@ -122,12 +121,15 @@ Recompiler::recompile()
 
     /* Scan the stack, saving the ncode elements of the frames. */
     JSStackFrame *firstFrame = NULL;
-    for (AllFramesIter i(cx); !i.done(); ++i) {
-        if (!firstFrame && i.fp()->script == script)
-            firstFrame = i.fp();
-        if (script->isValidJitCode(i.fp()->ncode)) {
-            if (!toPatch.append(findPatch(&i.fp()->ncode)))
-                return false;
+    for (CallStackIterator cs(cx); !cs.done(); ++cs) {
+        FrameIterator fp = cs.top();
+        for (FrameIterator fp = cs.top(); fp != cs.bottom(); ++fp) {
+            if (!firstFrame && fp.fp()->script == script)
+                firstFrame = fp.fp();
+            if (script->isValidJitCode(fp.fp()->ncode)) {
+                if (!toPatch.append(findPatch(&fp.fp()->ncode)))
+                    return false;
+            }
         }
     }
 
@@ -142,10 +144,9 @@ Recompiler::recompile()
         }
 
         void **machineReturn = f->returnAddressLocation();
-        if (script->isValidJitCode(*machineReturn)) {
+        if (script->isValidJitCode(*machineReturn))
             if (!toPatch.append(findPatch(machineReturn)))
                 return false;
-        }
     }
 
     ReleaseScriptCode(cx, script);
@@ -154,9 +155,6 @@ Recompiler::recompile()
     if (!firstFrame)
         return true;
 
-    /* If we get this far, the script is live, and we better be safe to re-jit. */
-    JS_ASSERT(cx->compartment->debugMode);
-
     Compiler c(cx, script, firstFrame->fun, firstFrame->scopeChain);
     if (c.Compile() != Compile_Okay)
         return false;
@@ -168,6 +166,42 @@ Recompiler::recompile()
     return true;
 }
 
+FrameIterator&
+FrameIterator::operator++() {
+    JS_ASSERT(curfp);
+    curfp = curfp->down;
+    return *this;
+}
+
+bool
+FrameIterator::operator==(const FrameIterator& other) const {
+    return curfp == other.curfp;
+}
+
+bool
+FrameIterator::operator!=(const FrameIterator& other) const {
+    return curfp != other.curfp;
+}
+
+CallStackIterator&
+CallStackIterator::operator++() {
+    JS_ASSERT(curcs);
+    curcs = curcs->getPreviousInMemory();
+    return *this;
+}
+
+FrameIterator
+CallStackIterator::top() const {
+    JS_ASSERT(curcs);
+    return FrameIterator(curcs->getCurrentFrame());
+}
+
+FrameIterator
+CallStackIterator::bottom() const {
+    JS_ASSERT(curcs);
+    return FrameIterator(curcs->getInitialFrame()->down);
+}
+
 } /* namespace mjit */
 } /* namespace js */
 
diff --git a/js/src/methodjit/Retcon.h b/js/src/methodjit/Retcon.h
index 8280329a8fe..49a916b882d 100644
--- a/js/src/methodjit/Retcon.h
+++ b/js/src/methodjit/Retcon.h
@@ -101,6 +101,41 @@ private:
     void applyPatch(Compiler& c, PatchableAddress& toPatch);
 };
 
+/*
+ * Utility classes to make iteration over the stack clean.
+ */
+class FrameIterator
+{
+public:
+    FrameIterator(JSStackFrame *frame) : curfp(frame) { };
+    
+    bool done() const { return curfp == NULL; }
+    FrameIterator& operator++();
+    bool operator==(const FrameIterator& other) const;
+    bool operator!=(const FrameIterator& other) const;
+    
+    JSStackFrame *fp() const { return curfp; }
+
+private:
+    JSStackFrame *curfp;
+};
+
+class CallStackIterator
+{
+public:
+    CallStackIterator(JSContext *cx) : curcs(cx->stack().getCurrentSegment()) { };
+  
+    bool done() const { return curcs == NULL; }
+    CallStackIterator& operator++();
+    FrameIterator top() const;
+    FrameIterator bottom() const;
+
+    CallStackSegment *cs() const { return curcs; }
+
+private:
+    CallStackSegment *curcs;    
+};
+
 } /* namespace mjit */
 } /* namespace js */
 
diff --git a/js/src/shell/js.cpp b/js/src/shell/js.cpp
index 29cd2350090..c4ab81b77ee 100644
--- a/js/src/shell/js.cpp
+++ b/js/src/shell/js.cpp
@@ -1462,20 +1462,6 @@ ValueToScript(JSContext *cx, jsval v)
     return script;
 }
 
-static JSBool
-SetDebug(JSContext *cx, JSObject *obj, uintN argc, jsval *argv, jsval *rval)
-{
-    if (argc == 0 || !JSVAL_IS_BOOLEAN(argv[0])) {
-        JS_ReportErrorNumber(cx, my_GetErrorMessage, NULL,
-                             JSSMSG_NOT_ENOUGH_ARGS, "setDebug");
-        return JS_FALSE;
-    }
-    
-    js_SetDebugMode(cx, JSVAL_TO_BOOLEAN(argv[0]));
-    *rval = JSVAL_VOID;
-    return JS_TRUE;
-}
-
 static JSBool
 GetTrapArgs(JSContext *cx, uintN argc, jsval *argv, JSScript **scriptp,
             int32 *ip)
@@ -3947,7 +3933,6 @@ static JSFunctionSpec shell_functions[] = {
 #ifdef JS_GC_ZEAL
     JS_FN("gczeal",         GCZeal,         1,0),
 #endif
-    JS_FS("setDebug",       SetDebug,       1,0,0),
     JS_FS("trap",           Trap,           3,0,0),
     JS_FS("untrap",         Untrap,         2,0,0),
     JS_FS("line2pc",        LineToPC,       0,0,0),
@@ -4049,7 +4034,6 @@ static const char *const shell_help_messages[] = {
 #ifdef JS_GC_ZEAL
 "gczeal(level)            How zealous the garbage collector should be",
 #endif
-"setDebug(debug)          Set debug mode",
 "trap([fun, [pc,]] exp)   Trap bytecode execution",
 "untrap(fun[, pc])        Remove a trap",
 "line2pc([fun,] line)     Map line number to PC",
diff --git a/js/src/trace-test/tests/basic/testBug552248.js b/js/src/trace-test/tests/basic/testBug552248.js
deleted file mode 100644
index 28782b665bb..00000000000
--- a/js/src/trace-test/tests/basic/testBug552248.js
+++ /dev/null
@@ -1,36 +0,0 @@
-setDebug(true);
-var a = new Array();
-
-function i(save) {
-    var x = 9;
-    evalInFrame(0, "a.push(x)", save);
-    evalInFrame(1, "a.push(z)", save);
-    evalInFrame(2, "a.push(z)", save);
-    evalInFrame(3, "a.push(y)", save);
-    evalInFrame(4, "a.push(x)", save);
-}
-
-function h() {
-    var z = 5;
-    evalInFrame(0, "a.push(z)");
-    evalInFrame(1, "a.push(y)");
-    evalInFrame(2, "a.push(x)");
-    evalInFrame(0, "i(false)");
-    evalInFrame(0, "a.push(z)", true);
-    evalInFrame(1, "a.push(y)", true);
-    evalInFrame(2, "a.push(x)", true);
-    evalInFrame(0, "i(true)", true);
-}
-
-function g() {
-    var y = 4;
-    h();
-}
-
-function f() {
-    var x = 3;
-    g();
-}
-
-f();
-assertEq(a+'', [5, 4, 3, 9, 5, 5, 4, 3, 5, 4, 3, 9, 5, 5, 4, 3]+'');
diff --git a/js/src/trace-test/tests/jaeger/bug563000/eif-call-newvar.js b/js/src/trace-test/tests/jaeger/bug563000/eif-call-newvar.js
deleted file mode 100644
index df6fc4aaa17..00000000000
--- a/js/src/trace-test/tests/jaeger/bug563000/eif-call-newvar.js
+++ /dev/null
@@ -1,13 +0,0 @@
-setDebug(true);
-
-function callee() {
-  assertJit();
-  evalInFrame(1, "var x = 'success'");
-}
-function caller() {
-  assertJit();
-  callee();
-  return x;
-}
-assertEq(caller(), "success");
-assertEq(typeof x, "undefined");
diff --git a/js/src/trace-test/tests/jaeger/bug563000/eif-call-typechange.js b/js/src/trace-test/tests/jaeger/bug563000/eif-call-typechange.js
deleted file mode 100644
index 8daf03877b4..00000000000
--- a/js/src/trace-test/tests/jaeger/bug563000/eif-call-typechange.js
+++ /dev/null
@@ -1,13 +0,0 @@
-setDebug(true);
-
-function callee() {
-  assertJit();
-  evalInFrame(1, "x = 'success'");
-}
-function caller() {
-  assertJit();
-  var x = ({ dana : "zuul" });
-  callee();
-  return x;
-}
-assertEq(caller(), "success");
diff --git a/js/src/trace-test/tests/jaeger/bug563000/eif-call.js b/js/src/trace-test/tests/jaeger/bug563000/eif-call.js
deleted file mode 100644
index 67ac02caa08..00000000000
--- a/js/src/trace-test/tests/jaeger/bug563000/eif-call.js
+++ /dev/null
@@ -1,13 +0,0 @@
-setDebug(true);
-
-function callee() {
-  assertJit();
-  evalInFrame(1, "x = 'success'");
-}
-function caller() {
-  assertJit();
-  var x = "failure";
-  callee();
-  return x;
-}
-assertEq(caller(), "success");
diff --git a/js/src/trace-test/tests/jaeger/bug563000/eif-getter-newvar.js b/js/src/trace-test/tests/jaeger/bug563000/eif-getter-newvar.js
deleted file mode 100644
index ee7c8643816..00000000000
--- a/js/src/trace-test/tests/jaeger/bug563000/eif-getter-newvar.js
+++ /dev/null
@@ -1,9 +0,0 @@
-setDebug(true);
-
-__defineGetter__("someProperty", function () { evalInFrame(1, "var x = 'success'"); });
-function caller(obj) {
-  assertJit();
-  obj.someProperty;
-  return x;
-}
-assertEq(caller(this), "success");
diff --git a/js/src/trace-test/tests/jaeger/bug563000/eif-getter-typechange.js b/js/src/trace-test/tests/jaeger/bug563000/eif-getter-typechange.js
deleted file mode 100644
index 5170ccbd9a4..00000000000
--- a/js/src/trace-test/tests/jaeger/bug563000/eif-getter-typechange.js
+++ /dev/null
@@ -1,10 +0,0 @@
-setDebug(true);
-
-__defineGetter__("someProperty", function () { evalInFrame(1, "var x = 'success'"); });
-function caller(obj) {
-  assertJit();
-  var x = ({ dana : 'zuul' });
-  obj.someProperty;
-  return x;
-}
-assertEq(caller(this), "success");
diff --git a/js/src/trace-test/tests/jaeger/bug563000/eif-getter.js b/js/src/trace-test/tests/jaeger/bug563000/eif-getter.js
deleted file mode 100644
index 5d03c99c817..00000000000
--- a/js/src/trace-test/tests/jaeger/bug563000/eif-getter.js
+++ /dev/null
@@ -1,10 +0,0 @@
-setDebug(true);
-
-__defineGetter__("someProperty", function () { evalInFrame(1, "x = 'success'"); });
-function caller(obj) {
-  assertJit();
-  var x = "failure";
-  obj.someProperty;
-  return x;
-}
-assertEq(caller(this), "success");
diff --git a/js/src/trace-test/tests/jaeger/bug563000/eif-trap-newvar.js b/js/src/trace-test/tests/jaeger/bug563000/eif-trap-newvar.js
deleted file mode 100644
index 60a67e76ea5..00000000000
--- a/js/src/trace-test/tests/jaeger/bug563000/eif-trap-newvar.js
+++ /dev/null
@@ -1,9 +0,0 @@
-setDebug(true);
-
-function nop(){}
-function caller(obj) {
-  assertJit();
-  return x;
-}
-trap(caller, 9, "var x = 'success'; nop()");
-assertEq(caller(this), "success");
diff --git a/js/src/trace-test/tests/jaeger/bug563000/eif-trap-typechange.js b/js/src/trace-test/tests/jaeger/bug563000/eif-trap-typechange.js
deleted file mode 100644
index 0c97d65fa08..00000000000
--- a/js/src/trace-test/tests/jaeger/bug563000/eif-trap-typechange.js
+++ /dev/null
@@ -1,10 +0,0 @@
-setDebug(true);
-
-function nop(){}
-function caller(obj) {
-  assertJit();
-  var x = ({ dana : "zuul" });
-  return x;
-}
-trap(caller, 22, "x = 'success'; nop()");
-assertEq(caller(this), "success");
diff --git a/js/src/trace-test/tests/jaeger/bug563000/eif-trap.js b/js/src/trace-test/tests/jaeger/bug563000/eif-trap.js
deleted file mode 100644
index 8120c9126b7..00000000000
--- a/js/src/trace-test/tests/jaeger/bug563000/eif-trap.js
+++ /dev/null
@@ -1,10 +0,0 @@
-setDebug(true);
-
-function nop(){}
-function caller(obj) {
-  assertJit();
-  var x = "failure";
-  return x;
-}
-trap(caller, 16, "x = 'success'; nop()");
-assertEq(caller(this), "success");
diff --git a/js/src/trace-test/tests/jaeger/bug563000/simple-trap-1.js b/js/src/trace-test/tests/jaeger/bug563000/simple-trap-1.js
index 266db65090d..0f8163d8901 100644
--- a/js/src/trace-test/tests/jaeger/bug563000/simple-trap-1.js
+++ b/js/src/trace-test/tests/jaeger/bug563000/simple-trap-1.js
@@ -1,4 +1,3 @@
-setDebug(true);
 var x = "failure";
 function main() { x = "success"; }
 
diff --git a/js/src/trace-test/tests/jaeger/bug563000/simple-trap-2.js b/js/src/trace-test/tests/jaeger/bug563000/simple-trap-2.js
index 3d119fb32fa..05e741225f7 100644
--- a/js/src/trace-test/tests/jaeger/bug563000/simple-trap-2.js
+++ b/js/src/trace-test/tests/jaeger/bug563000/simple-trap-2.js
@@ -1,4 +1,3 @@
-setDebug(true);
 var x = "notset";
 function main() { x = "failure"; }
 function success() { x = "success"; }
diff --git a/js/src/trace-test/tests/jaeger/bug563000/simple-untrap.js b/js/src/trace-test/tests/jaeger/bug563000/simple-untrap.js
index 2f89f58bc3d..54a8bae4405 100644
--- a/js/src/trace-test/tests/jaeger/bug563000/simple-untrap.js
+++ b/js/src/trace-test/tests/jaeger/bug563000/simple-untrap.js
@@ -1,4 +1,3 @@
-setDebug(true);
 var x = "notset";
 function main() { x = "success"; }
 function failure() { x = "failure"; }
diff --git a/js/src/trace-test/tests/jaeger/bug563000/trap-force-return-1.js b/js/src/trace-test/tests/jaeger/bug563000/trap-force-return-1.js
index fcb2eab3ef1..01eb90791ba 100644
--- a/js/src/trace-test/tests/jaeger/bug563000/trap-force-return-1.js
+++ b/js/src/trace-test/tests/jaeger/bug563000/trap-force-return-1.js
@@ -1,4 +1,3 @@
-setDebug(true);
 function main() {
   return "failure";
 }
diff --git a/js/src/trace-test/tests/jaeger/bug563000/trap-force-return-2.js b/js/src/trace-test/tests/jaeger/bug563000/trap-force-return-2.js
index 3c22ba383dc..9c7a740a1c8 100644
--- a/js/src/trace-test/tests/jaeger/bug563000/trap-force-return-2.js
+++ b/js/src/trace-test/tests/jaeger/bug563000/trap-force-return-2.js
@@ -1,4 +1,3 @@
-setDebug(true);
 function main() {
   return 1;
 }
diff --git a/js/src/trace-test/tests/jaeger/bug563000/trap-own-callsite.js b/js/src/trace-test/tests/jaeger/bug563000/trap-own-callsite.js
index 6c815c7b997..3fb42627b19 100644
--- a/js/src/trace-test/tests/jaeger/bug563000/trap-own-callsite.js
+++ b/js/src/trace-test/tests/jaeger/bug563000/trap-own-callsite.js
@@ -1,4 +1,3 @@
-setDebug(true);
 x = "notset";
 function myparent(nested) {
   if (nested) {
diff --git a/js/src/trace-test/tests/jaeger/bug563000/trap-parent-from-trap.js b/js/src/trace-test/tests/jaeger/bug563000/trap-parent-from-trap.js
index 1e5fb19307f..309ba8db1c3 100644
--- a/js/src/trace-test/tests/jaeger/bug563000/trap-parent-from-trap.js
+++ b/js/src/trace-test/tests/jaeger/bug563000/trap-parent-from-trap.js
@@ -1,4 +1,3 @@
-setDebug(true);
 x = "notset";
 
 function child() {
diff --git a/js/src/trace-test/tests/jaeger/bug563000/trap-parent.js b/js/src/trace-test/tests/jaeger/bug563000/trap-parent.js
index 3805303c371..50a9ba38be9 100644
--- a/js/src/trace-test/tests/jaeger/bug563000/trap-parent.js
+++ b/js/src/trace-test/tests/jaeger/bug563000/trap-parent.js
@@ -1,4 +1,3 @@
-setDebug(true);
 x = "notset";
 function child() {
   /* JSOP_STOP in parent. */
diff --git a/js/src/trace-test/tests/jaeger/bug563000/trap-self-as-parent.js b/js/src/trace-test/tests/jaeger/bug563000/trap-self-as-parent.js
index eefc0bb8600..723ea2d8e95 100644
--- a/js/src/trace-test/tests/jaeger/bug563000/trap-self-as-parent.js
+++ b/js/src/trace-test/tests/jaeger/bug563000/trap-self-as-parent.js
@@ -1,4 +1,3 @@
-setDebug(true);
 x = "notset";
 
 function myparent(nested) {
diff --git a/js/src/trace-test/tests/jaeger/bug563000/trap-self-from-trap.js b/js/src/trace-test/tests/jaeger/bug563000/trap-self-from-trap.js
index b898d166e15..ef675199938 100644
--- a/js/src/trace-test/tests/jaeger/bug563000/trap-self-from-trap.js
+++ b/js/src/trace-test/tests/jaeger/bug563000/trap-self-from-trap.js
@@ -1,4 +1,3 @@
-setDebug(true);
 x = "notset";
 
 function doNothing() { }
diff --git a/js/src/trace-test/tests/jaeger/bug563000/trap-self.js b/js/src/trace-test/tests/jaeger/bug563000/trap-self.js
index b828c0c9b06..bfd069b91e8 100644
--- a/js/src/trace-test/tests/jaeger/bug563000/trap-self.js
+++ b/js/src/trace-test/tests/jaeger/bug563000/trap-self.js
@@ -1,4 +1,3 @@
-setDebug(true);
 x = "notset";
 function main() {
   /* The JSOP_STOP in a. */
diff --git a/js/src/trace-test/tests/jaeger/bug563000/untrap-own-trapsite.js b/js/src/trace-test/tests/jaeger/bug563000/untrap-own-trapsite.js
index 20324c007e7..42d70642683 100644
--- a/js/src/trace-test/tests/jaeger/bug563000/untrap-own-trapsite.js
+++ b/js/src/trace-test/tests/jaeger/bug563000/untrap-own-trapsite.js
@@ -1,4 +1,3 @@
-setDebug(true);
 x = "notset";
 function child() {
   /* JSOP_STOP in parent */
diff --git a/js/src/trace-test/tests/jaeger/bug563000/untrap-self.js b/js/src/trace-test/tests/jaeger/bug563000/untrap-self.js
index 4c18db52e8e..58878f42364 100644
--- a/js/src/trace-test/tests/jaeger/bug563000/untrap-self.js
+++ b/js/src/trace-test/tests/jaeger/bug563000/untrap-self.js
@@ -1,4 +1,3 @@
-setDebug(true);
 x = "notset";
 function main() {
   /* JSOP_STOP in main. */