diff --git a/js/src/jscntxtinlines.h b/js/src/jscntxtinlines.h
index a06cbf0253b8..4cd3787eec04 100644
--- a/js/src/jscntxtinlines.h
+++ b/js/src/jscntxtinlines.h
@@ -324,8 +324,6 @@ StackSpace::pushInvokeFrame(JSContext *cx, const CallArgs &args,
 {
     JS_ASSERT(firstUnused() == args.argv() + args.argc());
 
-    JSStackFrame *fp = fg->regs_.fp;
-    fp->setPrev(cx->regs);
     if (JS_UNLIKELY(!currentSegment->inContext())) {
         cx->pushSegmentAndFrame(currentSegment, fg->regs_);
     } else {
@@ -392,8 +390,6 @@ StackSpace::pushInlineFrame(JSContext *cx, JSScript *script, JSStackFrame *fp,
     JS_ASSERT(isCurrentAndActive(cx));
     JS_ASSERT(cx->regs == regs && script == fp->script());
 
-    fp->setPrev(regs);
-
     regs->fp = fp;
     regs->pc = script->code;
     regs->sp = fp->slots() + script->nfixed;
diff --git a/js/src/jsinterp.cpp b/js/src/jsinterp.cpp
index 9a155087dbf9..ea2898080cd2 100644
--- a/js/src/jsinterp.cpp
+++ b/js/src/jsinterp.cpp
@@ -830,7 +830,7 @@ Execute(JSContext *cx, JSObject *chain, JSScript *script,
     JSObject *initialVarObj;
     if (prev) {
         JS_ASSERT(chain == &prev->scopeChain());
-        frame.fp()->initEvalFrame(script, prev, prev->pc(cx), flags);
+        frame.fp()->initEvalFrame(cx, script, prev, flags);
 
         /*
          * We want to call |prev->varobj()|, but this requires knowing the
diff --git a/js/src/jsinterp.h b/js/src/jsinterp.h
index a1937da7190c..f5f9de5f827e 100644
--- a/js/src/jsinterp.h
+++ b/js/src/jsinterp.h
@@ -137,6 +137,8 @@ struct JSStackFrame
     friend class js::FrameRegsIter;
     friend struct JSContext;
 
+    inline void initPrev(JSContext *cx);
+
   public:
     /*
      * Stack frame sort (see JSStackFrame comment above)
@@ -195,8 +197,8 @@ struct JSStackFrame
     inline void initCallFrameLatePrologue();
 
     /* Used for eval. */
-    inline void initEvalFrame(JSScript *script, JSStackFrame *prev,
-                              jsbytecode *prevpc, uint32 flags);
+    inline void initEvalFrame(JSContext *cx, JSScript *script, JSStackFrame *prev,
+                              uint32 flags);
     inline void initGlobalFrame(JSScript *script, JSObject &chain, uint32 flags);
 
     /* Used when activating generators. */
@@ -223,27 +225,7 @@ struct JSStackFrame
         return prev_;
     }
 
-    void setPrev(JSStackFrame *prev, jsbytecode *prevpc) {
-        JS_ASSERT(flags_ & JSFRAME_HAS_PREVPC);
-        prev_ = prev;
-        if (prev) {
-            prevpc_ = prevpc;
-            JS_ASSERT_IF(!prev->isDummyFrame() && !prev->hasImacropc(),
-                         uint32(prevpc - prev->script()->code) < prev->script()->length);
-        }
-    }
-
-    void setPrev(JSFrameRegs *regs) {
-        JS_ASSERT(flags_ & JSFRAME_HAS_PREVPC);
-        if (regs) {
-            prev_ = regs->fp;
-            prevpc_ = regs->pc;
-            JS_ASSERT_IF(!prev_->isDummyFrame() && !prev_->hasImacropc(),
-                         uint32(prevpc_ - prev_->script()->code) < prev_->script()->length);
-        } else {
-            prev_ = NULL;
-        }
-    }
+    inline void resetGeneratorPrev(JSContext *cx);
 
     /*
      * Frame slots
diff --git a/js/src/jsinterpinlines.h b/js/src/jsinterpinlines.h
index f8f02f756c9f..41447266d34b 100644
--- a/js/src/jsinterpinlines.h
+++ b/js/src/jsinterpinlines.h
@@ -40,6 +40,29 @@
 #ifndef jsinterpinlines_h__
 #define jsinterpinlines_h__
 
+inline void
+JSStackFrame::initPrev(JSContext *cx)
+{
+    JS_ASSERT(flags_ & JSFRAME_HAS_PREVPC);
+    if (JSFrameRegs *regs = cx->regs) {
+        prev_ = regs->fp;
+        prevpc_ = regs->pc;
+        JS_ASSERT_IF(!prev_->isDummyFrame() && !prev_->hasImacropc(),
+                     uint32(prevpc_ - prev_->script()->code) < prev_->script()->length);
+    } else {
+        prev_ = NULL;
+#ifdef DEBUG
+        prevpc_ = (jsbytecode *)0xbadc;
+#endif
+    }
+}
+
+inline void
+JSStackFrame::resetGeneratorPrev(JSContext *cx)
+{
+    initPrev(cx);
+}
+
 inline void
 JSStackFrame::initCallFrame(JSContext *cx, JSObject &callee, JSFunction *fun,
                             uint32 nactual, uint32 flagsArg)
@@ -54,7 +77,7 @@ JSStackFrame::initCallFrame(JSContext *cx, JSObject &callee, JSFunction *fun,
     exec.fun = fun;
     args.nactual = nactual;  /* only need to write if over/under-flow */
     scopeChain_ = callee.getParent();
-    /* prevpc_, prev_ initialized by push*Frame */
+    initPrev(cx);
     JS_ASSERT(!hasImacropc());
     JS_ASSERT(!hasHookData());
     JS_ASSERT(annotation() == NULL);
@@ -89,7 +112,6 @@ JSStackFrame::initCallFrameCallerHalf(JSContext *cx, uint32 nactual, uint32 flag
 inline void
 JSStackFrame::initCallFrameEarlyPrologue(JSFunction *fun, void *ncode)
 {
-    /* Initialize state that gets set early in a jitted function's prologue. */
     exec.fun = fun;
     ncode_ = ncode;
 }
@@ -105,8 +127,7 @@ JSStackFrame::initCallFrameLatePrologue()
 }
 
 inline void
-JSStackFrame::initEvalFrame(JSScript *script, JSStackFrame *prev,
-                            jsbytecode *prevpc, uint32 flagsArg)
+JSStackFrame::initEvalFrame(JSContext *cx, JSScript *script, JSStackFrame *prev, uint32 flagsArg)
 {
     JS_ASSERT(flagsArg & JSFRAME_EVAL);
     JS_ASSERT((flagsArg & ~(JSFRAME_EVAL | JSFRAME_DEBUGGER)) == 0);
@@ -133,10 +154,12 @@ JSStackFrame::initEvalFrame(JSScript *script, JSStackFrame *prev,
     } else {
         exec.script = script;
     }
+
     scopeChain_ = &prev->scopeChain();
     JS_ASSERT_IF(isFunctionFrame(), &callObj() == &prev->callObj());
 
-    setPrev(prev, prevpc);
+    prev_ = prev;
+    prevpc_ = prev->pc(cx);
     JS_ASSERT(!hasImacropc());
     JS_ASSERT(!hasHookData());
     setAnnotation(prev->annotation());
@@ -157,7 +180,6 @@ JSStackFrame::initGlobalFrame(JSScript *script, JSObject &chain, uint32 flagsArg
     exec.script = script;
     args.script = (JSScript *)0xbad;
     scopeChain_ = &chain;
-
     prev_ = NULL;
     JS_ASSERT(!hasImacropc());
     JS_ASSERT(!hasHookData());
@@ -169,7 +191,7 @@ JSStackFrame::initDummyFrame(JSContext *cx, JSObject &chain)
 {
     js::PodZero(this);
     flags_ = JSFRAME_DUMMY | JSFRAME_HAS_PREVPC | JSFRAME_HAS_SCOPECHAIN;
-    setPrev(cx->regs);
+    initPrev(cx);
     chain.isGlobal();
     setScopeChainNoCallObj(chain);
 }
diff --git a/js/src/jsiter.cpp b/js/src/jsiter.cpp
index a5d18f38abcf..772415a27df6 100644
--- a/js/src/jsiter.cpp
+++ b/js/src/jsiter.cpp
@@ -1271,7 +1271,7 @@ SendToGenerator(JSContext *cx, JSGeneratorOp op, JSObject *obj,
 
         /* Copy frame onto the stack. */
         stackfp->stealFrameAndSlots(stackvp, genfp, genvp, gen->regs.sp);
-        stackfp->setPrev(cx->regs);
+        stackfp->resetGeneratorPrev(cx);
         stackfp->unsetFloatingGenerator();
         RebaseRegsFromTo(&gen->regs, genfp, stackfp);
         MUST_FLOW_THROUGH("restore");