Fix some bugs when we fail to get a translation

If we failed to get the translation for a cloned closure, we didnt
clean the registers.

VMRegAnchor::VMRegAncor(ActRec*,bool) didnt know how to set things
up for continuations, and had an unused bool parameter.

RetFromInterpretedFrame isnt suitable for returning from a
generator - so just preserve m_savedRip across the doFCall.

hphp/runtime/vm/bytecode.cpp

@@ -1790,7 +1790,14 @@ bool VMExecutionContext::prepareFuncEntry(ActRec *ar,
     func = ar->m_func;
   }
 
-  pushLocalsAndIterators(func, nlocals);
+  if (LIKELY(!func->isGenerator())) {
+    /*
+     * we only get here from callAndResume
+     * if we failed to get a translation for
+     * a generator's prologue
+     */
+    pushLocalsAndIterators(func, nlocals);
+  }
 
   /*
    * If we're reentering, make sure to finalize the ActRec before

hphp/runtime/vm/translator/translator-inline.h

@@ -90,27 +90,21 @@ struct VMRegAnchor : private boost::noncopyable {
     m_old = tl_regState;
     Translator::Get()->sync();
   }
-  VMRegAnchor(ActRec* ar, bool atFCall=false) {
+  VMRegAnchor(ActRec* ar) {
     // Some C++ entry points have an ActRec prepared from after a call
     // instruction. This syncs us to right after the call instruction.
     assert(tl_regState == REGSTATE_DIRTY);
     m_old = REGSTATE_DIRTY;
     tl_regState = REGSTATE_CLEAN;
-    int numArgs = ar->numArgs();
 
-    const Func* prevF = ((ActRec*)(ar->m_savedRbp))->m_func;
-    vmsp() = (TypedValue*)ar - numArgs;
+    auto prevAr = (ActRec*)ar->m_savedRbp;
+    const Func* prevF = prevAr->m_func;
+    vmsp() = ar->m_func->isGenerator() ?
+      Stack::generatorStackBase(ar) :
+      (TypedValue*)ar - ar->numArgs();
     assert(g_vmContext->m_stack.isValidAddress((uintptr_t)vmsp()));
     vmpc() = prevF->unit()->at(prevF->base() + ar->m_soff);
-    if (atFCall) {
-      // VMExecutionContext::doFCall expects vmfp to be the caller's
-      // ActRec, but if we call VMRegAnchor while executing the FCall
-      // sequence (in TargetCache::callAndResume), we actually have the
-      // callee's ActRec.
-      vmfp() = (TypedValue*)ar->m_savedRbp;
-    } else {
-      vmfp() = (TypedValue*)ar;
-    }
+    vmfp() = (TypedValue*)prevAr;
   }
   ~VMRegAnchor() {
     tl_regState = m_old;

hphp/runtime/vm/translator/translator-x64-helpers.cpp

@@ -78,6 +78,29 @@ void TranslatorX64::reqLitHelper(const ReqLitStaticArgs* args) {
   framePtr->m_savedRbp = (uint64_t)ec->m_fp;
 }
 
+static void setupAfterProlog(ActRec* fp) {
+  g_vmContext->m_fp = fp;
+  g_vmContext->m_stack.top() = sp;
+  int nargs = fp->numArgs();
+  int nparams = fp->m_func->numParams();
+  Offset firstDVInitializer = InvalidAbsoluteOffset;
+  if (nargs < nparams) {
+    const Func::ParamInfoVec& paramInfo = fp->m_func->params();
+    for (int i = nargs; i < nparams; ++i) {
+      Offset dvInitializer = paramInfo[i].funcletOff();
+      if (dvInitializer != InvalidAbsoluteOffset) {
+        firstDVInitializer = dvInitializer;
+        break;
+      }
+    }
+  }
+  if (firstDVInitializer != InvalidAbsoluteOffset) {
+    g_vmContext->m_pc = fp->m_func->unit()->entry() + firstDVInitializer;
+  } else {
+    g_vmContext->m_pc = fp->m_func->getEntry();
+  }
+}
+
 /*
  * fcallHelperThunk--
  *
@@ -93,10 +116,13 @@ static TCA callAndResume(ActRec *ar) {
      * array is just being used as entry points for the
      * dv funclets. Dont run the prolog again.
      */
-    VMRegAnchor _(ar, true);
+    VMRegAnchor _(ar);
+    uint64_t rip = ar->m_savedRip;
     g_vmContext->doFCall<true>(ar, g_vmContext->m_pc);
+    ar->m_savedRip = rip;
     return Translator::Get()->getResumeHelperRet();
   }
+  setupAfterProlog(ar);
   return Translator::Get()->getResumeHelper();
 }
 
@@ -218,34 +244,14 @@ asm (
  * neither requires different entry points for different callsite arities.
  */
 TCA funcBodyHelper(ActRec* fp) {
-  g_vmContext->m_fp = fp;
-  g_vmContext->m_stack.top() = sp;
-  int nargs = fp->numArgs();
-  int nparams = fp->m_func->numParams();
-  Offset firstDVInitializer = InvalidAbsoluteOffset;
-  if (nargs < nparams) {
-    const Func::ParamInfoVec& paramInfo = fp->m_func->params();
-    for (int i = nargs; i < nparams; ++i) {
-      Offset dvInitializer = paramInfo[i].funcletOff();
-      if (dvInitializer != InvalidAbsoluteOffset) {
-        firstDVInitializer = dvInitializer;
-        break;
-      }
-    }
-  }
-  if (firstDVInitializer != InvalidAbsoluteOffset) {
-    g_vmContext->m_pc = fp->m_func->unit()->entry() + firstDVInitializer;
-  } else {
-    g_vmContext->m_pc = fp->m_func->getEntry();
-  }
+  setupAfterProlog(fp);
   tl_regState = REGSTATE_CLEAN;
   Func* func = const_cast<Func*>(fp->m_func);
-  SrcKey sk(func, func->base());
 
   TCA tca;
   if (func->isGenerator()) {
-    assert(nargs == 1);
-    tca = tx64->funcPrologue(func, nargs);
+    assert(fp->numArgs() == 1);
+    tca = tx64->funcPrologue(func, 1);
   } else {
     tca = tx64->getCallArrayProlog(func);
   }