Get rid of contEnterHelper* (revert the revert)

It was identical to fcallHelper, except that if it couldn't get
a translation, it skipped over the prolog (and didnt call
the FunctionEntry hook, for example). That seems like a bug.

This removes it, cleans up funcBodyHelper to remove the special
cases for isGenerator, and modifies ContEnter to use
Func::prologTable()[1], rather than Func::funcBody() to dispatch.

hphp/runtime/vm/func.cpp

@@ -114,9 +114,7 @@ void Func::setFullName() {
 }
 
 void Func::initPrologues(int numParams, bool isGenerator) {
-  m_funcBody = (isGenerator ?
-                (TCA)HPHP::VM::Transl::contEnterHelperThunk :
-                (TCA)HPHP::VM::Transl::funcBodyHelperThunk);
+  m_funcBody = (TCA)HPHP::VM::Transl::funcBodyHelperThunk;
 
   int maxNumPrologues = Func::getMaxNumPrologues(numParams);
   int numPrologues =

hphp/runtime/vm/translator/hopt/hhbctranslator.cpp

@@ -702,7 +702,7 @@ void HhbcTranslator::emitContEnter(int32_t returnBcOffset) {
   SSATmp* contAR = m_tb->genLdRaw(cont, RawMemSlot::ContARPtr, Type::StkPtr);
 
   SSATmp* func = m_tb->genLdARFuncPtr(contAR, m_tb->genDefConst<int64_t>(0));
-  SSATmp* funcBody = m_tb->genLdRaw(func, RawMemSlot::FuncBody, Type::TCA);
+  SSATmp* funcBody = m_tb->genLdRaw(func, RawMemSlot::ContEntry, Type::TCA);
 
   m_tb->genContEnter(contAR, funcBody, returnBcOffset);
 

hphp/runtime/vm/translator/hopt/ir.h

@@ -1393,7 +1393,7 @@ class RawMemSlot {
 
   enum Kind {
     ContLabel, ContDone, ContShouldThrow, ContRunning, ContARPtr,
-    StrLen, FuncNumParams, FuncRefBitVec, FuncBody, MisBaseStrOff,
+    StrLen, FuncNumParams, FuncRefBitVec, ContEntry, MisBaseStrOff,
     MisCtx,
     MaxKind
   };
@@ -1408,7 +1408,7 @@ class RawMemSlot {
       case StrLen:          return GetStrLen();
       case FuncNumParams:   return GetFuncNumParams();
       case FuncRefBitVec:   return GetFuncRefBitVec();
-      case FuncBody:        return GetFuncBody();
+      case ContEntry:       return GetContEntry();
       case MisBaseStrOff:   return GetMisBaseStrOff();
       case MisCtx:          return GetMisCtx();
       default: not_reached();
@@ -1456,8 +1456,10 @@ class RawMemSlot {
     static RawMemSlot m(Func::refBitVecOff(), sz::qword, Type::Int);
     return m;
   }
-  static RawMemSlot& GetFuncBody() {
-    static RawMemSlot m(Func::funcBodyOff(), sz::qword, Type::TCA);
+  static RawMemSlot& GetContEntry() {
+    static RawMemSlot m(
+      Func::prologueTableOff() + sizeof(HPHP::VM::Transl::TCA),
+      sz::qword, Type::TCA);
     return m;
   }
   static RawMemSlot& GetMisBaseStrOff() {

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

@@ -213,57 +213,21 @@ asm (
 #endif
 );
 
-asm (
-  ".byte 0\n"
-  ".align 16\n"
-  ".globl __contEnterHelperThunk\n"
-"__contEnterHelperThunk:\n"
-#if defined(__x86_64__)
-  // The generator body's AR is in rStashedAR. rVmFp still points to the frame
-  // above the generator. The prologue is responsible for setting rVmFp. Even
-  // if we can't get a prologue, funcBodyHelper syncs the new FP, and the
-  // "resume helper" sets the hardware FP from that.
-  // This helper is called from the tc - so we need to maintain stack parity,
-  // hence the pop/push
-  "pop 0x8(%r15)\n"
-  "mov %r15, %rdi\n"
-  "call funcBodyHelper\n"
-  "push 0x8(%r15)\n"
-  "jmp *%rax\n"
-  "ud2\n"
-#elif defined(__AARCH64EL__)
-  "brk 0\n"
-#else
-# error You sure have your work cut out for you
-#endif
-);
-
 /*
- * Two different "function"-entry paths come through here: entering functions
- * via FCallArray, and entering generator bodies. The common element is that
- * neither requires different entry points for different callsite arities.
+ * This is used to generate an entry point for the entry
+ * to a function, after the prologue has run.
  */
 TCA funcBodyHelper(ActRec* fp) {
   setupAfterProlog(fp);
   tl_regState = REGSTATE_CLEAN;
   Func* func = const_cast<Func*>(fp->m_func);
 
-  TCA tca;
-  if (func->isGenerator()) {
-    assert(fp->numArgs() == 1);
-    tca = tx64->funcPrologue(func, 1);
-  } else {
-    tca = tx64->getCallArrayProlog(func);
-  }
+  TCA tca = tx64->getCallArrayProlog(func);
 
   if (tca) {
     func->setFuncBody(tca);
   } else {
-    if (func->isGenerator()) {
-      tca = Translator::Get()->getResumeHelperRet();
-    } else {
-      tca = Translator::Get()->getResumeHelper();
-    }
+    tca = Translator::Get()->getResumeHelper();
   }
   tl_regState = REGSTATE_DIRTY;
   return tca;

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

@@ -7566,7 +7566,7 @@ void TranslatorX64::translateContEnter(const Tracelet& t,
 
   // We're between tracelets; hardcode the register
   a.    loadq  (rStashedAR[AROFF(m_func)], rax);
-  a.    loadq  (rax[Func::funcBodyOff()], rax);
+  a.    loadq  (rax[Func::prologueTableOff() + sizeof(TCA)], rax);
 
   a.    call   (rax);
 }

hphp/runtime/vm/translator/translator-x64.h

@@ -1121,7 +1121,6 @@ const size_t kMaxNumTrampolines = kTrampolinesBlockSize /
 
 void fcallHelperThunk() asm ("__fcallHelperThunk");
 void funcBodyHelperThunk() asm ("__funcBodyHelperThunk");
-void contEnterHelperThunk() asm ("__contEnterHelperThunk");
 
 // These could be static but are used in hopt/codegen.cpp
 void raiseUndefVariable(StringData* nm);