Replace ContSend by CGetL+CUnsetL

The behavior of ContSend is equivalent to CGetL+CUnsetL. Let's kill this
unnecessary opcode. Let's remove this logic from ContRaise opcode as
well.

hphp/compiler/analysis/emitter.cpp

@@ -7050,12 +7050,21 @@ static void emitContinuationMethod(UnitEmitter& ue, FuncEmitter* fe,
       ue.emitIVA(m == METH_SEND || m == METH_RAISE);
 
       const Offset ehStart = ue.bcPos();
-      static Op mOps[] = {
-        OpNull,
-        OpContSend,
-        OpContRaise,
-      };
-      ue.emitOp(mOps[m]);
+      switch(m) {
+        case METH_NEXT:
+          ue.emitOp(OpNull);
+          break;
+        case METH_RAISE:
+          ue.emitOp(OpContRaise);
+          // intentional fallthrough to push the exception on the stack
+        case METH_SEND:
+          ue.emitOp(OpCGetL); ue.emitIVA(0);
+          ue.emitOp(OpUnsetL); ue.emitIVA(0);
+          break;
+        default:
+          not_reached();
+      }
+
       ue.emitOp(OpContEnter);
       ue.emitOp(OpContStopped);
       ue.emitOp(OpNull);

hphp/doc/bytecode.specification

@@ -3732,17 +3732,10 @@ ContCheck <check started>    []  ->  []
   object. If the continuation is finished, already running, or not yet started
   and <check started> is enabled, an exception will be thrown.
 
-ContSend    []  ->  [C]
-
-  Prepare continuation to receive a value. $this must be a Continuation object
-  that passed ContCheck<true> check. The value in local 0 is moved to the stack
-  for sending to the Continuation by ContEnter.
-
-ContRaise    []  ->  [C:Obj:Exception]
+ContRaise    []  ->  []
 
   Prepare continuation to receive a thrown exception. $this must be a
-  Continuation object that passed ContCheck<true> check. The exception in
-  local 0 is moved to the stack for sending to the Continuation by ContEnter.
+  Continuation object that passed ContCheck<true> check.
 
 ContValid    []  ->  [C:Bool]
 

hphp/runtime/vm/bytecode.cpp

@@ -6865,23 +6865,11 @@ inline void OPTBLD_INLINE VMExecutionContext::iopContCheck(PC& pc) {
   cont->preNext();
 }
 
-inline void OPTBLD_INLINE VMExecutionContext::iopContSend(PC& pc) {
-  NEXT();
-
-  // prepare value to be sent by ContEnter
-  tvCopy(*frame_local(m_fp, 0), *m_stack.allocTV());
-  tvWriteUninit(frame_local(m_fp, 0));
-}
-
 inline void OPTBLD_INLINE VMExecutionContext::iopContRaise(PC& pc) {
   NEXT();
   c_Continuation* cont = this_continuation(m_fp);
   assert(cont->m_label);
   --cont->m_label;
-
-  // prepare exception to be sent by ContEnter
-  tvCopy(*frame_local(m_fp, 0), *m_stack.allocTV());
-  tvWriteUninit(frame_local(m_fp, 0));
 }
 
 inline void OPTBLD_INLINE VMExecutionContext::iopContValid(PC& pc) {

hphp/runtime/vm/hhbc.h

@@ -553,8 +553,7 @@ enum SetOpOp {
   O(ContSuspendK,    ONE(IVA),         TWO(CV,CV),      NOV,        CF) \
   O(ContRetC,        NA,               ONE(CV),         NOV,        CF_TF) \
   O(ContCheck,       ONE(IVA),         NOV,             NOV,        NF) \
-  O(ContSend,        NA,               NOV,             ONE(CV),    NF) \
-  O(ContRaise,       NA,               NOV,             ONE(CV),    NF) \
+  O(ContRaise,       NA,               NOV,             NOV,        NF) \
   O(ContValid,       NA,               NOV,             ONE(CV),    NF) \
   O(ContKey,         NA,               NOV,             ONE(CV),    NF) \
   O(ContCurrent,     NA,               NOV,             ONE(CV),    NF) \

hphp/runtime/vm/jit/hhbctranslator.cpp

@@ -1190,24 +1190,12 @@ void HhbcTranslator::emitContCheck(bool checkStarted) {
   gen(ContPreNext, getExitSlowTrace(), cont);
 }
 
-void HhbcTranslator::emitContSend() {
-  assert(curClass());
-
-  // prepare value to be sent by ContEnter
-  push(gen(LdLoc, Type::Cell, LocalId(0), m_tb->fp()));
-  gen(StLoc, LocalId(0), m_tb->fp(), m_tb->genDefUninit());
-}
-
 void HhbcTranslator::emitContRaise() {
   assert(curClass());
   SSATmp* cont = gen(LdThis, m_tb->fp());
   SSATmp* label = gen(LdRaw, Type::Int, cont, cns(RawMemSlot::ContLabel));
   label = gen(OpSub, label, cns(1));
   gen(StRaw, cont, cns(RawMemSlot::ContLabel), label);
-
-  // prepare value to be sent by ContEnter
-  push(gen(LdLoc, Type::Cell, LocalId(0), m_tb->fp()));
-  gen(StLoc, LocalId(0), m_tb->fp(), m_tb->genDefUninit());
 }
 
 void HhbcTranslator::emitContValid() {
@@ -3339,8 +3327,6 @@ uint32_t localOutputId(const NormalizedInstruction& inst) {
     case OpUnpackCont:
     case OpContSuspend:
     case OpContRetC:
-    case OpContSend:
-    case OpContRaise:
       return 0;
 
     case OpSetWithRefLM:

hphp/runtime/vm/jit/hhbctranslator.h

@@ -381,7 +381,6 @@ struct HhbcTranslator {
   void emitContSuspendK(int64_t labelId);
   void emitContRetC();
   void emitContCheck(bool checkStarted);
-  void emitContSend();
   void emitContRaise();
   void emitContValid();
   void emitContKey();

hphp/runtime/vm/jit/irtranslator.cpp

@@ -568,10 +568,6 @@ void Translator::translateContCheck(const NormalizedInstruction& i) {
   HHIR_EMIT(ContCheck, i.imm[0].u_IVA);
 }
 
-void Translator::translateContSend(const NormalizedInstruction& i) {
-  HHIR_EMIT(ContSend);
-}
-
 void Translator::translateContRaise(const NormalizedInstruction& i) {
   HHIR_EMIT(ContRaise);
 }

hphp/runtime/vm/jit/translator-instrs.h

@@ -134,7 +134,6 @@
   CASE(ContSuspendK) \
   CASE(ContRetC) \
   CASE(ContCheck) \
-  CASE(ContSend) \
   CASE(ContRaise) \
   CASE(ContValid) \
   CASE(ContKey) \

hphp/runtime/vm/jit/translator.cpp

@@ -1270,8 +1270,7 @@ static const struct {
   { OpContSuspendK,{Local|StackTop2,  None,         OutNone,          -2 }},
   { OpContRetC,    {Local|Stack1,     None,         OutNone,          -1 }},
   { OpContCheck,   {None,             None,         OutNone,           0 }},
-  { OpContSend,    {Local,            Stack1,       OutUnknown,        1 }},
-  { OpContRaise,   {Local,            Stack1,       OutUnknown,        1 }},
+  { OpContRaise,   {None,             None,         OutNone,           0 }},
   { OpContValid,   {None,             Stack1,       OutBoolean,        1 }},
   { OpContKey,     {None,             Stack1,       OutUnknown,        1 }},
   { OpContCurrent, {None,             Stack1,       OutUnknown,        1 }},
@@ -1841,8 +1840,6 @@ void Translator::getInputs(SrcKey startSk,
       case OpContSuspend:
       case OpContSuspendK:
       case OpContRetC:
-      case OpContSend:
-      case OpContRaise:
         loc = 0;
         break;
 

hphp/test/quick/debugger/flow_gen.php.expectf

@@ -53,6 +53,8 @@ Break at Continuation::send()
 step
 Break at Continuation::send()
 step
+Break at Continuation::send()
+step
 Break at genFoo$continuation() on line 11 of %s/flow_gen.php
   10 
   11 function genFoo($a) {
@@ -112,6 +114,8 @@ Break at Continuation::send()
 step
 Break at Continuation::send()
 step
+Break at Continuation::send()
+step
 Break at genFoo$continuation() on line 11 of %s/flow_gen.php
   10 
   11 function genFoo($a) {

hphp/test/quick/debugger/flow_gen.php.in

@@ -12,6 +12,7 @@ step
 step
 step
 step
+step
 next
 next
 next
@@ -23,6 +24,7 @@ step
 step
 step
 step
+step
 next
 next
 next