Updating async function implementation by desugaring to generators

This change removes the function wrapper implementation of async
functions. Now the async functions will behave similar to generator
functions. The actual function body will be in the sciptFunction field.
Symbols now need not be forced to slots. asyncspawn opcode and parse
node are no more needed.In the backend async functions are also
added to the generator JIT flag. await is desugared into yield.

Author: aneeshdk

lib/Backend/BailOut.cpp

@@ -1437,7 +1437,7 @@ BailOutRecord::BailOutHelper(Js::JavascriptCallStackLayout * layout, Js::ScriptF
     Js::InterpreterStackFrame* newInstance = nullptr;
     Js::Var* allocation = nullptr;
 
-    if (executeFunction->IsGenerator())
+    if (executeFunction->IsGenerator() || executeFunction->IsAsync())
     {
         // If the FunctionBody is a generator then this call is being made by one of the three
         // generator resuming methods: next(), throw(), or return().  They all pass the generator

lib/Backend/FlowGraph.cpp

@@ -1099,7 +1099,7 @@ FlowGraph::Destroy(void)
                 // Skipping Try blocks as we have dependency on blocks to get the last instr(see below in this function)
                 if (!fHasTry)
                 {
-                    if (this->func->GetJnFunction()->IsGenerator())
+                    if (this->func->GetJnFunction()->IsGenerator() || this->func->GetJnFunction()->IsAsync())
                     {
                         // the label could be a yield resume label, in which case we also need to remove it from the YieldOffsetResumeLabels list
                         this->func->MapUntilYieldOffsetResumeLabels([this, &labelInstr](int i, const YieldOffsetResumeLabel& yorl)

lib/Backend/Func.cpp

@@ -214,7 +214,7 @@ Func::Func(JitArenaAllocator *alloc, CodeGenWorkItem* workItem, const Js::Functi
         m_nonTempLocalVars = Anew(this->m_alloc, BVSparse<JitArenaAllocator>, this->m_alloc);
     }
 
-    if (this->m_jnFunction->IsGenerator())
+    if (this->m_jnFunction->IsGenerator() || this->m_jnFunction->IsAsync())
     {
         m_yieldOffsetResumeLabelList = YieldOffsetResumeLabelList::New(this->m_alloc);
     }
@@ -846,8 +846,8 @@ Func::AjustLocalVarSlotOffset()
 bool
 Func::DoGlobOptsForGeneratorFunc()
 {
-    // Disable GlobOpt optimizations for generators initially. Will visit and enable each one by one.
-    return !m_jnFunction->IsGenerator();
+    // Disable GlobOpt optimizations for generators and asyn functions initially. Will visit and enable each one by one.
+    return !m_jnFunction->IsGenerator() && !m_jnFunction->IsAsync();
 }
 
 void

lib/Backend/Func.h

@@ -281,12 +281,6 @@ static const unsigned __int64 c_debugFillPattern8 = 0xcececececececece;
         Assert(this->m_jnFunction);     // For now we always have a function body
         return this->m_jnFunction->GetIsGlobalFunc();
     }
-    bool IsGeneratorFunc() const
-    {
-        Assert(this->IsTopFunc());
-        Assert(this->m_jnFunction);     // For now we always have a function body
-        return this->m_jnFunction->IsGenerator();
-    }
     bool IsLambda() const
     {
         Assert(this->IsTopFunc());

lib/Backend/IRBuilder.cpp

@@ -1365,7 +1365,7 @@ IRBuilder::BuildImplicitArgIns()
 void
 IRBuilder::BuildGeneratorPreamble()
 {
-    if (!this->m_func->GetJnFunction()->IsGenerator())
+    if (!this->m_func->GetJnFunction()->IsGenerator() && !this->m_func->GetJnFunction()->IsAsync())
     {
         return;
     }

lib/Backend/JnHelperMethodList.h

@@ -494,7 +494,6 @@ HELPERCALL(ScopedLdSuperCtor,   Js::JavascriptOperators::OP_ScopedLdSuperCtor,
 HELPERCALL(SetHomeObj,          Js::JavascriptOperators::OP_SetHomeObj,         0)
 
 HELPERCALL(ResumeYield,   Js::JavascriptOperators::OP_ResumeYield,   AttrCanThrow)
-HELPERCALL(AsyncSpawn,    Js::JavascriptOperators::OP_AsyncSpawn,    AttrCanThrow)
 
 #include "ExternalHelperMethodList.h"
 

lib/Backend/Lower.cpp

@@ -2956,10 +2956,6 @@ Lowerer::LowerRange(IR::Instr *instrStart, IR::Instr *instrEnd, bool defaultDoFa
             break;
         }
 
-        case Js::OpCode::AsyncSpawn:
-            this->LowerBinaryHelperMem(instr, IR::HelperAsyncSpawn);
-            break;
-
         case Js::OpCode::FrameDisplayCheck:
             instrPrev = this->LowerFrameDisplayCheck(instr);
             break;
@@ -5088,7 +5084,7 @@ Lowerer::LowerNewScObjArrayNoArg(IR::Instr *newObjInstr)
 void
 Lowerer::LowerPrologEpilog()
 {
-    if (m_func->GetJnFunction()->IsGenerator())
+    if (m_func->GetJnFunction()->IsGenerator() || m_func->GetJnFunction()->IsAsync())
     {
         LowerGeneratorResumeJumpTable();
     }
@@ -5125,7 +5121,7 @@ Lowerer::LowerPrologEpilogAsmJs()
 void
 Lowerer::LowerGeneratorResumeJumpTable()
 {
-    Assert(m_func->GetJnFunction()->IsGenerator());
+    Assert(m_func->GetJnFunction()->IsGenerator() || m_func->GetJnFunction()->IsAsync());
 
     IR::Instr * jumpTableInstr = m_func->m_headInstr;
     AssertMsg(jumpTableInstr->IsEntryInstr(), "First instr isn't an EntryInstr...");
@@ -7572,7 +7568,7 @@ Lowerer::LoadArgumentCount(IR::Instr *const instr)
         instr->SetSrc1(IR::IntConstOpnd::New(instr->m_func->actualCount, TyUint32, instr->m_func, true));
         LowererMD::ChangeToAssign(instr);
     }
-    else if (instr->m_func->GetJnFunction()->IsGenerator())
+    else if (instr->m_func->GetJnFunction()->IsGenerator() || instr->m_func->GetJnFunction()->IsAsync())
     {
         IR::SymOpnd* symOpnd = LoadCallInfo(instr);
         instr->SetSrc1(symOpnd);
@@ -9611,7 +9607,7 @@ IR::Instr *Lowerer::LowerRestParameter(IR::Opnd *formalsOpnd, IR::Opnd *dstOpnd,
 
     LoadScriptContext(helperCallInstr);
 
-    BOOL isGenerator = this->m_func->GetJnFunction()->IsGenerator();
+    BOOL isGenerator = this->m_func->GetJnFunction()->IsGenerator() || this->m_func->GetJnFunction()->IsAsync();
 
     // Elements pointer = ebp + (formals count + formals offset + 1)*sizeof(Var)
     IR::RegOpnd *srcOpnd = isGenerator ? generatorArgsPtrOpnd : IR::Opnd::CreateFramePointerOpnd(this->m_func);
@@ -9719,7 +9715,7 @@ Lowerer::LowerArgIn(IR::Instr *instrArgIn)
             // $createRestArray
             instrArgIn->InsertBefore(createRestArrayLabel);
 
-            if (m_func->GetJnFunction()->IsGenerator())
+            if (m_func->GetJnFunction()->IsGenerator() || m_func->GetJnFunction()->IsAsync())
             {
                 generatorArgsPtrOpnd = LoadGeneratorArgsPtr(instrArgIn);
             }
@@ -9738,7 +9734,7 @@ Lowerer::LowerArgIn(IR::Instr *instrArgIn)
     if (argIndex == 1)
     {
         // The "this" argument is not source-dependent and doesn't need to be checked.
-        if (m_func->GetJnFunction()->IsGenerator())
+        if (m_func->GetJnFunction()->IsGenerator() || m_func->GetJnFunction()->IsAsync())
         {
             generatorArgsPtrOpnd = LoadGeneratorArgsPtr(instrArgIn);
             ConvertArgOpndIfGeneratorFunction(instrArgIn, generatorArgsPtrOpnd);
@@ -9792,7 +9788,7 @@ Lowerer::LowerArgIn(IR::Instr *instrArgIn)
 
     // Now insert all the checks and undef-assigns.
 
-    if (m_func->GetJnFunction()->IsGenerator())
+    if (m_func->GetJnFunction()->IsGenerator() || m_func->GetJnFunction()->IsAsync())
     {
         generatorArgsPtrOpnd = LoadGeneratorArgsPtr(instrInsert);
     }
@@ -9962,7 +9958,7 @@ Lowerer::LowerArgIn(IR::Instr *instrArgIn)
 void
 Lowerer::ConvertArgOpndIfGeneratorFunction(IR::Instr *instrArgIn, IR::RegOpnd *generatorArgsPtrOpnd)
 {
-    if (this->m_func->GetJnFunction()->IsGenerator())
+    if (this->m_func->GetJnFunction()->IsGenerator() || this->m_func->GetJnFunction()->IsAsync())
     {
         // Replace stack param operand with offset into arguments array held by
         // the generator object.
@@ -10668,7 +10664,7 @@ Lowerer::LoadCallInfo(IR::Instr * instrInsert)
     IR::SymOpnd * srcOpnd;
     Func * func = instrInsert->m_func;
 
-    if (func->GetJnFunction()->IsGenerator())
+    if (func->GetJnFunction()->IsGenerator() || func->GetJnFunction()->IsAsync())
     {
         // Generator function arguments and ArgumentsInfo are not on the stack.  Instead they
         // are accessed off the generator object (which is prm1).
@@ -18115,7 +18111,7 @@ IR::IndirOpnd*
 Lowerer::GetArgsIndirOpndForTopFunction(IR::Instr* ldElem, IR::Opnd* valueOpnd)
 {
     // Load argument set dst = [ebp + index] (or grab from the generator object if m_func is a generator function).
-    IR::RegOpnd *baseOpnd = m_func->GetJnFunction()->IsGenerator() ? LoadGeneratorArgsPtr(ldElem) : IR::Opnd::CreateFramePointerOpnd(m_func);
+    IR::RegOpnd *baseOpnd = (m_func->GetJnFunction()->IsGenerator() || m_func->GetJnFunction()->IsAsync()) ? LoadGeneratorArgsPtr(ldElem) : IR::Opnd::CreateFramePointerOpnd(m_func);
     IR::IndirOpnd* argIndirOpnd = nullptr;
     // The stack looks like this:
     //       ...
@@ -18129,7 +18125,7 @@ Lowerer::GetArgsIndirOpndForTopFunction(IR::Instr* ldElem, IR::Opnd* valueOpnd)
 
     //actual arguments offset is LowererMD::GetFormalParamOffset() + 1 (this)
 
-    uint16 actualOffset = m_func->GetJnFunction()->IsGenerator() ? 1 : GetFormalParamOffset() + 1; //5
+    uint16 actualOffset = (m_func->GetJnFunction()->IsGenerator() || m_func->GetJnFunction()->IsAsync()) ? 1 : GetFormalParamOffset() + 1; //5
     Assert(actualOffset == 5 || m_func->GetJnFunction()->IsGenerator());
     if (valueOpnd->IsIntConstOpnd())
     {
@@ -20327,6 +20323,7 @@ Lowerer::GenerateSetHomeObj(IR::Instr* instrInsert)
     Func *func = instrInsert->m_func;
 
     IR::LabelInstr *labelScriptFunction = IR::LabelInstr::New(Js::OpCode::Label, func, false);
+    IR::LabelInstr *labelForGeneratorScriptFunction = IR::LabelInstr::New(Js::OpCode::Label, func, false);
 
     IR::Opnd *src2Opnd = instrInsert->UnlinkSrc2();
     IR::Opnd *src1Opnd = instrInsert->UnlinkSrc1();
@@ -20338,10 +20335,16 @@ Lowerer::GenerateSetHomeObj(IR::Instr* instrInsert)
     LowererMD::CreateAssign(funcObjRegOpnd, src1Opnd, instrInsert);
 
     IR::Opnd * vtableAddressOpnd = this->LoadVTableValueOpnd(instrInsert, VTableValue::VtableJavascriptGeneratorFunction);
+    InsertCompareBranch(IR::IndirOpnd::New(funcObjRegOpnd, 0, TyMachPtr, func), vtableAddressOpnd,
+        Js::OpCode::BrEq_A, true, labelForGeneratorScriptFunction, instrInsert);
+
+    vtableAddressOpnd = this->LoadVTableValueOpnd(instrInsert, VTableValue::VtableJavascriptAsyncFunction);
     InsertCompareBranch(IR::IndirOpnd::New(funcObjRegOpnd, 0, TyMachPtr, func), vtableAddressOpnd,
         Js::OpCode::BrNeq_A, true, labelScriptFunction, instrInsert);
 
-    indirOpnd = IR::IndirOpnd::New(funcObjRegOpnd, Js::JavascriptGeneratorFunction::GetOffsetOfScriptFunction() , TyMachPtr, func);
+    instrInsert->InsertBefore(labelForGeneratorScriptFunction);
+
+    indirOpnd = IR::IndirOpnd::New(funcObjRegOpnd, Js::JavascriptGeneratorFunction::GetOffsetOfScriptFunction(), TyMachPtr, func);
     LowererMD::CreateAssign(funcObjRegOpnd, indirOpnd, instrInsert);
 
     instrInsert->InsertBefore(labelScriptFunction);
@@ -20363,7 +20366,7 @@ Lowerer::GenerateLoadNewTarget(IR::Instr* instrInsert)
 
     Assert(!func->IsInlinee());
 
-    if (func->GetJnFunction()->IsGenerator())
+    if (func->GetJnFunction()->IsGenerator() || func->GetJnFunction()->IsAsync())
     {
         instrInsert->SetSrc1(opndUndefAddress);
         LowererMD::ChangeToAssign(instrInsert);
@@ -21098,7 +21101,7 @@ void Lowerer::GenerateNullOutGeneratorFrame(IR::Instr* insertInstr)
 
 void Lowerer::LowerFunctionExit(IR::Instr* funcExit)
 {
-    if (m_func->GetJnFunction()->IsGenerator())
+    if (m_func->GetJnFunction()->IsGenerator() || m_func->GetJnFunction()->IsAsync())
     {
         GenerateNullOutGeneratorFrame(funcExit->m_prev);
     }

lib/Backend/amd64/LowererMDArch.cpp

@@ -140,7 +140,7 @@ LowererMDArch::Init(LowererMD *lowererMD)
 IR::Instr *
 LowererMDArch::LoadInputParamPtr(IR::Instr *instrInsert, IR::RegOpnd *optionalDstOpnd /* = nullptr */)
 {
-    if (this->m_func->GetJnFunction()->IsGenerator())
+    if (this->m_func->GetJnFunction()->IsGenerator() || this->m_func->GetJnFunction()->IsAsync())
     {
         IR::RegOpnd * argPtrRegOpnd = Lowerer::LoadGeneratorArgsPtr(instrInsert);
         IR::IndirOpnd * indirOpnd = IR::IndirOpnd::New(argPtrRegOpnd, 1 * MachPtr, TyMachPtr, this->m_func);
@@ -380,7 +380,7 @@ LowererMDArch::LoadHeapArguments(IR::Instr *instrArgs, bool force /* = false */,
             this->m_func->SetArgOffset(paramSym, 2 * MachPtr);
             IR::Opnd * srcOpnd = IR::SymOpnd::New(paramSym, TyMachReg, func);
 
-            if (this->m_func->GetJnFunction()->IsGenerator())
+            if (this->m_func->GetJnFunction()->IsGenerator() || this->m_func->GetJnFunction()->IsAsync())
             {
                 // the function object for generator calls is a GeneratorVirtualScriptFunction object
                 // and we need to pass the real JavascriptGeneratorFunction object so grab it instead
@@ -430,7 +430,7 @@ LowererMDArch::LoadFuncExpression(IR::Instr *instrFuncExpr)
         paramOpnd = IR::SymOpnd::New(paramSym, TyMachReg, this->m_func);
     }
 
-    if (instrFuncExpr->m_func->GetJnFunction()->IsGenerator())
+    if (instrFuncExpr->m_func->GetJnFunction()->IsGenerator() || instrFuncExpr->m_func->GetJnFunction()->IsAsync())
     {
         // the function object for generator calls is a GeneratorVirtualScriptFunction object
         // and we need to return the real JavascriptGeneratorFunction object so grab it before

lib/Backend/arm/LowerMD.cpp

@@ -1993,7 +1993,7 @@ LowererMD::Init(Lowerer *lowerer)
 IR::Instr *
 LowererMD::LoadInputParamPtr(IR::Instr * instrInsert, IR::RegOpnd * optionalDstOpnd /* = nullptr */)
 {
-    if (this->m_func->GetJnFunction()->IsGenerator())
+    if (this->m_func->GetJnFunction()->IsGenerator() || this->m_func->GetJnFunction()->IsAsync())
     {
         IR::RegOpnd * argPtrRegOpnd = Lowerer::LoadGeneratorArgsPtr(instrInsert);
         IR::IndirOpnd * indirOpnd = IR::IndirOpnd::New(argPtrRegOpnd, 1 * MachPtr, TyMachPtr, this->m_func);
@@ -2087,7 +2087,7 @@ LowererMD::LoadStackArgPtr(IR::Instr * instr)
         instr->SetSrc1(tmpOpnd);
         instr->SetSrc2(IR::IntConstOpnd::New(sizeof(Js::Var), TyMachReg, this->m_func));
     }
-    else if (this->m_func->GetJnFunction()->IsGenerator())
+    else if (this->m_func->GetJnFunction()->IsGenerator() || this->m_func->GetJnFunction()->IsAsync())
     {
         IR::Instr *instr2 = LoadInputParamPtr(instr, instr->UnlinkDst()->AsRegOpnd());
         instr->Remove();

lib/Backend/i386/LowererMDArch.cpp

@@ -137,7 +137,7 @@ LowererMDArch::Init(LowererMD *lowererMD)
 IR::Instr *
 LowererMDArch::LoadInputParamPtr(IR::Instr *instrInsert, IR::RegOpnd *optionalDstOpnd /* = nullptr */)
 {
-    if (this->m_func->GetJnFunction()->IsGenerator())
+    if (this->m_func->GetJnFunction()->IsGenerator() || this->m_func->GetJnFunction()->IsAsync())
     {
         IR::RegOpnd * argPtrRegOpnd = Lowerer::LoadGeneratorArgsPtr(instrInsert);
         IR::IndirOpnd * indirOpnd = IR::IndirOpnd::New(argPtrRegOpnd, 1 * MachPtr, TyMachPtr, this->m_func);
@@ -334,7 +334,7 @@ LowererMDArch::LoadHeapArguments(IR::Instr *instrArgs, bool force, IR::Opnd* opn
             this->m_func->SetArgOffset(paramSym, 2 * MachPtr);
             IR::Opnd *srcOpnd = IR::SymOpnd::New(paramSym, TyMachReg, func);
 
-            if (this->m_func->GetJnFunction()->IsGenerator())
+            if (this->m_func->GetJnFunction()->IsGenerator() || this->m_func->GetJnFunction()->IsAsync())
             {
                 // the function object for generator calls is a GeneratorVirtualScriptFunction object
                 // and we need to pass the real JavascriptGeneratorFunction object so grab it instead
@@ -501,7 +501,7 @@ LowererMDArch::LoadFuncExpression(IR::Instr *instrFuncExpr)
         paramOpnd = IR::SymOpnd::New(paramSym, TyMachReg, func);
     }
 
-    if (instrFuncExpr->m_func->GetJnFunction()->IsGenerator())
+    if (instrFuncExpr->m_func->GetJnFunction()->IsGenerator() || instrFuncExpr->m_func->GetJnFunction()->IsAsync())
     {
         // the function object for generator calls is a GeneratorVirtualScriptFunction object
         // and we need to return the real JavascriptGeneratorFunction object so grab it before