Mark as "reuse" to make jit happy

Author: ShortDevelopment

lib/Runtime/ByteCode/ByteCodeEmitter.cpp

@@ -57,22 +57,28 @@ static void EmitOptionalChainWrapper(ParseNodeUni *pnodeOptChain, ByteCodeGenera
     Js::ByteCodeLabel skipLabel = byteCodeGenerator->Writer()->DefineLabel();
     funcInfo->currentOptionalChainSkipLabel = skipLabel;
 
-    // Acquire slot for the result value
-    // Prefill it with `undefined` (Fallback for short-circuiting)
-    Js::RegSlot resultSlot = funcInfo->AcquireLoc(pnodeOptChain);
-    byteCodeGenerator->Writer()->Reg1(Js::OpCode::LdUndef, resultSlot);
-
     // Copy values from wrapper to inner expression
     ParseNodePtr innerNode = pnodeOptChain->pnode1;
     innerNode->isUsed = pnodeOptChain->isUsed;
-    innerNode->location = pnodeOptChain->location;
 
     // emit chain expression
     // Every `?.` node will call `EmitNullPropagation`
     // `EmitNullPropagation` short-circuits to `skipLabel` in case of a nullish value
     emitChainContent(innerNode);
+    funcInfo->ReleaseLoc(innerNode);
+
+    Js::ByteCodeLabel doneLabel = byteCodeGenerator->Writer()->DefineLabel();
+
+    // Acquire slot for the result value
+    Js::RegSlot resultSlot = funcInfo->AcquireLoc(pnodeOptChain);
+    byteCodeGenerator->Writer()->Reg2(Js::OpCode::Ld_A_ReuseLoc, resultSlot, innerNode->location);
+    byteCodeGenerator->Writer()->Br(Js::OpCode::Br, doneLabel);
 
     byteCodeGenerator->Writer()->MarkLabel(skipLabel);
+    // Fill with `undefined` (short-circuiting)
+    byteCodeGenerator->Writer()->Reg1(Js::OpCode::LdUndef, resultSlot);
+
+    byteCodeGenerator->Writer()->MarkLabel(doneLabel);
     funcInfo->currentOptionalChainSkipLabel = previousSkipLabel;
 }