Fix struct promotion check for SIMD field

src/jit/lclvars.cpp

@@ -2011,7 +2011,7 @@ void Compiler::lvaPromoteStructVar(unsigned lclNum, lvaStructPromotionInfo* Stru
             fieldVarDsc->lvArgReg   = varDsc->lvArgReg;
             fieldVarDsc->setPrefReg(varDsc->lvArgReg, this); // Set the preferred register
 #if FEATURE_MULTIREG_ARGS && defined(FEATURE_SIMD)
-            if (varTypeIsSIMD(fieldVarDsc))
+            if (varTypeIsSIMD(fieldVarDsc) && !lvaIsImplicitByRefLocal(lclNum))
             {
                 // This field is a SIMD type, and will be considered to be passed in multiple registers
                 // if the parent struct was. Note that this code relies on the fact that if there is