Fix lowering usage of an unset LSRA field.

src/coreclr/jit/lower.cpp

@@ -3098,22 +3098,17 @@ void Lowering::LowerStoreLocCommon(GenTreeLclVarCommon* lclStore)
         }
     }
 
-    if ((varTypeUsesFloatReg(lclStore) != varTypeUsesFloatReg(src)) && !lclStore->IsPhiDefn() &&
-        (src->TypeGet() != TYP_STRUCT))
-    {
-        if (m_lsra->isRegCandidate(varDsc))
-        {
-            GenTree* bitcast = comp->gtNewBitCastNode(lclStore->TypeGet(), src);
-            lclStore->gtOp1  = bitcast;
-            src              = lclStore->gtGetOp1();
-            BlockRange().InsertBefore(lclStore, bitcast);
-            ContainCheckBitCast(bitcast);
-        }
-        else
-        {
-            // This is an actual store, we'll just retype it.
-            lclStore->gtType = src->TypeGet();
-        }
+    // TODO-CQ: the condition could be improved for the struct types, for example,
+    // /--*  CALL      simd8  hackishModuleName.hackishMethodName
+    // *  STORE_LCL_VAR struct<HVA64_01[Byte], 8> V03 tmp1
+    // does not need a bitcast because the struct enreg type is SIMD8.
+    if ((varTypeUsesFloatReg(lclStore) != varTypeUsesFloatReg(src)) && !src->TypeIs(TYP_STRUCT))
+    {
+        GenTree* bitcast = comp->gtNewBitCastNode(lclStore->TypeGet(), src);
+        lclStore->gtOp1  = bitcast;
+        src              = lclStore->gtGetOp1();
+        BlockRange().InsertBefore(lclStore, bitcast);
+        ContainCheckBitCast(bitcast);
     }
 
     if (srcIsMultiReg || lclStore->IsMultiRegLclVar())
@@ -6571,8 +6566,10 @@ void Lowering::ContainCheckBitCast(GenTree* node)
         {
             op1->SetContained();
         }
-        LclVarDsc* varDsc = &comp->lvaTable[op1->AsLclVar()->GetLclNum()];
-        if (!m_lsra->isRegCandidate(varDsc))
+        const LclVarDsc* varDsc = comp->lvaGetDesc(op1->AsLclVar());
+        // TODO-Cleanup: we want to check if the local is already known not
+        // to be on reg, for example, because local enreg is disabled.
+        if (varDsc->lvDoNotEnregister)
         {
             op1->SetContained();
         }

src/tests/JIT/Regression/JitBlue/Runtime_54466/Runtime_54466.cs

@@ -0,0 +1,32 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Numerics;
+using System.Runtime.CompilerServices;
+
+namespace Runtime_54466
+{
+    public class Test
+    {
+        static int Main()
+        {
+            return t(1, 1, 1, 1, Vector2.One, Vector2.One, Vector2.One, Vector2.One);
+        }
+
+
+        [MethodImplAttribute(MethodImplOptions.NoInlining)]
+        static int t(int a1, int a2, int a3, int a4, Vector2 x1, Vector2 x2, Vector2 x3, Vector2 x4)
+        {
+           if (x1 != Vector2.One) 
+           {
+               Console.WriteLine("FAIL");
+               return 101;
+           }
+           return 100;
+        }
+    }
+
+}
+
+

src/tests/JIT/Regression/JitBlue/Runtime_54466/Runtime_54466.csproj

@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <DebugType>None</DebugType>
+    <Optimize>True</Optimize>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="$(MSBuildProjectName).cs" />
+  </ItemGroup>
+</Project>