From 90f19901444f20b4d7ddf0fcc2b5af714ab0b0f5 Mon Sep 17 00:00:00 2001
From: Carol Eidt <carol.eidt@microsoft.com>
Date: Wed, 10 Jun 2020 10:06:43 -0700
Subject: [PATCH] Fix issue exposed by #37280

---
 src/coreclr/src/jit/liveness.cpp | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/coreclr/src/jit/liveness.cpp b/src/coreclr/src/jit/liveness.cpp
index f8da2e346c166..dc24bdffc2bab 100644
--- a/src/coreclr/src/jit/liveness.cpp
+++ b/src/coreclr/src/jit/liveness.cpp
@@ -1645,18 +1645,19 @@ bool Compiler::fgComputeLifeUntrackedLocal(VARSET_TP&           life,
 
     for (unsigned i = varDsc.lvFieldLclStart; i < varDsc.lvFieldLclStart + varDsc.lvFieldCnt; ++i)
     {
+        LclVarDsc* fieldVarDsc = lvaGetDesc(i);
 #if !defined(TARGET_64BIT)
-        if (!varTypeIsLong(lvaTable[i].lvType) || !lvaTable[i].lvPromoted)
+        if (!varTypeIsLong(fieldVarDsc->lvType) || !fieldVarDsc->lvPromoted)
 #endif // !defined(TARGET_64BIT)
         {
-            noway_assert(lvaTable[i].lvIsStructField);
+            noway_assert(fieldVarDsc->lvIsStructField);
         }
-        if (lvaTable[i].lvTracked)
+        if (fieldVarDsc->lvTracked)
         {
-            const unsigned varIndex = lvaTable[i].lvVarIndex;
+            const unsigned varIndex = fieldVarDsc->lvVarIndex;
             noway_assert(varIndex < lvaTrackedCount);
             VarSetOps::AddElemD(this, fieldSet, varIndex);
-            if (isDef && !VarSetOps::IsMember(this, life, varIndex))
+            if (isDef && lclVarNode->IsMultiRegLclVar() && !VarSetOps::IsMember(this, life, varIndex))
             {
                 // Dead definition.
                 lclVarNode->AsLclVar()->SetLastUse(i - varDsc.lvFieldLclStart);