Handle direct addresses for statics in IsFieldAddr (#64846)

* DEBUG-ONLY: FieldInfo

Allows this change to be tested via SPMI.

* Handle direct addresses in IsFieldAddr

* Always use NotAField in IsFieldAddr

No diffs.

* Revert "DEBUG-ONLY: FieldInfo"

This reverts commit b17817e0354a63319256a0fa0d21b74c2cfbf781.

Author: SingleAccretion

src/coreclr/jit/gentree.cpp

@@ -16061,10 +16061,11 @@ bool GenTreeIntConCommon::AddrNeedsReloc(Compiler* comp)
 //------------------------------------------------------------------------
 // IsFieldAddr: Is "this" a static or class field address?
 //
-// Recognizes the following three patterns:
-//    this: [Zero FldSeq]
-//    this: ADD(baseAddr, CONST FldSeq)
-//    this: ADD(CONST FldSeq, baseAddr)
+// Recognizes the following patterns:
+//    this: ADD(baseAddr, CONST [FldSeq])
+//    this: ADD(CONST [FldSeq], baseAddr)
+//    this: CONST [FldSeq]
+//    this: Zero [FldSeq]
 //
 // Arguments:
 //    comp      - the Compiler object
@@ -16089,7 +16090,7 @@ bool GenTree::IsFieldAddr(Compiler* comp, GenTree** pBaseAddr, FieldSeqNode** pF
     *pFldSeq   = FieldSeqStore::NotAField();
 
     GenTree*      baseAddr = nullptr;
-    FieldSeqNode* fldSeq   = nullptr;
+    FieldSeqNode* fldSeq   = FieldSeqStore::NotAField();
 
     if (OperIs(GT_ADD))
     {
@@ -16113,26 +16114,28 @@ bool GenTree::IsFieldAddr(Compiler* comp, GenTree** pBaseAddr, FieldSeqNode** pF
             assert(!baseAddr->TypeIs(TYP_REF) || !comp->GetZeroOffsetFieldMap()->Lookup(baseAddr));
         }
     }
+    else if (IsCnsIntOrI() && IsIconHandle(GTF_ICON_STATIC_HDL))
+    {
+        assert(!comp->GetZeroOffsetFieldMap()->Lookup(this) && (AsIntCon()->gtFieldSeq != nullptr));
+        fldSeq   = AsIntCon()->gtFieldSeq;
+        baseAddr = nullptr;
+    }
     else if (comp->GetZeroOffsetFieldMap()->Lookup(this, &fldSeq))
     {
         baseAddr = this;
     }
     else
     {
-        // TODO-VNTypes-CQ: recognize the simple GTF_ICON_STATIC_HDL case here. It
-        // is not recognized right now to preserve previous behavior of this method.
         return false;
     }
 
-    // If we don't have a valid sequence, bail. Note that above we have overloaded an empty
-    // ("nullptr") sequence as "NotAField", as that's the way it is treated on tree nodes.
-    if ((fldSeq == nullptr) || (fldSeq == FieldSeqStore::NotAField()) || fldSeq->IsPseudoField())
+    assert(fldSeq != nullptr);
+
+    if ((fldSeq == FieldSeqStore::NotAField()) || fldSeq->IsPseudoField())
     {
         return false;
     }
 
-    assert(baseAddr != nullptr);
-
     // The above screens out obviously invalid cases, but we have more checks to perform. The
     // sequence returned from this method *must* start with either a class (NOT struct) field
     // or a static field. To avoid the expense of calling "getFieldClass" here, we will instead