Use FIELD_ADDR for all ldfldas (#78226)

src/coreclr/jit/compiler.h

@@ -5681,22 +5681,9 @@ class Compiler
     // know will be dereferenced.  To know that reliance on implicit null checking is sound, we must further know that
     // all offsets between the top-level indirection and the bottom are constant, and that their sum is sufficiently
     // small; hence the other fields of MorphAddrContext.
-    enum MorphAddrContextKind
-    {
-        MACK_Ind,
-        MACK_Addr,
-    };
     struct MorphAddrContext
     {
-        MorphAddrContextKind m_kind;
-        bool                 m_allConstantOffsets; // Valid only for "m_kind == MACK_Ind".  True iff all offsets between
-                                                   // top-level indirection and here have been constants.
-        size_t m_totalOffset; // Valid only for "m_kind == MACK_Ind", and if "m_allConstantOffsets" is true.
-                              // In that case, is the sum of those constant offsets.
-
-        MorphAddrContext(MorphAddrContextKind kind) : m_kind(kind), m_allConstantOffsets(true), m_totalOffset(0)
-        {
-        }
+        size_t m_totalOffset = 0; // Sum of offsets between the top-level indirection and here (current context).
     };
 
 #ifdef FEATURE_SIMD

src/coreclr/jit/gentree.cpp

@@ -7584,7 +7584,11 @@ GenTreeField* Compiler::gtNewFieldRef(var_types type, CORINFO_FIELD_HANDLE fldHn
 }
 
 //------------------------------------------------------------------------
-// gtNewFieldRef: Create a new GT_FIELD_ADDR node.
+// gtNewFieldAddrNode: Create a new GT_FIELD_ADDR node.
+//
+// TODO-ADDR: consider creating a variant of this which would skip various
+// no-op constructs (such as struct fields with zero offsets), and fold
+// others (LCL_VAR_ADDR + FIELD_ADDR => LCL_FLD_ADDR).
 //
 // Arguments:
 //    type   - type for the address node
@@ -7601,10 +7605,27 @@ GenTreeField* Compiler::gtNewFieldAddrNode(var_types type, CORINFO_FIELD_HANDLE
 
     GenTreeField* fieldNode = new (this, GT_FIELD_ADDR) GenTreeField(GT_FIELD_ADDR, type, obj, fldHnd, offset);
 
-    // TODO-ADDR: add GTF_EXCEPT handling here and delete it from callers.
-    // TODO-ADDR: delete this zero-diff quirk.
-    fieldNode->gtFlags |= GTF_GLOB_REF;
+    // If "obj" is the address of a local, note that a field of that struct local has been accessed.
+    if ((obj != nullptr) && obj->OperIs(GT_ADDR) && varTypeIsStruct(obj->AsUnOp()->gtOp1) &&
+        obj->AsUnOp()->gtOp1->OperIs(GT_LCL_VAR))
+    {
+        LclVarDsc* varDsc = lvaGetDesc(obj->AsUnOp()->gtOp1->AsLclVarCommon());
+
+        varDsc->lvFieldAccessed = 1;
+
+        if (lvaIsImplicitByRefLocal(lvaGetLclNum(varDsc)))
+        {
+            // TODO-ADDR: delete this zero-diff quirk.
+            fieldNode->gtFlags |= GTF_GLOB_REF;
+        }
+    }
+    else
+    {
+        // TODO-ADDR: delete this zero-diff quirk.
+        fieldNode->gtFlags |= GTF_GLOB_REF;
+    }
 
+    // TODO-ADDR: add GTF_EXCEPT handling here and delete it from callers.
     return fieldNode;
 }
 

src/coreclr/jit/gentree.h

@@ -4055,6 +4055,7 @@ struct GenTreeField : public GenTreeUnOp
     // True if this field is a volatile memory operation.
     bool IsVolatile() const
     {
+        assert(((gtFlags & GTF_FLD_VOLATILE) == 0) || OperIs(GT_FIELD));
         return (gtFlags & GTF_FLD_VOLATILE) != 0;
     }
 

src/coreclr/jit/importer.cpp

@@ -9524,11 +9524,7 @@ void Compiler::impImportBlockCode(BasicBlock* block)
                             obj = impGetStructAddr(obj, objType, CHECK_SPILL_ALL, true);
                         }
 
-                        DWORD typeFlags = info.compCompHnd->getClassAttribs(resolvedToken.hClass);
-
-                        // TODO-ADDR: use FIELD_ADDR for all fields, not just those of classes.
-                        //
-                        if (isLoadAddress && ((typeFlags & CORINFO_FLG_VALUECLASS) == 0))
+                        if (isLoadAddress)
                         {
                             op1 = gtNewFieldAddrNode(varTypeIsGC(obj) ? TYP_BYREF : TYP_I_IMPL, resolvedToken.hField,
                                                      obj, fieldInfo.offset);
@@ -9550,17 +9546,11 @@ void Compiler::impImportBlockCode(BasicBlock* block)
                             op1->gtFlags |= GTF_EXCEPT;
                         }
 
-                        if (StructHasOverlappingFields(typeFlags))
+                        if (StructHasOverlappingFields(info.compCompHnd->getClassAttribs(resolvedToken.hClass)))
                         {
                             op1->AsField()->gtFldMayOverlap = true;
                         }
 
-                        // Wrap it in a address of operator if necessary.
-                        if (isLoadAddress && op1->OperIs(GT_FIELD))
-                        {
-                            op1 = gtNewOperNode(GT_ADDR, varTypeIsGC(obj) ? TYP_BYREF : TYP_I_IMPL, op1);
-                        }
-
                         if (!isLoadAddress && compIsForInlining() &&
                             impInlineIsGuaranteedThisDerefBeforeAnySideEffects(nullptr, nullptr, obj,
                                                                                impInlineInfo->inlArgInfo))
@@ -12938,41 +12928,27 @@ bool Compiler::impIsInvariant(const GenTree* tree)
 //
 // Remarks:
 //   This is a variant of GenTree::IsLocalAddrExpr that is more suitable for
-//   use during import. Unlike that function, this one handles GT_FIELD nodes.
+//   use during import. Unlike that function, this one handles field nodes.
 //
 bool Compiler::impIsAddressInLocal(const GenTree* tree, GenTree** lclVarTreeOut)
 {
-    if (tree->gtOper != GT_ADDR)
-    {
-        return false;
-    }
-
-    GenTree* op = tree->AsOp()->gtOp1;
-    while (op->gtOper == GT_FIELD)
+    const GenTree* op = tree;
+    while (op->OperIs(GT_FIELD_ADDR) && op->AsField()->IsInstance())
     {
         op = op->AsField()->GetFldObj();
-        if (op && op->gtOper == GT_ADDR) // Skip static fields where op will be NULL.
-        {
-            op = op->AsOp()->gtOp1;
-        }
-        else
-        {
-            return false;
-        }
     }
 
-    if (op->gtOper == GT_LCL_VAR)
+    if (op->OperIs(GT_ADDR) && op->AsUnOp()->gtOp1->OperIs(GT_LCL_VAR))
     {
         if (lclVarTreeOut != nullptr)
         {
-            *lclVarTreeOut = op;
+            *lclVarTreeOut = op->AsUnOp()->gtOp1;
         }
+
         return true;
     }
-    else
-    {
-        return false;
-    }
+
+    return false;
 }
 
 //------------------------------------------------------------------------