JIT: Enable addressing modes for gc types (#70749)

src/coreclr/jit/codegenarmarch.cpp

@@ -4430,6 +4430,16 @@ void CodeGen::genLeaInstruction(GenTreeAddrMode* lea)
         }
         else
         {
+#ifdef TARGET_ARM64
+            // Handle LEA with "contained" BFIZ
+            if (index->isContained() && index->OperIs(GT_BFIZ))
+            {
+                assert(scale == 0);
+                scale = (DWORD)index->gtGetOp2()->AsIntConCommon()->IconValue();
+                index = index->gtGetOp1()->gtGetOp1();
+            }
+#endif
+
             // Then compute target reg from [base + index*scale]
             genScaledAdd(size, lea->GetRegNum(), memBase->GetRegNum(), index->GetRegNum(), scale);
         }

src/coreclr/jit/lower.cpp

@@ -5364,7 +5364,7 @@ bool Lowering::TryCreateAddrMode(GenTree* addr, bool isContainable, GenTree* par
 
     // Check if we can "contain" LEA(BFIZ) in order to extend 32bit index to 64bit as part of load/store.
     if ((index != nullptr) && index->OperIs(GT_BFIZ) && index->gtGetOp1()->OperIs(GT_CAST) &&
-        index->gtGetOp2()->IsCnsIntOrI() && (varTypeIsIntegral(targetType) || varTypeIsFloating(targetType)))
+        index->gtGetOp2()->IsCnsIntOrI() && !varTypeIsStruct(targetType))
     {
         // BFIZ node is a binary op where op1 is GT_CAST and op2 is GT_CNS_INT
         GenTreeCast* cast = index->gtGetOp1()->AsCast();

src/coreclr/jit/morph.cpp

@@ -4728,8 +4728,8 @@ GenTree* Compiler::fgMorphIndexAddr(GenTreeIndexAddr* indexAddr)
     // we at least will be able to hoist/CSE "index + elemOffset" in some cases.
     // See https://github.com/dotnet/runtime/pull/61293#issuecomment-964146497
 
-    // Use 2) form only for primitive types for now - it significantly reduced number of size regressions
-    if (!varTypeIsIntegral(elemTyp) && !varTypeIsFloating(elemTyp))
+    // Don't use 2) for structs to reduce number of size regressions
+    if (varTypeIsStruct(elemTyp))
     {
         groupArrayRefWithElemOffset = false;
     }