diff --git a/runtime/check_jni.cc b/runtime/check_jni.cc
index 7d6cee9..6c27bc6 100644
--- a/runtime/check_jni.cc
+++ b/runtime/check_jni.cc
@@ -282,7 +282,7 @@
       return false;
     }
 
-    ArtField* f = CheckFieldID(soa, fid);
+    ArtField* f = CheckFieldID(fid);
     if (f == nullptr) {
       return false;
     }
@@ -362,7 +362,7 @@
   bool CheckStaticFieldID(ScopedObjectAccess& soa, jclass java_class, jfieldID fid)
       REQUIRES_SHARED(Locks::mutator_lock_) {
     ObjPtr<mirror::Class> c = soa.Decode<mirror::Class>(java_class);
-    ArtField* f = CheckFieldID(soa, fid);
+    ArtField* f = CheckFieldID(fid);
     if (f == nullptr) {
       return false;
     }
@@ -681,7 +681,7 @@
     if (!is_static && !CheckInstanceFieldID(soa, obj, fid)) {
       return false;
     }
-    ArtField* field = soa.DecodeField(fid);
+    ArtField* field = jni::DecodeArtField(fid);
     DCHECK(field != nullptr);  // Already checked by Check.
     if (is_static != field->IsStatic()) {
       AbortF("attempt to access %s field %s: %p",
@@ -843,7 +843,7 @@
       case 'c':  // jclass
         return CheckInstance(soa, kClass, arg.c, false);
       case 'f':  // jfieldID
-        return CheckFieldID(soa, arg.f) != nullptr;
+        return CheckFieldID(arg.f) != nullptr;
       case 'm':  // jmethodID
         return CheckMethodID(arg.m) != nullptr;
       case 'r':  // release int
@@ -961,7 +961,7 @@
       }
       case 'f': {  // jfieldID
         jfieldID fid = arg.f;
-        ArtField* f = soa.DecodeField(fid);
+        ArtField* f = jni::DecodeArtField(fid);
         *msg += ArtField::PrettyField(f);
         if (!entry) {
           StringAppendF(msg, " (%p)", fid);
@@ -1146,13 +1146,12 @@
     return true;
   }
 
-  ArtField* CheckFieldID(ScopedObjectAccess& soa, jfieldID fid)
-      REQUIRES_SHARED(Locks::mutator_lock_) {
+  ArtField* CheckFieldID(jfieldID fid) REQUIRES_SHARED(Locks::mutator_lock_) {
     if (fid == nullptr) {
       AbortF("jfieldID was NULL");
       return nullptr;
     }
-    ArtField* f = soa.DecodeField(fid);
+    ArtField* f = jni::DecodeArtField(fid);
     // TODO: Better check here.
     if (!Runtime::Current()->GetHeap()->IsValidObjectAddress(f->GetDeclaringClass().Ptr())) {
       Runtime::Current()->GetHeap()->DumpSpaces(LOG_STREAM(ERROR));
diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index e7e5be7..6d45dad 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -63,6 +63,7 @@
 #include "jit/jit.h"
 #include "jit/jit_code_cache.h"
 #include "jit/offline_profiling_info.h"
+#include "jni_internal.h"
 #include "leb128.h"
 #include "linear_alloc.h"
 #include "mirror/class.h"
@@ -1124,13 +1125,12 @@
            class_loader->GetClass();
 }
 
-static mirror::String* GetDexPathListElementName(ScopedObjectAccessUnchecked& soa,
-                                                 ObjPtr<mirror::Object> element)
+static mirror::String* GetDexPathListElementName(ObjPtr<mirror::Object> element)
     REQUIRES_SHARED(Locks::mutator_lock_) {
   ArtField* const dex_file_field =
-      soa.DecodeField(WellKnownClasses::dalvik_system_DexPathList__Element_dexFile);
+      jni::DecodeArtField(WellKnownClasses::dalvik_system_DexPathList__Element_dexFile);
   ArtField* const dex_file_name_field =
-      soa.DecodeField(WellKnownClasses::dalvik_system_DexFile_fileName);
+      jni::DecodeArtField(WellKnownClasses::dalvik_system_DexFile_fileName);
   DCHECK(dex_file_field != nullptr);
   DCHECK(dex_file_name_field != nullptr);
   DCHECK(element != nullptr);
@@ -1154,9 +1154,9 @@
   DCHECK(error_msg != nullptr);
   ScopedObjectAccessUnchecked soa(Thread::Current());
   ArtField* const dex_path_list_field =
-      soa.DecodeField(WellKnownClasses::dalvik_system_BaseDexClassLoader_pathList);
+      jni::DecodeArtField(WellKnownClasses::dalvik_system_BaseDexClassLoader_pathList);
   ArtField* const dex_elements_field =
-      soa.DecodeField(WellKnownClasses::dalvik_system_DexPathList_dexElements);
+      jni::DecodeArtField(WellKnownClasses::dalvik_system_DexPathList_dexElements);
   CHECK(dex_path_list_field != nullptr);
   CHECK(dex_elements_field != nullptr);
   while (!ClassLinker::IsBootClassLoader(soa, class_loader)) {
@@ -1183,7 +1183,7 @@
             *error_msg = StringPrintf("Null dex element at index %d", i);
             return false;
           }
-          ObjPtr<mirror::String> const name = GetDexPathListElementName(soa, element);
+          ObjPtr<mirror::String> const name = GetDexPathListElementName(element);
           if (name == nullptr) {
             *error_msg = StringPrintf("Null name for dex element at index %d", i);
             return false;
@@ -1733,7 +1733,7 @@
         ObjPtr<mirror::Object> element = elements->GetWithoutChecks(i);
         if (element != nullptr) {
           // If we are somewhere in the middle of the array, there may be nulls at the end.
-          loader_dex_file_names.push_back(GetDexPathListElementName(soa, element));
+          loader_dex_file_names.push_back(GetDexPathListElementName(element));
         }
       }
       // Ignore the number of image dex files since we are adding those to the class loader anyways.
@@ -2425,16 +2425,17 @@
   // Handle as if this is the child PathClassLoader.
   // The class loader is a PathClassLoader which inherits from BaseDexClassLoader.
   // We need to get the DexPathList and loop through it.
-  ArtField* const cookie_field = soa.DecodeField(WellKnownClasses::dalvik_system_DexFile_cookie);
+  ArtField* const cookie_field =
+      jni::DecodeArtField(WellKnownClasses::dalvik_system_DexFile_cookie);
   ArtField* const dex_file_field =
-      soa.DecodeField(WellKnownClasses::dalvik_system_DexPathList__Element_dexFile);
+      jni::DecodeArtField(WellKnownClasses::dalvik_system_DexPathList__Element_dexFile);
   ObjPtr<mirror::Object> dex_path_list =
-      soa.DecodeField(WellKnownClasses::dalvik_system_BaseDexClassLoader_pathList)->
-      GetObject(class_loader.Get());
+      jni::DecodeArtField(WellKnownClasses::dalvik_system_BaseDexClassLoader_pathList)->
+          GetObject(class_loader.Get());
   if (dex_path_list != nullptr && dex_file_field != nullptr && cookie_field != nullptr) {
     // DexPathList has an array dexElements of Elements[] which each contain a dex file.
     ObjPtr<mirror::Object> dex_elements_obj =
-        soa.DecodeField(WellKnownClasses::dalvik_system_DexPathList_dexElements)->
+        jni::DecodeArtField(WellKnownClasses::dalvik_system_DexPathList_dexElements)->
         GetObject(dex_path_list);
     // Loop through each dalvik.system.DexPathList$Element's dalvik.system.DexFile and look
     // at the mCookie which is a DexFile vector.
@@ -8137,7 +8138,7 @@
   StackHandleScope<11> hs(self);
 
   ArtField* dex_elements_field =
-      soa.DecodeField(WellKnownClasses::dalvik_system_DexPathList_dexElements);
+      jni::DecodeArtField(WellKnownClasses::dalvik_system_DexPathList_dexElements);
 
   Handle<mirror::Class> dex_elements_class(hs.NewHandle(dex_elements_field->GetType<true>()));
   DCHECK(dex_elements_class.Get() != nullptr);
@@ -8150,13 +8151,13 @@
       hs.NewHandle(dex_elements_class->GetComponentType());
 
   ArtField* element_file_field =
-      soa.DecodeField(WellKnownClasses::dalvik_system_DexPathList__Element_dexFile);
+      jni::DecodeArtField(WellKnownClasses::dalvik_system_DexPathList__Element_dexFile);
   DCHECK_EQ(h_dex_element_class.Get(), element_file_field->GetDeclaringClass());
 
-  ArtField* cookie_field = soa.DecodeField(WellKnownClasses::dalvik_system_DexFile_cookie);
+  ArtField* cookie_field = jni::DecodeArtField(WellKnownClasses::dalvik_system_DexFile_cookie);
   DCHECK_EQ(cookie_field->GetDeclaringClass(), element_file_field->GetType<false>());
 
-  ArtField* file_name_field = soa.DecodeField(WellKnownClasses::dalvik_system_DexFile_fileName);
+  ArtField* file_name_field = jni::DecodeArtField(WellKnownClasses::dalvik_system_DexFile_fileName);
   DCHECK_EQ(file_name_field->GetDeclaringClass(), element_file_field->GetType<false>());
 
   // Fill the elements array.
@@ -8206,7 +8207,7 @@
   DCHECK(h_path_class_loader.Get() != nullptr);
   // Set DexPathList.
   ArtField* path_list_field =
-      soa.DecodeField(WellKnownClasses::dalvik_system_BaseDexClassLoader_pathList);
+      jni::DecodeArtField(WellKnownClasses::dalvik_system_BaseDexClassLoader_pathList);
   DCHECK(path_list_field != nullptr);
   path_list_field->SetObject<false>(h_path_class_loader.Get(), h_dex_path_list.Get());
 
diff --git a/runtime/common_runtime_test.cc b/runtime/common_runtime_test.cc
index 3409938..8226e60 100644
--- a/runtime/common_runtime_test.cc
+++ b/runtime/common_runtime_test.cc
@@ -520,17 +520,17 @@
 
   // The class loader is a PathClassLoader which inherits from BaseDexClassLoader.
   // We need to get the DexPathList and loop through it.
-  ArtField* cookie_field = soa.DecodeField(WellKnownClasses::dalvik_system_DexFile_cookie);
+  ArtField* cookie_field = jni::DecodeArtField(WellKnownClasses::dalvik_system_DexFile_cookie);
   ArtField* dex_file_field =
-      soa.DecodeField(WellKnownClasses::dalvik_system_DexPathList__Element_dexFile);
+      jni::DecodeArtField(WellKnownClasses::dalvik_system_DexPathList__Element_dexFile);
   ObjPtr<mirror::Object> dex_path_list =
-      soa.DecodeField(WellKnownClasses::dalvik_system_BaseDexClassLoader_pathList)->
-      GetObject(class_loader.Get());
+      jni::DecodeArtField(WellKnownClasses::dalvik_system_BaseDexClassLoader_pathList)->
+          GetObject(class_loader.Get());
   if (dex_path_list != nullptr && dex_file_field!= nullptr && cookie_field != nullptr) {
     // DexPathList has an array dexElements of Elements[] which each contain a dex file.
     ObjPtr<mirror::Object> dex_elements_obj =
-        soa.DecodeField(WellKnownClasses::dalvik_system_DexPathList_dexElements)->
-        GetObject(dex_path_list);
+        jni::DecodeArtField(WellKnownClasses::dalvik_system_DexPathList_dexElements)->
+            GetObject(dex_path_list);
     // Loop through each dalvik.system.DexPathList$Element's dalvik.system.DexFile and look
     // at the mCookie which is a DexFile vector.
     if (dex_elements_obj != nullptr) {
diff --git a/runtime/debugger.cc b/runtime/debugger.cc
index 8cc6232..dc2ae2e 100644
--- a/runtime/debugger.cc
+++ b/runtime/debugger.cc
@@ -2008,7 +2008,7 @@
   mirror::Object* thread_object = gRegistry->Get<mirror::Object*>(thread_id, &error);
   CHECK(thread_object != nullptr) << error;
   ArtField* java_lang_Thread_name_field =
-      soa.DecodeField(WellKnownClasses::java_lang_Thread_name);
+      jni::DecodeArtField(WellKnownClasses::java_lang_Thread_name);
   ObjPtr<mirror::String> s(java_lang_Thread_name_field->GetObject(thread_object)->AsString());
   if (s != nullptr) {
     *name = s->ToModifiedUtf8();
@@ -2033,7 +2033,7 @@
   } else if (error == JDWP::ERR_NONE) {
     ObjPtr<mirror::Class> c = soa.Decode<mirror::Class>(WellKnownClasses::java_lang_Thread);
     CHECK(c != nullptr);
-    ArtField* f = soa.DecodeField(WellKnownClasses::java_lang_Thread_group);
+    ArtField* f = jni::DecodeArtField(WellKnownClasses::java_lang_Thread_group);
     CHECK(f != nullptr);
     ObjPtr<mirror::Object> group = f->GetObject(thread_object);
     CHECK(group != nullptr);
@@ -2075,7 +2075,7 @@
     return error;
   }
   ScopedAssertNoThreadSuspension ants("Debugger: GetThreadGroupName");
-  ArtField* f = soa.DecodeField(WellKnownClasses::java_lang_ThreadGroup_name);
+  ArtField* f = jni::DecodeArtField(WellKnownClasses::java_lang_ThreadGroup_name);
   CHECK(f != nullptr);
   ObjPtr<mirror::String> s = f->GetObject(thread_group)->AsString();
 
@@ -2094,7 +2094,7 @@
   ObjPtr<mirror::Object> parent;
   {
     ScopedAssertNoThreadSuspension ants("Debugger: GetThreadGroupParent");
-    ArtField* f = soa.DecodeField(WellKnownClasses::java_lang_ThreadGroup_parent);
+    ArtField* f = jni::DecodeArtField(WellKnownClasses::java_lang_ThreadGroup_parent);
     CHECK(f != nullptr);
     parent = f->GetObject(thread_group);
   }
@@ -2103,13 +2103,13 @@
   return JDWP::ERR_NONE;
 }
 
-static void GetChildThreadGroups(ScopedObjectAccessUnchecked& soa, mirror::Object* thread_group,
+static void GetChildThreadGroups(mirror::Object* thread_group,
                                  std::vector<JDWP::ObjectId>* child_thread_group_ids)
     REQUIRES_SHARED(Locks::mutator_lock_) {
   CHECK(thread_group != nullptr);
 
   // Get the int "ngroups" count of this thread group...
-  ArtField* ngroups_field = soa.DecodeField(WellKnownClasses::java_lang_ThreadGroup_ngroups);
+  ArtField* ngroups_field = jni::DecodeArtField(WellKnownClasses::java_lang_ThreadGroup_ngroups);
   CHECK(ngroups_field != nullptr);
   const int32_t size = ngroups_field->GetInt(thread_group);
   if (size == 0) {
@@ -2117,7 +2117,7 @@
   }
 
   // Get the ThreadGroup[] "groups" out of this thread group...
-  ArtField* groups_field = soa.DecodeField(WellKnownClasses::java_lang_ThreadGroup_groups);
+  ArtField* groups_field = jni::DecodeArtField(WellKnownClasses::java_lang_ThreadGroup_groups);
   ObjPtr<mirror::Object> groups_array = groups_field->GetObject(thread_group);
 
   CHECK(groups_array != nullptr);
@@ -2155,7 +2155,7 @@
   // Add child thread groups.
   {
     std::vector<JDWP::ObjectId> child_thread_groups_ids;
-    GetChildThreadGroups(soa, thread_group, &child_thread_groups_ids);
+    GetChildThreadGroups(thread_group, &child_thread_groups_ids);
     expandBufAdd4BE(pReply, child_thread_groups_ids.size());
     for (JDWP::ObjectId child_thread_group_id : child_thread_groups_ids) {
       expandBufAddObjectId(pReply, child_thread_group_id);
@@ -2167,7 +2167,7 @@
 
 JDWP::ObjectId Dbg::GetSystemThreadGroupId() {
   ScopedObjectAccessUnchecked soa(Thread::Current());
-  ArtField* f = soa.DecodeField(WellKnownClasses::java_lang_ThreadGroup_systemThreadGroup);
+  ArtField* f = jni::DecodeArtField(WellKnownClasses::java_lang_ThreadGroup_systemThreadGroup);
   ObjPtr<mirror::Object> group = f->GetObject(f->GetDeclaringClass());
   return gRegistry->Add(group);
 }
@@ -2257,14 +2257,13 @@
   return JDWP::ERR_NONE;
 }
 
-static bool IsInDesiredThreadGroup(ScopedObjectAccessUnchecked& soa,
-                                   mirror::Object* desired_thread_group, mirror::Object* peer)
+static bool IsInDesiredThreadGroup(mirror::Object* desired_thread_group, mirror::Object* peer)
     REQUIRES_SHARED(Locks::mutator_lock_) {
   // Do we want threads from all thread groups?
   if (desired_thread_group == nullptr) {
     return true;
   }
-  ArtField* thread_group_field = soa.DecodeField(WellKnownClasses::java_lang_Thread_group);
+  ArtField* thread_group_field = jni::DecodeArtField(WellKnownClasses::java_lang_Thread_group);
   DCHECK(thread_group_field != nullptr);
   ObjPtr<mirror::Object> group = thread_group_field->GetObject(peer);
   return (group == desired_thread_group);
@@ -2297,7 +2296,7 @@
       // Doing so might help us report ZOMBIE threads too.
       continue;
     }
-    if (IsInDesiredThreadGroup(soa, thread_group, peer)) {
+    if (IsInDesiredThreadGroup(thread_group, peer)) {
       thread_ids->push_back(gRegistry->Add(peer));
     }
   }
@@ -4372,7 +4371,7 @@
     CHECK(type == CHUNK_TYPE("THCR") || type == CHUNK_TYPE("THNM")) << type;
     ScopedObjectAccessUnchecked soa(Thread::Current());
     StackHandleScope<1> hs(soa.Self());
-    Handle<mirror::String> name(hs.NewHandle(t->GetThreadName(soa)));
+    Handle<mirror::String> name(hs.NewHandle(t->GetThreadName()));
     size_t char_count = (name.Get() != nullptr) ? name->GetLength() : 0;
     const jchar* chars = (name.Get() != nullptr) ? name->GetValue() : nullptr;
     bool is_compressed = (name.Get() != nullptr) ? name->IsCompressed() : false;
diff --git a/runtime/jni_internal.cc b/runtime/jni_internal.cc
index b083593..01a2ad8 100644
--- a/runtime/jni_internal.cc
+++ b/runtime/jni_internal.cc
@@ -235,7 +235,7 @@
                                    sig, name, c->GetDescriptor(&temp));
     return nullptr;
   }
-  return soa.EncodeField(field);
+  return jni::EncodeArtField(field);
 }
 
 static void ThrowAIOOBE(ScopedObjectAccess& soa, mirror::Array* array, jsize start,
@@ -380,7 +380,7 @@
       return nullptr;
     }
     ObjPtr<mirror::Field> field = ObjPtr<mirror::Field>::DownCast(obj_field);
-    return soa.EncodeField(field->GetArtField());
+    return jni::EncodeArtField(field->GetArtField());
   }
 
   static jobject ToReflectedMethod(JNIEnv* env, jclass, jmethodID mid, jboolean) {
@@ -401,7 +401,7 @@
   static jobject ToReflectedField(JNIEnv* env, jclass, jfieldID fid, jboolean) {
     CHECK_NON_NULL_ARGUMENT(fid);
     ScopedObjectAccess soa(env);
-    ArtField* f = soa.DecodeField(fid);
+    ArtField* f = jni::DecodeArtField(fid);
     return soa.AddLocalReference<jobject>(
         mirror::Field::CreateFromArtField<kRuntimePointerSize>(soa.Self(), f, true));
   }
@@ -1237,14 +1237,14 @@
     CHECK_NON_NULL_ARGUMENT(fid);
     ScopedObjectAccess soa(env);
     ObjPtr<mirror::Object> o = soa.Decode<mirror::Object>(obj);
-    ArtField* f = soa.DecodeField(fid);
+    ArtField* f = jni::DecodeArtField(fid);
     return soa.AddLocalReference<jobject>(f->GetObject(o));
   }
 
   static jobject GetStaticObjectField(JNIEnv* env, jclass, jfieldID fid) {
     CHECK_NON_NULL_ARGUMENT(fid);
     ScopedObjectAccess soa(env);
-    ArtField* f = soa.DecodeField(fid);
+    ArtField* f = jni::DecodeArtField(fid);
     return soa.AddLocalReference<jobject>(f->GetObject(f->GetDeclaringClass()));
   }
 
@@ -1254,7 +1254,7 @@
     ScopedObjectAccess soa(env);
     ObjPtr<mirror::Object> o = soa.Decode<mirror::Object>(java_object);
     ObjPtr<mirror::Object> v = soa.Decode<mirror::Object>(java_value);
-    ArtField* f = soa.DecodeField(fid);
+    ArtField* f = jni::DecodeArtField(fid);
     f->SetObject<false>(o, v);
   }
 
@@ -1262,7 +1262,7 @@
     CHECK_NON_NULL_ARGUMENT_RETURN_VOID(fid);
     ScopedObjectAccess soa(env);
     ObjPtr<mirror::Object> v = soa.Decode<mirror::Object>(java_value);
-    ArtField* f = soa.DecodeField(fid);
+    ArtField* f = jni::DecodeArtField(fid);
     f->SetObject<false>(f->GetDeclaringClass(), v);
   }
 
@@ -1271,13 +1271,13 @@
   CHECK_NON_NULL_ARGUMENT_RETURN_ZERO(fid); \
   ScopedObjectAccess soa(env); \
   ObjPtr<mirror::Object> o = soa.Decode<mirror::Object>(instance); \
-  ArtField* f = soa.DecodeField(fid); \
+  ArtField* f = jni::DecodeArtField(fid); \
   return f->Get ##fn (o)
 
 #define GET_STATIC_PRIMITIVE_FIELD(fn) \
   CHECK_NON_NULL_ARGUMENT_RETURN_ZERO(fid); \
   ScopedObjectAccess soa(env); \
-  ArtField* f = soa.DecodeField(fid); \
+  ArtField* f = jni::DecodeArtField(fid); \
   return f->Get ##fn (f->GetDeclaringClass())
 
 #define SET_PRIMITIVE_FIELD(fn, instance, value) \
@@ -1285,13 +1285,13 @@
   CHECK_NON_NULL_ARGUMENT_RETURN_VOID(fid); \
   ScopedObjectAccess soa(env); \
   ObjPtr<mirror::Object> o = soa.Decode<mirror::Object>(instance); \
-  ArtField* f = soa.DecodeField(fid); \
+  ArtField* f = jni::DecodeArtField(fid); \
   f->Set ##fn <false>(o, value)
 
 #define SET_STATIC_PRIMITIVE_FIELD(fn, value) \
   CHECK_NON_NULL_ARGUMENT_RETURN_VOID(fid); \
   ScopedObjectAccess soa(env); \
-  ArtField* f = soa.DecodeField(fid); \
+  ArtField* f = jni::DecodeArtField(fid); \
   f->Set ##fn <false>(f->GetDeclaringClass(), value)
 
   static jboolean GetBooleanField(JNIEnv* env, jobject obj, jfieldID fid) {
diff --git a/runtime/jni_internal.h b/runtime/jni_internal.h
index 0e462d5..b3837c4 100644
--- a/runtime/jni_internal.h
+++ b/runtime/jni_internal.h
@@ -38,6 +38,7 @@
 
 namespace art {
 
+class ArtField;
 class ArtMethod;
 
 const JNINativeInterface* GetJniNativeInterface();
@@ -53,6 +54,16 @@
 namespace jni {
 
 ALWAYS_INLINE
+static inline ArtField* DecodeArtField(jfieldID fid) {
+  return reinterpret_cast<ArtField*>(fid);
+}
+
+ALWAYS_INLINE
+static inline jfieldID EncodeArtField(ArtField* field) {
+  return reinterpret_cast<jfieldID>(field);
+}
+
+ALWAYS_INLINE
 static inline jmethodID EncodeArtMethod(ArtMethod* art_method) {
   return reinterpret_cast<jmethodID>(art_method);
 }
diff --git a/runtime/oat_file_manager.cc b/runtime/oat_file_manager.cc
index cf9efe0..347d32b 100644
--- a/runtime/oat_file_manager.cc
+++ b/runtime/oat_file_manager.cc
@@ -28,6 +28,7 @@
 #include "gc/scoped_gc_critical_section.h"
 #include "gc/space/image_space.h"
 #include "handle_scope-inl.h"
+#include "jni_internal.h"
 #include "mirror/class_loader.h"
 #include "oat_file_assistant.h"
 #include "obj_ptr-inl.h"
@@ -248,7 +249,6 @@
 }
 
 static void IterateOverPathClassLoader(
-    ScopedObjectAccessAlreadyRunnable& soa,
     Handle<mirror::ClassLoader> class_loader,
     MutableHandle<mirror::ObjectArray<mirror::Object>> dex_elements,
     std::function<bool(const DexFile*)> fn) REQUIRES_SHARED(Locks::mutator_lock_) {
@@ -256,17 +256,18 @@
   // Handle as if this is the child PathClassLoader.
   // The class loader is a PathClassLoader which inherits from BaseDexClassLoader.
   // We need to get the DexPathList and loop through it.
-  ArtField* const cookie_field = soa.DecodeField(WellKnownClasses::dalvik_system_DexFile_cookie);
+  ArtField* const cookie_field =
+      jni::DecodeArtField(WellKnownClasses::dalvik_system_DexFile_cookie);
   ArtField* const dex_file_field =
-      soa.DecodeField(WellKnownClasses::dalvik_system_DexPathList__Element_dexFile);
+      jni::DecodeArtField(WellKnownClasses::dalvik_system_DexPathList__Element_dexFile);
   ObjPtr<mirror::Object> dex_path_list =
-      soa.DecodeField(WellKnownClasses::dalvik_system_BaseDexClassLoader_pathList)->
-      GetObject(class_loader.Get());
+      jni::DecodeArtField(WellKnownClasses::dalvik_system_BaseDexClassLoader_pathList)->
+          GetObject(class_loader.Get());
   if (dex_path_list != nullptr && dex_file_field != nullptr && cookie_field != nullptr) {
     // DexPathList has an array dexElements of Elements[] which each contain a dex file.
     ObjPtr<mirror::Object> dex_elements_obj =
-        soa.DecodeField(WellKnownClasses::dalvik_system_DexPathList_dexElements)->
-        GetObject(dex_path_list);
+        jni::DecodeArtField(WellKnownClasses::dalvik_system_DexPathList_dexElements)->
+            GetObject(dex_path_list);
     // Loop through each dalvik.system.DexPathList$Element's dalvik.system.DexFile and look
     // at the mCookie which is a DexFile vector.
     if (dex_elements_obj != nullptr) {
@@ -323,7 +324,7 @@
       hs.NewHandle<mirror::ObjectArray<mirror::Object>>(nullptr));
   Handle<mirror::ClassLoader> h_class_loader(hs.NewHandle(class_loader));
 
-  IterateOverPathClassLoader(soa, h_class_loader, dex_elements, GetDexFilesFn);
+  IterateOverPathClassLoader(h_class_loader, dex_elements, GetDexFilesFn);
 
   return true;
 }
@@ -337,9 +338,10 @@
     return;
   }
 
-  ArtField* const cookie_field = soa.DecodeField(WellKnownClasses::dalvik_system_DexFile_cookie);
+  ArtField* const cookie_field =
+      jni::DecodeArtField(WellKnownClasses::dalvik_system_DexFile_cookie);
   ArtField* const dex_file_field =
-      soa.DecodeField(WellKnownClasses::dalvik_system_DexPathList__Element_dexFile);
+      jni::DecodeArtField(WellKnownClasses::dalvik_system_DexPathList__Element_dexFile);
   ObjPtr<mirror::Class> const element_class = soa.Decode<mirror::Class>(
       WellKnownClasses::dalvik_system_DexPathList__Element);
   ObjPtr<mirror::Class> const dexfile_class = soa.Decode<mirror::Class>(
diff --git a/runtime/scoped_thread_state_change-inl.h b/runtime/scoped_thread_state_change-inl.h
index a8640c0..d4469f4 100644
--- a/runtime/scoped_thread_state_change-inl.h
+++ b/runtime/scoped_thread_state_change-inl.h
@@ -86,18 +86,6 @@
   return ObjPtr<T, kPoison>::DownCast(Self()->DecodeJObject(obj));
 }
 
-inline ArtField* ScopedObjectAccessAlreadyRunnable::DecodeField(jfieldID fid) const {
-  Locks::mutator_lock_->AssertSharedHeld(Self());
-  DCHECK(IsRunnable());  // Don't work with raw objects in non-runnable states.
-  return reinterpret_cast<ArtField*>(fid);
-}
-
-inline jfieldID ScopedObjectAccessAlreadyRunnable::EncodeField(ArtField* field) const {
-  Locks::mutator_lock_->AssertSharedHeld(Self());
-  DCHECK(IsRunnable());  // Don't work with raw objects in non-runnable states.
-  return reinterpret_cast<jfieldID>(field);
-}
-
 inline bool ScopedObjectAccessAlreadyRunnable::IsRunnable() const {
   return self_->GetState() == kRunnable;
 }
diff --git a/runtime/scoped_thread_state_change.h b/runtime/scoped_thread_state_change.h
index 65362c8..b499258 100644
--- a/runtime/scoped_thread_state_change.h
+++ b/runtime/scoped_thread_state_change.h
@@ -94,10 +94,6 @@
   template<typename T, bool kPoison = kIsDebugBuild>
   ObjPtr<T, kPoison> Decode(jobject obj) const REQUIRES_SHARED(Locks::mutator_lock_);
 
-  ArtField* DecodeField(jfieldID fid) const REQUIRES_SHARED(Locks::mutator_lock_);
-
-  jfieldID EncodeField(ArtField* field) const REQUIRES_SHARED(Locks::mutator_lock_);
-
   ALWAYS_INLINE bool IsRunnable() const;
 
  protected:
diff --git a/runtime/thread.cc b/runtime/thread.cc
index 1e3d4db..2d8ee49 100644
--- a/runtime/thread.cc
+++ b/runtime/thread.cc
@@ -410,9 +410,9 @@
     self->tlsPtr_.opeer = soa.Decode<mirror::Object>(self->tlsPtr_.jpeer).Ptr();
     self->GetJniEnv()->DeleteGlobalRef(self->tlsPtr_.jpeer);
     self->tlsPtr_.jpeer = nullptr;
-    self->SetThreadName(self->GetThreadName(soa)->ToModifiedUtf8().c_str());
+    self->SetThreadName(self->GetThreadName()->ToModifiedUtf8().c_str());
 
-    ArtField* priorityField = soa.DecodeField(WellKnownClasses::java_lang_Thread_priority);
+    ArtField* priorityField = jni::DecodeArtField(WellKnownClasses::java_lang_Thread_priority);
     self->SetNativePriority(priorityField->GetInt(self->tlsPtr_.opeer));
     Dbg::PostThreadStart(self);
 
@@ -430,7 +430,7 @@
 
 Thread* Thread::FromManagedThread(const ScopedObjectAccessAlreadyRunnable& soa,
                                   mirror::Object* thread_peer) {
-  ArtField* f = soa.DecodeField(WellKnownClasses::java_lang_Thread_nativePeer);
+  ArtField* f = jni::DecodeArtField(WellKnownClasses::java_lang_Thread_nativePeer);
   Thread* result = reinterpret_cast<Thread*>(static_cast<uintptr_t>(f->GetLong(thread_peer)));
   // Sanity check that if we have a result it is either suspended or we hold the thread_list_lock_
   // to stop it from going away.
@@ -562,7 +562,7 @@
   if (VLOG_IS_ON(threads)) {
     ScopedObjectAccess soa(env);
 
-    ArtField* f = soa.DecodeField(WellKnownClasses::java_lang_Thread_name);
+    ArtField* f = jni::DecodeArtField(WellKnownClasses::java_lang_Thread_name);
     ObjPtr<mirror::String> java_name =
         f->GetObject(soa.Decode<mirror::Object>(java_peer))->AsString();
     std::string thread_name;
@@ -823,7 +823,7 @@
 
   ScopedObjectAccess soa(self);
   StackHandleScope<1> hs(self);
-  MutableHandle<mirror::String> peer_thread_name(hs.NewHandle(GetThreadName(soa)));
+  MutableHandle<mirror::String> peer_thread_name(hs.NewHandle(GetThreadName()));
   if (peer_thread_name.Get() == nullptr) {
     // The Thread constructor should have set the Thread.name to a
     // non-null value. However, because we can run without code
@@ -834,7 +834,7 @@
     } else {
       InitPeer<false>(soa, thread_is_daemon, thread_group, thread_name.get(), thread_priority);
     }
-    peer_thread_name.Assign(GetThreadName(soa));
+    peer_thread_name.Assign(GetThreadName());
   }
   // 'thread_name' may have been null, so don't trust 'peer_thread_name' to be non-null.
   if (peer_thread_name.Get() != nullptr) {
@@ -845,13 +845,13 @@
 template<bool kTransactionActive>
 void Thread::InitPeer(ScopedObjectAccess& soa, jboolean thread_is_daemon, jobject thread_group,
                       jobject thread_name, jint thread_priority) {
-  soa.DecodeField(WellKnownClasses::java_lang_Thread_daemon)->
+  jni::DecodeArtField(WellKnownClasses::java_lang_Thread_daemon)->
       SetBoolean<kTransactionActive>(tlsPtr_.opeer, thread_is_daemon);
-  soa.DecodeField(WellKnownClasses::java_lang_Thread_group)->
+  jni::DecodeArtField(WellKnownClasses::java_lang_Thread_group)->
       SetObject<kTransactionActive>(tlsPtr_.opeer, soa.Decode<mirror::Object>(thread_group));
-  soa.DecodeField(WellKnownClasses::java_lang_Thread_name)->
+  jni::DecodeArtField(WellKnownClasses::java_lang_Thread_name)->
       SetObject<kTransactionActive>(tlsPtr_.opeer, soa.Decode<mirror::Object>(thread_name));
-  soa.DecodeField(WellKnownClasses::java_lang_Thread_priority)->
+  jni::DecodeArtField(WellKnownClasses::java_lang_Thread_priority)->
       SetInt<kTransactionActive>(tlsPtr_.opeer, thread_priority);
 }
 
@@ -947,8 +947,8 @@
   DumpStack(os, dump_native_stack, backtrace_map);
 }
 
-mirror::String* Thread::GetThreadName(const ScopedObjectAccessAlreadyRunnable& soa) const {
-  ArtField* f = soa.DecodeField(WellKnownClasses::java_lang_Thread_name);
+mirror::String* Thread::GetThreadName() const {
+  ArtField* f = jni::DecodeArtField(WellKnownClasses::java_lang_Thread_name);
   if (tlsPtr_.opeer == nullptr) {
     return nullptr;
   }
@@ -1306,17 +1306,18 @@
   // cause ScopedObjectAccessUnchecked to deadlock.
   if (gAborting == 0 && self != nullptr && thread != nullptr && thread->tlsPtr_.opeer != nullptr) {
     ScopedObjectAccessUnchecked soa(self);
-    priority = soa.DecodeField(WellKnownClasses::java_lang_Thread_priority)
+    priority = jni::DecodeArtField(WellKnownClasses::java_lang_Thread_priority)
         ->GetInt(thread->tlsPtr_.opeer);
-    is_daemon = soa.DecodeField(WellKnownClasses::java_lang_Thread_daemon)
+    is_daemon = jni::DecodeArtField(WellKnownClasses::java_lang_Thread_daemon)
         ->GetBoolean(thread->tlsPtr_.opeer);
 
     ObjPtr<mirror::Object> thread_group =
-        soa.DecodeField(WellKnownClasses::java_lang_Thread_group)->GetObject(thread->tlsPtr_.opeer);
+        jni::DecodeArtField(WellKnownClasses::java_lang_Thread_group)
+            ->GetObject(thread->tlsPtr_.opeer);
 
     if (thread_group != nullptr) {
       ArtField* group_name_field =
-          soa.DecodeField(WellKnownClasses::java_lang_ThreadGroup_name);
+          jni::DecodeArtField(WellKnownClasses::java_lang_ThreadGroup_name);
       ObjPtr<mirror::String> group_name_string =
           group_name_field->GetObject(thread_group)->AsString();
       group_name = (group_name_string != nullptr) ? group_name_string->ToModifiedUtf8() : "<null>";
@@ -1792,10 +1793,10 @@
 
     // this.nativePeer = 0;
     if (Runtime::Current()->IsActiveTransaction()) {
-      soa.DecodeField(WellKnownClasses::java_lang_Thread_nativePeer)
+      jni::DecodeArtField(WellKnownClasses::java_lang_Thread_nativePeer)
           ->SetLong<true>(tlsPtr_.opeer, 0);
     } else {
-      soa.DecodeField(WellKnownClasses::java_lang_Thread_nativePeer)
+      jni::DecodeArtField(WellKnownClasses::java_lang_Thread_nativePeer)
           ->SetLong<false>(tlsPtr_.opeer, 0);
     }
     Dbg::PostThreadDeath(self);
@@ -1803,7 +1804,7 @@
     // Thread.join() is implemented as an Object.wait() on the Thread.lock object. Signal anyone
     // who is waiting.
     ObjPtr<mirror::Object> lock =
-        soa.DecodeField(WellKnownClasses::java_lang_Thread_lock)->GetObject(tlsPtr_.opeer);
+        jni::DecodeArtField(WellKnownClasses::java_lang_Thread_lock)->GetObject(tlsPtr_.opeer);
     // (This conditional is only needed for tests, where Thread.lock won't have been set.)
     if (lock != nullptr) {
       StackHandleScope<1> hs(self);
@@ -1894,7 +1895,7 @@
 void Thread::RemoveFromThreadGroup(ScopedObjectAccess& soa) {
   // this.group.removeThread(this);
   // group can be null if we're in the compiler or a test.
-  ObjPtr<mirror::Object> ogroup = soa.DecodeField(WellKnownClasses::java_lang_Thread_group)
+  ObjPtr<mirror::Object> ogroup = jni::DecodeArtField(WellKnownClasses::java_lang_Thread_group)
       ->GetObject(tlsPtr_.opeer);
   if (ogroup != nullptr) {
     ScopedLocalRef<jobject> group(soa.Env(), soa.AddLocalReference<jobject>(ogroup));
diff --git a/runtime/thread.h b/runtime/thread.h
index 4f26803..f3001be 100644
--- a/runtime/thread.h
+++ b/runtime/thread.h
@@ -333,8 +333,7 @@
   }
 
   // Returns the java.lang.Thread's name, or null if this Thread* doesn't have a peer.
-  mirror::String* GetThreadName(const ScopedObjectAccessAlreadyRunnable& ts) const
-      REQUIRES_SHARED(Locks::mutator_lock_);
+  mirror::String* GetThreadName() const REQUIRES_SHARED(Locks::mutator_lock_);
 
   // Sets 'name' to the java.lang.Thread's name. This requires no transition to managed code,
   // allocation, or locking.