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diff --git a/deps/v8/src/turbo-assembler.cc b/deps/v8/src/turbo-assembler.cc
new file mode 100644
index 0000000000..079feabb2e
--- /dev/null
+++ b/deps/v8/src/turbo-assembler.cc
@@ -0,0 +1,122 @@
+// Copyright 2018 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "src/turbo-assembler.h"
+
+#include "src/builtins/builtins.h"
+#include "src/builtins/constants-table-builder.h"
+#include "src/heap/heap-inl.h"
+#include "src/snapshot/serializer-common.h"
+
+namespace v8 {
+namespace internal {
+
+TurboAssemblerBase::TurboAssemblerBase(Isolate* isolate,
+                                       const AssemblerOptions& options,
+                                       void* buffer, int buffer_size,
+                                       CodeObjectRequired create_code_object)
+    : Assembler(options, buffer, buffer_size), isolate_(isolate) {
+  if (create_code_object == CodeObjectRequired::kYes) {
+    code_object_ = Handle<HeapObject>::New(
+        ReadOnlyRoots(isolate).self_reference_marker(), isolate);
+  }
+}
+
+void TurboAssemblerBase::IndirectLoadConstant(Register destination,
+                                              Handle<HeapObject> object) {
+  CHECK(isolate()->ShouldLoadConstantsFromRootList());
+  CHECK(root_array_available_);
+
+  // Before falling back to the (fairly slow) lookup from the constants table,
+  // check if any of the fast paths can be applied.
+
+  int builtin_index;
+  Heap::RootListIndex root_index;
+  if (isolate()->heap()->IsRootHandle(object, &root_index)) {
+    // Roots are loaded relative to the root register.
+    LoadRoot(destination, root_index);
+  } else if (isolate()->builtins()->IsBuiltinHandle(object, &builtin_index)) {
+    // Similar to roots, builtins may be loaded from the builtins table.
+    LoadRootRelative(destination,
+                     RootRegisterOffsetForBuiltinIndex(builtin_index));
+  } else if (object.is_identical_to(code_object_) &&
+             Builtins::IsBuiltinId(maybe_builtin_index_)) {
+    // The self-reference loaded through Codevalue() may also be a builtin
+    // and thus viable for a fast load.
+    LoadRootRelative(destination,
+                     RootRegisterOffsetForBuiltinIndex(maybe_builtin_index_));
+  } else {
+    // Ensure the given object is in the builtins constants table and fetch its
+    // index.
+    BuiltinsConstantsTableBuilder* builder =
+        isolate()->builtins_constants_table_builder();
+    uint32_t index = builder->AddObject(object);
+
+    // Slow load from the constants table.
+    LoadFromConstantsTable(destination, index);
+  }
+}
+
+void TurboAssemblerBase::IndirectLoadExternalReference(
+    Register destination, ExternalReference reference) {
+  CHECK(isolate()->ShouldLoadConstantsFromRootList());
+  CHECK(root_array_available_);
+
+  if (IsAddressableThroughRootRegister(isolate(), reference)) {
+    // Some external references can be efficiently loaded as an offset from
+    // kRootRegister.
+    intptr_t offset =
+        RootRegisterOffsetForExternalReference(isolate(), reference);
+    LoadRootRegisterOffset(destination, offset);
+  } else {
+    // Otherwise, do a memory load from the external reference table.
+
+    // Encode as an index into the external reference table stored on the
+    // isolate.
+    ExternalReferenceEncoder encoder(isolate());
+    ExternalReferenceEncoder::Value v = encoder.Encode(reference.address());
+    CHECK(!v.is_from_api());
+
+    LoadRootRelative(destination,
+                     RootRegisterOffsetForExternalReferenceIndex(v.index()));
+  }
+}
+
+// static
+int32_t TurboAssemblerBase::RootRegisterOffset(Heap::RootListIndex root_index) {
+  return (root_index << kPointerSizeLog2) - kRootRegisterBias;
+}
+
+// static
+int32_t TurboAssemblerBase::RootRegisterOffsetForExternalReferenceIndex(
+    int reference_index) {
+  return Heap::roots_to_external_reference_table_offset() - kRootRegisterBias +
+         ExternalReferenceTable::OffsetOfEntry(reference_index);
+}
+
+// static
+intptr_t TurboAssemblerBase::RootRegisterOffsetForExternalReference(
+    Isolate* isolate, const ExternalReference& reference) {
+  return static_cast<intptr_t>(reference.address()) - kRootRegisterBias -
+         reinterpret_cast<intptr_t>(isolate->heap()->roots_array_start());
+}
+
+// static
+bool TurboAssemblerBase::IsAddressableThroughRootRegister(
+    Isolate* isolate, const ExternalReference& reference) {
+  Address start = reinterpret_cast<Address>(isolate);
+  Address end = isolate->heap()->root_register_addressable_end();
+  Address address = reference.address();
+  return start <= address && address < end;
+}
+
+// static
+int32_t TurboAssemblerBase::RootRegisterOffsetForBuiltinIndex(
+    int builtin_index) {
+  return Heap::roots_to_builtins_offset() - kRootRegisterBias +
+         builtin_index * kPointerSize;
+}
+
+}  // namespace internal
+}  // namespace v8