1 files changed, 40 insertions, 0 deletions
diff --git a/deps/v8/src/x64/macro-assembler-x64.cc b/deps/v8/src/x64/macro-assembler-x64.cc
index 2d6bd08139..670bd05028 100644
--- a/deps/v8/src/x64/macro-assembler-x64.cc
+++ b/deps/v8/src/x64/macro-assembler-x64.cc
@@ -4033,6 +4033,46 @@ void MacroAssembler::LoadContext(Register dst, int context_chain_length) {
   }
 }
 
+
+void MacroAssembler::LoadTransitionedArrayMapConditional(
+    ElementsKind expected_kind,
+    ElementsKind transitioned_kind,
+    Register map_in_out,
+    Register scratch,
+    Label* no_map_match) {
+  // Load the global or builtins object from the current context.
+  movq(scratch, Operand(rsi, Context::SlotOffset(Context::GLOBAL_INDEX)));
+  movq(scratch, FieldOperand(scratch, GlobalObject::kGlobalContextOffset));
+
+  // Check that the function's map is the same as the expected cached map.
+  int expected_index =
+      Context::GetContextMapIndexFromElementsKind(expected_kind);
+  cmpq(map_in_out, Operand(scratch, Context::SlotOffset(expected_index)));
+  j(not_equal, no_map_match);
+
+  // Use the transitioned cached map.
+  int trans_index =
+      Context::GetContextMapIndexFromElementsKind(transitioned_kind);
+  movq(map_in_out, Operand(scratch, Context::SlotOffset(trans_index)));
+}
+
+
+void MacroAssembler::LoadInitialArrayMap(
+    Register function_in, Register scratch, Register map_out) {
+  ASSERT(!function_in.is(map_out));
+  Label done;
+  movq(map_out, FieldOperand(function_in,
+                             JSFunction::kPrototypeOrInitialMapOffset));
+  if (!FLAG_smi_only_arrays) {
+    LoadTransitionedArrayMapConditional(FAST_SMI_ONLY_ELEMENTS,
+                                        FAST_ELEMENTS,
+                                        map_out,
+                                        scratch,
+                                        &done);
+  }
+  bind(&done);
+}
+
 #ifdef _WIN64
 static const int kRegisterPassedArguments = 4;
 #else