Reland r20974: Unify and simplify the FastCloneShallowArrayStub

src/arm64/full-codegen-arm64.cc

 // Copyright 2013 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 "v8.h"
 
 #if V8_TARGET_ARCH_ARM64
 
 #include "code-stubs.h"
 #include "codegen.h"
@@ skipping 1777 matching lines @@
   if (has_fast_elements && !FLAG_allocation_site_pretenuring) {
     // If the only customer of allocation sites is transitioning, then
     // we can turn it off if we don't have anywhere else to transition to.
     allocation_site_mode = DONT_TRACK_ALLOCATION_SITE;
   }
 
   __ Ldr(x3, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
   __ Ldr(x3, FieldMemOperand(x3, JSFunction::kLiteralsOffset));
   __ Mov(x2, Smi::FromInt(expr->literal_index()));
   __ Mov(x1, Operand(constant_elements));
-  if (has_fast_elements && constant_elements_values->map() ==
-      isolate()->heap()->fixed_cow_array_map()) {
-    FastCloneShallowArrayStub stub(
-        isolate(),
-        FastCloneShallowArrayStub::COPY_ON_WRITE_ELEMENTS,
-        allocation_site_mode,
-        length);
-    __ CallStub(&stub);
-    __ IncrementCounter(
-        isolate()->counters()->cow_arrays_created_stub(), 1, x10, x11);
-  } else if ((expr->depth() > 1) || Serializer::enabled(isolate()) ||
-             length > FastCloneShallowArrayStub::kMaximumClonedLength) {
+  if (expr->depth() > 1) {
     __ Mov(x0, Smi::FromInt(flags));
     __ Push(x3, x2, x1, x0);
     __ CallRuntime(Runtime::kHiddenCreateArrayLiteral, 4);
   } else {
-    ASSERT(IsFastSmiOrObjectElementsKind(constant_elements_kind) ||
-           FLAG_smi_only_arrays);
-    FastCloneShallowArrayStub::Mode mode =
-        FastCloneShallowArrayStub::CLONE_ANY_ELEMENTS;
-
-    if (has_fast_elements) {
-      mode = FastCloneShallowArrayStub::CLONE_ELEMENTS;
-    }
-
-    FastCloneShallowArrayStub stub(isolate(),
-                                   mode,
-                                   allocation_site_mode,
-                                   length);
+    FastCloneShallowArrayStub stub(isolate(), allocation_site_mode);
     __ CallStub(&stub);
   }
 
   bool result_saved = false;  // Is the result saved to the stack?
 
   // Emit code to evaluate all the non-constant subexpressions and to store
   // them into the newly cloned array.
   for (int i = 0; i < length; i++) {
     Expression* subexpr = subexprs->at(i);
     // If the subexpression is a literal or a simple materialized literal it
@@ skipping 3072 matching lines @@
   return previous_;
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM64