Revert r20974: Unify and simplify the FastCloneShallowArrayStub

src/ia32/full-codegen-ia32.cc

Index: src/ia32/full-codegen-ia32.cc
diff --git a/src/ia32/full-codegen-ia32.cc b/src/ia32/full-codegen-ia32.cc
index 9854bb6e27829cf73fd45574517dd4d9146ac5d9..bfdc7bb6614a771fee5d5052a1fba47bc776dae1 100644
--- a/src/ia32/full-codegen-ia32.cc
+++ b/src/ia32/full-codegen-ia32.cc
@@ -1758,7 +1758,24 @@ void FullCodeGenerator::VisitArrayLiteral(ArrayLiteral* expr) {
     allocation_site_mode = DONT_TRACK_ALLOCATION_SITE;
   }
 
-  if (expr->depth() > 1) {
+  Heap* heap = isolate()->heap();
+  if (has_constant_fast_elements &&
+      constant_elements_values->map() == heap->fixed_cow_array_map()) {
+    // If the elements are already FAST_*_ELEMENTS, the boilerplate cannot
+    // change, so it's possible to specialize the stub in advance.
+    __ IncrementCounter(isolate()->counters()->cow_arrays_created_stub(), 1);
+    __ mov(ebx, Operand(ebp, JavaScriptFrameConstants::kFunctionOffset));
+    __ mov(eax, FieldOperand(ebx, JSFunction::kLiteralsOffset));
+    __ mov(ebx, Immediate(Smi::FromInt(expr->literal_index())));
+    __ mov(ecx, Immediate(constant_elements));
+    FastCloneShallowArrayStub stub(
+        isolate(),
+        FastCloneShallowArrayStub::COPY_ON_WRITE_ELEMENTS,
+        allocation_site_mode,
+        length);
+    __ CallStub(&stub);
+  } else if (expr->depth() > 1 || Serializer::enabled() ||
+             length > FastCloneShallowArrayStub::kMaximumClonedLength) {
     __ mov(ebx, Operand(ebp, JavaScriptFrameConstants::kFunctionOffset));
     __ push(FieldOperand(ebx, JSFunction::kLiteralsOffset));
     __ push(Immediate(Smi::FromInt(expr->literal_index())));
@@ -1766,11 +1783,25 @@ void FullCodeGenerator::VisitArrayLiteral(ArrayLiteral* expr) {
     __ push(Immediate(Smi::FromInt(flags)));
     __ CallRuntime(Runtime::kHiddenCreateArrayLiteral, 4);
   } else {
+    ASSERT(IsFastSmiOrObjectElementsKind(constant_elements_kind) ||
+           FLAG_smi_only_arrays);
+    FastCloneShallowArrayStub::Mode mode =
+        FastCloneShallowArrayStub::CLONE_ANY_ELEMENTS;
+
+    // If the elements are already FAST_*_ELEMENTS, the boilerplate cannot
+    // change, so it's possible to specialize the stub in advance.
+    if (has_constant_fast_elements) {
+      mode = FastCloneShallowArrayStub::CLONE_ELEMENTS;
+    }
+
     __ mov(ebx, Operand(ebp, JavaScriptFrameConstants::kFunctionOffset));
     __ mov(eax, FieldOperand(ebx, JSFunction::kLiteralsOffset));
     __ mov(ebx, Immediate(Smi::FromInt(expr->literal_index())));
     __ mov(ecx, Immediate(constant_elements));
-    FastCloneShallowArrayStub stub(isolate(), allocation_site_mode);
+    FastCloneShallowArrayStub stub(isolate(),
+                                   mode,
+                                   allocation_site_mode,
+                                   length);
     __ CallStub(&stub);
   }