Add pretenuring support to HAllocateObject.

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index 42c6e9148e71d6b5fe16dc810ac643efe43b8ce7..648a812765d3239bd9c0e72694ab4a9a9aa4c090 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -5039,11 +5039,15 @@ void LCodeGen::DoAllocateObject(LAllocateObject* instr) {
          initial_map->unused_property_fields() -
          initial_map->inobject_properties() == 0);
 
-  __ Allocate(instance_size, result, no_reg, scratch, deferred->entry(),
-              TAG_OBJECT);
+  AllocationFlags flags = TAG_OBJECT;
+  if (instr->hydrogen()->CanAllocateInOldPointerSpace()) {
+    flags = static_cast<AllocationFlags>(flags | PRETENURE_OLD_POINTER_SPACE);
+  }
+
+  __ Allocate(instance_size, result, no_reg, scratch, deferred->entry(), flags);
 
   __ bind(deferred->exit());
-  if (FLAG_debug_code) {
+  if (FLAG_debug_code && !instr->hydrogen()->CanAllocateInOldPointerSpace()) {
     Label is_in_new_space;
     __ JumpIfInNewSpace(result, scratch, &is_in_new_space);
     __ Abort("Allocated object is not in new-space");
@@ -5053,6 +5057,7 @@ void LCodeGen::DoAllocateObject(LAllocateObject* instr) {
   // Load the initial map.
   Register map = scratch;
   __ LoadHeapObject(scratch, constructor);
+  // Recording the map slot can be skipped, because maps are not compacted.
   __ movq(map, FieldOperand(scratch, JSFunction::kPrototypeOrInitialMapOffset));
 
   if (FLAG_debug_code) {
@@ -5099,7 +5104,11 @@ void LCodeGen::DoDeferredAllocateObject(LAllocateObject* instr) {
 
   PushSafepointRegistersScope scope(this);
   __ Push(Smi::FromInt(instance_size));
-  CallRuntimeFromDeferred(Runtime::kAllocateInNewSpace, 1, instr);
+  if (instr->hydrogen()->CanAllocateInOldPointerSpace()) {
+    CallRuntimeFromDeferred(Runtime::kAllocateInOldPointerSpace, 1, instr);
+  } else {
+    CallRuntimeFromDeferred(Runtime::kAllocateInNewSpace, 1, instr);
+  }
   __ StoreToSafepointRegisterSlot(result, rax);
 }