MIPS: The gc should be able to traverse all AllocationSites for decision making.

Port r15715 (2e830d4)

Original commit message:
The gc should be able to traverse all AllocationSites for decision making. The sites are threaded into a weak list. Special problems include:

* Allocations of AllocationSites occur in generated code, so generated code needs to be able to add to the list. For now I have a special hydrogen instruction, though it would be nice to use general purpose instructions.
* The snapshot contains AllocationSites, and these need to be re-threaded into the list on deserialization.

Something nice is that the AllocationSites are only created in old space, so a special new space visitor isn't required.

BUG=

Review URL: https://codereview.chromium.org/19635002
Patch from Balazs Kilvady <kilvadyb@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15732 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/lithium-codegen-mips.cc

@@ -2794,6 +2794,19 @@ void LCodeGen::DoStoreGlobalGeneric(LStoreGlobalGeneric* instr) {
 }
 
 
+void LCodeGen::DoLinkObjectInList(LLinkObjectInList* instr) {
+  Register object = ToRegister(instr->object());
+  ExternalReference sites_list_address = instr->GetReference(isolate());
+
+  __ li(at, Operand(sites_list_address));
+  __ lw(at, MemOperand(at));
+  __ sw(at, FieldMemOperand(object,
+                            instr->hydrogen()->store_field().offset()));
+  __ li(at, Operand(sites_list_address));
+  __ sw(object, MemOperand(at));
+}
+
+
 void LCodeGen::DoLoadContextSlot(LLoadContextSlot* instr) {
   Register context = ToRegister(instr->context());
   Register result = ToRegister(instr->result());

src/mips/lithium-mips.cc

@@ -277,6 +277,24 @@ void LCallConstantFunction::PrintDataTo(StringStream* stream) {
 }
 
 
+ExternalReference LLinkObjectInList::GetReference(Isolate* isolate) {
+  switch (hydrogen()->known_list()) {
+    case HLinkObjectInList::ALLOCATION_SITE_LIST:
+      return ExternalReference::allocation_sites_list_address(isolate);
+  }
+
+  UNREACHABLE();
+  // Return a dummy value
+  return ExternalReference::isolate_address(isolate);
+}
+
+
+void LLinkObjectInList::PrintDataTo(StringStream* stream) {
+  object()->PrintTo(stream);
+  stream->Add(" offset %d", hydrogen()->store_field().offset());
+}
+
+
 void LLoadContextSlot::PrintDataTo(StringStream* stream) {
   context()->PrintTo(stream);
   stream->Add("[%d]", slot_index());
@@ -2035,6 +2053,13 @@ LInstruction* LChunkBuilder::DoStoreGlobalGeneric(HStoreGlobalGeneric* instr) {
 }
 
 
+LInstruction* LChunkBuilder::DoLinkObjectInList(HLinkObjectInList* instr) {
+  LOperand* object = UseRegister(instr->value());
+  LLinkObjectInList* result = new(zone()) LLinkObjectInList(object);
+  return result;
+}
+
+
 LInstruction* LChunkBuilder::DoLoadContextSlot(HLoadContextSlot* instr) {
   LOperand* context = UseRegisterAtStart(instr->value());
   LInstruction* result =

src/mips/lithium-mips.h

@@ -120,6 +120,7 @@ class LCodeGen;
   V(IsUndetectableAndBranch)                    \
   V(Label)                                      \
   V(LazyBailout)                                \
+  V(LinkObjectInList)                           \
   V(LoadContextSlot)                            \
   V(LoadExternalArrayPointer)                   \
   V(LoadFunctionPrototype)                      \
@@ -1662,6 +1663,23 @@ class LStoreGlobalGeneric: public LTemplateInstruction<0, 2, 0> {
 };
 
 
+class LLinkObjectInList: public LTemplateInstruction<0, 1, 0> {
+ public:
+  explicit LLinkObjectInList(LOperand* object) {
+    inputs_[0] = object;
+  }
+
+  LOperand* object() { return inputs_[0]; }
+
+  ExternalReference GetReference(Isolate* isolate);
+
+  DECLARE_CONCRETE_INSTRUCTION(LinkObjectInList, "link-object-in-list")
+  DECLARE_HYDROGEN_ACCESSOR(LinkObjectInList)
+
+  virtual void PrintDataTo(StringStream* stream);
+};
+
+
 class LLoadContextSlot: public LTemplateInstruction<1, 1, 0> {
  public:
   explicit LLoadContextSlot(LOperand* context) {