[stubs] Introduce a dedicated FastNewObjectStub.

src/mips/code-stubs-mips.cc

Index: src/mips/code-stubs-mips.cc
diff --git a/src/mips/code-stubs-mips.cc b/src/mips/code-stubs-mips.cc
index 0792403885318010b362929c9f396f8b987d9f12..dc224a985dc52746c5a33c633d809aa82445d2f7 100644
--- a/src/mips/code-stubs-mips.cc
+++ b/src/mips/code-stubs-mips.cc
@@ -4748,6 +4748,132 @@ void InternalArrayConstructorStub::Generate(MacroAssembler* masm) {
 }
 
 
+void FastNewObjectStub::Generate(MacroAssembler* masm) {
+  // ----------- S t a t e -------------
+  //  -- a1 : target
+  //  -- a3 : new target
+  //  -- cp : context
+  //  -- ra : return address
+  // -----------------------------------
+  __ AssertFunction(a1);
+  __ AssertReceiver(a3);
+
+  // Verify that the new target is a JSFunction.
+  Label new_object;
+  __ GetObjectType(a3, a2, a2);
+  __ Branch(&new_object, ne, a2, Operand(JS_FUNCTION_TYPE));
+
+  // Load the initial map and verify that it's in fact a map.
+  __ lw(a2, FieldMemOperand(a3, JSFunction::kPrototypeOrInitialMapOffset));
+  __ JumpIfSmi(a2, &new_object);
+  __ GetObjectType(a2, a0, a0);
+  __ Branch(&new_object, ne, a2, Operand(MAP_TYPE));
+
+  // Fall back to runtime if the target differs from the new target's
+  // initial map constructor.
+  __ lw(a0, FieldMemOperand(a2, Map::kConstructorOrBackPointerOffset));
+  __ Branch(&new_object, ne, a0, Operand(a1));
+
+  // Allocate the JSObject on the heap.
+  Label allocate, done_allocate;
+  __ lbu(t0, FieldMemOperand(a2, Map::kInstanceSizeOffset));
+  __ Allocate(t0, v0, t1, a0, &allocate, SIZE_IN_WORDS);
+  __ bind(&done_allocate);
+
+  // Initialize the JSObject fields.
+  __ sw(a2, MemOperand(v0, JSObject::kMapOffset));
+  __ LoadRoot(a3, Heap::kEmptyFixedArrayRootIndex);
+  __ sw(a3, MemOperand(v0, JSObject::kPropertiesOffset));
+  __ sw(a3, MemOperand(v0, JSObject::kElementsOffset));
+  STATIC_ASSERT(JSObject::kHeaderSize == 3 * kPointerSize);
+  __ Addu(a1, v0, Operand(JSObject::kHeaderSize));
+
+  // ----------- S t a t e -------------
+  //  -- v0 : result (untagged)
+  //  -- a1 : result fields (untagged)
+  //  -- t1 : result end (untagged)
+  //  -- a2 : initial map
+  //  -- cp : context
+  //  -- ra : return address
+  // -----------------------------------
+
+  // Perform in-object slack tracking if requested.
+  Label slack_tracking;
+  STATIC_ASSERT(Map::kNoSlackTracking == 0);
+  __ lw(a3, FieldMemOperand(a2, Map::kBitField3Offset));
+  __ And(at, a3, Operand(Map::ConstructionCounter::kMask));
+  __ Branch(USE_DELAY_SLOT, &slack_tracking, ne, at, Operand(0));
+  __ LoadRoot(a0, Heap::kUndefinedValueRootIndex);  // In delay slot.
+  {
+    // Initialize all in-object fields with undefined.
+    __ InitializeFieldsWithFiller(a1, t1, a0);
+
+    // Add the object tag to make the JSObject real.
+    STATIC_ASSERT(kHeapObjectTag == 1);
+    __ Ret(USE_DELAY_SLOT);
+    __ Addu(v0, v0, Operand(kHeapObjectTag));  // In delay slot.
+  }
+  __ bind(&slack_tracking);
+  {
+    // Decrease generous allocation count.
+    STATIC_ASSERT(Map::ConstructionCounter::kNext == 32);
+    __ Subu(a3, a3, Operand(1 << Map::ConstructionCounter::kShift));
+    __ sw(a3, FieldMemOperand(a2, Map::kBitField3Offset));
+
+    // Initialize the in-object fields with undefined.
+    __ lbu(t0, FieldMemOperand(a2, Map::kUnusedPropertyFieldsOffset));
+    __ sll(t0, t0, kPointerSizeLog2);
+    __ subu(t0, t1, t0);
+    __ InitializeFieldsWithFiller(a1, t0, a0);
+
+    // Initialize the remaining (reserved) fields with one pointer filler map.
+    __ LoadRoot(a0, Heap::kOnePointerFillerMapRootIndex);
+    __ InitializeFieldsWithFiller(a1, t1, a0);
+
+    // Check if we can finalize the instance size.
+    Label finalize;
+    STATIC_ASSERT(Map::kSlackTrackingCounterEnd == 1);
+    __ And(a3, a3, Operand(Map::ConstructionCounter::kMask));
+    __ Branch(USE_DELAY_SLOT, &finalize, eq, a3, Operand(zero_reg));
+    STATIC_ASSERT(kHeapObjectTag == 1);
+    __ Addu(v0, v0, Operand(kHeapObjectTag));  // In delay slot.
+    __ Ret();
+
+    // Finalize the instance size.
+    __ bind(&finalize);
+    {
+      FrameScope scope(masm, StackFrame::INTERNAL);
+      __ Push(v0, a2);
+      __ CallRuntime(Runtime::kFinalizeInstanceSize);
+      __ Pop(v0);
+    }
+    __ Ret();
+  }
+
+  // Fall back to %AllocateInNewSpace.
+  __ bind(&allocate);
+  {
+    FrameScope scope(masm, StackFrame::INTERNAL);
+    STATIC_ASSERT(kSmiTag == 0);
+    STATIC_ASSERT(kSmiTagSize == 1);
+    __ sll(t0, t0, kPointerSizeLog2 + kSmiTagSize);
+    __ Push(a2, t0);
+    __ CallRuntime(Runtime::kAllocateInNewSpace);
+    __ Pop(a2);
+  }
+  STATIC_ASSERT(kHeapObjectTag == 1);
+  __ Subu(v0, v0, Operand(kHeapObjectTag));
+  __ lbu(t1, FieldMemOperand(a2, Map::kInstanceSizeOffset));
+  __ Lsa(t1, v0, t1, kPointerSizeLog2);
+  __ jmp(&done_allocate);
+
+  // Fall back to %NewObject.
+  __ bind(&new_object);
+  __ Push(a1, a3);
+  __ TailCallRuntime(Runtime::kNewObject);
+}
+
+
 void FastNewRestParameterStub::Generate(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- a1 : function