Fix inobject slack tracking for both subclassing and non-subclassing cases.

src/mips/builtins-mips.cc

 // Copyright 2012 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.
 
 #if V8_TARGET_ARCH_MIPS
 
 #include "src/codegen.h"
 #include "src/debug/debug.h"
 #include "src/deoptimizer.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 375 matching lines @@
         __ Branch(&rt_call, ne, a1, Operand(t1));
 
         // Check that the constructor is not constructing a JSFunction (see
         // comments in Runtime_NewObject in runtime.cc). In which case the
         // initial map's instance type would be JS_FUNCTION_TYPE.
         // a1: constructor function
         // a2: initial map
         __ lbu(t5, FieldMemOperand(a2, Map::kInstanceTypeOffset));
         __ Branch(&rt_call, eq, t5, Operand(JS_FUNCTION_TYPE));
 
-        if (!is_api_function) {
-          Label allocate;
-          MemOperand bit_field3 = FieldMemOperand(a2, Map::kBitField3Offset);
-          // Check if slack tracking is enabled.
-          __ lw(t0, bit_field3);
-          __ DecodeField<Map::Counter>(t2, t0);
-          __ Branch(&allocate, lt, t2, Operand(Map::kSlackTrackingCounterEnd));
-          // Decrease generous allocation count.
-          __ Subu(t0, t0, Operand(1 << Map::Counter::kShift));
-          __ Branch(USE_DELAY_SLOT, &allocate, ne, t2,
-                    Operand(Map::kSlackTrackingCounterEnd));
-          __ sw(t0, bit_field3);  // In delay slot.
-
-          // Push the constructor, new_target and map to the stack, and
-          // the map again as an argument to the runtime call.
-          __ Push(a1, a3, a2, a2);
-          __ CallRuntime(Runtime::kFinalizeInstanceSize, 1);
-
-          __ Pop(a1, a3, a2);
-          __ li(t2, Operand(Map::kSlackTrackingCounterEnd - 1));
-
-          __ bind(&allocate);
-        }
-
         // Now allocate the JSObject on the heap.
         // a1: constructor function
         // a2: initial map
         // a3: new target
-        // t2: slack tracking counter (non-API function case)
         __ lbu(t3, FieldMemOperand(a2, Map::kInstanceSizeOffset));
 
         __ Allocate(t3, t4, t3, t6, &rt_call, SIZE_IN_WORDS);
 
         // Allocated the JSObject, now initialize the fields. Map is set to
         // initial map and properties and elements are set to empty fixed array.
         // a1: constructor function
         // a2: initial map
         // a3: new target
-        // t4: JSObject (not tagged)
+        // t4: JSObject (not HeapObject tagged - the actual address).
         // t3: start of next object
-        // t2: slack tracking counter (non-API function case)
         __ LoadRoot(t6, Heap::kEmptyFixedArrayRootIndex);
         __ mov(t5, t4);
         STATIC_ASSERT(0 * kPointerSize == JSObject::kMapOffset);
         __ sw(a2, MemOperand(t5, JSObject::kMapOffset));
         STATIC_ASSERT(1 * kPointerSize == JSObject::kPropertiesOffset);
         __ sw(t6, MemOperand(t5, JSObject::kPropertiesOffset));
         STATIC_ASSERT(2 * kPointerSize == JSObject::kElementsOffset);
         __ sw(t6, MemOperand(t5, JSObject::kElementsOffset));
         STATIC_ASSERT(3 * kPointerSize == JSObject::kHeaderSize);
         __ Addu(t5, t5, Operand(3 * kPointerSize));
 
+        // Add the object tag to make the JSObject real, so that we can continue
+        // and jump into the continuation code at any time from now on.
+        __ Addu(t4, t4, Operand(kHeapObjectTag));
+
         // Fill all the in-object properties with appropriate filler.
+        // t4: JSObject (tagged)
         // t5: First in-object property of JSObject (not tagged)
-
-        // Use t7 to hold undefined, which is used in several places below.
         __ LoadRoot(t7, Heap::kUndefinedValueRootIndex);
 
         if (!is_api_function) {
           Label no_inobject_slack_tracking;
 
+          MemOperand bit_field3 = FieldMemOperand(a2, Map::kBitField3Offset);
           // Check if slack tracking is enabled.
+          __ lw(t0, bit_field3);
+          __ DecodeField<Map::Counter>(t2, t0);
+          // t2: slack tracking counter
           __ Branch(&no_inobject_slack_tracking, lt, t2,
                     Operand(Map::kSlackTrackingCounterEnd));
+          // Decrease generous allocation count.
+          __ Subu(t0, t0, Operand(1 << Map::Counter::kShift));
+          __ sw(t0, bit_field3);
 
           // Allocate object with a slack.
           __ lbu(a0, FieldMemOperand(a2, Map::kUnusedPropertyFieldsOffset));
           __ sll(a0, a0, kPointerSizeLog2);
           __ subu(a0, t3, a0);
           // a0: offset of first field after pre-allocated fields
           if (FLAG_debug_code) {
             __ Assert(le, kUnexpectedNumberOfPreAllocatedPropertyFields, t5,
                       Operand(a0));
           }
           __ InitializeFieldsWithFiller(t5, a0, t7);
 
           // To allow truncation fill the remaining fields with one pointer
           // filler map.
           __ LoadRoot(t7, Heap::kOnePointerFillerMapRootIndex);
+          __ InitializeFieldsWithFiller(t5, t3, t7);
+
+          // t2: slack tracking counter value before decreasing.
+          __ Branch(&allocated, ne, t2, Operand(Map::kSlackTrackingCounterEnd));
+
+          // Push the constructor, new_target and the object to the stack,
+          // and then the initial map as an argument to the runtime call.
+          __ Push(a1, a3, t4, a2);
+          __ CallRuntime(Runtime::kFinalizeInstanceSize, 1);
+          __ Pop(a1, a3, t4);
+
+          // Continue with JSObject being successfully allocated.
+          // a1: constructor function
+          // a3: new target
+          // t4: JSObject
+          __ jmp(&allocated);
 
           __ bind(&no_inobject_slack_tracking);
         }
 
         __ InitializeFieldsWithFiller(t5, t3, t7);
 
-        // Add the object tag to make the JSObject real, so that we can continue
-        // and jump into the continuation code at any time from now on.
-        __ Addu(t4, t4, Operand(kHeapObjectTag));
-
         // Continue with JSObject being successfully allocated.
         // a1: constructor function
         // a3: new target
         // t4: JSObject
         __ jmp(&allocated);
       }
 
       // Allocate the new receiver object using the runtime call.
       // a1: constructor function
       // a3: new target
@@ skipping 1490 matching lines @@
   }
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS