Revert r11835 'Unify promotion and allocation limit computation' due to V8 Splay performance regres…

src/heap.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1341 matching lines @@
   }
 
   inline intptr_t OldGenerationSpaceAvailable() {
     return old_gen_allocation_limit_ - PromotedTotalSize();
   }
 
   inline intptr_t OldGenerationCapacityAvailable() {
     return max_old_generation_size_ - PromotedTotalSize();
   }
 
-  static const intptr_t kMinPromotionLimit = 5 * Page::kPageSize;
-  static const intptr_t kMinAllocationLimit =
+  static const intptr_t kMinimumPromotionLimit = 5 * Page::kPageSize;
+  static const intptr_t kMinimumAllocationLimit =
       8 * (Page::kPageSize > MB ? Page::kPageSize : MB);
 
-  intptr_t OldGenLimit(intptr_t old_gen_size, intptr_t min_limit) {
-    const int divisor = FLAG_stress_compaction ? 8 : 2;
-    intptr_t limit = Max(old_gen_size + old_gen_size / divisor, min_limit);
+  intptr_t OldGenPromotionLimit(intptr_t old_gen_size) {
+    const int divisor = FLAG_stress_compaction ? 10 : 3;
+    intptr_t limit =
+        Max(old_gen_size + old_gen_size / divisor, kMinimumPromotionLimit);
     limit += new_space_.Capacity();
     limit *= old_gen_limit_factor_;
     intptr_t halfway_to_the_max = (old_gen_size + max_old_generation_size_) / 2;
+    return Min(limit, halfway_to_the_max);
+  }
+
+  intptr_t OldGenAllocationLimit(intptr_t old_gen_size) {
+    const int divisor = FLAG_stress_compaction ? 8 : 2;
+    intptr_t limit =
+        Max(old_gen_size + old_gen_size / divisor, kMinimumAllocationLimit);
+    limit += new_space_.Capacity();
+    limit *= old_gen_limit_factor_;
+    intptr_t halfway_to_the_max = (old_gen_size + max_old_generation_size_) / 2;
     return Min(limit, halfway_to_the_max);
   }
 
   // Implements the corresponding V8 API function.
   bool IdleNotification(int hint);
 
   // Declare all the root indices.
   enum RootListIndex {
 #define ROOT_INDEX_DECLARATION(type, name, camel_name) k##camel_name##RootIndex,
     STRONG_ROOT_LIST(ROOT_INDEX_DECLARATION)
@@ skipping 1308 matching lines @@
   AssertNoAllocation no_alloc;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG || LIVE_OBJECT_LIST
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_H_