Reimplement Maps and Sets in JS

src/hydrogen.h

 // 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.
 
 #ifndef V8_HYDROGEN_H_
 #define V8_HYDROGEN_H_
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
@@ skipping 1829 matching lines @@
 
   HValue* BuildCloneShallowArrayEmpty(HValue* boilerplate,
                                       HValue* allocation_site,
                                       AllocationSiteMode mode);
 
   HValue* BuildCloneShallowArrayNonEmpty(HValue* boilerplate,
                                          HValue* allocation_site,
                                          AllocationSiteMode mode,
                                          ElementsKind kind);
 
-  HValue* BuildElementIndexHash(HValue* index);
+  HValue* BuildComputeIntegerHash(HValue* value, uint32_t seed);
+
+  HValue* BuildElementIndexHash(HValue* index) {

[Sven Panne, 2015/02/23 09:26:53]

When we have %_HashSeed() (for isolate()->heap()->HashSeed()), this can be
expressed purely in JavaScript. As it is, it is too specialized.

[adamk, 2015/02/23 18:43:35]

Yeah, I only reused this for expediency, there's no reason we couldn't compute
Smi hashes in JS (String hashes are more complex, and I think there are more
tradeoffs there).

[adamk, 2015/03/16 17:35:06]

I've now written a JS version of this.

+    return BuildComputeIntegerHash(index, isolate()->heap()->HashSeed());
+  }
 
   enum MapEmbedding { kEmbedMapsDirectly, kEmbedMapsViaWeakCells };
 
   void BuildCompareNil(HValue* value, Type* type, HIfContinuation* continuation,
                        MapEmbedding map_embedding = kEmbedMapsDirectly);
 
   void BuildCreateAllocationMemento(HValue* previous_object,
                                     HValue* previous_object_size,
                                     HValue* payload);
 
@@ skipping 1171 matching lines @@
   }
 
  private:
   HGraphBuilder* builder_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_H_