Reimplement Maps and Sets in JS

src/hydrogen.h

Index: src/hydrogen.h
diff --git a/src/hydrogen.h b/src/hydrogen.h
index 8411b6ddf9e9f5967fae701c48118d42b4be6020..6c28b1dff64eb105058145fb43e99db324309b04 100644
--- a/src/hydrogen.h
+++ b/src/hydrogen.h
@@ -1847,7 +1847,11 @@ class HGraphBuilder {
                                          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 };