Property caches revisited

Property caches are a well-known technique invented over 30 years ago to improve dynamic object accesses. They have been adapted to JavaScript, which they have greatly contributed to accelerate. However, this technique is applicable only when some constraints are satisfied by the objects, the properties, and the property access sites. In this work, we propose enhancements to improve two common usage patterns: prototype accesses and megamorphic accesses. We have implemented these in the Hopc AOT JavaScript compiler and we have measured their impact. We observe that they effectively complement traditional caches. They reduce cache misses and consequently accelerate execution. Moreover, they do not cause a slowdown in the handling of the other usage patterns.