Tadeu Zagallo: A New Bytecode Format for JavaScriptCore

"In revision r237547 we introduced a new bytecode format for JavaScriptCore (JSC). The goals of the new format were to improve memory usage and allow the bytecode to be cached on disk, while the previous format was optimized for interpreter throughput at the cost of memory usage."

Speaking of bytecode, I found out this year at WWDC that iOS applications which use JavaScriptCore directly can't load WebAssembly modules. Since WebAssembly is translated directly into native code, with no interpreted fallback, it's a no-go as far as Apple is concerned.