You're confusing Crankshaft with type inference. Crankshaft, which landed around Chrome 10, is an SSA-based optimization infrastructure. Type inference augments an optimization infrastructure with additional information. The two are complementary. V8 does not use type inference.
I don't think that's quite correct. IonMonkey also uses an SSA-based intermediate representation, and Crankshaft does generate type specialized code (as does TraceMonkey).
The big thing that IonMonkey is adding is type inference through static analysis, which is a big deal for JavaScript.
He's correct. This type inference is actually being added to JaegerMonkey according to the article, though IonMonkey will have it too when it's ready.
Crankshaft uses type feedback, not type inference. Ie: it will monitor the types of objects to generate type-specialized code, but will not do static type inference on the code to generate type-specialized code.
> Type Optimizations: One of the most important aspects of enabling performance on JavaScript is to create an efficient type system. The IE9 script engine uses many of the techniques common in modern dynamic language implementations, including type representation, polymorphic inline caching (also called type evolution or hidden classes), and efficient implementation of machine types.
