Apparently Google's toying with the idea of using "use asm" as a signal to opt into TurboFan[1]. While not the AOT compilation envisioned by the asm.js creators, it speaks to the importance asm.js has already gained.
That said, personally I'd rather see time spend optimising the new ES6 features so they can be used without a big performance hit.
Mozilla tracks TurboFan performance on its "Are We Fast Yet?" benchmarks. TurboFan is clearly a work-in-progress because it is not scoring well on the common JS benchmarks:
To be fair, the arewefastyet benchmarks are intentionally very broad, and stress test many different parts of a JS engine. It may be the case that TurboFan has a very fast sweet spot for numeric code (which would explain why they'd want to use it for asm.js), but is slower for the more general cases.
I'd be interested to see how TurboFan performs on individual test cases; for example, Octane has several asm-specific tests, and based on their planning I wonder whether TurboFan is faster than Crankshaft for those individual tests even if it's slower for the rest of them.
Huh super interesting. It looks like currently TurboFan is competitive w/Crankshaft on the asm.js benchmarks, and much, much slower on everything else. I wonder if the V8 team expects TurboFan to someday beat Crankshaft on the asm benchmarks, given current perf differences.
That said, personally I'd rather see time spend optimising the new ES6 features so they can be used without a big performance hit.
[1] https://code.google.com/p/v8/issues/detail?id=2599#c77