1648196 - Consider atomizing strings when tenuring

Status: NEW

(Core :: JavaScript Engine, enhancement, P3)

Description

[Steve Fink [:sfink] [:s:]]

I'm not sure what the costs of using atoms is, but now that we have string deduplication at tenure time, we're already computing the hashes of all tenured strings. Would it make sense to convert some or all linear non-dependent strings to atoms?

Or a weaker variant: when mallocing a buffer for a long-ish string, allocate extra space for a hash value. When tenuring the string, compute the hash for deduplication and store it after the string, setting a bit in the header to say that the hash is avilable. Reuse it if you ever atomize the string.