159081 2016-06-23 21:09:03 -0700 make rest parameters faster 2016-07-10 18:54:51 -0700 1 1 1 Unclassified WebKit JavaScriptCore WebKit Local Build Unspecified Unspecified NEW P2 Normal --- 159612 1 saam saam benjamin fpizlo ggaren gskachkov keith_miller mark.lam msaboff oliver sukolsak ysuzuki oldest_to_newest 1205023 0 saam 2016-06-23 21:09:03 -0700 .... 1205137 1 fpizlo 2016-06-24 10:39:25 -0700 Thought about this more. I like that CopyRest is a node. If only we could make it so that the use of the rest array for forwarding arguments was also a node so that: function foo(a, b, c, ...args) { return bar(b, c, d, ...args); } looked like this: w: CopyRest(...) x: NewArray(b, c, d) y: ConcatArray(@x, @w) z: TailCallVarargs(bar, @y) I'm not sure how we'll compile "...args" in the call to bar(), but I'm pretty sure it'll be more obfuscated than this. If we could get to a point where the DFG saw this, then we could have arguments forwarding turn this into code that never allocated anything.