Context Navigation

Changes between Version 18 and Version 19 of JavaScript performance improvement ideas

v18	v19
19	19	* Use bytecode or something similar to make the interpreter non-recursive so it doesn't use so much stack. But the inner loop has to be coded carefully because obvious ways of doing will regress performance instead of speeding it up. (direct threading, subroutine threading, context threading)
20	20
21		* Constant folding. This could be done purely by the parser, for strings, numbers, even regexps.
	21	* Constant folding. This could be done purely by the parser, for strings, numbers, even regexps. Only a couple tests use constants which could be folded (long strings built with +), however none of those do so in a loop (where we would see much benefit).
22	22
23	23	* Special-case numeric code. If we can prove some values are guaranteed to be numeric, we could evaluate expressions involving them purely using doubles, without converting intermediate values to immediate values or NumberImps at all.