On Sat, Feb 23, 2008 at 08:46:51PM +0100, Lemmih wrote:
In E.SSimplify.collectOccurance the 'arg' function is used quite often and I can't tell why. The function clears usage information for free variables and is primarily used for types. It would be a great help if you'd add a short description to collectOccurance and collectDs. Any information about invariants and/or what they're trying to do would be appreciated.
Basically, occurance collection figured out how many times and in what way variables are used. it figures out things like whether a variable has been used at most once and whether it is in a lambda. If a variable ever appears as an argument to another function, you can't know anything (at least not in this analysis) about how it is used, so the function 'arg' tells it that all the variables in its argument should be considered used an unknown number of times. likewise, types get passed around a lot, and better usage information for them doesn't usually help because a lot of them (but not all) are erased by run time, so we just take the conservative approach and treat them like they were used as an argument to a function, used an unknown number of times. John -- John Meacham - ⑆repetae.net⑆john⑈