At Wed, 25 Aug 2010 08:17:32 -0600, Matthew Flatt wrote: > There's a `set!' implicit in the `letrec' that is implicit in the use > of internal definitions. Maybe the Typed Racket optimizations confuse > the compiler so that it doesn't see how to convert the `let' into a > `letrec'.
One requirement for converting a `letrec' to a `let' is that the right-hand side can't capture the current continuation and invoke it multiple times, because continuations can expose the different times at which `let' and `letrec' allocate locations for their bindings. That's the part of the optimizer that was confused by the use of unsafe operations. Unsafe operations by themselves aren't confusing, but the optimizer also tentatively rotates arguments between the unsafe call and a surrounding `let' to work toward a particular combination that the JIT prefers. The extra `let' layer (which goes away in the end, in this case) confused the optimizer's no-`call/cc' test. The solution was to improve the no-`call/cc' test. _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/dev
