The JIT is able to recognize (the expansion of) simple `struct` forms and specialize uses of the selectors that are bound by `struct`. Adding a property in `struct` interferes with that specialization, currently.
At Mon, 23 Jun 2014 22:30:05 -0700, Eric Dobson wrote: > I added gen:equal+hash to a struct type and noticed that accessing > fields of the struct got slower, even though I never used equal? or > hash functions. Is this expected? And if so what is the cause of it? > > #lang racket > > (struct foo (x) #:transparent) > (struct bar (x) #:transparent > #:methods gen:equal+hash > [(define (equal-proc x y recur) > (recur (bar-x x) (bar-x y))) > (define (hash-proc x recur) (recur (bar-x x))) > (define (hash2-proc x recur) (recur (bar-x x)))]) > > > > > > > (define N 10000000) > (define f (foo 3)) > (define b (bar 3)) > (for ((j 5)) > (time > (for ((i (in-range N))) > (equal? (foo-x f) (foo-x f)))) > (time > (for ((i (in-range N))) > (equal? (bar-x b) (bar-x b))))) > > My timings showing a 10% slowdown. > > cpu time: 296 real time: 296 gc time: 0 > > cpu time: 334 real time: 334 gc time: 0 > > cpu time: 297 real time: 297 gc time: 0 > > cpu time: 340 real time: 340 gc time: 0 > > cpu time: 303 real time: 302 gc time: 0 > > cpu time: 340 real time: 339 gc time: 0 > > cpu time: 292 real time: 292 gc time: 0 > > cpu time: 327 real time: 326 gc time: 0 > > cpu time: 291 real time: 291 gc time: 0 > > cpu time: 323 real time: 322 gc time: 0 > ____________________ > Racket Users list: > http://lists.racket-lang.org/users ____________________ Racket Users list: http://lists.racket-lang.org/users
