Deriving Typeable for enumerations seems expensive
I have a module
A10000 that looks like this:
module A10000 where data A = A | A00001 | A00002 ... | A10000
Currently compiling it with
./inplace/bin/ghc-stage2 A10000.hs +RTS -s produces:
[1 of 1] Compiling A10000 ( A10000.hs, A10000.o ) 4,133,470,392 bytes allocated in the heap 1,194,866,080 bytes copied during GC 141,604,816 bytes maximum residency (14 sample(s)) 813,104 bytes maximum slop 341 MB total memory in use (0 MB lost due to fragmentation) Tot time (elapsed) Avg pause Max pause Gen 0 329 colls, 0 par 0.551s 0.551s 0.0017s 0.0246s Gen 1 14 colls, 0 par 0.453s 0.453s 0.0323s 0.1031s TASKS: 4 (1 bound, 3 peak workers (3 total), using -N1) SPARKS: 0 (0 converted, 0 overflowed, 0 dud, 0 GC'd, 0 fizzled) INIT time 0.000s ( 0.000s elapsed) MUT time 1.498s ( 1.730s elapsed) GC time 1.004s ( 1.004s elapsed) EXIT time 0.000s ( 0.006s elapsed) Total time 2.502s ( 2.740s elapsed) Alloc rate 2,759,911,143 bytes per MUT second Productivity 59.9% of total user, 63.4% of total elapsed
I've noticed a lot of code getting generated (>500k lines of ASM), particularly interesting was code that supported
I've tried again disabling the generation of
TyCons by modifying:
mkTypeRepTodoBinds :: [TypeRepTodo] -> TcM TcGblEnv mkTypeRepTodoBinds _ = getGblEnv
This is the result:
[1 of 1] Compiling A10000 ( A10000.hs, A10000.o ) 1,731,693,280 bytes allocated in the heap 280,362,376 bytes copied during GC 41,423,608 bytes maximum residency (10 sample(s)) 746,272 bytes maximum slop 102 MB total memory in use (0 MB lost due to fragmentation) Tot time (elapsed) Avg pause Max pause Gen 0 401 colls, 0 par 0.111s 0.111s 0.0003s 0.0065s Gen 1 10 colls, 0 par 0.124s 0.124s 0.0124s 0.0298s TASKS: 4 (1 bound, 3 peak workers (3 total), using -N1) SPARKS: 0 (0 converted, 0 overflowed, 0 dud, 0 GC'd, 0 fizzled) INIT time 0.000s ( 0.000s elapsed) MUT time 0.773s ( 0.889s elapsed) GC time 0.235s ( 0.235s elapsed) EXIT time 0.000s ( 0.007s elapsed) Total time 1.008s ( 1.130s elapsed) Alloc rate 2,241,052,377 bytes per MUT second Productivity 76.7% of total user, 79.2% of total elapsed
It appears that by default I pay >50% of compile time for a feature that I probably won't use.
I'm sorry if this is a duplicate, I've looked at https://ghc.haskell.org/trac/ghc/wiki/Typeable, but nothing seemed relevant.