I tested my code on GHC 8.2.1, there is a good news and a bad news. The good news is that with 8.2.1 performance of my code has improved by a huge margin of around 20%, I had reported a similar perf improvement earlier in another one of my package with 8.2. The bad news is that the problem that I reported today is not fixed. I am still seeing a 15% difference between automatic and manual inlining. I guess I should raise a ticket. -harendra On 8 September 2017 at 17:10, Mikolaj Konarski wrote:

Hello,

I've had a similar problem that's been fixed in 8.2.1:

https://ghc.haskell.org/trac/ghc/ticket/12603

You can also use some extreme global flags, such as

ghc-options: -fexpose-all-unfoldings -fspecialise-aggressively

to get most the GHC subtlety and shyness out of the way when experimenting.

Good luck Mikolaj

...

Hi,

I have this code snippet for the bind implementation of a Monad:

AsyncT m >>= f = AsyncT $ \_ stp yld -> let run x = (runAsyncT x) Nothing stp yld yield a _ Nothing = run $ f a yield a _ (Just r) = run $ f a <> (r >>= f) in m Nothing stp yield

I want to have multiple versions of this implementation parameterized by a function, like this:

bindWith k (AsyncT m) f = AsyncT $ \_ stp yld -> let run x = (runAsyncT x) Nothing stp yld yield a _ Nothing = run $ f a yield a _ (Just r) = run $ f a `k` (bindWith k r f) in m Nothing stp yield

And then the bind function becomes:

(>>=) = bindWith (<>)

But this leads to a performance degradation of more than 10%. inlining does not help, I tried INLINE pragma as well as the "inline" GHC builtin. I thought this should be a more or less straightforward replacement making

On Fri, Sep 8, 2017 at 11:21 AM, Harendra Kumar wrote: the

...

second version equivalent to the first one. But apparently there is something going on here that makes it perform worse.

I did not look at the core, stg or asm yet. Hoping someone can quickly comment on it. Any ideas why is it so? Can this be worked around somehow?

Thanks, Harendra

_______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs