No let’s not revert.  But:

· Please put a list of the tickets (there are several) on the wiki page (where is the wiki page?)

o perf/compiler/T783

o #11163: perf/compiler/T5642

o

· Let’s have a flag to skip overlap testing so that there is always a workaround

· Are you happy to continue to work on these perf issues?

Simon

From: George Karachalias [mailto:george.karachalias@gmail.com]
Sent: 04 December 2015 09:41
To: Simon Peyton Jones <simonpj@microsoft.com>
Subject: Re: [GHC] #11160: New exhaustiveness checker breaks ghcirun004

Simon,

On Fri, Dec 4, 2015 at 10:34 AM, GHC <ghc-devs@haskell.org> wrote:

Comment (by simonpj):

 Very fast response thank you.

 Your commit message is very informative.  Did you include the same
 information in a `Note` in the code, so that we don't lose the information
 here?

I haven't yet but I can. Actually, I wanted to ask you something. At the moment
I pass all the normal tests but I fail some performance tests. They do compile but there is a
deviation from the expected and HEAD is broken. For the additional expressive power I expected

some more memory and time. For example, for perf/compiler/T783.hs which has 500 guards in a
single function definition I take ~5 sec to compile but the deviation in allocated bytes is 753%,

compared to what the "expected" is. I feel terrible since we are really close to the freeze and I

think I am stalling everyone. I know of no good way to reduce memory consumption without

losing substantial expressivity. Do you think I shall revert?

George

--

things you own end up owning you