Hi,
I used to think that the policy for being eligible for -O1 is that C must
be non-positive, e.g. that the compile times don't suffer at all.
Everything beyond that (well, given that R is positive) should be -O2 only.
There's precedent at least for Late Lambda Lifting (which is only run for
`-O2` is not a very rationally considered flag from what I understand.
It only enables `-fspec-constr` and `-fliberate-case`. The later also
triggers another simplification pass.
`-fspec-constr` is quite limited as it only works in the definition
module. I have never trusted it to optimise my
I think at first you just give it a -f flag, and let experience determine
whether it should be part of -O or -O2.
On Tue, Aug 27, 2019 at 12:10 PM Andreas Klebinger
wrote:
> Hello ghc-devs and haskell users.
>
> I'm looking for opinions on when an optimization should be enabled by
> default.
>
Hello ghc-devs and haskell users.
I'm looking for opinions on when an optimization should be enabled by
default.
-O is currently the base line for an optimized build.
-O2 adds around 10-20% compile time for a few % (around 2% if I remember
correctly) in performance for most things.
The
