Two Hoopl questions

Simon Marlow marlowsd at
Tue Aug 13 12:13:50 CEST 2013

On 26/07/13 22:56, Edward Z. Yang wrote:
>> Thank you Edward. I am aware of these requirements - my problem is writing the code in which these
>> will always hold (I'm optimizing Cmm and hand-written Cmm files tend to cause many problems that
>> don't appear in automatically generated Cmm). Having a debugging tool in form of Fuel would be
>> helpful for me, because instead of getting a freeze and seeing no output from -ddump-cmm I would
>> see incorrectly transformed Cmm that would allow me to track bugs more easily.
> In that case, I would recommend taking a look at when -dopt-fuel got removed
> and seeing if you can put it back in.  I quite liked this feature and it is
> too bad it is gone.

Guilty.  I got rid of the fuel (in GHC's version of the dataflow 
algorithm).  I think removing it was worth a percent or two in 
compile-time performance - not a lot, but this was one of a whole heap 
of such things that I did to get the new codegen from about 100% to 5% 

I've no objection to the idea of optimisation fuel, but it should be an 
optional thing that doesn't cost anything if you don't use it.


More information about the ghc-devs mailing list