[llvm-dev] Trouble when suppressing a portion of fast-math-transformations

Ristow, Warren via llvm-dev llvm-dev at lists.llvm.org
Fri Sep 29 19:16:23 PDT 2017

Hi Hal,

>> 4. To fix this, I think that additional fast-math-flags are likely 
>> needed in the IR.  Instead of the following set:
>> 'nnan' + 'ninf' + 'nsz' + 'arcp' + 'contract'
>> something like this:
>> 'reassoc' + 'libm' + 'nnan' + 'ninf' + 'nsz' + 'arcp' + 'contract'
>> would be more useful.  Related to this, the current 'fast' flag which acts
>> as an umbrella (enabling 'nnan' + 'ninf' + 'nsz' + 'arcp' + 'contract') may
>> not be needed.  A discussion on this point was raised last November on the
>> mailing list:
>> http://lists.llvm.org/pipermail/llvm-dev/2016-November/107104.html
> I agree. I'm happy to help review the patches. It will be best to have 
> only the finer-grained flags where there's no "fast" flag that implies 
> all of the others.

Thanks for the quick response, and for the willingness to review.  I won't let
this languish so long, like the post from last November.

Happy to hear that you feel it's best not to have the umbrella "fast" flag.

Thanks again,

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