[RFC] Fix PR28684

[Clint Whaley]

Revital,

>vectorization does not need strength reduction so far.
>I did not see such transformation in the list of transformations
>which I though might fit the flag.
>The fact that it is not controlled by the flag
>was implicitly mentioned in the definition -
>
>An example of a transformation which is not allowed by this flag is
>transforming x * 0 to 0 as the result is not IEEE compliant when x
>is Inf.
>
>Should I add a comment about it in the definition?

I don't think we need to comment things we *don't* do :)  However, I think
strength reduction crept into the discussion based on this line from the
most recent discussion:

>NOTE: may reorder or strength reduce floating-point comparisons as
>well, and so may not be used when ordered comparisons are required.

I think this is a hold-over from an earlier discussion, where strength
reduction was in the set of flags.  Based on what you say above, maybe
this should be reworded:

>NOTE: may reorder floating-point comparisons as well, and so may not be
>used when ordered comparisons are required.

Thanks,
Clint