[RFC] Fix PR28684

Geert Bosch bosch@adacore.com
Thu Nov 16 16:12:00 GMT 2006


On Nov 16, 2006, at 09:30, Revital1 Eres wrote:
>> I believe we may also inhibit or create underflow or overflow with
>> re-ordering for example
>> (X + C1) - C2 to X + (C1 - C2)
>> for X near FLT_MAX and C1 sufficiently large.
>
> Right.
>
>> Even transforming
>> X + Y - Y to X
>> may fail to propagate a NaN Y to the result.
>>
>
> Is transforming X + Y - Y to X is allowed by our flag?
> Isn't it like x * 0 -> 0?

It seems we really need a table with a row for each transformation,
and columns indicating which flags allow or inhibit the compiler
to perform the transformation. Shall I start such a page on the Wiki?
When we converge to a list that people can agree with, this would
then be moved to the regular documentation.

   -Geert



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