Reporting bugs: there is nothing to gain in frustrating reporters

Robert Dewar dewar@adacore.com
Sat Jun 18 21:37:00 GMT 2005


Laurent GUERBY wrote:
> On Sat, 2005-06-18 at 16:45 -0400, Robert Dewar wrote:
> 
>>Mattias Karlsson wrote:
>>
>>
>>>Since the "gcc-is-buggy" solution of changing x87 rounding modes will:
>>>1) Be a lot of work.
>>>2) Cause a lot of regressions.
>>
>>To this you can add
>>
>>   3) generate less efficient code
> 
> 
> Changing the default rounding of the processor will make code less
> efficient?
> 
> Laurent

Yes, if you have to change it backwards and forwards for float and
double ... and if you insist on getting the range right as well as
the precision, then you have to do extra stores. Changing the
rounding mode alone does not give what people call IEEE behavior.



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