(j3.2006) [Fwd: [Wg25-full] Fwd: [Numeric-interest] reproducible floating-point results and 754R]

Dan Nagle dannagle
Fri May 18 21:00:56 EDT 2007


Van Snyder wrote:
> On Fri, 2007-05-18 at 15:58 -0500, Bill Long wrote:


>> There would be two prices - the user sees bad performance, and the 
>> vendor has to spend xxx man-years rewriting the guts of the optimizer to 
>> conform to a specified (by whom?) set of rules on order of evaluation.  
>> The number of Fortran programmers willing to pay the performance penalty 
>> is, from what I see, essentially zero.  If the want bad performance, 
>> there are lots of options other than Fortran.   The number of corporate 
>> bean counters willing to fund a rewrite of the compiler to appeal to a 
>> group of zero size is also zero.
> The way Ada handled this was to provide a block in which a "strict
> arithmetic" pragma has effect.  Users realize that the "strict
> arithmetic" pragma might turn off optimization.

As is currently being discussed in c.l.a, the actual effect is that
Ada compilers only have strict mode due to the costs of implementing
a second mode.


Dan Nagle
Purple Sage Computing Solutions, Inc.

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