Floating point trouble with x86's extended precision

[Robert Dewar]

> You don't think it's a bug.
> 
> I, and other people, think that the inability to get predictable 
> behavior from GCC (even from an option that you might not like to use 
> because of speed or other issues) is a bug.
> 
> And this is just about the end of the story.

It seems silly to me to argue about whether or not this is a bug. Formally
it probably isn't wrt at least most of the language standards, but so
what?

The issue is not what the language standards require, but rather what is
useful to a sufficient number of users to be worth implementing.

> I, and at least some 
> other people, think that GCC should include at least one model of 
> floating-point arithmetic for the x86 that allows one to deduce the 
> types and precisions of all variables, operations, etc., by examining 
> the source code.  It does not (and it probably will not for the 
> foreseeable future).

Sounds like a useful feature to include this model, I think you should
implement such a model, and we can see how useful it is in practice.

> Telling people that not having a predictable 
> model of what their program will do is a feature, not a bug, doesn't 
> cut it.

Neither does simply complaining :-) All that is needed here is someone
to do the work. Those interested in this feature should either implement
it, or pay someone to implement it!