Re: [glean-dev] catching FP exceptions in C++

[Keith W. <ke...@tu...>]

Brian Paul wrote:

> Getting back to the Glean test, I think it might be OK as-is: pass some 
> inf/nan values into GL and pass if we don't crash.  But if someone wants 
> to dig deeper, having an option to enable exceptions in particular cases 
> might be useful.

It is also useful from the perspective of someone trying to figure out
	- does a hardware rasterizer or tnl engine lock up if passed a NaN?
	- what about other aspects of hardware state?

Of course execptions don't help a lot for those questions...

For hardware tnl, it would be interesting to see if it is possible to 
characterize the hardware's floating point characteristics from outside - if we 
set up state so that at some point in the pipeline, vertex attributes are forced 
  so close to zero that they would have to be represented as denormals, does the 
hardware preserve their values or flush them to zero?  Does it appear that 
values are represented with less than 32 bit floats internally?

I guess these aren't correctness issues, so probably quite a low priority...

Keith