Simon Marlow wrote:
On 27/09/2011 10:02, Roman Leshchinskiy wrote:
Colin Paul Adams wrote:
A quick google for signalling NaNs seems to suggest that on the x86 architecture, you have to set a flag to raise an exception when encountering signalling NaNs. Otherwise they are just treated as quiet NaNs. But you have to create the signalling NaNs manually. They are not created as a result of arithmetic operations.
IIRC, with the appropriate flags set, arithmetic operations throw exceptions instead of creating NaNs. You can't really create a signalling NaN in a register because as soon as you do, you get a signal.
But they don't throw a Haskell exception, they throw a processor exception which kills your whole program. If we want a Haskell exception to result from 0/0, we have to insert extra checking code, which I'm sure you won't like :-)
I would, of course, expect the RTS to convert the processor exception to a Haskell exception! Roman