[LLVMdev] Floating-Point Overflow check
rjmccall at apple.com
Fri Jul 23 10:36:37 PDT 2010
On Jul 23, 2010, at 7:20 AM, Steffen Geißinger wrote:
> i need to check if an overflow of an floating-point arithmetic operation occured.
> Currently I'm doing something like this (for addition):
> (LHS > 0 && RHS > 0 && sum <= 0) || (LHS < 0 && RHS < 0 && sum >= 0)
IEEE floating-point doesn't overflow like this; if the magnitude of a result is too
large to represent, it becomes an infinity rather than wrapping around like integer
arithmetic. You want to check whether the result is infinite.
I think the easiest way of doing that is to check whether (x - x) != (x - x).
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