On Tue, Sep 06, 2022 at 09:29:01AM +0200, Aldy Hernandez wrote:
> The gfortran.dg/minlocval*.f90 tests are generating conditionals past
> the infinities. For example:
>
> if (x <= +Inf)
> foo (x);
> else
> bar (x);
>
> It seems to me that the only possible value for x on the false side is
> either NAN or undefined (for !HONOR_NANS).
No, none of the ==, <, <=, >, >= comparisons are ever true if one
or both operands are NaN (only != will be true in those cases from the
standard comparisons, when not counting UNORDERED_EXPR and the likes).
So, x < -Inf or x > +Inf are always false, we just can't optimize those
away without -ffast-math because they could raise an exception on sNaN.
But I think not optimizing such operations away if we care about exceptions
is the duty of DCE etc.
Jakub
