Hi!
On Tue, May 31, 2022 at 06:56:00PM -0500, Segher Boessenkool wrote:
> It's not clear to me how this can ever happen without finite_math_only?
> The patch is safe, sure, but it may the real problem is elsewhere.
So, it is incorrect the RTL for our bcd{add,sub} insns uses CCFP at all.
CCFP stands for the result of a 4-way comparison, regular float
comparison: lt gt eq un. But bcdadd does not have an unordered at all.
Instead, it has the result of a 3-way comparison (lt gt eq), and bit 3
is set if an overflow happened -- but still exactly one of bits 0..2 is
set then! (If one of the inputs is an invalid number it sets bits 0..3
to 0001 though.)
So it would be much more correct and sensible to use regular integer
comparison results here, so, CC.
Does that fix the problem?
Segher
