https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101254
--- Comment #2 from Andrew Macleod <amacleod at redhat dot com> --- Created attachment 51082 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51082&action=edit patch I *think* this is correct. but wrapv and signed stuff sometimes confuses me :-) when -fwrapv is on, +INf - -INF is -1 ? is this correct? in which case, the relations that were being added for minus were not quite correct in this case. given lhs = op1 - op2 if op1 > op2, we were producing a range of [1, +INF]. which is fine for unsigned. but for signed, that edge condition for -INF means the range should be [0, +INF]. likewise, if op1 >= op2, then result range would be [0, +INF] Is this is correct? I hope that -INF - -INF still equals 0 tho? Thats the only other case that might need consideration. The attached patch implements the above and appears to fix the test. I just want to be sure I have it right.
