On Tue, 4 May 2021, Jakub Jelinek via Gcc-patches wrote:
2) the pr94589-2.C testcase should be matching just 12 times each, but runs into operator>=(strong_ordering, unspecified) being defined as (_M_value&1)==_M_value rather than _M_value>=0. When not honoring NaNs, the 2 case should be unreachable and so (_M_value&1)==_M_value is then equivalent to _M_value>=0, but is not a single use but two uses. I'll need to pattern match that case specially.
Somewhere in RTL (_M_value&1)==_M_value is turned into (_M_value&-2)==0, that could be worth doing already in GIMPLE.
-- Marc Glisse
