https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83750
Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Last reconfirmed| |2018-01-09 Ever confirmed|0 |1 --- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> --- In the past we've done canonicalization instead, so I'd "fold" erfc (x) to 1.0 - erf (x) and then at a later stage when ! canonicalize_math_p () replace 1.0 - erf (x) with erfc (x) again. Thus, add two patterns to match.pd to achieve this.