[Bug c/59159] Need opaque pass-through as optimization barrier

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59159

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Or have a pass that automates your asm() barrier instrumentation for all values
that are life across a FENV affecting call.