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

[joseph at codesourcery dot com]

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

--- Comment #5 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
On Mon, 18 Nov 2013, rguenth at gcc dot gnu.org wrote:

> I wonder whether a very early pass splitting functions at FENV clobber
> points and preventing re-inlining would be a better solution in the end

That sounds like a nasty hack, not a sensible solution for properly 
supporting exceptions and rounding modes.  For interval arithmetic you 
want code changing rounding modes (or using the FENV_ROUND pragma proposed 
in DTS 18661-1) to be handled reasonably efficiently rather than resulting 
in a split into separate functions (really, a function with FENV_ACCESS 
enabled should be inlinable into one without, though I could certainly 
imagine an initial implementation controlling flags only on a per-function 
basis and preventing inlining).