[Bug middle-end/84997] Optimize integer operations on floating point constants without -ffast-math

[joseph at codesourcery dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84997

--- Comment #4 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
On Wed, 21 Mar 2018, rguenth at gcc dot gnu.org wrote:

> > That would need -fno-trapping-math, because if the addition results in a 
> > double value larger than INT_MAX, under Annex F the conversion back to int 
> > is defined to raise FE_INVALID along with producing an unspecified value.
> 
> If it produces an unspecified value it doesn't raise undefined behavior, right?

In the presence of Annex F, it doesn't raise undefined behavior.

In the absence of Annex F it does raise undefined behavior (but I don't 
think we want -fno-trapping-math to mean it's undefined, just that the 
FE_INVALID exception might be missing).