On Wednesday, 14 July 2021 09:39:42 CEST Richard Biener wrote:
> -ffast-math decomposes to quite some flag_* and those generally are not
> reflected into the IL but can be different per function (and then
> prevent inlining).
Is there any chance the "and then prevent inlining" can be eliminated? Because
then I could write my own fast<float> class in C++, marking all operators with
__attribute__((optimize("-Ofast")))...
> There's one "related" IL feature used by the Fortran frontend - PAREN_EXPR
> prevents association across it. So for Fortran (when not
> -fno-protect-parens which is enabled by -Ofast), (a + b) - b cannot be
> optimized to a. Eventually this could be used to wrap intrinsic results
> since most of the issues in the end require association. Note PAREN_EXPR
> isn't exposed to the C family frontends but we could of course add a
> builtin-like thing for this _Noassoc ( .... ) or so. Note PAREN_EXPR
> survives -Ofast so it's the frontends that would need to choose to emit or
> not emit it (or always emit it).
Interesting. I want that builtin in C++. Currently I use inline asm to achieve
a similar effect. But the inline asm hammer is really too big for the problem.
--
──────────────────────────────────────────────────────────────────────────
Dr. Matthias Kretz https://mattkretz.github.io
GSI Helmholtz Centre for Heavy Ion Research https://gsi.de
std::experimental::simd https://github.com/VcDevel/std-simd
──────────────────────────────────────────────────────────────────────────
