On Mon, 15 Jun 2015 16:56:28 +0200 Siarhei Zirukin <ftrvxm...@gmail.com> wrote:
> On Mon, Jun 15, 2015 at 3:41 PM, Ethan Grammatikidis > <eeke...@fastmail.fm> wrote: > > On Mon, 15 Jun 2015 09:21:56 +0100 > > Charles Forsyth <charles.fors...@gmail.com> wrote: > > > >> If you're using gcc 4.8.2 to compile ... anything, really ... but certainly > >> Plan 9 or Inferno components, > >> and those use for loops with arrays, be sure to include the compilation > >> options > >> -fno-strict-aliasing\ > >> -fno-aggressive-loop-optimizations\ > >> and it will save you some time and effort. > >> It will save compilation time (not that you'll notice with that sluggard) > >> because it won't > >> fuss even more with your program, and it will save effort, because you > >> won't have > >> to debug simple loops that have bounds changed, are removed completely, or > >> otherwise wrecked. > >> You can find discussions of it elsewhere (which is how I found compiler > >> options to stop it). > >> I'd forgotten all about it until it surfaced again. > > > > Thanks. Reminds me I liked gcc when it applied very few optimizations. > > I guess it must have been focused on machine-specific optimizations > > back in 2007/2008. I had a cpu newer than gcc had support for, and > > compilation was actually quick. Anyone know if -O0 is a reasonable > > option these days? (I mean tested well enough to be reasonably > > bug-free.) > > I've recenetly seen a few examples where -O0 would produce a > segfaulting executable, while any other -Ox would work fine. > Also, I don't know what gcc authors are smoking, but "strcpy(tmp, > "what.");" will be compiled to a few mov instructions with -O0, while > -Os still has a call to strcpy, just the way it *should* always be, > imho. I just checked this once again (gcc-4.8.4) and it still applies. > So -O0 hasn't improved since 2008 then. Time to switch to clang, I guess. -- Developing the austere intellectual discipline of keeping things sufficiently simple is in this environment a formidable challenge, both technically and educationally. -- Dijstraka, EWD898, 1984
