Re: [9fans] make passive aggressive gcc

[dexen deVries <dexen.devries@gmail.com>]

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>
> 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.


not that it's any excuse, but -fno-builtin helps.

On Mon, Jun 15, 2015 at 4:56 PM, Siarhei Zirukin <ftrvxmtrx@gmail.com>
wrote:

> On Mon, Jun 15, 2015 at 3:41 PM, Ethan Grammatikidis
> <eekee57@fastmail.fm> wrote:
> > On Mon, 15 Jun 2015 09:21:56 +0100
> > Charles Forsyth <charles.forsyth@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.
>
>

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