Re: [PATCH 03/18] Do not stack-protect ifunc resolvers.

[Mike Frysinger <vapier at gentoo dot org>]

On 09 Mar 2016 23:48, Nix wrote:
> On 9 Mar 2016, Mike Frysinger told this:
> > On 08 Mar 2016 13:50, Nix wrote:
> >> +AC_CACHE_CHECK(if $CC accepts -fno-stack-protector with \
> >> +__attribute__ ((__optimize__)), libc_cv_cc_no_stack_protector, [dnl
> >> +cat > conftest.c <<EOF
> >> +void
> >> +__attribute__ ((__optimize__ ("-fno-stack-protector")))
> >> +foo (void) {}
> >> +EOF
> >
> > actually, which versions of gcc *don't* support this ?  if it's in gcc-4.7
> > and newer, then we don't need this test as we require that already.
> 
> Good question. The worrying thing is that support for
> __attribute__((__optimize__)) may not be enough: IIRC, that attribute
> was not exactly perfectly functional in the first release or two after
> it landed, IIRC.
> 
> Let's see...
> 
> ... GCC 4.4?! OK, way older than I remembered. We can definitely drop
> this: there have been fixes to fix things like target-specific options
> with __attribute__((__optimize__)) right up until recently, but nothing
> that would perturb -fno-stack-protector (and nothing at *all* between
> 4.6.x and 4.8.x, and I know 4.8.x works).
> 
> So I'll drop this bit.
> 
> (Technically this makes libc_cv_ssp useless too, because
> -fstack-protector is *much* older than __attribute__((__optimize__)),
> but it's consistent with the checks for -fstack-protector-strong and
> -all to have it there, and those are much newer and still not
> consistently supported on all targets. I can tear libc_cv_ssp and
> have_ssp out as well if you think it worth doing.)

checking for the flag itself we prob want to keep because not all targets
support SSP
-mike

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