[PATCH] X86: Provide a CTOR for stringop_algs [PR100246].

[Richard Biener]

On Mon, Jul 5, 2021 at 3:04 PM Iain Sandoe <iain@sandoe.co.uk> wrote:
>
> Hi Richard,
>
> > On 5 Jul 2021, at 11:50, Richard Biener via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
> >
> > On Sun, Jul 4, 2021 at 10:04 PM Iain Sandoe <iain@sandoe.co.uk> wrote:
>
> >> Several older compilers fail to build modern GCC because of missing
> >> or incomplete C++11 support.
> >>
> >> (although the PR mentions clang, specifically, this has also been reported
> >> for some GCC versions within the range that should be able to bootstrap
> >> GCC)
> >>
> >> There are several possible solutions proposed in the PR, this one seems
> >> the least invasive.
> >>
> >> The header is pulled into the gcov code that builds with C, so we have to
> >> make the CTOR conditional on C++.
> >>
> >> tested on Darwin12 with xcode-6, bootstrapped on x86_64-darwin and linux.
> >> OK for master / GCC-11?
> >
> > Hmm, what is specifically built with a C compiler?  gcov.c not, I think.
>
> any C compilation that includes tm.h
>
> well, libgcc2 fails too on a quick check here -  but ISTR there was something in
> libgcov and I checked with Martin that it was intentionally compiled with C compiler.
>
> > Instead of commenting the CTOR, does it work to comment the whole stringop_algs
> > type?
>
> I don’t think that will work because it’s in a header that’s transitively included by tm.h
> which is then included loads of places.
>
> >  Also it seems on trunk this CTOR is no more?
>
> The addition of the CTOR is the fix for the C++ compile fail in the PR, the conditional is
> only there because the same header is compiled by C and C++.

Whoops sorry - I was confused.  The patch looks OK to me if you add a comment
before the CTOR why it was added (maybe quoting the error that happens)

Richard.

> thanks
> Iain
> >
> >> thanks
> >> Iain
> >>
> >> Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
> >>
> >> PR bootstrap/100246 - [11/12 Regression] GCC will not bootstrap with clang 3.4/3.5 [xcode 5/6, Darwin 12/13]
> >>
> >>        PR bootstrap/100246
> >>
> >> gcc/ChangeLog:
> >>
> >>        * config/i386/i386.h (struct stringop_algs): Define a CTOR for
> >>        this type.
> >> ---
> >> gcc/config/i386/i386.h | 5 +++++
> >> 1 file changed, 5 insertions(+)
> >>
> >> diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
> >> index 6e0340a4b60..84151156999 100644
> >> --- a/gcc/config/i386/i386.h
> >> +++ b/gcc/config/i386/i386.h
> >> @@ -73,6 +73,11 @@ struct stringop_algs
> >> {
> >>   const enum stringop_alg unknown_size;
> >>   const struct stringop_strategy {
> >> +#ifdef __cplusplus
> >> +    stringop_strategy(int _max = -1, enum stringop_alg _alg = libcall,
> >> +                     int _noalign = false)
> >> +      : max (_max), alg (_alg), noalign (_noalign) {}
> >> +#endif
> >>     const int max;
> >>     const enum stringop_alg alg;
> >>     int noalign;
> >> --
> >> 2.24.1
>