Re: [PATCH v2] configure: Avoid clobbering x18 on arm64 when building with clang

[Martin Storsjö]

On Sat, 24 Jun 2017, André Hentschel wrote:
> Am 21.06.2017 um 12:39 schrieb Martin Storsjo:
> > On aarch64/arm64, clang/LLVM feels free to use x18 for normal code
> > generation on linux (while the register is reserved on iOS/darwin).
> > For windows/arm64, this register must not be clobbered.
> >
> > If targeting arm64, check for the clang cflags that allows this
> > register to be left untouched.
> >
> > This makes sure that wine for aarch64 built with clang doesn't
> > crash immediately on startup.
> >
> > Signed-off-by: Martin Storsjo <martin(a)martin.st>
> > ---
> > Now with the sign-off included, which was forgotten in v1.
> > ---
> >  configure.ac | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/configure.ac b/configure.ac
> > index 7ae29f7..5b5a1d8 100644
> > --- a/configure.ac
> > +++ b/configure.ac
> > @@ -179,6 +179,11 @@ case $host in
> >      CFLAGS="$CFLAGS -marm"
> >      AC_SUBST(TARGETFLAGS,"-marm")
> >      ;;
> > +  aarch64*)
> > +    # Clang needs these flags in order not to clobber the x18 register
> > +    WINE_TRY_CFLAGS([-Xclang -target-feature -Xclang +reserve-x18],
> > +                    [CFLAGS="$CFLAGS -Xclang -target-feature -Xclang +reserve-x18"])
> > +    ;;
> >    i[[3456789]]86*)
> >      enable_win16=${enable_win16:-yes}
> >      ;;
>
> I think it's worthwhile adding it
>
> Signed-off-by: André Hentschel <nerv(a)dawncrow.de>

FWIW, in case Alexandre also reconsiders merging it since you think it's 
worthwhile adding it - I reposted a v3, using the gcc compatible flag 
syntax and with an improved commit message.

// Martin