Re: [PATCH 00/15] Add support for clang LTO

[Mark Rutland]

On Fri, Nov 03, 2017 at 11:36:33AM -0700, Nick Desaulniers wrote:
> On Fri, Nov 3, 2017 at 11:29 AM, Mark Rutland <mark.rutland@xxxxxxx> wrote:
> > On Fri, Nov 03, 2017 at 11:07:04AM -0700, Nick Desaulniers wrote:
> >> On Fri, Nov 3, 2017 at 10:51 AM, Mark Rutland <mark.rutland@xxxxxxx> wrote:
> >> > I had to create an aarch64-linux-gnu-clang wrapper, too. I'm not sure if
> >> > there's build system help to avoid needing that?
> >>
> >> Gah!  So a BIG difference with Clang vs GCC for cross compiling is
> >> that Clang by default ships with all backends enabled, and uses a
> >> `-target <triple>` CFLAG to determine the arch to cross compile for,
> >> while GCC is configured at compile time to support one back end, IIUC.
> >
> > Yup.
> >
> > I initally tried passing CC=clang\ --target=aarch64-linux-gnu
> >
> > ... but since that conflicts with CROSS_COMPILE, you then have to
> > override AS, LD, OBJCOPY, etc, separately too.
> 
> make CC=clang CROSS_COMPILE=aarch64-linux-gnu-
> 
> I think you may need a trailing hyphen on your target as it gets
> prefixed onto as and ld:
> 
> Makefile:
> 
>  348 # Make variables (CC, etc...)
>  349 AS    = $(CROSS_COMPILE)as
>  350 LD    = $(CROSS_COMPILE)ld

I thought CC=clang CROSS_COMPILE=foo- would result in foo-clang, but
evidently this is not the case.

I must've meseed up something else; sorry for the noise.

Thanks for correcting me; now I can go delete my wrapper. :)

Thanks,
Mark.