On Mon, Aug 25, 2014 at 08:35:17PM +0100, Maciej W. Rozycki wrote:
> On Mon, 25 Aug 2014, Ralf Baechle wrote:
>
> > > >> +cflags-$(CONFIG_CPU_LOONGSON3) += -D_MIPS_ARCH_LOONGSON3A
> > > >
> > > > The _MIPS_ARCH_* namespace belongs to GCC. While it seems current GCC
> > > > does not define this symbol _MIPS_ARCH_LOONGSON3A runs into the danger
> > > > of causing a conflict when GCC eventually will define the symbol.
> > > When this symbol will be defined? With option '-march=loongson3a'?
> >
> > Well, not currently (at least not in my gcc 4.9.0) - but it might. In
> > fact, I'm wondering why it doesn't. Maciej?
>
> No idea, a _MIPS_ARCH_foo macro gets defined automagically by GCC
> whenever `-march=foo' is in effect (be it implicitly or with the use of a
> command-line option), so there should be one.
>
> Has support for "loongson3a" been present in 4.9.x (it is in trunk)? If
> so, then what _MIPS_ARCH_* macro gets defined for `-march=loongson3a'?
Hmm - I must have fatfingered something. Now I'm getting:
$ mips-linux-gcc < /dev/null -E -C -dM -march=loongson3a - | grep _MIPS_ARCH
#define _MIPS_ARCH_LOONGSON3A 1
#define _MIPS_ARCH "loongson3a"
$
So that would conflict with a manual definition, thus the patch would not
be acceptable as it because:
$ cat > c.c << EOF
foo(){}
EOF
$ mips-linux-gcc -D_MIPS_ARCH_LOONGSON3A -march=loongson3a -Wall -c c.c
c.c:1:1: warning: return type defaults to ‘int’ [-Wreturn-type]
foo(){}
^
c.c: In function ‘foo’:
c.c:1:1: warning: control reaches end of non-void function [-Wreturn-type]
foo(){}
^
$
Ralf
