RE: [PATCH] MIPS: Changed current_thread_info() to an equivalent supported by both clang and GCC

[Daniel Sanders <Daniel.Sanders@imgtec.com>]

Hi,

Thanks for the quick reply.

> -----Original Message-----
> From: Sergei Shtylyov [mailto:sergei.shtylyov@cogentembedded.com]
> Sent: 09 January 2015 12:18
> To: Daniel Sanders; linux-mips@linux-mips.org; Ralf Baechle
> Cc: Paul Burton; Markos Chandras; James Hogan; Behan Webster
> Subject: Re: [PATCH] MIPS: Changed current_thread_info() to an equivalent
> supported by both clang and GCC
> 
> Hello.
> 
> On 1/9/2015 3:06 PM, Daniel Sanders wrote:
> 
> > Without this, a 'break' instruction is executed very early in the boot and
> > the boot hangs.
> 
> > The problem is that clang doesn't honour named registers on local variables
> > and silently treats them as normal uninitialized variables. However, it
> > does honour them on global variables.
> 
> > Signed-off-by: Daniel Sanders <daniel.sanders@imgtec.com>
> 
> [...]
> 
> > diff --git a/arch/mips/include/asm/thread_info.h
> b/arch/mips/include/asm/thread_info.h
> > index 99eea59..2a2f3c4 100644
> > --- a/arch/mips/include/asm/thread_info.h
> > +++ b/arch/mips/include/asm/thread_info.h
> > @@ -58,11 +58,11 @@ struct thread_info {
> >   #define init_stack		(init_thread_union.stack)
> >
> >   /* How to get the thread information struct from C.  */
> > +register struct thread_info *current_gp_register asm("$28");
> 
>     *static* missing?
> 
> WBR, Sergei

Combining 'register' and 'static' is invalid.

gcc gives:
arch/mips/include/asm/thread_info.h:61:1: error: multiple storage classes in declaration specifiers
 static register struct thread_info *current_gp_register asm("$28");
 ^

and clang gives:
arch/mips/include/asm/thread_info.h:61:8: error: cannot combine with previous 'static' declaration specifier
static register struct thread_info *current_gp_register asm("$28");
       ^