Subject: Re: [PATCH] selftests/powerpc: Fix build failures with GCC 9

From: Segher Boessenkool <[email-masked]>
Date: Thu, 1 Aug 2019 13:24:51 -0500

On Thu, Aug 01, 2019 at 10:26:28PM +1000, Michael Ellerman wrote:
> GCC 9 fails to build some of the ptrace TM tests, with errors such as:
> 
>   ptrace-tm-spd-vsx.c: In function 'tm_spd_vsx':
>   ptrace-tm-spd-vsx.c:51:2: error: listing the stack pointer register 'r1' in a clobber list is deprecated [-Werror=deprecated]
>      51 |  asm __volatile__(
>         |  ^~~
>   ptrace-tm-spd-vsx.c:51:2: note: the value of the stack pointer after an 'asm' statement must be the same as it was before the statement
> 
> Which is probably fair enough.

Maybe you shouldn't build the tests with -Werror though?  (And you could
include the much more useful -Wextra while you're at it ;-) ).

> Some of these inline asm blocks are doing quite a lot and are probably
> pushing the boundaries of what's sane to do with inline asm,

These are just testcases, you sometimes need to do evil things there.
But yeah :-)

> but they shouldn't actually be returning with r1 modified.

But they *do* modify lr, and that one isnt't listed; I guess the r1
clobber was there because of the call in the asm, but that needs an
lr clobber, instead.

(Or it was because of the "or 1,1,1")?

Segher