Re: Deprecating cc0 (and consequently cc0 targets)

[Hans-Peter Nilsson <hp@axis.com>]

> From: Jeff Law <law@redhat.com>
> Date: Fri, 20 Sep 2019 17:38:38 +0200

Hi.  I'm not going to question

> The first step in that process is to drop support for cc0.

but could you please elaborate on...

> [cc0 support in gcc core]
> code is broken in various ways,

> particularly WRT exceptions.

...that last part?

If you mean asynchronous exceptions then perhaps in theory,
except there's no need to (and no state to) "unwind" to
in-between cc0 setter and user.  But I guess that goes for
"MODE_CC" targets too; exception information isn't that precise.

> This patch deprecates the affected targets.

(Not applied yet?  Before the gcc-10 branch?  Can you please
consider dropping cris* from that part when rebasing it, as per
contents on master and my pledge to merge axis/cris-decc0?)

> diff --git a/gcc/config.gcc b/gcc/config.gcc
> index 69d0a024d85..0c1637e8be1 100644
> --- a/gcc/config.gcc
> +++ b/gcc/config.gcc
> @@ -248,6 +248,12 @@ md_file=
>  # Obsolete configurations.
>  case ${target} in
>    tile*-*-*				\
> +  avr*-*-*				\
> +  h8300*-*-*				\
> +  cris*-*-*				\
> +  m68k*-*-*				\
> +  vax*-*-*				\
> +  cr16*-*-*				\
>   )
>      if test "x$enable_obsolete" != xyes; then
> 	 echo "*** Configuration ${target} is obsolete." >&2
> @@ -273,7 +279,6 @@ case ${target} in
>   | arm*-*-uclinux*			\
>   | i[34567]86-go32-*			\
>   | i[34567]86-*-go32*			\
> - | m68k-*-uclinuxoldabi*		\
>   | mips64orion*-*-rtems*		\
>   | pdp11-*-bsd				\
>   | powerpc*-*-linux*paired*		\
> @@ -294,7 +299,6 @@ case ${target} in
>   | *-*-solaris2.[0-9].*			\
>   | *-*-solaris2.10*			\
>   | *-*-sysv*				\
> - | vax-*-vms*				\
>   )
> 	  echo "*** Configuration ${target} not supported" 1>&2
> 	  exit 1

Beware, the two last hunks shouldn't be applied, else the patch
will actually make m68k-*-uclinuxoldabi* andvax-*-vms* available
(by --enable-obsolete).

That part would go in when actually removing the targets.

I may have lost track of the conversation that followed; maybe
the patch was itself obsoleted.

brgds, H-P