[Linux-ia64] gcc -O2

[Linux-ia64] gcc -O2

[Steve Tynor]

I'm using 

    # gcc -v
    Reading specs from /usr/lib/gcc-lib/ia64-cygnus-linux/2.9-ia64-000216-final/specs
    gcc version 2.9-ia64-000216-final

as bundled in Turbolinux 0823

   # uname -a
   Linux impromptu 2.4.0test7-000823-42 #1 Sat Aug 26 16:31:32 PDT 2000 ia64 unknown


I've diagnosed a seg fault that seems to stem from a bad optimization by
gcc -O2.  I can't find any FAQ that discusses known problems with the
ia64 gcc. Is there one?  Is -O2 considered generally usable? or is it
well known that one ought to avoid it in this release?  How 'bout
vanilla -O? (my particular test case works OK with -O but it's hardly an
exhaustive test...).

Where should I direct gcc bug reports -- on this list, or to the general
gcc bug reporting mechanism (a query on GNATS on gcc.gnu.org shows no
matches on the search string "ia64"... Mmmm.... :-)).

Ought I avoid gcc and skip directly to the SGI sgicc? 

Steve

Re: [Linux-ia64] gcc -O2

[H . J . Lu]

On Mon, Oct 02, 2000 at 01:20:09PM -0400, Steve Tynor wrote:
> I'm using 
> 
>     # gcc -v
>     Reading specs from /usr/lib/gcc-lib/ia64-cygnus-linux/2.9-ia64-000216-final/specs
>     gcc version 2.9-ia64-000216-final
> 

That compiler is too old. The current one is 0925 + patch.022.


H.J.

Re: [Linux-ia64] gcc -O2

[Steve Tynor]

H . J . Lu wrote:

| On Mon, Oct 02, 2000 at 01:20:09PM -0400, Steve Tynor wrote:
| > I'm using 
| > 
| >     # gcc -v
| >     Reading specs from /usr/lib/gcc-lib/ia64-cygnus-linux/2.9-ia64-000216-final/specs
| >     gcc version 2.9-ia64-000216-final
| > 
| 
| That compiler is too old. The current one is 0925 + patch.022.

Aha!   The cygnus toolchain link on the linuxia64.org web page just
points at a tarball dated something like 1 May 2000 -- where am I
expected to find this 0925 version?  Should I be cvs up'ing from
cygnus?  Are there rpm's available?  

Thanks!
Steve

Re: [Linux-ia64] gcc -O2

[Jim Wilson]

All optimizing compilers have bugs.  You shouldn't panic when you find one.
The -O2 option is definitely usable.  Entire linux distributions have been
built with it.

There are some known problems with the C++ support in the 000216 release.
There was a lot of C++ front end development work happening at the time, and
we ended up with an FSF gcc snapshot that has a few instabilities in the C++
front end.  Otherwise, the release has held up very well.  There haven't been
very many problems with it.

Bug reports sent here are OK.  Bug reports sent to the usual FSF addresses
are OK, if you make it clear that you are using one of the unofficial releases
that the ia64-linux project is using.

There is a new toolchain release that you can try if you are interested.
I expect that the next series of linux distributions will use this new
toolchain.  It is located on ftp.cygnus.com in pub/ia64-linux.

I am not too interested in bug reports against the old toolchain at this point,
but I will help if I can.

Jim

Re: [Linux-ia64] gcc -O2

[Steve Tynor]

Jim Wilson wrote:

| There is a new toolchain release that you can try if you are interested.
| I expect that the next series of linux distributions will use this new
| toolchain.  It is located on ftp.cygnus.com in pub/ia64-linux.

Excellent -- I'll grab that.  If the bug still remains, I'll submit a
bug report.

Perhaps someone can fix the link in the www.linuxia64.org homepage to
point to a this?  The current link points to what appears to be a 010500
snapshot (http://www.cygnus.com/ia64 which resovles to
ftp://ftp.cygnus.com/private/intel/).

Thanks for the help,
Steve

Re: [Linux-ia64] gcc -O2

[Jim Wilson]

>Perhaps someone can fix the link in the www.linuxia64.org homepage to
>point to a this?  The current link points to what appears to be a 010500
>snapshot (http://www.cygnus.com/ia64 which resovles to
>ftp://ftp.cygnus.com/private/intel/).

It isn't clear to me what to do about this.  The www.linuxia64.org page points
to the current release that is in use by all existing linux distributions,
and is known to be OK.

The new release is not ABI compatible with the old release, and there are no
linux distributions yet that use the new release.  Also, the new release is
still getting the bugs worked out, and may not be as reliable as the old
release yet.  Certainly, I'll want the link changes when this becomes the
recommended compiler, but we aren't quite there yet.

Jim