[Bug target/112868] New: GCC passes -many to the assembler for --enable-checking=release builds

[Bug target/112868] New: GCC passes -many to the assembler for --enable-checking=release builds

[bergner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112868

            Bug ID: 112868
           Summary: GCC passes -many to the assembler for
                    --enable-checking=release builds
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: bergner at gcc dot gnu.org
  Target Milestone: ---

Since commit r10-580-ge154242724b084 gcc no longer passes -many to the
assembler for --enable-checking=yes builds.  However, we still pass -many to
the assembler for --enable-checking=release builds.  This can hide wrong code
bugs like in PR112707.

This bugzilla is to discuss whether should we remove passing -many to the
assembler under all conditions or should we leave things as they are?

Let the bikeshedding begin! :-)

[Bug target/112868] GCC passes -many to the assembler for --enable-checking=release builds

[bergner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112868

Peter Bergner <bergner at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2023-12-05
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
                 CC|                            |amodra at gcc dot gnu.org,
                   |                            |dje at gcc dot gnu.org,
                   |                            |linkw at gcc dot gnu.org,
                   |                            |meissner at gcc dot gnu.org,
                   |                            |npiggin at gmail dot com,
                   |                            |segher at gcc dot gnu.org

--- Comment #1 from Peter Bergner <bergner at gcc dot gnu.org> ---
CCing interested parties for their input.

[Bug target/112868] GCC passes -many to the assembler for --enable-checking=release builds

[dje at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112868

--- Comment #2 from David Edelsohn <dje at gcc dot gnu.org> ---
Narrowing the ISA dialect range accepted by the assembler is good in theory to
catch problems.  We need to ensure that this doesn't break a lot of existing
code and make POWER more tedious.

Most people want to download a pre-built package.  If someone downloads source
code, they want it to configure, build and run without problems.

While this change will ensure that new packages are more strictly conformant
and may not cause problems with new Linux distro releases, it could prevent
older packages from building with newer releases of GCC.

[Bug target/112868] GCC passes -many to the assembler for --enable-checking=release builds

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112868

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
The behavior shouldn't change dependent on --enable-checking.  Can't we make
sure to pass -mno-any (if that exists...) during bootstrap and testsuite
instead?

[Bug target/112868] GCC passes -many to the assembler for --enable-checking=release builds

[sjames at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112868

Sam James <sjames at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sjames at gcc dot gnu.org

--- Comment #4 from Sam James <sjames at gcc dot gnu.org> ---
I was quite surprised by this behaviour. It should really be documented if
we're going to stick with it, but I don't think we should at all..

[Bug target/112868] GCC passes -many to the assembler for --enable-checking=release builds

[bergner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112868

--- Comment #5 from Peter Bergner <bergner at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #3)
> Can't we make sure to pass -mno-any (if that exists...) during bootstrap
> and testsuite instead?

-mno-any does not exist.

[Bug target/112868] GCC passes -many to the assembler for --enable-checking=release builds

[bergner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112868

Peter Bergner <bergner at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |jeevitha at gcc dot gnu.org

--- Comment #6 from Peter Bergner <bergner at gcc dot gnu.org> ---
(In reply to Sam James from comment #4)
> I was quite surprised by this behaviour. It should really be documented if
> we're going to stick with it, but I don't think we should at all..

I have asked Jeevitha to prepare a patch to remove the -many assembler option
usage on --enable-checking=release builds.

It would be nice if we can get some distro help to do some practice distro
builds using the patch to verify whether there it causes any fallout on distro
builds to help decide whether we should push the patch or leave things as they
are.

[Bug target/112868] GCC passes -many to the assembler for --enable-checking=release builds

[sjames at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112868

--- Comment #7 from Sam James <sjames at gcc dot gnu.org> ---
(In reply to Peter Bergner from comment #6)

Thanks Peter. We're happy to help with that in Gentoo. If you remember, please
CC me on the patch and we'll give it a spin.

[Bug target/112868] GCC passes -many to the assembler for --enable-checking=release builds

[jeevitha at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112868

Jeevitha <jeevitha at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jeevitha at gcc dot gnu.org

--- Comment #8 from Jeevitha <jeevitha at gcc dot gnu.org> ---
Created attachment 57584
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=57584&action=edit
Removed -many from the options passed by default to the assembler.

Sam James, can you do a practice distro build using this patch?

[Bug target/112868] GCC passes -many to the assembler for --enable-checking=release builds

[sjames at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112868

--- Comment #9 from Sam James <sjames at gcc dot gnu.org> ---
(In reply to Jeevitha from comment #8)
> Created attachment 57584 [details]
> Removed -many from the options passed by default to the assembler.
> 
> Sam James, can you do a practice distro build using this patch?

Hi Jeevitha, I've added this to our patchset tonight and asked some people to
give it a spin on top of that too.

[Bug target/112868] GCC passes -many to the assembler for --enable-checking=release builds

[sjames at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112868

--- Comment #10 from Sam James <sjames at gcc dot gnu.org> ---
No problems reported yet and we have several people testing on ppc w/ gcc 14.

[Bug target/112868] GCC passes -many to the assembler for --enable-checking=release builds

[bergner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112868

--- Comment #11 from Peter Bergner <bergner at gcc dot gnu.org> ---
(In reply to Sam James from comment #10)
> No problems reported yet and we have several people testing on ppc w/ gcc 14.

Thanks for the testing!  This is clearly a stage1 patch, so we'll wait until
then before submitting it.

[Bug target/112868] GCC passes -many to the assembler for --enable-checking=release builds

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112868

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |nisse at lysator dot liu.se

--- Comment #12 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 114813 has been marked as a duplicate of this bug. ***

[Bug target/112868] GCC passes -many to the assembler for --enable-checking=release builds

[nisse at lysator dot liu.se]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112868

--- Comment #13 from Niels Möller <nisse at lysator dot liu.se> ---
(In reply to Peter Bergner from comment #11)

> This is clearly a stage1 patch, so we'll wait until
> then before submitting it.

I'm not that familiar with gcc development procedures. Do I understand you
correctly, that a fix for this bug will not be included in gcc-14 (according to
https://gcc.gnu.org/develop.html#timeline, gcc-14 stage1 ended several months
ago), it will have to wait for gcc-15?

[Bug target/112868] GCC passes -many to the assembler for --enable-checking=release builds

[bergner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112868

--- Comment #14 from Peter Bergner <bergner at gcc dot gnu.org> ---
(In reply to Niels Möller from comment #13)
> I'm not that familiar with gcc development procedures. Do I understand you
> correctly, that a fix for this bug will not be included in gcc-14 (according
> to https://gcc.gnu.org/develop.html#timeline, gcc-14 stage1 ended several
> months ago), it will have to wait for gcc-15?

Correct, I meant waiting for GCC 15 stage1.  I want it to burn-in on trunk for
a long while, because it had the potential to disrupt distro package builds. 
It seems clean so far with the practice Gentoo builds, but I'll feel more
comfortable when other distros start using it too. 

That said, Jeevitha, now that we're in stage1, can you please post your patch?

[Bug target/112868] GCC passes -many to the assembler for --enable-checking=release builds

[jeevitha at linux dot ibm.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112868

--- Comment #15 from jeevitha at linux dot ibm.com ---
On 07/05/24 1:53 am, bergner at gcc dot gnu.org wrote:

> That said, Jeevitha, now that we're in stage1, can you please post your patch?
> 
Sure Peter.

[Bug target/112868] GCC passes -many to the assembler for --enable-checking=release builds

[sjames at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112868

--- Comment #16 from Sam James <sjames at gcc dot gnu.org> ---
(In reply to Peter Bergner from comment #14)
> (In reply to Niels Möller from comment #13)
> > I'm not that familiar with gcc development procedures. Do I understand you
> > correctly, that a fix for this bug will not be included in gcc-14 (according
> > to https://gcc.gnu.org/develop.html#timeline, gcc-14 stage1 ended several
> > months ago), it will have to wait for gcc-15?
> 
> Correct, I meant waiting for GCC 15 stage1.  I want it to burn-in on trunk
> for a long while, because it had the potential to disrupt distro package
> builds.  It seems clean so far with the practice Gentoo builds, but I'll
> feel more comfortable when other distros start using it too. 

FWIW, we're keeping it going forward (so it'll be in e.g. our GCC 14 patchset
when we unleash that on the masses). Just keep in mind that very few
distributions build with > release checking.

We only do default-checking for the branch when it's in development still and
also optionally via USE=debug. So, while testing by others is still valuable, I
don't expect you'll get that much - at least without people specifically
knowing to turn on checking and ensure stuff doesn't break.

(Of course, making sure release checking works fine now too is important, but
you get my point.)