[Bug c/102472] New: Infinite loop on m68k

[Bug c/102472] New: Infinite loop on m68k

[giulio.benetti at benettiengineering dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102472

            Bug ID: 102472
           Summary: Infinite loop on m68k
           Product: gcc
           Version: 11.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: giulio.benetti at benettiengineering dot com
  Target Milestone: ---

When building python-uvloop package on Buildroot for m68k gcc enters an
infinite loop on:
'''
/home/giuliobenetti/autobuild/run/instance-3/output-1/host/bin/m68k-linux-gcc
-Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O3 -Wall
-D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -g2
-D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -g2
-D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -fPIC
-I/home/giuliobenetti/autobuild/run/instance-3/output-1/host/m68k-buildroot-linux-uclibc/sysroot/usr/include/python3.9
-c uvloop/loop.c -o build/temp.linux-x86_64-3.9/uvloop/loop.o -O2
'''

To reproduce it:

# git clone git://git.busybox.net/buildroot
# wget https://git.busybox.net/buildroot-test/tree/utils/br-reproduce-build

- modify BASE_GIT=... with your buildroot path in br-reproduce-build then:
# chmod a+x br-reproduce-build
# ./br-reproduce-build 17d6e6422abadcd6313c430c40f2a5d7162dbbd3

The only way I've found to build correctly is to turn off optimization
overriding CFLAGS with -O0.

In this case that we have an infinite loop, I don't know how provide .i and .s
files. Can you please point me some instruction for this case?

Thanks in advance

[Bug target/102472] Infinite loop on m68k

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102472

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2021-09-23
          Component|c                           |target
             Status|UNCONFIRMED                 |WAITING
     Ever confirmed|0                           |1
           Keywords|                            |compile-time-hog

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
>In this case that we have an infinite loop, I don't know how provide .i and .s files. Can you please point me some instruction for this case?

https://gcc.gnu.org/bugs/ has instructions on how to get the .i file. 
Basically add -save-temps to gcc command line (add -v too)

[Bug target/102472] Infinite loop on m68k

[giulio.benetti at benettiengineering dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102472

--- Comment #2 from Giulio Benetti <giulio.benetti at benettiengineering dot com> ---
Oh, I didn't know it could produce .i and .s even when hanging. But yes, that
happens before really building. So .i .s files follow.

Thank you and
Best regards

[Bug target/102472] Infinite loop on m68k

[giulio.benetti at benettiengineering dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102472

--- Comment #3 from Giulio Benetti <giulio.benetti at benettiengineering dot com> ---
Created attachment 51505
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51505&action=edit
Pre-processed loop.c(loop.i)

[Bug target/102472] Infinite loop on m68k

[giulio.benetti at benettiengineering dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102472

--- Comment #4 from Giulio Benetti <giulio.benetti at benettiengineering dot com> ---
Created attachment 51506
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51506&action=edit
Pre-processed loop.c(loop.s)

[Bug target/102472] Infinite loop on m68k

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102472

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |UNCONFIRMED
     Ever confirmed|1                           |0

[Bug target/102472] Infinite loop on m68k

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102472

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
On the GCC 11 branch head I cannot reproduce this with a x86_64-linux ->
m68k-linux cross cc1, using -O2 -fwrapv -fPIC -g2 -Wno-unused-result
-Wsign-compare -Wall

Can you clarify that it is the compiler that enters an infinite loop rather
than the object being miscompiled and python-uvloop entering an infinite loop?

Can you also please quote the output of the compiler-command when you add -v to
the command-line that causes the hang?  In particular the line showing the cc1
execution is useful.

Note I did not test GCC 11.2.0 exactly.

[Bug target/102472] Infinite loop on m68k

[giulio.benetti at benettiengineering dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102472

Giulio Benetti <giulio.benetti at benettiengineering dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |INVALID
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #6 from Giulio Benetti <giulio.benetti at benettiengineering dot com> ---
Oh sorry, I've just found out now that loop.c takes very very long time to
build(it's 7M of .c source file) and Buildroot autobuilder times out. We need
to retrim timeout value there.
Sorry for the noise, I close this bug as RESOLVED->INVALID.

Best regards