[Bug rtl-optimization/96015] [10/11 Regression] gcc-10.1.0 miscompiles Python on hppa

[slyfox at inbox dot ru]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96015

--- Comment #31 from Sergei Trofimovich <slyfox at inbox dot ru> ---
(In reply to Martin Liška from comment #28)
> > Bisected down to:
> > 
> > $ git bisect good
> > 8c3785c43d490d4f234e21c9dee6bb1bb8d1dbdf is the first bad commit
> > commit 8c3785c43d490d4f234e21c9dee6bb1bb8d1dbdf
> > Author: Martin Liska <mliska@suse.cz>
> > Date:   Wed Dec 4 11:13:49 2019 +0100
> > 
> >     Initialize a BB count in switch lowering.

> Thank you for the bisection. However, this one is not a culprit commit, it
> only made it visible.
> Let's wait for can Erik find out.

For my own curiosity I applied "Initialize a BB count in switch lowering." to
gcc-9 and found that it's indeed is already broken.

I attempted a bisection between gcc-8 and gcc-9 while applying this patch to
get the idea where it surfaced. Got arrived at:

$ git bisect good
9427422ddacdf1c2914adfb6e8edca87f250fdfc is the first bad commit
commit 9427422ddacdf1c2914adfb6e8edca87f250fdfc
Author: Jeff Law <law@redhat.com>
Date:   Wed Apr 3 10:03:37 2019 -0600

    re PR rtl-optimization/81025 (gcc ICE while building glibc for MIPS
soft-float multi-lib variant)

            PR rtl-optimization/81025
            * reorg.c (skip_consecutive_labels): Do not skip past a BARRIER.

    From-SVN: r270129

 gcc/ChangeLog |  5 +++++
 gcc/reorg.c   | 15 ++++++++++++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=9427422ddacdf1c2914adfb6e8edca87f250fdfc