[Bug bootstrap/100820] New: [12 regression] bootstrap hangs during stage2 on power 10

[seurer at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100820

            Bug ID: 100820
           Summary: [12 regression] bootstrap hangs during stage2 on power
                    10
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: bootstrap
          Assignee: unassigned at gcc dot gnu.org
          Reporter: seurer at gcc dot gnu.org
  Target Milestone: ---

g:a8764071f2eb6b4cdc9ecb788dfaa2b095b52598, r12-1020

Author: Aaron Sawdey <acsaw...@linux.ibm.com>
Date:   Tue Mar 2 18:06:37 2021 -0600
    Fusion patterns for add-logical/logical-add

This is causing a hang during stage2 of bootstrapping for trunk on power 10.  I
tried r12-1019 and it was fine.

Here is one example that happens when configure is running:

. . .
checking for powerpc64le-unknown-linux-gnu-gfortran...
/home/seurer/gcc/git/build/gcc-trunk-bootstrap/./gcc/gfortran
-B/home/seurer/gcc/git/build/gcc-trunk-bootstrap/./gcc/
-B/home/seurer/gcc/git/install/gcc-trunk-bootstrap/powerpc64le-unknown-linux-gnu/bin/
-B/home/seurer/gcc/git/install/gcc-trunk-bootstrap/powerpc64le-unknown-linux-gnu/lib/
-isystem
/home/seurer/gcc/git/install/gcc-trunk-bootstrap/powerpc64le-unknown-linux-gnu/include
-isystem
/home/seurer/gcc/git/install/gcc-trunk-bootstrap/powerpc64le-unknown-linux-gnu/sys-include
  -fno-checking
checking whether we are using the GNU Fortran compiler... 
(and here it hangs)


3912958 pts/0    R+     2:12
/home/seurer/gcc/git/build/gcc-trunk-bootstrap/./gcc/f951 conftest.F
-ffixed-form -cpp=/tmp/cc5vO5dZ.f90 -quiet -iprefix
/home/seurer/gcc/git/build/gcc-trunk-bootstrap/gcc/../lib/gcc/powerpc64le-unknown-linux-gnu/12.0.0/
-isystem /home/seurer/gcc/git/build/gcc-trunk-bootstrap/./gcc/include -isystem
/home/seurer/gcc/git/build/gcc-trunk-bootstrap/./gcc/include-fixed -isystem
/home/seurer/gcc/git/install/gcc-trunk-bootstrap/powerpc64le-unknown-linux-gnu/include
-isystem
/home/seurer/gcc/git/install/gcc-trunk-bootstrap/powerpc64le-unknown-linux-gnu/sys-include
conftest.F -quiet -dumpbase conftest.F -dumpbase-ext .F -mcpu=power10
-fno-checking -fintrinsic-modules-path finclude
-fpre-include=/usr/include/finclude/math-vector-fortran.h -o /tmp/cc6Kgdbr.s

This should finish almost instantly but never does.

seurer@ltcden2-lp1:~/gcc/git/build/gcc-trunk-bootstrap$ cat
./powerpc64le-unknown-linux-gnu/libgomp/conftest.F
      program main
#ifndef __GNUC__
       choke me
#endif

      end