[Bug other/81931] New: [8 regression] r251260 breaks many tests on powerpc64

[seurer at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81931

            Bug ID: 81931
           Summary: [8 regression] r251260 breaks many tests on powerpc64
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
          Assignee: unassigned at gcc dot gnu.org
          Reporter: seurer at gcc dot gnu.org
  Target Milestone: ---

This change to wide-int.h breaks many tests on powerpc64 both LE and BE.  The
symptom is the compiled code hangs.  There are hundreds of test cases that time
out then fail.  One example:

Running /home/seurer/gcc/gcc-test2/gcc/testsuite/gcc.dg/atomic/atomic.exp ...
WARNING: program timed out.
FAIL: gcc.dg/atomic/c11-atomic-exec-5.c   -O1  execution test
WARNING: program timed out.
FAIL: gcc.dg/atomic/c11-atomic-exec-5.c   -O2  execution test
WARNING: program timed out.
FAIL: gcc.dg/atomic/c11-atomic-exec-5.c   -O3 -fomit-frame-pointer
-funroll-loops -fpeel-loops -ftracer -finline-functions  execution test
WARNING: program timed out.
FAIL: gcc.dg/atomic/c11-atomic-exec-5.c   -O3 -g  execution test
WARNING: program timed out.
...etc...

That particular one is doing floating point arithmetic tests on atomic floats
using threads.  At least some (not sure if all) of the other failing tests are
doing similar things.