[Bug regression/103318] New: Spec 2017 benchmark perlbench_r fails on PowerPC for -Ofast and -O3, passes with -O2

["meissner at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103318

            Bug ID: 103318
           Summary: Spec 2017 benchmark perlbench_r fails on PowerPC for
                    -Ofast and -O3, passes with -O2
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: regression
          Assignee: unassigned at gcc dot gnu.org
          Reporter: meissner at gcc dot gnu.org
  Target Milestone: ---

The Spec 2017 benchmark perlbench_r compiles fine but produces the wrong output
when compiled with -O3 or -Ofast options on both power9 and power10.  Using -O2
produces the right results on power10.  In going back with the previous runs
that I've done on power10, it worked with sources checked out on October 17th,
but failed with sources checked out on November 4th and November 17th.

For power10, the options that I use are:
-g -mlittle -save-temps=obj -ffast-math -Ofast -mcpu=power10 -mrecip \
-funroll-loops -m64  -fgnu89-inline -Wno-multichar -DSPEC_LP64 \
-frandom-seed=spec2017 -D_XOPEN_SOURCE=500 -DSPEC_LINUX_PPC_LE \
-fno-strict-aliasing -std=gnu11 -Wno-builtin-macro-redefined -w