[Bug target/114698] New: dcfldd produces wrong sha256 sum on ppc64le and -O3

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114698

            Bug ID: 114698
           Summary: dcfldd produces wrong sha256 sum on ppc64le and -O3
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: bergner at gcc dot gnu.org
  Target Milestone: ---

Building the dcfldd v1.9.1 package on powerpc64le-linux when configured to use
-O3 produces an incorrect sha256 sum for GCC trunk, 13 and 12.  GCC 11 and
earlier produces correct output.  For example (-O3 trunk build):

bergner@ltcden2-lp1:dcfldd [v1.9.1]$ echo TestInput | ./src/dcfldd hash=sha256
TestInput

Total (sha256):
d627605bdee37e388a5c232dc407cb5cd287d27187d6787999ad3bb59d383e9a

0+1 records in
0+1 records out

...versus expected output from an -O2 trunk build:

bergner@ltcden2-lp1:dcfldd [v1.9.1]$ echo TestInput | ./src/dcfldd hash=sha256
TestInput

Total (sha256):
8021973df8498a650e444fd84c705d9168639a246bc6024066e4091b2b450da6

0+1 records in
0+1 records out

...and from sha256sum:

bergner@ltcden2-lp1:dcfldd-git [v1.9.1]$ echo TestInput | /usr/bin/sha256sum 
8021973df8498a650e444fd84c705d9168639a246bc6024066e4091b2b450da6  -


Current steps to recreate:

git clone https://github.com/resurrecting-open-source-projects/dcfldd.git
cd dcfldd/
git checkout v1.9.1 -b v1.9.1
./autogen.sh
./configure CFLAGS="-O3"
make
echo TestInput | ./src/dcfldd hash=sha256