[Bug c/123869] New: Negation of _Float16 can yield a different value at -O0

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123869

            Bug ID: 123869
           Summary: Negation of _Float16 can yield a different value at
                    -O0
           Product: gcc
           Version: 15.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: antoyo at gcc dot gnu.org
  Target Milestone: ---

Created attachment 63520
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=63520&action=edit
Reproducer for the bug

Hi.
When running the attached program on x86-64 when compiled at -O1, -O2 or -O3,
we get the following output:

left: 32256
right: 31786
left: 65024
right: 64554

But when using -O0, we get:

left: 32256
right: 31786
left: 65024
right: 65066

(the last value is different)

I observed the same behavior with Clang.