[Bug target/86444] New: [X86] Implementation of SSE comi/ucomi intrinsics does not match recent versions of icc, clang, or MSVC

["craig.topper at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86444

            Bug ID: 86444
           Summary: [X86] Implementation of SSE comi/ucomi intrinsics does
                    not match recent versions of icc, clang, or MSVC
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: craig.topper at gmail dot com
  Target Milestone: ---

It looks like gcc does not match the behavior of the most recent versions of
icc, clang, and MSVC with respect to the behavior or NaNs in the COMI
intrinsics. The other compilers are all returning 0 when the compare result is
unordered. As can be seen here: https://godbolt.org/g/xxEKqg

Clang changed to this behavior in version 3.9. According to this comment from 
https://bugs.llvm.org/show_bug.cgi?id=28510#c10, the original icc behavior was
the same as gcc’s current behavior, but it was changed at least 10 years ago.