[Bug c++/60779] New: -fcx-fortran-rules ignored when using -flto

[Bug c++/60779] New: -fcx-fortran-rules ignored when using -flto

[dturnbull at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60779

            Bug ID: 60779
           Summary: -fcx-fortran-rules ignored when using -flto
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dturnbull at gmail dot com

Using the following test code on g++-4.9 (GCC) 4.9.0 20140330

if (isnan((complex<float>(1,0) / complex<float>(0,0)).real())) {
    cout << "Fortran rules: \n";
} else {
    cout << "ISO rules: \n";
}

The -fcx-fortran-rules option behaves as expected. The test code indicates
Fortran rules are being used and performance indicates the NaN checking is
indeed disabled.

When enabling both -fcx-fortran-rules and -flto the test code indicates ISO
rules are being used and performance is identical to compiling without
-fcx-fortran-rules.

This happens in both the C and C++ compilers.

[Bug c++/60779] -fcx-fortran-rules ignored when using -flto

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60779

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Can you provide the extra command line you used?

[Bug c++/60779] -fcx-fortran-rules ignored when using -flto

[dturnbull at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60779

David Turnbull <dturnbull at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #2 from David Turnbull <dturnbull at gmail dot com> ---
Sorry. My bad. Closing. Makefile bug :(

[Bug lto/60779] -fcx-fortran-rules ignored when using -flto

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60779

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |lto, missed-optimization
             Status|RESOLVED                    |ASSIGNED
   Last reconfirmed|                            |2014-04-08
          Component|c++                         |lto
         Resolution|INVALID                     |---
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Well, LTO unconditionally sets flag_complex_method to 2 currently.  It does not
yet conservatively merge TU choices and complex lowering happens too late.

Thus, confirmed and mine.

[Bug lto/60779] -fcx-fortran-rules ignored when using -flto

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60779

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Note this applies to the case where you don't specify any -fcx-* flag on the
linker command-line (or on any of the input TUs, but merging conflicting
flags there doesn't work).