[Bug c++/66172] New: -fno-threadsafe-statics suppresses guard functions but not guard variables

[Bug c++/66172] New: -fno-threadsafe-statics suppresses guard functions but not guard variables

[eleventen at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66172

            Bug ID: 66172
           Summary: -fno-threadsafe-statics suppresses guard functions but
                    not guard variables
           Product: gcc
           Version: 4.9.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: eleventen at gmail dot com
  Target Milestone: ---

The use of the -fno-threadsafe-statics eliminates the function references to
the guard functions,

__cxa_guard_acquire
__cxa_guard_release


but it doesn't eliminate the variables used to guard the initialization.  A
compiled version of the attached file using the g++ command line therein
generated no references to the guard functions, but the guard variable remains.

# nm -C guard | grep guard
0000000000600a88 b guard variable for f()::a

--- Comment #1 from Marc Singer <eleventen at gmail dot com> ---
I neglected to include the version information:

# g++ --version
g++ (Debian 4.9.2-10) 4.9.2

[Bug c++/66172] -fno-threadsafe-statics suppresses guard functions but not guard variables

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66172

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

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

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
You need the variable even without thread safe ones because calling the
function twice means it gets initlized only once rather twice. There is no
other way around this because the variable only gets initialized if the
function is called.

[Bug c++/66172] -fno-threadsafe-statics suppresses guard functions but not guard variables

[eleventen at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66172

--- Comment #3 from Marc Singer <eleventen at gmail dot com> ---
I've come to the same conclusion.  My hope was that I could eliminate the guard
and force the compiler to initialize block scoped statics at the start of
execution.  It looks like the standard stands in the way of this
simplification.

[Bug c++/66172] -fno-threadsafe-statics suppresses guard functions but not guard variables

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66172

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 66173 has been marked as a duplicate of this bug. ***