Re: Ping: [PATCH v2 1/2] testsuite: Add dg-require-atomic-cmpxchg-word

[Christophe Lyon <christophe.lyon@linaro.org>]

LGTM but I'm not a maintainer ;-)

On Thu, 12 Oct 2023 at 04:21, Hans-Peter Nilsson <hp@axis.com> wrote:
>
> Ping.
>
> > From: Hans-Peter Nilsson <hp@axis.com>
> > Date: Wed, 4 Oct 2023 19:04:55 +0200
> >
> > > From: Hans-Peter Nilsson <hp@axis.com>
> > > Date: Wed, 4 Oct 2023 17:15:28 +0200
> >
> > > New version coming up.
> >
> > Using pointer-sized int instead of int,
> > __atomic_compare_exchange instead of __atomic_exchange,
> > renamed to atomic-cmpxchg-word from atomic-exchange, and
> > updating a comment that already seemed reasonably well
> > placed.
> >
> > Tested as with v1 1/2.
> >
> > Ok to commit?
> >
> > -- >8 --
> > Some targets (armv6-m) support inline atomic load and store,
> > i.e. dg-require-thread-fence matches, but not atomic operations like
> > compare and exchange.
> >
> > This directive can be used to replace uses of dg-require-thread-fence
> > where an atomic operation is actually used.
> >
> >       * testsuite/lib/dg-options.exp (dg-require-atomic-cmpxchg-word):
> >       New proc.
> >       * testsuite/lib/libstdc++.exp (check_v3_target_atomic_cmpxchg_word):
> >       Ditto.
> > ---
> >  libstdc++-v3/testsuite/lib/dg-options.exp |  9 ++++++
> >  libstdc++-v3/testsuite/lib/libstdc++.exp  | 37 +++++++++++++++++++++++
> >  2 files changed, 46 insertions(+)
> >
> > diff --git a/libstdc++-v3/testsuite/lib/dg-options.exp b/libstdc++-v3/testsuite/lib/dg-options.exp
> > index 84ad0c65330b..850442b6b7c1 100644
> > --- a/libstdc++-v3/testsuite/lib/dg-options.exp
> > +++ b/libstdc++-v3/testsuite/lib/dg-options.exp
> > @@ -133,6 +133,15 @@ proc dg-require-thread-fence { args } {
> >      return
> >  }
> >
> > +proc dg-require-atomic-cmpxchg-word { args } {
> > +    if { ![ check_v3_target_atomic_cmpxchg_word ] } {
> > +     upvar dg-do-what dg-do-what
> > +     set dg-do-what [list [lindex ${dg-do-what} 0] "N" "P"]
> > +     return
> > +    }
> > +    return
> > +}
> > +
> >  proc dg-require-atomic-builtins { args } {
> >      if { ![ check_v3_target_atomic_builtins ] } {
> >       upvar dg-do-what dg-do-what
> > diff --git a/libstdc++-v3/testsuite/lib/libstdc++.exp b/libstdc++-v3/testsuite/lib/libstdc++.exp
> > index 608056e5068e..4bedb36dc6f9 100644
> > --- a/libstdc++-v3/testsuite/lib/libstdc++.exp
> > +++ b/libstdc++-v3/testsuite/lib/libstdc++.exp
> > @@ -1221,6 +1221,43 @@ proc check_v3_target_thread_fence { } {
> >      }]
> >  }
> >
> > +proc check_v3_target_atomic_cmpxchg_word { } {
> > +    return [check_v3_target_prop_cached et_atomic_cmpxchg_word {
> > +     global cxxflags
> > +     global DEFAULT_CXXFLAGS
> > +
> > +     # Set up and link a C++11 test program that depends on
> > +     # atomic-compare-exchange being available for a pointer-sized
> > +     # integer.  It should be sufficient as gcc can derive all
> > +     # other operations when a target implements this operation.
> > +     set src atomic_cmpxchg_word[pid].cc
> > +
> > +     set f [open $src "w"]
> > +     puts $f "
> > +     __UINTPTR_TYPE__ i, j, k;
> > +     int main() {
> > +     __atomic_compare_exchange (&i, &j, &k, 1, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
> > +     return 0;
> > +     }"
> > +     close $f
> > +
> > +     set cxxflags_saved $cxxflags
> > +     set cxxflags "$cxxflags $DEFAULT_CXXFLAGS -Werror -std=gnu++11"
> > +
> > +     set lines [v3_target_compile $src /dev/null executable ""]
> > +     set cxxflags $cxxflags_saved
> > +     file delete $src
> > +
> > +     if [string match "" $lines] {
> > +         # No error message, linking succeeded.
> > +         return 1
> > +     } else {
> > +         verbose "check_v3_target_atomic_cmpxchg_word: compilation failed" 2
> > +         return 0
> > +     }
> > +    }]
> > +}
> > +
> >  # Return 1 if atomics_bool and atomic_int are always lock-free, 0 otherwise.
> >  proc check_v3_target_atomic_builtins { } {
> >      return [check_v3_target_prop_cached et_atomic_builtins {
> > --
> > 2.30.2
> >