[PATCH] libstdc++ testsuite: atomic_float/value_init.cc requires libatomic

[David Edelsohn via Gcc-patches]

atomic_float/value_init.cc requires libatomic on some targets, i.e.,
when it tries to perform an atomic operation with a 64 bit floating
point double type on a 32 bit target.  This patch adds AIX to the list
of targets that require the libatomic option and adds the option to
the atomic_float/value_init.cc testcase.

Bootstrapped on powerpc-ibm-aix7.2.0.0

Okay?

Thanks, David

    2020-07-28  David Edelsohn  <dje....@gmail.com>
                        Jonathan Wakely  <jwak...@redhat.com>

            * testsuite/lib/dg-options.exp (add_options_for_libatomic): Add
            target powerpc-ibm-aix*.
            * testsuite/29_atomics/atomic_float/value_init.cc: Add options
            for libatomic.

diff --git a/libstdc++-v3/testsuite/29_atomics/atomic_float/value_init.cc
b/libstdc++-v3/testsuite/29_atomics/atomic_float/value_init.cc
index 237c0dd13ed..38af9bdc8d4 100644
--- a/libstdc++-v3/testsuite/29_atomics/atomic_float/value_init.cc
+++ b/libstdc++-v3/testsuite/29_atomics/atomic_float/value_init.cc
@@ -17,6 +17,7 @@

 // { dg-options "-std=gnu++2a" }
 // { dg-do run { target c++2a } }
+// { dg-add-options libatomic }

 #include <atomic>
 #include <testsuite_hooks.h>

diff --git a/libstdc++-v3/testsuite/lib/dg-options.exp
b/libstdc++-v3/testsuite/lib/dg-options.exp
index 9bfae71adf3..bf6219c3042 100644
--- a/libstdc++-v3/testsuite/lib/dg-options.exp
+++ b/libstdc++-v3/testsuite/lib/dg-options.exp
@@ -260,7 +260,8 @@ proc add_options_for_net_ts { flags } {
 # Add to FLAGS all the target-specific flags to link to libatomic, if required.

 proc add_options_for_libatomic { flags } {
-    if { [istarget hppa*-*-hpux*] || [istarget riscv*-*-*] } {
+    if { [istarget hppa*-*-hpux*] || [istarget riscv*-*-*]
+        || [istarget powerpc-ibm-aix*] } {
        return "$flags -L../../libatomic/.libs -latomic"
     }
     return $flags