[Bug libstdc++/66146] New: call_once not C++11-compliant on ppc64le

["andrey.vul at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66146

            Bug ID: 66146
           Summary: call_once not C++11-compliant on ppc64le
           Product: gcc
           Version: 5.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: andrey.vul at gmail dot com
  Target Milestone: ---

std::call_once is not C++11 (or even N2447) compliant on ppc64le.

According to N2447, "If the invocation of func results in an exception being
thrown, the exception is propagated to the caller and the effects are as-if
this invocation of call_once did not occur."

Given the code

#include <mutex>

int call_count = 0;
void func_() {
printf("Inside func_ call_count %d\n", call_count);
if (++call_count < 2)
throw 0;
}
int main() {
std::once_flag flag_;
printf("Before calling call_once flag_: %d\n", *(int*)&flag_);
try { std::call_once(flag_, func_); } catch(...) { printf("Inside catch all
excepton flag_: %d\n", *(int*)&flag_); }
printf("before the 2nd call to call_once flag_: %d\n", *(int*)&flag_);
std::call_once(flag_, func_);
}

the output on amd64 is
Before calling call_once flag_: 0
Inside func_ call_count 0
Inside catch all excepton flag_: 0
before the 2nd call to call_once flag_: 0

but on ppc64el is
Before calling call_once flag_: 0
Inside func_ call_count 0
Inside catch all excepton flag_: 1
before the 2nd call to call_once flag_: 1

amd64 has the correct behavior.

ppc64le gcc tested:
$gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/powerpc64le-linux-gnu/4.9/lto-wrapper
Target: powerpc64le-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.9.1-16ubuntu6'
--with-bugurl=file:///usr/share/doc/gcc-4.9/README.Bugs
--enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.9 --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--with-gxx-include-dir=/usr/include/c++/4.9 --libdir=/usr/lib --enable-nls
--with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --enable-gnu-unique-object --disable-libsanitizer
--disable-libquadmath --enable-plugin --with-system-zlib
--disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.9-ppc64el/jre --enable-java-home
--with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.9-ppc64el
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.9-ppc64el
--with-arch-directory=ppc64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar
--enable-objc-gc --enable-secureplt --with-cpu=power7 --with-tune=power8
--disable-multilib --enable-multiarch --disable-werror --with-long-double-128
--enable-checking=release --build=powerpc64le-linux-gnu
--host=powerpc64le-linux-gnu --target=powerpc64le-linux-gnu
Thread model: posix
gcc version 4.9.1 (Ubuntu 4.9.1-16ubuntu6) 

$gcc-5.1 -v
Using built-in specs.
COLLECT_GCC=/home/andreyv/nfs/gcc/bin/gcc-5.1
COLLECT_LTO_WRAPPER=/nfs/home/andreyv/gcc/bin/../libexec/gcc/powerpc64le-unknown-linux-gnu/5.1.0/lto-wrapper
Target: powerpc64le-unknown-linux-gnu
Configured with: ../gcc-5.1.0/configure --prefix=/nfs/home/andreyv/gcc/
--program-suffix=-5.1 --enable-languages=c,c++,lto CFLAGS='-O2 -mtune=native'
CXXFLAGS='-O2 -mtune=native'
Thread model: posix
gcc version 5.1.0 (GCC) 

Both versions compiled and run on Ubuntu 14.10 on a Power8.
gcc-5.1 invocation: $ ~/nfshome/gcc/bin/g++-5.1 -std=c++11 -lpthread
-Wl,-rpath=~/nfshome/gcc/lib64 -Wall -Wextra a.cc
gcc-4.9 invocation: g++ -std=c++11 -lpthread -Wall -Wextra a.cc