GCC 4.8 Improves Its Runtime Library (libstdc++)

There's been many Phoronix articles already covering features and changes coming to GCC 4.8, the next major compiler update to come out of the Free Software Foundation in March or April. One of the areas that's seen improvements in GCC 4.8 and not talked about much yet is the improvements to its runtime library, libstdc++, with new features being present.

Among the changes talked about already for GCC 4.8 is its greater optimizations, 64-bit ARM support, the Local Register Allocator, improved C++11 support, and other new features.

When it comes to the libstdc++ runtime library for GCC 4.8, the in-development documentation now cites improved experimental support for the ISO C++11 standard, improvements to random, and a --disable-libstdcxx-verbose configuration option for disabling diagnostic messages from abnormal process termination.

The libstdc++ improvements for C++11 in this next GNU Compiler Collection release includes forward_list meeting the allocator-aware container requirements, and the following are defined by default: this_thread::sleep_for(), this_thread::sleep_until(), this_thread::yield().

The random improvements include an SSE-optimized normal_distribution function and random_device now supports using the hardware RNG instruction on newer x86 processors. RNG is present with the new Intel Ivy Bridge processors thanks to its "Bull Mountain" hardware-based random number generator. Also improving the randomness is a new random number engine simd_fast_mersenne_twister_engine with an optimized SSE version and eight new random number distributions (beta_distribution, normal_mv_distribution, rice_distribution, nakagami_distribution, pareto_distribution, k_distribution, arcsine_distribution, hoyt_distribution).

While there's been many C++11 improvements within the GCC 4.8 compiler itself and the libstdc++ runtime library, the support as of GCC 4.8 is still deemed experimental. The current state of C++11 support within libstdc++ is listed within the GCC online documentation.

Other recent C++11 news of interest is More Open-Source Projects Eyeing Up C++11, C++11 Support In Qt 5.0, and LLVM Developers Ponder Using C++11 Features.

Separate from GCC's libstdc++, LLVM's libc++ standard library continues maturing as well too with a focus on C++11 compliance. The latest details on LLVM's C++ library are available from its LLVM.org project site. The brief current status is still displayed as, "libc++ is a 100% complete C++11 implementation on Apple's OS X. LLVM and Clang can self host in C++ and C++11 mode with libc++ on Linux."