Link-time optimization (LTO) has been improved in a number of ways, so that it is faster, consumes less memory, and generates smaller object files.

Inter-procedural analysis (IPA) has been improved, and speculative devirtualization optimization has been added.

Support for profiling code has been made more reliable.

The Intel AVX-512 target architecture is now supported, as well as a number of new Intel microarchitectures.

Support for C11 has been improved, and ISO C11 atomics, generic selections, and thread-local storage are now supported.

A subset of the functionality of C++11 auto is now provided in GNU C through a new extension, __auto_type.

The C and C++ compilers now support the OpenMP 4.0 specification.

The g++ compiler offers improved support for various features of the C++ standard, including generic lambdas, variable-length arrays, and digit separators.

The C++ runtime library C++11 support has been improved and now includes experimental support for the upcoming ISO C++ standard, C++14.

GCC now adds support for Cilk+, an extension to the C and C++ languages for parallel programming.

Python scripting support has been enhanced in a number of ways.

Several new commands and enhancements in GDB/MI have been added.

Support for the CTF (Common Trace Format) has been added.

The btrace record target has been enhanced in a number of ways.

The remote protocol and GDBserver, the GDB remote stub, have been enhanced in a number of ways.

The objcopy utility now supports wildcards for section names in command line options.

The AVX-512 (512-bit Advanced Vector Extensions) are now supported.