New features since the previous release
* Shared libgcc: If all modules are linked with -shared-libgcc, exceptions can be thrown across DLL boundaries.
* Shared libstdc++: Add -lstdc++_s to your link flags to link against a DLL version of libstdc++.
* Zero cost exceptions: New exception model Dwarf only has performance penalty when being thrown. The old model, SJLJ, is no longer available.
* Thread local storage support: The __thread keyword is honoured.
* Native language translations.
* New language: Java 1.5, using Eclipse front end
* New language: Objective-C++, intended to bridge C++ and Objective-C code
* Improved optimisation: SSA optimisation framework, IPA support, autovectorization of loops, and more.
* Support for new IA-32 processors and SIMD instruction sets
* Support for TR1 and experimental support for the next C++ standard
* Fortran language rewritten to support new standards
* Improved debugging information: Dwarf-2 debugging is now the default.
* OpenMP support