References

GCC C language extension
http://gcc.gnu.org/onlinedocs/gcc/C-Extensions.html
GCC C++ language extension
http://gcc.gnu.org/onlinedocs/gcc/C_002b_002b-Extensions.html#C_002b_002b-Extensions
GCC common Pre-defined macros:
http://gcc.gnu.org/onlinedocs/cpp/Common-Predefined-Macros.html
GCC Pragmas:
http://gcc.gnu.org/onlinedocs/gcc/Pragmas.html#Pragmas
GCC Function attributes:
http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#Function-Attributes