From Fedora Project Wiki

GCC Compiler Collection

This release of Fedora has been built with GCC 4.3.2, which is included with the distribution.

For more information on GCC 4.3, refer to:

http://gcc.gnu.org/gcc-4.3/

Target-Specific Improvements

IA-32/x86-64

ABI changes

  • Starting with GCC 4.3.1, decimal floating point variables are aligned to their natural boundaries when they are passed on the stack for i386.

Command-line changes

  • Starting with GCC 4.3.1, the -mcld option has been added to automatically generate a cld instruction in the prologue of functions that use string instructions. This option is used for backward compatibility on some operating systems and can be enabled by default for 32-bit x86 targets by configuring GCC with the --enable-cld configure option.