Gcc has been released in several versions, whose documentation is here:

• 3.1
• 2.95.2
• 2.8.ecgs
• 2.7.2
• 2.7.2.1.1

The gcc product used to also contain the GNU debugger, and the "ddd" debugger graphical front end. These have now been split off into separate products

• gdb the GNU debugger
• dddebugger the graphical debugger front end.