How Gcc compile itself ?

[Alan Xin]

Hi all,

Recently, I do some modification in Gcc-4.2.4 in several files like c-parser.c, c-decl.c, c-common.c. And when I recompile the patched gcc, I found the modification effect the new gcc in construction processing. 

In my conjecture, Gcc first build part of it , and use this part to compile other part ,then the modification affect itself. 
How does this happen exactly? Is there any paper or doc talking about this part ?

Thanks~