makefiles in gcc

[ratnadeep joshi]

hello ,

  I am  trying  writng a small front end for gcc . for 
that i want to know the  exact role of makefiles in the 
building and compiling gcc.
  There is one main makefile in which all other 
makefiles in the subdirectories are called ....
  In this what role  the files makefiles.vms and 
make-lang.in in each subdirectory play ?
   Which makefiles are created by configure and how 
they are created ?

   Thanking lot !!
   
  - Ratnadeep Joshi
   I