processor specific information while compiling

[ranjith kumar]

While compiling, gcc uses information about processor's architecture,
instruction set......etc.
1) In what form this information is stored??
       I want to see those file. where they are located?

2) I want to write a 'c' program to convert AST(abstract synax tree)
to  machine code.
     Any links on this topic please.

Thanks in advance.