list of gcc files/purpose?

[Gary Funck]

Is there a document describing the various files in a gcc source
distributino, and their purpose?  I looked in the various gcc-related
docs. and didn't find this.  thanks.

I'm looking for something as simple as:

expr.c -      semantic analysis of C expressions
[...]
c-parse.in - Yacc grammar describing C syntax,
	     preprocessed to generate c-parse.y
c-parse.y -  YACC-based C language parser,
	     generated by pre-processing c-parse.y