GCC Abstract Syntax Tree

The trees are built up by the GCC Language Front Ends[?]. They provide a relatively high level description of the original source program.

The GCC 'middle-end' performs some transformations on the trees, and then generates RTL from them.

The tree representation of a program is more-or-less independent of the processor being targeted. However, the meaning of a tree is somewhat different for different language front-ends, and front-ends can provide their own tree codes.

The tree is a c language union, a concept related to the Set theoretic union of the various Abstract_syntax_tree_tree_types[?] types that are subdivided by codes Abstract_syntax_tree_tree_code[?].

See also : wendling's overview : [1] (http://www.ncsa.uiuc.edu/~wendling/tree) doxygen's output : [2] (http://www.nondot.org/gcc/uniontree__node)