[RFC] Design issues with multiple IRs

[Neil Booth]

Diego Novillo wrote:-

> Another place where we are abusing void pointers is in
> annotations attached to flowgraph nodes and trees.  The 'aux'
> fields are being used to hold analysis information.  For
> instance, trees use the 'aux' pointer to hold a pointer to the
> basic block that contains the tree (only for statement trees), a
> pointer to a list of references for VAR_DECLs, a pointer to the
> most recent definition of a VAR_DECL (for building the SSA web).

Why not use a union?

If you give it a single letter, access is not so tedious, or wrap it
in a macro like we do now.  But if you can make even a bit of progress
on getting away from "everything is a tree" to "everything is a
pointer to a specific type" like we discussed the other day, that
would be great.

Neil.