SSA usage question

[Richard Kenner]

Suppose I have a INTEGER_TYPE with a TYPE_MAX_VALUE that's an expression
(originally a SAVE_EXPR).  That can be gimplified in the routine that
handles decls so then it's a VAR_DECL.

But whose job is it to mark the variable used?  I see only five places
where set_is_used is called, three in tree-outof-ssa.c and two in
tree-ssa-live.c.

None of them make any attempt to mark the variables in variable-sized or
positioned types as being used.

It needs to mark TYPE_SIZE, TYPE_SIZE_UNIT, DECL_FIELD_OFFSET, TYPE_MIN_VALUE,
TYPE_MAX_VALUE, and perhaps some others.

Where is this supposed to be done?