DECL_RTL vs. explicit make_decl_rtl calls

[Neil Booth]

law@redhat.com wrote:-

> The #2 abuser of garbage collected memory is make_node, also with 15%
> of the calls to allocate garbage collected memory.  I haven't investigated
> this call chain at all.

Note that IDENTIFIER_NODE is never garbage collected, and should be
allocated separately from GC.  They should not really be trees, either,
but that would take some fixing, but save a bunch of memory, as almost
all of struct tree_common is unused for them.

Neil.