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Re: RFC: GIMPLE tuples. Design and implementation proposal
- From: Andi Kleen <andi at firstfloor dot org>
- To: Andrew MacLeod <amacleod at redhat dot com>
- Cc: gcc at gcc dot gnu dot org
- Date: 10 Apr 2007 23:07:30 +0200
- Subject: Re: RFC: GIMPLE tuples. Design and implementation proposal
- References: <461B175A.1050407@redhat.com.suse.lists.egcs> <998d0e4a0704101054j3a1f7a61hc3ef0ee6313b8b68@mail.gmail.com.suse.lists.egcs> <1176228779.9669.25.camel@localhost.localdomain.suse.lists.egcs>
Andrew MacLeod <amacleod@redhat.com> writes:
>
> Do you mean implement this as a single linked list and then to find the
> previous instruction, start at the beginning of the block and traverse
> forward? Back in the early days of tree-ssa we did such a thing with the
> tree iterators. It was too slow. there are many LARGE basic blocks which
> make the computation too expensive for any pass that goes backwards
> through a block.
In theory you could use xor lists (xor next and prev and if you know
one element you can get the other). Problem is that garbage collectors
require special casing for them and debuggers need special macros
to walk those.
-Andi