------- Comment #4 from amylaar at gcc dot gnu dot org 2009-02-08 12:49 -------
(In reply to comment #2)
> This is related to some work done in the past for auto-increment addressing
> modes
Actually, the problem with constants that are loaded into registers -
and in the same basic block, at that - is much simpler.
If the targets rtx_cost works properly, then reload_cse_move2add should
fix up this code.
We need, however, some way to deal with the case where constants are expensive
addresses; this is completely broken at the moment. Complete unrolling of
loops accessing static arrays can create oodles of constant addresses; I've
managed to split these up with LEGITIMIZE_ADDRESS, the movsi expander, and
a patch to momory_address, however, gcse just recombines the costly constants,
irrespective of what rtx_cost and address_cost says.
And the havoc that gcse can wreak transcends basic blocks, so any attempt to
clean up after if with lesser scope is bound to be inferior.
--
amylaar at gcc dot gnu dot org changed:
What |Removed |Added
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CC| |amylaar at gcc dot gnu dot
| |org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33699
