------- Comment #16 from uweigand at gcc dot gnu dot org  2010-09-06 16:57 
(In reply to comment #15)
> Ulrih, I've just wanted to post the following when I found that you already
> posted analogous conclusion.  I should have been on CC to see your comment
> right away.  The problem is really fundamental.  Code for
> merge_assigned_reloads ignores inheritance (and dependencies between reloads
> because of inheritance) at all.  Here is my post wanted to add.

I just noticed that even in the complete absence of reload inheritance, the
allocate_reload_reg routine performs free_for_value_p checks, and therefore
implicitly takes reload ordering into account.  This seems to imply that even
if we'd do merge_assigned_reloads only if no inheritance has taken place, we'd
still have a problem.

Does anybody have any idea how much merge_assigned_reloads actually contributes
to performance on i386, in particular now that we have a bit more post-reload
optimizers that potentially clear up duplicate code of the type generated by
unmerged reloads?



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