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Re: Fix a tcb crash and a potential bug on mainline
On Wed, 2004-10-20 at 07:27, Steven Bosscher wrote:
>
> > 2 - The issue may also exist outside cleanup_control_flow, so why does
> > remove_phi_arg_num have to remove the PHI node when is removes the last
> > argument.
>
> That is what I believe to be the problem. Jeff thinks this is "the
> right thing" to do.
What I think is right is to ensure that we release the dead PHIs
and their associated PHI_RESULTs. What Andrew made clearer in
his message is that we would get a chance to collect them when
we remove unreachable blocks since the only time we can have a
PHI with no args is when we have unreachable blocks.
I'm pretty sure we don't release PHIs and SSA_NAMEs in that code,
but it shouldn't be terribly hard to add it in a way that is
safe (since the unreachable block removal code is used by both
trees and rtl).
>
>
> > Why not allow the PHI node to exist with no arguments.
>
> That would work too, I guess.
And I like that a lot better than removing the PHI and leaving
in references to the result.