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Re: [RFC] ABI change for variable sized types
- From: kenner at vlsi1 dot ultra dot nyu dot edu (Richard Kenner)
- To: rth at redhat dot com
- Cc: gcc at gcc dot gnu dot org
- Date: Wed, 14 Jul 04 18:03:31 EDT
- Subject: Re: [RFC] ABI change for variable sized types
Then David Edelsohn asked me why we didn't just change the ABI.
Somehow, it had never occurred to me that this was an option. One
I've grown more and more fond of as I've thought about it over the
past two days.
It would affect, as far as I can tell, only Ada, and only in cases
in which the size of the type is variable but whose size is not
computed from the object itself (CONTAINS_PLACEHOLDER_P).
That's not a problem at all. There's absolutely no requirement in
Ada that variable-sized types be passed by value. The only types that
*must* be able to be passed by values are scalars. And the issue of
backwards compatibility from an ABI point of view isn't a concern
since Ada users expect "private" calling conventions between Ada
subprograms anyway.