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Re: Link-time optimzation
- From: Kenneth Zadeck <Kenneth dot Zadeck at NaturalBridge dot com>
- To: Ian Lance Taylor <ian at airs dot com>
- Cc: gcc mailing list <gcc at gcc dot gnu dot org>
- Date: Thu, 17 Nov 2005 11:16:56 -0500 (EST)
- Subject: Re: Link-time optimzation
- Reply-to: Kenneth dot Zadeck at NaturalBridge dot com
Mark Mitchell <firstname.lastname@example.org> writes:
> Section 4.2 (Executable Representation) describes the GVM as a stack
> machine, and mentions load, store, duplicate, and swap operations.
> But it also discusses having registers which correspond to GIMPLE
> local variables. The way I put this together is that a MODIFY_EXPR
> which sets a local variable, say, will be converted to something that
> computes the expression using a stack and then assigns the value to a
> register. It's easy to see how to convert such a MODIFY_EXPR into a
> stack machine and back. But it's not easy to see why that stack
> machine is going to need, e.g, a swap operation. There is no GIMPLE
> swap operator. So I may still be confused about something.
You are most likely correct. We either do not need a swap or do not
want to encourage people to try to optimize the trees so much that
they need a swap.