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Re: Question on fixup_abnormal_edges
- From: Jeff Law <law at porcupine dot cygnus dot com>
- To: kenner at vlsi1 dot ultra dot nyu dot edu (Richard Kenner)
- Cc: rth at redhat dot com, gcc at gcc dot gnu dot org
- Date: Mon, 21 Oct 2002 09:58:47 -0600
- Subject: Re: Question on fixup_abnormal_edges
- Reply-to: law at redhat dot com
In message <10210161140.AA20375@vlsi1.ultra.nyu.edu>, Richard Kenner writes:
> Admittedly some of the code for that isn't written, but it's possible.
> It would be easier to disallow call-clobbered registers across that
> edge.
>
>Agreed, especially since caller-save registers are a borderline
>optimization anyway.
Consider a target where all registers in a particular class are
caller-saved. This happens (for example) on 32bit Sparc ABI for the
floating point registers. If you don't do caller-save you lose
so badly it's not even funny. I have no idea if this applies to the
64bit Sparc ABI.
jeff