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Re: gcc 3.4.0 20040121 / ia32 / read-write constraint does not allow a register
- From: Joern Rennecke <joern dot rennecke at superh dot com>
- To: aph at redhat dot com (Andrew Haley)
- Cc: etienne_lorrain at yahoo dot fr (Etienne Lorrain), gcc at gcc dot gnu dot org
- Date: Thu, 29 Jan 2004 14:22:10 +0000 (GMT)
- Subject: Re: gcc 3.4.0 20040121 / ia32 / read-write constraint does not allow a register
> It's complaining about the in-out memory constraint. Use this
> instead:
>
> : "+S" (src), "+D" (dst), "+c" (size), "=m" (*memory)
> : "m" (*memory)
> : "cc"
That's not the same, it doesn't guarantee that the input is the same
as the output.
And matching onstraing can't be made to work reliably for memory.
Support for "+" memory constraints was added as a feature for these
reasons; why do we warn about this now?