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Re: [PATCH] - Use of powerpc 64bit instructions in 32bit ABI
- From: David Edelsohn <dje at watson dot ibm dot com>
- To: "Ulrich Weigand" <Ulrich dot Weigand at de dot ibm dot com>
- Cc: ian at wasabisystems dot com, rth at redhat dot com, fjahanian at apple dot com, davem at redhat dot com, gcc-patches at gcc dot gnu dot org
- Date: Thu, 23 Oct 2003 15:19:39 -0400
- Subject: Re: [PATCH] - Use of powerpc 64bit instructions in 32bit ABI
>>>>> Ulrich Weigand writes:
Ulrich> Why would you have word_mode == SImode? I've been playing around with
Ulrich> the same issue on zSeries, and found I could get it working pretty well
Ulrich> with setting word_mode to DImode, allowing DImode in GPRs, but forcing
Ulrich> function arguments/return values to register pairs using PARALLEL.
Ulrich> (When having word_mode == SImode, everything broke because there appears
Ulrich> to be the assumption that every word_mode-sized SUBREG of a GPR must
Ulrich> be directly accessible - which is not the case at least on zSeries ...)
Have you read the earler discussion thread?
If word_mode is changed to DImode, there are numerous places in
the compiler that assume arguments are word_mode. David Miller and
Richard Henderson argued against changes to make a distinction.
David