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Re: hard_regno_nregs == 0 ?

From: Jim Wilson <wilson at specifix dot com>
To: DJ Delorie <dj at redhat dot com>
Cc: iant at google dot com, gcc at gcc dot gnu dot org
Date: Wed, 09 Jan 2008 12:17:45 -0800
Subject: Re: hard_regno_nregs == 0 ?
References: <200801082013.m08KDLeU011644@greed.delorie.com> <m3d4sbymp3.fsf@localhost.localdomain> <200801091647.m09Gl4Qp021266@greed.delorie.com>

DJ Delorie wrote:

Are there any ports besides m32c that have registers which can hold HI
(or SI I suppose) but not QI values?

IA-64 has branch registers that are only allowed to hold DImode values. We use CANNOT_CHANGE_MODE_CLASS to enforce this.

On x86, the vector registers can hold SImode, but do not allow HImode/QImode loads, and again CANNOT_CHANGE_MODE_CLASS is used to enforce this.

I'm sure that there are other examples out there.
--
Jim Wilson, GNU Tools Support, http://www.specifix.com

References:
- hard_regno_nregs == 0 ?
  - From: DJ Delorie
- Re: hard_regno_nregs == 0 ?
  - From: Ian Lance Taylor
- Re: hard_regno_nregs == 0 ?
  - From: DJ Delorie

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