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Re: CLASS_CANNOT_CHANGE_MODE

To: Alan Modra <alan at linuxcare dot com dot au>
Subject: Re: CLASS_CANNOT_CHANGE_MODE
From: Richard Henderson <rth at redhat dot com>
Date: Tue, 13 Feb 2001 17:14:25 -0800
Cc: gcc-bugs at gcc dot gnu dot org
References: <Pine.LNX.4.21.0102141143180.32094-100000@front.linuxcare.com.au>

On Wed, Feb 14, 2001 at 12:05:43PM +1100, Alan Modra wrote:
> Is this code in regclass.c:record_operand_costs in error?
[...]
> What seems to be missing is any sort of test on the register class before
> calling CLASS_CANNOT_CHANGE_MODE_P, which is wrong according to tm.texi

No, because we're not dealing with hard registers at all, 
but pseudos.  We're recording that for some subreg there
is a mode change that would be illegal if that pseudo
were to be allocated to the CLASS_CANNOT_CHANGE_MODE class.

r~

References:
- CLASS_CANNOT_CHANGE_MODE
  - From: Alan Modra

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