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To: Richard Henderson <rth@redhat.com>
Cc: Richard Sandiford <rsandifo@redhat.com>,
	"Maciej W. Rozycki" <macro@linux-mips.org>,
	Nigel Stephens <nigel@mips.com>, gcc-patches@gcc.gnu.org,
	linux-mips@linux-mips.org
Subject: Re: [patch] MIPS/gcc: Revert removal of DImode shifts for 32-bit
 targets
References: <Pine.LNX.4.58L.0407261325470.3873@blysk.ds.pg.gda.pl>
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	<Pine.LNX.4.58L.0408042123030.31930@blysk.ds.pg.gda.pl>
	<87r7qiwz54.fsf@redhat.com> <20040809220838.GE16493@redhat.com>
	<87zn5336h7.fsf@redhat.com> <20040810232020.GA21922@redhat.com>
From: Andreas Schwab <schwab@suse.de>
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Date: Wed, 11 Aug 2004 02:24:37 +0200
In-Reply-To: <20040810232020.GA21922@redhat.com> (Richard Henderson's
 message of "Tue, 10 Aug 2004 16:20:20 -0700")
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Richard Henderson <rth@redhat.com> writes:

> Patch seems ok then.  We'd have to add a new macro/target flag
> to handle non-truncating shifts -- we've got cases:
>
>   (1) Large shift shifts out all bits (ARM)
>   (2) Large shifts trap (VAX)
>   (3) Shift count truncated to 31, always, which means QI/HI
>       shifts are yield undefined results with large shifts.  (i386)
    (4) Shift count reduced modulo 64 (m68k)

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux AG, Maxfeldstraße 5, 90409 Nürnberg, Germany
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