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Re: [m68k] fix denorm mult
- From: Andreas Schwab <schwab at suse dot de>
- To: Nathan Sidwell <nathan at codesourcery dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Tue, 31 Jan 2006 17:08:30 +0100
- Subject: Re: [m68k] fix denorm mult
- References: <43DF81FE.9030806@codesourcery.com>
Nathan Sidwell <nathan@codesourcery.com> writes:
> The 'movew imm,reg' instruction only sets the bottom 16 bits of reg. This led
> to a problem in mulsf3 when the second operand was a denormal -- we'd end up
> with an iteration count of 0xffff0017 instead of 0x17.
The real bug is that DBcc was not correctly replaced for the coldfire.
DBcc is a word operation, but for the coldfire it was replaced by a long
operation. Thus on the m68k everything works correctly.
> I went through lb1sf68 auditing all the uses of 'movew imm', replacing
> them with moveq where appropriate.
On the other hand, moveq is faster (on some models) and smaller than
movew, so this is ok.
Andreas.
--
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
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