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Re: Patch to implement rotates by zero
- From: Eric Christopher <echristo at redhat dot com>
- To: "Maciej W. Rozycki" <macro at ds2 dot pg dot gda dot pl>
- Cc: cgd at broadcom dot com, rsandifo at redhat dot com, binutils at sources dot redhat dot com
- Date: 20 Aug 2002 10:07:27 -0700
- Subject: Re: Patch to implement rotates by zero
- References: <Pine.GSO.3.96.1020820150718.8700D-100000@delta.ds2.pg.gda.pl>
On Tue, 2002-08-20 at 06:19, Maciej W. Rozycki wrote:
> On 17 Aug 2002 cgd@broadcom.com wrote:
>
> > AFAIK, 'sll' w/ a shift of 0 is only guaranteed to sign-extend by
> > MIPS64. I've seen no previous documentation that defined that it must
> > work that way.
>
> Well, the behaviour is defined explicitly for "sll" and "sllv" by "MIPS
> R4000 Microprocessor User's Manual" (pp. A-140, A-141), the original spec
> for the original MIPS III processor, so the assumption should be any MIPS
> III+ implementation must do them this way; otherwise it is non-compliant
> (or simply broken). There is a note on broken code generated by some
> assemblers there, though. The book is available from www.mips.com.
That's a pretty big assumption though :) I think I like it the other
way.
-eric
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