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From: kenj@yarra.oz.au (Ken McDonell)
Newsgroups: comp.sys.pyramid,gnu.gcc.bug
Subject: Re: assembler problem with gcc on Pyramid
Keywords: gcc, pyramid, ISIS, cvt
Message-ID: <64654@yarra.oz.au>
Date: 7 Aug 90 01:43:37 GMT
References: <1990Aug5.034045.2636@monu6.cc.monash.edu.au> <1990Aug06.071459.26116@comp.vuw.ac.nz>
Followup-To: comp.sys.pyramid
Organization: Pyramid Technology Corp PL, Melb., Australia
Lines: 38

jonathan@comp.vuw.ac.nz (Jonathan) writes:


>In article <1990Aug5.034045.2636@monu6.cc.monash.edu.au> rdt201x@monu6.cc.monash.edu.au (mr  c.m. greif) writes:
[ stuff deleted ... see my earlier posting re. original problem ]

>The OSx 5.0 assembler seems to be saying that,  on ISIS machines,
>the cvtfw and cvtfd instructions clobber their source operand, and
>that therefore the source operand of these instructions may not
>overlap the destination operand. I know how to fix GCC for
>these particular instructions.  Follow-ups on the reported bug should
>be posted to gnu.gcc.bug.

>But I do not know if there are any other instructions that have
>similar restrictions on the ISIS architecture. Plausible candidates
>are cvtdw, cvtdf, and perhaps fixed-to-float conversions.  ...
>...  Can someone
>from Pyramid please answer this?

I'll try.  The 6 instructions that are subject to source-destination
conflict are as follows ...
     cvtwf
     cvtwd
     cvtfw
     cvtfd
     cvtdw
     cvtdf

The conditions under which the conflict arises are
a. S1 class, (r1 equal to r2) or (rx non-zero and rx equal to r2), or
b. S2 class, (r1 non-zero or rx non zero) and
	     ((r1 equals r2 and rx zero) or rx equals r2)

Hope this helps.
-- 
Ken McDonell			  E-mail:     kenj@pyramid.com kenj@yarra.oz.au
Performance Analysis Group	  Phone:      +61 3 820 0711
Pyramid Technology Corporation	  Disclaimer: I speak for me alone, of course.