Re: -m68020 -fnobitfields != -mcpu32 ?

• Date: Thu, 17 Oct 1996 08:00:46 +1000 (EST)
• From:
  Timothy Potter <timbo@moshpit.air.net.au>
• Reply-To:
  Timothy Potter <timbo@moshpit.air.net.au>
• cc: crossgcc@cygnus.com
• Content-Type: TEXT/PLAIN; charset=US-ASCII
• In-Reply-To: <199610151517.KAA15076@eli.wariat.org>

On Tue, 15 Oct 1996, Robert J. Brown wrote:

> Timothy> The Motorola CPU32 is nearly a 68020 lacking only the
> Timothy> bitfield instructions and a couple of addressing modes
> Timothy> (plus a couple of extra instructions).  Gas takes an

> Try telling gcc to output assembler source code, then assembling it
> with the -m68020 -fnobitfields options.  This should flag as errors
> any place where the unsupported instructions occurred.  I suspect this
> will be relatively infrequent.  You can either patch the assembler
> code, of edit the C source to generate different instructions.  I know
> it kludgy, but its pragmatic.

I've had a closer look at the m68k back end, and according to CPP1_SPEC 
(or maybe it is ASM_SPEC) -m68332 seems to be exactly the same as 
defining -m68020 and -fnobitfields.  I guess this means that whoever 
wrote this bit of the back end knows that no illegal instructions will be 
generated.  I don't know whether I'll go through the machine description 
file and check this - it will probably take too much time.  Maybe someone 
on a gnu.gcc.* newsgroup will know the answer.


Tim.

> 
> -- 
> --------  "And there came a writing to him from Elijah"  [2Ch 21:12]  --------
> Robert Jay Brown III  rj@eli.wariat.org  http://eli.wariat.org  1 847 705-0424
> Elijah Laboratories Inc.;  37 South Greenwood Avenue;  Palatine, IL 60067-6328
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• Re: -m68020 -fnobitfields != -mcpu32 ?
• From: "Robert J. Brown" <rj@eli.wariat.org>

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