linux-mips
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r4600 flag

To: "Kevin D. Kissell" <kevink@mips.com>, Ralf Baechle <ralf@uni-koblenz.de>
Subject: r4600 flag
From: Pete Popov <ppopov@pacbell.net>
Date: Mon, 30 Jul 2001 22:55:35 -0700
Cc: linux-mips@oss.sgi.com
Reply-to: ppopov@pacbell.net
Sender: owner-linux-mips@oss.sgi.com
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:0.9.2) Gecko/20010628
in arch/mips/Makefile, we use the -mcpu=r4600 flag for MIPS32. What's interesting is that the use of this flag can cause the toolchain to generate incorrect code. For example:

la k0, 1f
nop
1: nop


The la macro is split into a lui and a daddiu. The daddiu is not correct for a mips32 cpu. Getting rid of the -mcpu=4600 fixes the problem and the daddiu is then changed addiu.

Is there a truly correct -mcpu option for a mips32 cpu?

Pete


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