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Date: Mon, 18 Oct 2010 17:05:00 -0000
From:   "Maciej W. Rozycki" <macro@linux-mips.org>
To:     Richard Sandiford <rdsandiford@googlemail.com>
cc:     binutils@sourceware.org
Subject: Re: [PATCH 1/2] MIPS/GAS: Fix o32 LD to the base register
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On Mon, 18 Oct 2010, Richard Sandiford wrote:

> > Disassembly of section .text:
> >
> > 00000000 <.text>:
> >    0:	00800821 	move	at,a0
> >    4:	8c240000 	lw	a0,0(at)
> >    8:	8c250004 	lw	a1,4(at)
> 
> Why are you doing it this way, rather than reversing the loads?

 Because I've got a hole in my imagination here? :/

> Seems a shame to use $at when we don't need to.

 Indeed, although we're no better elsewhere, consider e.g.:

$ cat ld-base-1.s
	.comm	foo, 1024
	ld	$4, foo
$ as -32 -o ld-base-1.o ld-base-1.s
$ objdump -dr ld-base-1.o

ld-base-1.o:     file format elf32-tradbigmips


Disassembly of section .text:

00000000 <.text>:
   0:	3c010000	lui	at,0x0
			0: R_MIPS_HI16	foo
   4:	8c240000	lw	a0,0(at)
			4: R_MIPS_LO16	foo
   8:	8c250004	lw	a1,4(at)
			8: R_MIPS_LO16	foo
   c:	00000000	nop

where $a1 could be used in place of $at, couldn't it?

 I'll cook up something, though I only have worms to offer it would seem.

  Maciej