MIPS RDHWR instruction reordering

[Ian Lance Taylor]

Atsushi Nemoto <anemo@mba.ocn.ne.jp> writes:

> And with r108713 I got:
> 
> foo:
> 	.frame	$sp,0,$31		# vars= 0, regs= 0/0, args= 0, gp= 0
> 	.mask	0x00000000,0
> 	.fmask	0x00000000,0
> 	.set	noreorder
> 	.cpload	$25
> 	.set	nomacro
> 	
> 	beq	$4,$0,$L7
> 	.set	push
> 	.set	mips32r2	
> 	rdhwr	$3,$29
> 	.set	pop
> 
> 	lw	$2,%gottprel(x)($28)
> 	nop
> 	addu	$2,$2,$3
> 	lw	$2,0($2)
> 	j	$31
> 	nop
> 
> $L7:
> 	j	$31
> 	move	$2,$0
> 
> And I can not see why the commit make such a difference...

I also don't see why revision 108713 would affect this.

But I do note that this version is still bad.  The rdhwr instruction
is in the branch delay slot, and is therefore always executed.

Ian