PR 13722 candidate fix

[Zack Weinberg]

Richard Henderson <rth@redhat.com> writes:

> On Thu, Jan 22, 2004 at 11:43:40PM -0800, Zack Weinberg wrote:
>> +	    out[0] = adjust_automodify_address
>> +	      (in, DImode, gen_rtx_POST_INC (Pmode, base), 0);
>> +
>> +	    if (GET_CODE (XEXP (offset, 1)) == REG)
>> +	      {
>> +		rtx reg = XEXP (offset, 1);
>> +		/* Tweak the index register, then emit the first move as
>> +		   a POST_INC and the second as the original POST_MODIFY.  */
>> +		emit_insn (GEN_FCN (add_optab->handlers[GET_MODE (reg)].insn_code)
>> +			   (reg, reg, GEN_INT (-8)));
>
> You can't modify the POST_MODIFY operand.
> You need to modify the address register a third time, ie.

Duh, because the index register value might be needed again.  This
isn't true for constant POST_MODIFY, though, right?

(Gets me out of having to dig around in add_optab, though, yay.)

zw