Re: [PATCH] report message for operator %a on unaddressible exp

[Jiufu Guo <guojiufu@linux.ibm.com>]

Hi,

Thanks for your helpful comments!

Segher Boessenkool <segher@kernel.crashing.org> writes:

> Hi!
>
> On Mon, May 13, 2024 at 10:57:12AM +0800, Jiufu Guo wrote:
>> For PR96866, when gcc print asm code for modifier "%a" which requires
>> an address operand,
>
> It requires a *memory* operand, and it outputs its address.  This is a
> generic modifier btw (not rs6000).
Oh, yeap. it outputs the operands's address. I would update words like:
which requires an addressable operand.

>
>> while the operand is with the constraint "X" which
>> allow non-address form.  An error message would be reported to indicate
>> the invalid asm operands.
>
> "non-address form"?  Every mem has an address.
>
> But 'X' is not memory.  What is it at all?  Why do we use that when you
> *have to* have mem here?
"X" allows any thing.  This is the reason why the code is *invalid*.
Other constraints("r/m") should be better than "X" for "%a".

>
> The code you add that tests for address_operand looks wrong.  I would
> expect it to test the operand is memory, instead :-)
I understand your concern. While there is a tricky work:
before invoking print_operand_address/output_address, the orignal
operand (which would be 'mem') is stripped to it's address.
So, 'address_operand' is tested for print_operand_address is targets.

While I also wonder if "address_operand" is really needed. Because
under the condition:
```
  else if (SYMBOL_REF_P (x) || GET_CODE (x) == CONST
	   || GET_CODE (x) == LABEL_REF)
    {
```
'x' is already known, it only could be: SYMBOL_REF/LABEL_REF or CONST.
I would update the patch for this.

Thanks for your comments.

BR,
Jeff(Jiufu) Guo

>
>
> Segher