Re: [PING] [PATCH] Fix asm X constraint (PR inline-asm/59155)

[Jeff Law <law@redhat.com>]

On 06/06/2016 11:04 AM, Vladimir Makarov wrote:
> On 06/06/2016 09:32 AM, Bernd Edlinger wrote:
>> Ping...
>>
>> see https://gcc.gnu.org/ml/gcc-patches/2016-05/msg02010.html
>>
>>
> Thank you for working on the PR and sorry for the delay with LRA part of
> review.
>
> Change in lra-constraints.c is ok for me with the following change.
> Instead of just
>
> -          curr_alt[nop] = NO_REGS;
> +          curr_alt[nop] = ALL_REGS;
>            CLEAR_HARD_REG_SET (curr_alt_set[nop]);
>
> I'd like to see
>
> -          curr_alt[nop] = NO_REGS;
> +          curr_alt[nop] = ALL_REGS;
> -           CLEAR_HARD_REG_SET (curr_alt_set[nop]);
> +             COPY_HARD_REG_SET (curr_alt_set[nop],
> reg_class_contents[ALL_REGS]);
>
> Also I don't see /* { dg-do compile } */ in the tests (I don't know what
> dejagnu does when there is no any dejagnu actions in the test).
> But with the addition '/* { dg-do compile } */' the test pr59155-2.c is
> ok for me too.
>
> As for recog.c, I can not approve this as I am not a maintainer of it.
> I only can say that the code looks questionable to me.
I think the question on the recog part is a matter of how we choose to 
interpret what the "X" constraint means.

Does it literally mean accept anything, or accept some subset expressions?

I tend to think the former, which means that things like 
reg_overlap_mentioned_p or its callers have to be bullet-proofed.

jeff