> On Aug 26, 2024, at 10:40 AM, Michael Matz <m...@suse.de> wrote:
>
> Hello,
>
> On Mon, 26 Aug 2024, Paul Koning wrote:
>
>>>>> 550: [--sp] = 0 sp_off = 0 {pushexthisi_const}
>>>>> 551: [--sp] = 37 sp_off = -4 {pushexthisi_const}
>>>>> 552: [--sp] = r37 sp_off = -8 {movsi_m68k2}
>>>>> 554: [--sp] = r116 - r37 sp_off = -12 {subsi3}
>>>>> 556: call sp_off = -16
>>>>>
>>>>> insn 554 doesn't match its constraints and needs some reloads:
>>>>
>>>> I think you're right in that the current code isn't correct, but the
>>>> natural question is how in the world has this worked to-date. Though I
>>>> guess targets which push arguments are a dying breed (though I would
>>>> have expected i386 to have tripped over this at some point).
>>>
>>> Yeah, I wondered as well. For things to go wrong some instructions that
>>> contain pre/post-inc/dec of the stack pointer need to have reloads in such
>>> a way that the actual SP-change sideeffect moves to a different
>>> instruction.
>>
>> I think I've seen that in the past on PDP11, and reported it, but I
>> thought that particular issue was fixed not too long after.
>
> Do you have a reference handy? I'd like to take a look, if for nothing
> else than curiosity ;-)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87944
<https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87944> which says it was fixed in
GCC 14 on 5/30/2023.
paul
