[PATCH 04/11] cris: Update unexpected empty split condition

Kewen.Lin linkw@linux.ibm.com
Fri Jun 4 03:25:28 GMT 2021

on 2021/6/4 上午12:12, Hans-Peter Nilsson wrote:
>> From: Kewen.Lin <linkw@linux.ibm.com>
>> Date: Thu, 3 Jun 2021 07:45:57 +0200
>> on 2021/6/2 Hans-Peter Nilsson wrote:
>>>> From: Kewen Lin <linkw@linux.ibm.com>
>>>> Date: Wed, 2 Jun 2021 07:04:54 +0200
>>>> gcc/ChangeLog:
>>>> 	* config/cris/cris.md (*addi_reload): Fix empty split condition.
>>>> -  ""
>>>> +  "&& 1"
>>> Ok, thanks, if only for all-round consistency.
>>> In preparation for a warning for an empty condition?  I'm
>>> usually all for .md-warnings, but I'm not sure about the
>>> benefit of that one, though.  Those "&& 1" look...hackish.
>> Thanks!  Yeah, the 01/11 patch aims to raise one error message
>> for the define_insn_and_split whose split condition is empty
>> while insn condition isn't.  In most cases, when we write one
>> define_insn_and_split we want the splitting only to take effect
>> while we see the define_insn matching happen (insn cond holds),
>> but if we leave the split condition empty, the splitting will
>> be done always, it could result in some unexpected consequence.
>> Mostly this is unintentional.
> It certainly was in the patch above!
>>  The error message is to avoid
>> people to make it unintentionally.
>> As you may have seen from the discussion under the 00/11 thread,
>> we will probably end up with some other solution, so I will hold
>> the changes for the ports, sorry for wasting your time and the
>> other port maintainers'.
> No worries: I certainly don't consider it wasted and I'd
> prefer to have the patch above committed sooner than the
> conclusion of that discussion.  (If you don't get to it,
> I'll do it, after a round of testing.)

Thanks for your help on testing!

> If you're considering further target patches to adjust for
> eventually changed semantics in the define_insn_and_split
> split-condition, then whatever trivial patch to cris.md that
> gets the effect of the one you sent is preapproved.

OK, thanks again!


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