[llvm-dev] Instruction selection pattern for intrinsic returning llvm_any_ty
Matt Arsenault via llvm-dev
llvm-dev at lists.llvm.org
Wed Mar 30 03:01:04 PDT 2016
> On Mar 30, 2016, at 11:58, Mikael Holmén <mikael.holmen at ericsson.com> wrote:
>
>
>
> On 03/30/2016 11:51 AM, Matt Arsenault wrote:
>>
>>> On Mar 30, 2016, at 11:43, Mikael Holmén <mikael.holmen at ericsson.com> wrote:
>>>
>>> Hi,
>>>
>>> On 03/30/2016 11:38 AM, Matt Arsenault wrote:
>>>>
>>>>> On Mar 30, 2016, at 11:35, Mikael Holmén <mikael.holmen at ericsson.com
>>>>> <mailto:mikael.holmen at ericsson.com>> wrote:
>>>>>
>>>>> i16 (divm16_pseudo …)
>>>>>
>>>>> stuff?
>>>>>
>>>>> I've tried
>>>>> (i16, i16 (divm16_pseudo i16:$src1, i16:$src2)
>>>>> and
>>>>> ((i16, i16) (divm16_pseudo i16:$src1, i16:$src2)
>>>>> and a few other variants without managing to get it through.
>>>>>
>>>>> Thanks again,
>>>>> Mikael
>>>>
>>>> Are you trying to return multiple values?
>>>
>>> Yes, the intrisic returns a record
>>>
>>> %rec6 = type { i16, i16 }
>>>
>>> so at instructions selection the original call
>>>
>>> %_tmp3 = call %rec6 @llvm.phx.divm.u16.rec6(i16 %_tmp1, i16 %_tmp2)
>>>
>>> has been lowered to
>>>
>>> t6: i16,i16 = llvm.phx.divm.u16 TargetConstant:i16<3778>, t2, t4
>>>
>>> and the instruction I want to select also returns two values
>>>
>>> def divm16_pseudo : MyPseudoInst<
>>> (outs aNh_0_7:$dst, aNh_0_7:$dst2),
>>> (ins aNh_0_7:$src1, aNh_0_7:$src2)>;
>>>
>>> Both outs are i16.
>>>
>>> /Mikael
>>>
>>
>> The intrinsic itself should define multiple IR outputs rather than using any ty.
>
> But the intrinsic returns a record so in the input ll-file it is one result
>
> %_tmp3 = call %rec6 @llvm.phx.divm.u16.rec6(i16 %_tmp1, i16 %_tmp2)
>
> and then the return value struct is lowered to two i16:s by
This seems like a strange way to do it. Do you need it to be an arbitrary struct type for some reason? Having multiple result types that expand into a struct would be more normal
>
> SelectionDAGISel::SelectBasicBlock:
>
> // Lower the instructions. If a call is emitted as a tail call, cease emitting
> // nodes for this block.
> for (BasicBlock::const_iterator I = Begin; I != End && !SDB->HasTailCall; ++I)
> SDB->visit(*I);
>
> just prior to the selection.
>
>> I’m also not sure if tablegen currently supports patterns with multiple results
>
> Yes, me neither...
>
> /Mikael
>
>>
>> -Matt
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