[llvm-dev] Instruction selection pattern for intrinsic returning llvm_any_ty

[Matt Arsenault via llvm-dev]

> 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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