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

[Mikael Holmén via llvm-dev]

Hi,

On my out-of-tree target I have an intrinsic

def int_phx_divm_u16 : Intrinsic<[llvm_any_ty],
                                  [llvm_i16_ty, llvm_i16_ty],
                                  [IntrNoMem]>;

that I want to translate to the following instruction during instruction 
selection:

def divm16_pseudo : MyPseudoInst<
     (outs aNh_0_7:$dst, aNh_0_7:$dst2),
     (ins aNh_0_7:$src1, aNh_0_7:$src2)>;

So I've done a pattern the same way I've done for numerous other 
intrinsics (that returns simple types like i16/i32 etc):

def : Pat<(int_phx_divm_u16 i16:$src1, i16:$src2),
           (divm16_pseudo $src1, $src2)>;

But this doesn't work for me:

anonymous_1373(src1, src2):     (divm16_pseudo:i16:i16:i16 ?:i16:$src1, 
?:i16:$src2)

error: In anonymous_1373: Type inference contradiction found, merging 
'i16' into 'Any'
def : Pat<(int_phx_divm_u16 i16:$src1, i16:$src2),
^

So is there a way I can get around this?


Before ISel the call to my intrisic looks like

   %_tmp3 = call %rec6 @llvm.phx.divm.u16.rec6(i16 %_tmp1, i16 %_tmp2)

and %rec6 is

   %rec6 = type { i16, i16 }

Then at ISel, before selection the call is lowered to

   t6: i16,i16 = llvm.phx.divm.u16 TargetConstant:i16<3778>, t2, t4

which fits nicely to my divm16_pseudo that I want to select.

Is there any way I can select this with a tablegen pattern, and not 
having to do selection "manually" in my target's 
MytargetDAGToDAGISel::Select function?

I'm having a bunch of intrisics looking like this and I'd prefer 
selecting them with patterns rather than doing much more verbose stuff 
in C++.

I've tried to look in in-tree targets for something similar but I've 
failed to find anything.

Thanks,
Mikael