llvm dev - Aug 2014 - [LLVMdev] tablegen pattern

Hi Guys, 

I have a taget instruction which take a vec4 and returns a vec4.( say
instruction  “vec4:$dst mod( vec4:$src)"  )
And I want to use it to match i an  ir instruction/intrinsic function( say
" float:$dst  llvm.irmod( vec4:$src)"   which takes a vec4, output a
float.

I think the procedure is:  when  I see the intrinsic llvm.irmod, I need to call 
"extractlt( mod($src), 0)”,

So I tried to define a pattern “ def Pat<( i32 ( llvm.irmod vf432:$src)),
(extractelt( mod v4f32:$src ), 0)>”,  but it reports ERROR”  Cannot use
“extractelt” in an output pattern”.

I knew I can easily do it via lowering operation by separating the “extractelt”
node out. But can I do it via tablgen?


Best

kevin


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On 08/11/2014 02:24 PM, kewuzhang wrote:
> Hi Guys,
>
> I have a taget instruction which take a vec4 and returns a vec4.( say 
> instruction  "vec4:$dst mod( vec4:$src)"  )
> And I want to use it to match i an  ir instruction/intrinsic function( 
> say " float:$dst  llvm.irmod( vec4:$src)"   which takes a vec4,
output
> a float.
>
> I think the procedure is:  when  I see the intrinsic llvm.irmod, I 
> need to call  "extractlt( mod($src), 0)",
>
> So I tried to define a pattern " def Pat<( i32 ( llvm.irmod 
> vf432:$src)), (extractelt( mod v4f32:$src ), 0)>",  but it 
> reports*ERROR"  Cannot use "extractelt" in an output
pattern".*
> *
> *
> I knew I can easily do it via lowering operation by separating 
> the "extractelt" node out. But can I do it via tablgen?
You want the machine equivalent of the extract element, which will 
probably be something like (EXTRACT_SUBREG (mod $src), sub0)
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On Aug 11, 2014, at 5:32 PM, Matt Arsenault <Matthew.Arsenault at amd.com>
wrote:
> On 08/11/2014 02:24 PM, kewuzhang wrote:
>> Hi Guys, 
>> 
>> I have a taget instruction which take a vec4 and returns a vec4.( say
instruction  “vec4:$dst mod( vec4:$src)"  )
>> And I want to use it to match i an  ir instruction/intrinsic function(
say " float:$dst  llvm.irmod( vec4:$src)"   which takes a vec4, output
a float.
>> 
>> I think the procedure is:  when  I see the intrinsic llvm.irmod, I need
to call  "extractlt( mod($src), 0)”,
>> 
>> So I tried to define a pattern “ def Pat<( i32 ( llvm.irmod
vf432:$src)), (extractelt( mod v4f32:$src ), 0)>”,  but it reports ERROR” 
Cannot use “extractelt” in an output pattern”.
>> 
>> I knew I can easily do it via lowering operation by separating the
“extractelt” node out. But can I do it via tablgen?
> You want the machine equivalent of the extract element, which will probably
be something like (EXTRACT_SUBREG (mod $src), sub0)

tks, "machine equivalent” works, 


kevin
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