[cfe-dev] [llvm-dev] generate vectorized code

[Rail Shafigulin via cfe-dev]

On Wed, Mar 16, 2016 at 6:38 PM, Mehdi Amini <mehdi.amini at apple.com> wrote:

>
> On Mar 16, 2016, at 5:38 PM, Rail Shafigulin <rail at esenciatech.com> wrote:
>
> On Wed, Mar 16, 2016 at 11:48 AM, Mehdi Amini <mehdi.amini at apple.com>
> wrote:
>
>> Hi Rail,
>>
>> Two hints to begin with:
>>
>> 1) Makes sure you example is vectorized on X86 for example
>> 2) Is your target correctly overriding the TTI (declaring the vector
>> register size for example) so that the vectorizer can kicks-in (see
>> X86TTIImpl::getRegisterBitWidth for instance). Alternatively you can test
>> the SLP vectorizer by passing to clang: -mllvm -slp-max-reg-size -mllvm 512
>>  (I don't see an equivalent option for the loop vectorizer though).
>>
>> Well, it sort of worked. I added a getRegisterBitWidth(...) but then I
> got this error:
>
> fatal error: error in backend: Cannot select: 0x5e949a8: v4i32 =
> BUILD_VECTOR 0x5e91ae8, 0x5e91ae8, 0x5e91ae8, 0x5e91ae8 [ORD=16] [ID=16]
>   0x5e91ae8: i32 = Constant<0> [ID=5]
>   0x5e91ae8: i32 = Constant<0> [ID=5]
>   0x5e91ae8: i32 = Constant<0> [ID=5]
>   0x5e91ae8: i32 = Constant<0> [ID=5]
>
> What am I missing?
>
>
> I means that you have a vectorized IR that reached your backend, but your
> backend is not ready to deal with all the vector constructs in
> SelectionDAG.
> You need to express how to legalize/select the BUILD_VECTOR in
> SelectionDAG to instructions that your target supports. You can look at
> what other targets are doing.
>
> --
> Mehdi
>
>
Thanks for the reply. Do you mind pointing out the files I need to look at?
I looked at X86SelectionDAGInfo.cpp as well as ARMSelectionDAGInfo.cpp but
couldn't find anything relevant.

-- 
Rail Shafigulin
Software Engineer
Esencia Technologies
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