[LLVMdev] How to do bitcast for double to <2 x double>

[mats petersson]

So, you need to bitcast `pinst` to a pointer to Vector of double,
since it (I hope for your sake) is a pointer to integer. What you are
trying to do is bitcast a pointer into a vector, which probably will
lead to an assert or "bad code that doesn't work".

--
Mats

On 15 April 2015 at 21:57, zhi chen <zchenhn at gmail.com> wrote:
> What I want to do is to change the pInst from : 2%= load double* %1, align 8
> to 2% = load < 2 x double>* %1, align 16, where <2 x double> should be two
> double identical double values that is same as the one in the previous
> instruction
>
> Instruction* ScalarToVectorLoad(Instruction* pInst) {
>   Value *loadValue = pInst->getOperand(0);
>   Instruction *newLoad;   //this one should be 2% = load < 2 x double>* %1
>
>   BitCastInst *scalarToVector = new BitCastInst(loadValue,
> VectorType::get(Type::getDoubleTy(currF->getContext()), 2),
> "vectorizedLoad", pInst);
>   newLoad = new LoadInst(); //to be implemented...
>   return newLoad;
> }
>
> On Wed, Apr 15, 2015 at 1:03 PM, mats petersson <mats at planetcatfish.com>
> wrote:
>>
>> Create a type that is a "vector (array) of 2 double", and then a
>> pointer to that. Now use bitcast your on double pointer to that
>> pointer type you've created, and then create a load...
>>
>> If you need more help, it would help if you post the code you are working
>> on...
>>
>> --
>> Mats
>>
>> On 15 April 2015 at 19:51, zhi chen <zchenhn at gmail.com> wrote:
>> > How can I write code to generate IR for:
>> > %2 = bitcast double* %1 to <2 x double>*.
>> > %3 = load <2 x double>* %2, align 16
>> > Basically, it is similar to x86 _mm_load_pd1 intrinsics.
>> >
>> > Thanks,
>> > Zhi
>> >
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>
>