[llvm] r230965 - SLPVectorizer: Rewrite ArrayRef slice compare to be more idiomatic.

[Benjamin Kramer]

On Mon, Mar 2, 2015 at 7:43 PM, David Blaikie <dblaikie at gmail.com> wrote:
>
>
> On Mon, Mar 2, 2015 at 7:24 AM, Benjamin Kramer <benny.kra at googlemail.com>
> wrote:
>>
>> Author: d0k
>> Date: Mon Mar  2 09:24:36 2015
>> New Revision: 230965
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=230965&view=rev
>> Log:
>> SLPVectorizer: Rewrite ArrayRef slice compare to be more idiomatic.
>>
>> NFC intended.
>>
>> Modified:
>>     llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp
>>
>> Modified: llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp?rev=230965&r1=230964&r2=230965&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp (original)
>> +++ llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp Mon Mar  2
>> 09:24:36 2015
>> @@ -3178,15 +3178,11 @@ private:
>>  /// the WeakVH array.
>>  /// Vectorization of part of the VL array may cause later values in the
>> VL array
>>  /// to become invalid. We track when this has happened in the WeakVH
>> array.
>> -static bool hasValueBeenRAUWed(ArrayRef<Value *> &VL,
>> -                               SmallVectorImpl<WeakVH> &VH,
>> -                               unsigned SliceBegin,
>> -                               unsigned SliceSize) {
>> -  for (unsigned i = SliceBegin; i < SliceBegin + SliceSize; ++i)
>> -    if (VH[i] != VL[i])
>> -      return true;
>> -
>> -  return false;
>> +static bool hasValueBeenRAUWed(ArrayRef<Value *> VL, ArrayRef<WeakVH> VH,
>> +                               unsigned SliceBegin, unsigned SliceSize) {
>> +  VL = VL.slice(SliceBegin, SliceSize);
>> +  VH = VH.slice(SliceBegin, SliceSize);
>> +  return !std::equal(VL.begin(), VL.end(), VH.begin());
>
>
> Can we not just "return VL == VH;" here?

Currently ArrayRef::operator== requires both sides to be of the same
type (here it's Value * and WeakVH which implicitly converts to Value
*). This could be solved by making it a template, but I'm not sure
about the implications of that.

- Ben

>
>>
>>  }
>>
>>  bool SLPVectorizer::vectorizeStoreChain(ArrayRef<Value *> Chain,
>>
>>
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>
>