[PATCH] D118979: [AArch64] Set maximum VF with shouldMaximizeVectorBandwidth

[JinGu Kang via Phabricator via llvm-commits]

jaykang10 added a comment.

In D118979#3310637 <https://reviews.llvm.org/D118979#3310637>, @paulwalker-arm wrote:

> In D118979#3310625 <https://reviews.llvm.org/D118979#3310625>, @jaykang10 wrote:
>
>> In D118979#3310489 <https://reviews.llvm.org/D118979#3310489>, @paulwalker-arm wrote:
>>
>>> So I'm wondering why we don't just control the functionality with a default off command line flag.  That way it's available for testing, including unit-tests, until such a point where code generation is at a point where is makes sense to default it to on. Is this a terribly idea?
>>
>> There is an option `-vectorizer-maximize-bandwidth` to control the functionality in LV.
>>
>>   static cl::opt<bool> MaximizeBandwidth(
>>       "vectorizer-maximize-bandwidth", cl::init(false), cl::Hidden,
>>       cl::desc("Maximize bandwidth when selecting vectorization factor which "
>>                "will be determined by the smallest type in loop."));
>
> Oh sure, but that affects all targets.  Whereas I thought here we're talking about finding a migration path to enable it by default for AArch64 only.

We could add similar option to `AArch64TargetTransformInfo.cpp` and use it in the `shouldMaximizeVectorBandwidth` of AArch64.


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https://reviews.llvm.org/D118979