[PATCH] D114799: [SLP]Improve vectorization of cmp instructions sequences.

[Han Zhu via Phabricator via llvm-commits]

zhuhan0 added a comment.

In D114799#3226181 <https://reviews.llvm.org/D114799#3226181>, @ABataev wrote:

> In D114799#3226154 <https://reviews.llvm.org/D114799#3226154>, @zhuhan0 wrote:
>
>> Hi, we observed ~9% increase in `SLP.NumVectorInstructions` on SPEC's 508.namd_r with this change, using llvm-test-suite. I noticed the number is not reported here. Curious did you also see the same result? We tested on an Intel Skylake.
>
> I ttied with -march=native on Skylake, but did not see wuch results.

I see. `-march=native` is the difference. I can reproduce a no change on namd with that flag. However, the number of vector instructions decreased significantly compared with removing that flag, which I found counter-intuitive.

With `-march=native`

|                           | With this patch | Without this patch |
| SLP.NumVectorInstructions | 4446            | 4446               |
|

Without `-march=native`

|                           | With this patch | Without this patch |
| SLP.NumVectorInstructions | 5939            | 5473               |


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