[PATCH] D59723: [NewPassManager] Adding pass tuning options: loop vectorize.

[Alina Sbirlea via Phabricator via llvm-commits]

asbirlea marked an inline comment as done.
asbirlea added inline comments.


================
Comment at: lib/Transforms/Vectorize/LoopVectorize.cpp:288-293
+// Current defaults:
+  : InterleaveOnlyWhenForced(false),
+    VectorizeOnlyWhenForced(false) {}
+// Expected usage of defaults:
+//: InterleaveOnlyWhenForced(!SetLoopsInterleaved),
+//  VectorizeOnlyWhenForced(!RunLoopVectorization) {}
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chandlerc wrote:
> Not really sure what this commenting structure is trying to convey, but I don't think you want to use commented out code. I'd just write prose in a comment on the method that describes what's going on here.
I *really* don't want to leave this as is. It was meant as a discussion point. Sorry for not being clearer.

I wanted to use the "expected defaults", where interleaving and vectorization are enabled by default, but vectorization is disabled by default in the old pass manager.
Why is this?
[The interleaving is set to false already in the old pass manager, the `DisableUnrollLoops` variable.]

I guess I am asking why are having vectorization disabled by default in the old pass manager, but enabled by default when creating the LoopVectorizePass with no params?

We also have a strange (to me) behavior in `opt.cpp:351`: 
- if an opt-specific option to `disable-loop-vectorize` is set, then it's disabled.
- Otherwise, if it's explicitly enabled with `-vectorize-loops` or  `-loop-vectorize` (there's two?), then it's enabled.
- Otherwise, it assumes it's disabled (that's the default here...), and enables it if ` OptLevel > 1 && SizeLevel < 2`.
So I can't really change the default to enable vectorization, without some changes here.


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D59723/new/

https://reviews.llvm.org/D59723