[PATCH] D120223: [SLP] Fix assert from non-constant index in insertelement

[Anton Afanasyev via Phabricator via llvm-commits]

anton-afanasyev added inline comments.


================
Comment at: llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:5920-5922
+        Optional<unsigned> Idx = getInsertIndex(VU);
+        if (!Idx)
+          continue;
----------------
ABataev wrote:
> I think we need an extra check here. If the index is undefined - continue, but if the index is not constant, need to calculate the cost as extractelement+insertelement.
This is just a reversion to previous state, we can proceed with this and commit a separate patch for correct check. There is also another check we need here: that `EU.Scalar` is used as a first operand of insertelement.


================
Comment at: llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:5920-5922
+        Optional<unsigned> Idx = getInsertIndex(VU);
+        if (!Idx)
+          continue;
----------------
anton-afanasyev wrote:
> ABataev wrote:
> > I think we need an extra check here. If the index is undefined - continue, but if the index is not constant, need to calculate the cost as extractelement+insertelement.
> This is just a reversion to previous state, we can proceed with this and commit a separate patch for correct check. There is also another check we need here: that `EU.Scalar` is used as a first operand of insertelement.
As for `undef` index check, I'm not sure it should be processed specially: we still generate extractelement for `EU.Scalar` at `vectorizeTree()` stage.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D120223/new/

https://reviews.llvm.org/D120223