[PATCH] D79053: [SVE] Fix invalid use of VectorType::getNumElements() in Value Tracking

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

> So your proposal is that for scalable vectors, DemandedElts can have any value?

We'd ignore the value, yes.

Probably, for the sake of assertions etc., it would make sense to require it to be `APInt(1, 1)`, as opposed to actually making it unconstrained.  But that's not really important.



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Comment at: llvm/lib/Analysis/ValueTracking.cpp:1946
+  if (isa<ConstantVector>(V) && !EC->Scalable) {
+    const auto *CV = cast<ConstantVector>(V);
+    assert((CV->getNumOperands() == EC->Min) &&
----------------
ctetreau wrote:
> ctetreau wrote:
> > efriedma wrote:
> > > No reason to check Scalable; a ConstantVector is never scalable anyway.
> > ConstantVector::getSplat() can return a scalable ConstantVector
> I guess it actually returns a ConstantExpr?
Yes,  The fact that getSplat is an API on ConstantVector is a historical accident, I think.


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