Summary:
This patch fixes the following issues in visitInsertElementInst:
1. Bail out for scalable type when analysis requires fixed size number of vector elements.
2. Use cast<FixedVectorType> to get vector number of elements. This ensure assertion
on scalable vector type.
3. For scalable type, avoid folding a chain of insertelement into splat:
insertelt(insertelt(insertelt(insertelt X, %k, 0), %k, 1), %k, 2) ...
->
shufflevector(insertelt(X, %k, 0), undef, zero)
The length of scalable vector is unknown at compile-time, therefore we don't know if
given insertelement sequence is valid for splat.
Reviewers: sdesmalen, efriedma, spatel, nikic
Reviewed By: sdesmalen, efriedma
Subscribers: tschuett, hiraditya, rkruppe, psnobl, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D78895
Huihui Zhang