Luke Lau 79435de8a5 [ConstantFold] Support scalable constant splats in ConstantFoldCastInstruction (#133207) ...

Previously only fixed vector splats were handled. This adds supports for
scalable vectors too by allowing ConstantExpr splats.

We need to add the extra V->getType()->isVectorTy() check because a
ConstantExpr might be a scalar to vector bitcast.

By allowing ConstantExprs this also allow fixed vector ConstantExprs to
be folded, which causes the diffs in
llvm/test/Analysis/ValueTracking/known-bits-from-operator-constexpr.ll
and llvm/test/Transforms/InstSimplify/ConstProp/cast-vector.ll. I can
remove them from this PR if reviewers would prefer.

Fixes #132922

2025-04-03 16:24:56 +01:00

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