[llvm] [DAG] Fold extract_subvector(insert_subvector(x, y, c1), c2) --> extract_subvector(y,c2-c1) (PR #87925)

[Steven Johnson via llvm-commits]

steven-johnson wrote:

Echoing a comment from a specific commit:

Just a heads up, looks like this broke Halide SVE2 tests here: https://github.com/halide/Halide/blob/main/test/correctness/simd_op_check_sve2.cpp#L585.

Assertion triggered:

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:7061 in SDValue llvm::SelectionDAG::getNode(unsigned int, const SDLoc &, EVT, SDValue, SDValue, const SDNodeFlags): (VT.isFixedLengthVector() || N1VT.isScalableVector()) && "Cannot extract a scalable vector from a fixed length vector!"

I'm investigating now to see if this is a bug on the Halide side or the LLVM side, will update here as I get more info.

https://github.com/llvm/llvm-project/pull/87925