[PATCH] D140365: [SelectionDAG] Correctly widen bitcast of scalar to vector for big endian

[Nemanja Ivanovic via Phabricator via llvm-commits]

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For big endian targets that need a node such as this:
`v2i8 = bitcast i16:tN`

legalized by:

1. Promoting the `i16` input type
2. Widening the `v2i8` result type

The result will be incorrect because the legalizer will promote the input type and then produce a `scalar_to_vector` from that wider type to a vector of N elements of that type. That puts the desired bits into the low order bytes of element zero and they need to be in the high order bytes on big endian systems.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D140365

Files:
  llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
  llvm/test/CodeGen/PowerPC/vec_conv_i8_to_fp32_elts.ll
  llvm/test/CodeGen/PowerPC/widen-vec-correctly-be.ll

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