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Summary

  1. Revert "[X86][SSE] Fold unpack(hop(),hop()) -> permute(hop())" (details)
Commit d43a264a5dd3c72bf9dc663551c0993921b28136 by thakis
Revert "[X86][SSE] Fold unpack(hop(),hop()) -> permute(hop())"

This reverts commit 80dee7965dffdfb866afa9d74f3a4a97453708b2.
Makes clang sometimes hang forever. See
https://bugs.chromium.org/p/chromium/issues/detail?id=1164786#c6 for a
stand-alone repro.
The file was modifiedllvm/test/CodeGen/X86/horizontal-shuffle-2.ll
The file was modifiedllvm/lib/Target/X86/X86ISelLowering.cpp