Merging r367412 and r367429:

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r367412 | rksimon | 2019-07-31 13:35:01 +0200 (Wed, 31 Jul 2019) | 1 line

[X86][AVX] Add reduced test case for PR42833
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r367429 | rksimon | 2019-07-31 14:55:39 +0200 (Wed, 31 Jul 2019) | 3 lines

[X86][AVX] Ensure chained subvector insertions are the same size (PR42833)

Before combining insert_subvector(insert_subvector(vec, sub0, c0), sub1, c1) patterns, ensure that the subvectors are all the same type. On AVX512 targets especially we might have a mixture of 128/256 subvector insertions.
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llvm-svn: 369362