Merging r327651:
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r327651 | carrot | 2018-03-15 10:49:12 -0700 (Thu, 15 Mar 2018) | 9 lines
[PPC] Avoid non-simple MVT in STBRX optimization
PR35402 triggered this case. It bswap and stores a 48bit value, current STBRX optimization transforms it into STBRX. Unfortunately 48bit is not a simple MVT, there is no PPC instruction to support it, and it can't be automatically expanded by llvm, so caused a crash.
This patch detects the non-simple MVT and returns early.
Differential Revision: https://reviews.llvm.org/D44500
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_60@329641
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