Merging r181286:
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r181286 | arnolds | 2013-05-06 21:37:05 -0700 (Mon, 06 May 2013) | 7 lines

LoopVectorize: getConsecutiveVector must respect signed arithmetic

We were passing an i32 to ConstantInt::get where an i64 was needed and we must
also pass the sign if we pass negatives numbers. The start index passed to
getConsecutiveVector must also be signed.

Should fix PR15882.
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_33@181455 91177308-0d34-0410-b5e6-96231b3b80d8