Merging r258690:

Merging r258690:
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r258690 | jamesm | 2016-01-25 14:49:36 +0000 (Mon, 25 Jan 2016) | 7 lines

[DemandedBits] Fix computation of demanded bits for ICmps

The computation of ICmp demanded bits is independent of the individual operand being evaluated. We simply return a mask consisting of the minimum leading zeroes of both operands.

We were incorrectly passing "I" to ComputeKnownBits - this should be "UserI->getOperand(0)". In cases where we were evaluating the 1th operand, we were taking the minimum leading zeroes of it and itself.

This should fix PR26266.
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_38@258805 91177308-0d34-0410-b5e6-96231b3b80d8