As it's causing some bot failures (and per request from kbarton).
This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@358546 91177308-0d34-0410-b5e6-96231b3b80d8
Do simplifications common to all shift instructions based on the amount shifted:
1. If the shift amount is known larger than the bitwidth, the result is undefined.
2. If the valid bits of the shift amount are all known to be 0, it's a shift by zero, so the shift operand is the result.
Note that we could generalize the shift-by-zero transform into a shift-by-constant if all of the valid bits in the shift
amount are known, but that would have to be done in InstCombine rather than here because it would mean we need to create
a new shift instruction.
Differential Revision: http://reviews.llvm.org/D19874
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@269114 91177308-0d34-0410-b5e6-96231b3b80d8
Eric Christopher