[X86] Add test cases for (shift x (and y, (BitWidth-1))) to the BMI2 shift test.

We should use SHLX and similar instructions for these patterns, but we currently don't.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@308590 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed