Adam Nemet d07494f102 [DAGCombiner] Distribute TRUNC through AND in rotation amount
This is already done for shifts.  Allow it for rotations as well. E.g.:

   (rotl:i32 x, (trunc (and y, 31))) -> (rotl:i32 x, (and (trunc y), 31))

Use the newly factored-out distributeTruncateThroughAnd.

With this patch and some X86.td tweaks we should be able to remove redundant
masking of the rotation amount like in the example above.  HW implicitly
performs this masking.

The testcase will be added as part of the X86 patch.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203316 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-07 23:56:30 +00:00
..