Mark test/TableGen/listconcat.td as XFAIL:vg_leak. llvm-tblgen is ignorant of vg_leak.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208337 91177308-0d34-0410-b5e6-96231b3b80d8
test: fix test on Windows

When building on Windows, the default target is Windows.  Windows on ARM does
not support ARM mode compilation, resulting in test failures.  Simply specify a
triple to ensure that we are testing the correct behaviour.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208340 91177308-0d34-0410-b5e6-96231b3b80d8
[X86] Add target specific combine rules to fold SSE2/AVX2 packed arithmetic shift intrinsics.

This patch teaches the backend how to combine packed SSE2/AVX2 arithmetic shift
intrinsics.

The rules are:
 - Always fold a packed arithmetic shift by zero to its first operand;
 - Convert a packed arithmetic shift intrinsic dag node into a ISD::SRA only if
   the shift count is known to be smaller than the vector element size.

This patch also teaches to function 'getTargetVShiftByConstNode' how fold
target specific vector shifts by zero.

Added two new tests to verify that the DAGCombiner is able to fold
sequences of SSE2/AVX2 packed arithmetic shift calls.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208342 91177308-0d34-0410-b5e6-96231b3b80d8