Don't use a potentially expensive shift if all we want is one set bit.

No functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186095 91177308-0d34-0410-b5e6-96231b3b80d8
Add back code for supporting old mingw versions. Should bring the bots back.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186096 91177308-0d34-0410-b5e6-96231b3b80d8
Use SmallVectorImpl& instead of SmallVector to avoid repeating small vector size.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186098 91177308-0d34-0410-b5e6-96231b3b80d8
PPCDAGToDAGISel::isRunOfOnes should return false on zero

This fixes a bug (found by csmith) at -O0 where we attempt to create a RLWIMI
with an out-of-range operand. Most uses of the isRunOfOnes function are guarded
by a condition that the value is not zero. This was not true in two places, and
in both places a zero input would result in an out-of-rage MB value (= 32).

To fix this, isRunOfOnes returns false on a zero input (and I've remove one
now-redundant guard).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186101 91177308-0d34-0410-b5e6-96231b3b80d8