PPC: Improve code generation for mixed-precision reciprocal sqrt

The DAGCombine logic that recognized a/sqrt(b) and transformed it into
a multiplication by the reciprocal sqrt did not handle cases where the
sqrt and the division were separated by an fpext or fptrunc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178801 91177308-0d34-0410-b5e6-96231b3b80d8
Rename the current PPC BCL definition to BCLalways

BCL is normally a conditional branch-and-link instruction, but has
an unconditional form (which is used in the SjLj code, for example).
To make clear that this BCL instruction definition is specifically
the special unconditional form (which does not meaningfully take
a condition-register input), rename it to BCLalways.

No functionality change intended.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178803 91177308-0d34-0410-b5e6-96231b3b80d8
typo

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178804 91177308-0d34-0410-b5e6-96231b3b80d8