SelectionDAG: Add sext_inreg optimizations

v2: use dyn_cast
    fixup comments
v3: use cast

Reviewed-by: Matt Arsenault <arsenm2@gmail.com>
Signed-off-by: Jan Vesely <jan.vesely@rutgers.edu>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220044 91177308-0d34-0410-b5e6-96231b3b80d8
R600: Add EG to FMA test

Reviewed-by: Tom Stellard <tom@stellard.net>
Signed-off-by: Jan Vesely <jan.vesely@rutgers.edu>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220045 91177308-0d34-0410-b5e6-96231b3b80d8
Mips: Only set divrem i64 to custom on 64bit

Reviewed-by: Daniel Sanders <daniel.sanders@imgtec.com>
Signed-off-by: Jan Vesely <jan.vesely@rutgers.edu>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220046 91177308-0d34-0410-b5e6-96231b3b80d8