Everything except long/ulong is handled by just casting to the next larger type,
doing the math and then shifting/casting the result.
For 64-bit types, we break the high/low parts of each operand apart, and do
a FOIL-based multiplication.
v2:
Discard the stack-overflow implementation due to copyright concerns.
- The implementation is still FOIL-based, but discards the previous code.
Reviewed-by: Tom Stellard <thomas.stellard@amd.com>
llvm-svn: 188684