Eli Friedman b4b8b0cc90 Add a target-specific branchless method for double-width relational
comparisons on x86.  Essentially, the way this works is that SUB+SBB sets
the relevant flags the same way a double-width CMP would.

This is a substantial improvement over the generic lowering in LLVM. The output
is also shorter than the gcc-generated output; I haven't done any detailed
benchmarking, though.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127852 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-18 02:34:11 +00:00
..
2011-03-17 18:42:05 +00:00