Recommit r338204 "[X86] Correct the immediate cost for 'add/sub i64 %x, 0x80000000'."

This checks in a more direct way without triggering a UBSAN error.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@338273 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed