1.
[(set GR32:$dst, (add GR32:$src1, GR32:$src2)),
 (modify EFLAGS)]
This indicates the source pattern expects the instruction would produce 2 values. The first is the result of the addition. The second is an implicit definition in register EFLAGS.
2.
def : Pat<(parallel (addc GR32:$src1, GR32:$src2), (modify EFLAGS)), ()>
Similar to #1 except this is used for def : Pat patterns.

llvm-svn: 41897