On Wed, Oct 2, 2019 at 5:30 PM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote: > > Replace 'cmp reg, 0' with 'test reg, reg' for comparisons against > zero. Saves 1 byte of instruction encoding per occurrence. The flag > results of test 'reg, reg' are identical to 'cmp reg, 0' in all > cases except for AF which we don't use/care about. In terms of > macro-fusibility in combination with a subsequent conditional jump > instruction, both have the same properties for the jumps used in > the JIT translation. For example, same JITed Cilium program can > shrink a bit from e.g. 12,455 to 12,317 bytes as tests with 0 are > used quite frequently. > > Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> Acked-by: Song Liu <songliubraving@xxxxxx>
