[RTL-ifcvt] Improve conditional select ops on immediates
* ifcvt.c (noce_try_store_flag_constants): Make logic of the case
when diff == STORE_FLAG_VALUE or diff == -STORE_FLAG_VALUE more
explicit. Prefer to add the flag whenever possible.
(noce_process_if_block): Try noce_try_store_flag_constants before
noce_try_cmove.
* gcc.target/aarch64/csel_bfx_1.c: New test.
* gcc.target/aarch64/csel_imms_inc_1.c: Likewise.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@226491 138bc75d-0d04-0410-961f-82ee72b054a4