On Thu, May 25, 2023 at 8:13 AM Takayuki 'January June' Suwa
<jjsuwa_sys3...@yahoo.co.jp> wrote:
>
> This patch makes try to eliminate using temporary pseudo for
> '(minus:SI (const_int) (reg:SI))' if the addition of negative constant
> value can be emitted in a single machine instruction.
>
> /* example */
> int test0(int x) {
> return 1 - x;
> }
> int test1(int x) {
> return 100 - x;
> }
> int test2(int x) {
> return 25600 - x;
> }
>
> ;; before
> test0:
> movi.n a9, 1
> sub a2, a9, a2
> ret.n
> test1:
> movi a9, 0x64
> sub a2, a9, a2
> ret.n
> test2:
> movi.n a9, 0x19
> slli a9, a9, 10
> sub a2, a9, a2
> ret.n
>
> ;; after
> test0:
> addi.n a2, a2, -1
> neg a2, a2
> ret.n
> test1:
> addi a2, a2, -100
> neg a2, a2
> ret.n
> test2:
> addmi a2, a2, -0x6400
> neg a2, a2
> ret.n
>
> gcc/ChangeLog:
>
> * config/xtensa/xtensa-protos.h (xtensa_m1_or_1_thru_15):
> New prototype.
> * config/xtensa/xtensa.cc (xtensa_m1_or_1_thru_15):
> New function.
> * config/xtensa/constraints.md (O):
> Change to use the above function.
> * config/xtensa/xtensa.md (*subsi3_from_const):
> New insn_and_split pattern.
> ---
> gcc/config/xtensa/constraints.md | 2 +-
> gcc/config/xtensa/xtensa-protos.h | 1 +
> gcc/config/xtensa/xtensa.cc | 7 +++++++
> gcc/config/xtensa/xtensa.md | 24 ++++++++++++++++++++++++
> 4 files changed, 33 insertions(+), 1 deletion(-)
Regtested for target=xtensa-linux-uclibc, no new regressions.
Committed to master.
--
Thanks.
-- Max
