Hi Suwa-san,
On Tue, Sep 5, 2023 at 2:29 AM Takayuki 'January June' Suwa
<jjsuwa_sys3...@yahoo.co.jp> wrote:
>
> This patch optimizes the boolean evaluation for equality to 0 in SImode
> using the MINU (Minimum Value Unsigned) machine instruction available
> when TARGET_MINMAX is configured, for example, (x != 0) to MINU(x, 1)
> and (x == 0) to (MINU(x, 1) ^ 1).
>
> /* example */
> int test0(int x) {
> return x == 0;
> }
> int test1(int x) {
> return x != 0;
> }
>
> ;; before
> test0:
> mov.n a10, a2
> movi.n a9, 1
> movi.n a2, 0
> moveqz a2, a9, a10
> ret.n
> test1:
> mov.n a10, a2
> movi.n a9, 1
> movi.n a2, 0
> movnez a2, a9, a10
> ret.n
>
> ;; after (prereq. TARGET_MINMAX)
> test0:
> movi.n a9, 1
> minu a2, a2, a9
> xor a2, a2, a9
> ret.n
ISTM that test0 could be done with movnez in the same three instructions:
movi a9, 1
movnez a2, a9, a2
xor a2, a2, a9
> test1:
> movi.n a9, 1
> minu a2, a2, a9
> ret.n
ISTM that test1 could be done with movnez in the same two instructions:
movi a9, 1
movnez a2, a9, a2
--
Thanks.
-- Max
