[Bug target/122018] x86 doesn't use BTS bitmanip instruction to both set and test bit

[liuhongt at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122018

--- Comment #4 from Hongtao Liu <liuhongt at gcc dot gnu.org> ---
(In reply to Hongtao Liu from comment #3)
> Maybe we should have a peephole for that, to optimize bts + bt to just bts.

And similar for btc/btr?

#include <stdbool.h>
void g();
int f(int a, int b) {
    bool t = false;
    t = a & (1 << b);
    a = a | (1 << b);
    if(t)
        g();
    return a;
}

int f1(int a, int b) {
    bool t = false;
    t = a & (1 << b);
    a = a ^ (1 << b);
    if(t)
        g();
    return a;
}

int f2(int a, int b) {
    bool t = false;
    t = a & (1 << b);
    a = a & ~(1 << b);
    if(t)
        g();
    return a;
}