[Bug target/115749] Non optimal assembly for integer modulo by a constant on x86-64 CPUs

[lingling.kong7 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115749

--- Comment #11 from kong lingling <lingling.kong7 at gmail dot com> ---
After adjusted rtx_cost of imulq for COST_N_INSNS (4) to COST_N_INSNS (3), I
tested the benchmark on Sierra Forest machine based on gcc trunk, and the
algorithm with 2 multiplications is 2% faster. For Spec2017 performance
improvement is around 0.2%  (1 copy,  -march=native -Ofast -funroll-loops -flto
/ -mtune=generic -O2 -march=x86-64-v3).