[Bug target/81616] Update -mtune=generic for the current Intel and AMD processors

[andrewm.roberts at sky dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81616

--- Comment #29 from Andrew Roberts <andrewm.roberts at sky dot com> ---
And rerunning all the tests for matrix.c on Ryzen using:
-march=$amarch -mtune=$amtune -mprefer-vector-width=none -mno-fma -O3

The winners were:
mult took 118145 clocks -march=broadwell -mtune=broadwell
mult took 118912 clocks -march=core-avx2 -mtune=core-avx2

Top -mtune=znver1
mult took 121845 clocks -march=core-avx2 -mtune=znver1
mult took 129241 clocks -march=znver1 -mtune=znver1

And the bottom of the list no longer has a cluster of -mtune= btverX, bdverX,
znver1

Worst cases:
mult took 253400 clocks -march=x86-64 -mtune=haswell
mult took 254006 clocks -march=bonnell -mtune=westmere
mult took 254624 clocks -march=bonnell -mtune=silvermont
mult took 258577 clocks -march=bonnell -mtune=nehalem
mult took 260612 clocks -march=bonnell -mtune=corei7
mult took 277789 clocks -march=nocona -mtune=nano-x4

---------

And rerunning all the tests for matrix.c on Ryzen using:
-march=$amarch -mtune=$amtune -mprefer-vector-width=none -mno-fma -mno-avx2
-Ofast

The winners were:
mult took 116405 clocks -march=broadwell -mtune=broadwell
mult took 117314 clocks -march=ivybridge -mtune=haswell
mult took 117551 clocks -march=broadwell -mtune=bdver2

Top znver1:
mult took 119951 clocks -march=knl -mtune=znver1
mult took 120442 clocks -march=znver1 -mtune=znver1

Worst cases:
mult took 239640 clocks -march=nehalem -mtune=bdver3
mult took 240623 clocks -march=athlon64-sse3 -mtune=silvermont
mult took 241143 clocks -march=eden-x2 -mtune=nano-2000
mult took 241547 clocks -march=core2 -mtune=intel
mult took 241870 clocks -march=nehalem -mtune=bdver2
mult took 248251 clocks -march=nocona -mtune=intel

The differences between broadwell and znver1 is within the margin of error I
would suggest, with these options.