Default build: disable-native?

[jodavies]

Due to the issue of #704 cropping up (again), I wonder if it makes sense to not enable march native for the default build? Actually on my system (AMD Zen4) I would tentatively suggest that it makes tform ~1% slower?

test	default/--disable-native
trace	1.02 ± 0.02
mincer	1.02 ± 0.00
minceex	1.00 ± 0.00
mass-fact	1.02 ± 0.00
forcer	1.01 ± 0.00
forcer-exp	1.01 ± 0.01
mbox1l	0.98 ± 0.03
color	1.02 ± 0.01
chromatic	1.00 ± 0.00

[tueda]

Somehow, I got similar results... -march=native is slower than the default (-march=x86_64 or something like that)??
(CPU=16, Alder Lake, gcc-15.2, flint-3.3.1 (configure option: --host=$(gcc -dumpmachine)), Ubuntu 25.04 on Docker; host: Ubuntu 20.04):

Running trace
Benchmark 1: /form/build/sources/tform
  Time (mean ± σ):      1.402 s ±  0.064 s    [User: 21.222 s, System: 0.192 s]
  Range (min … max):    1.249 s …  1.537 s    60 runs

Benchmark 2: /form/build-disable-native/sources/tform
  Time (mean ± σ):      1.372 s ±  0.076 s    [User: 20.730 s, System: 0.192 s]
  Range (min … max):    1.222 s …  1.539 s    60 runs

Summary
  /form/build-disable-native/sources/tform ran
    1.02 ± 0.07 times faster than /form/build/sources/tform


Running minceex
Benchmark 1: /form/build/sources/tform
  Time (mean ± σ):     48.559 s ±  0.266 s    [User: 539.331 s, System: 1.533 s]
  Range (min … max):   48.065 s … 48.992 s    12 runs

Benchmark 2: /form/build-disable-native/sources/tform
  Time (mean ± σ):     47.921 s ±  0.198 s    [User: 532.118 s, System: 1.544 s]
  Range (min … max):   47.668 s … 48.420 s    12 runs

Summary
  /form/build-disable-native/sources/tform ran
    1.01 ± 0.01 times faster than /form/build/sources/tform


Running forcer
Benchmark 1: /form/build/sources/tform
  Time (mean ± σ):     163.715 s ±  1.036 s    [User: 826.400 s, System: 20.714 s]
  Range (min … max):   162.511 s … 165.165 s    6 runs

Benchmark 2: /form/build-disable-native/sources/tform
  Time (mean ± σ):     163.140 s ±  0.758 s    [User: 831.020 s, System: 20.810 s]
  Range (min … max):   162.092 s … 164.003 s    6 runs

Summary
  /form/build-disable-native/sources/tform ran
    1.00 ± 0.01 times faster than /form/build/sources/tform


Running forcer-exp
Benchmark 1: /form/build/sources/tform
  Time (mean ± σ):     87.863 s ±  0.540 s    [User: 553.178 s, System: 19.795 s]
  Range (min … max):   86.800 s … 88.742 s    8 runs

Benchmark 2: /form/build-disable-native/sources/tform
  Time (mean ± σ):     86.217 s ±  0.542 s    [User: 549.549 s, System: 20.428 s]
  Range (min … max):   85.342 s … 87.199 s    8 runs

Summary
  /form/build-disable-native/sources/tform ran
    1.02 ± 0.01 times faster than /form/build/sources/tform


Running mbox1l
Benchmark 1: /form/build/sources/tform
  Time (mean ± σ):     12.944 s ±  0.260 s    [User: 82.939 s, System: 0.543 s]
  Range (min … max):   12.495 s … 13.542 s    30 runs

Benchmark 2: /form/build-disable-native/sources/tform
  Time (mean ± σ):     12.869 s ±  0.309 s    [User: 83.262 s, System: 0.520 s]
  Range (min … max):   12.070 s … 13.437 s    30 runs

Summary
  /form/build-disable-native/sources/tform ran
    1.01 ± 0.03 times faster than /form/build/sources/tform


Running color
Benchmark 1: /form/build/sources/tform
  Time (mean ± σ):     11.961 s ±  0.261 s    [User: 139.446 s, System: 1.493 s]
  Range (min … max):   11.465 s … 12.678 s    30 runs

Benchmark 2: /form/build-disable-native/sources/tform
  Time (mean ± σ):     11.526 s ±  0.232 s    [User: 134.363 s, System: 1.464 s]
  Range (min … max):   11.166 s … 12.183 s    30 runs

Summary
  /form/build-disable-native/sources/tform ran
    1.04 ± 0.03 times faster than /form/build/sources/tform


Running chromatic
Benchmark 1: /form/build/sources/tform
  Time (mean ± σ):     80.767 s ±  0.654 s    [User: 813.736 s, System: 2.251 s]
  Range (min … max):   79.928 s … 81.815 s    8 runs

Benchmark 2: /form/build-disable-native/sources/tform
  Time (mean ± σ):     79.725 s ±  0.328 s    [User: 829.202 s, System: 2.260 s]
  Range (min … max):   79.281 s … 80.105 s    8 runs

Summary
  /form/build-disable-native/sources/tform ran
    1.01 ± 0.01 times faster than /form/build/sources/tform