cgen: reduce write calls (string_builder + gen.c)

[felipensp]

This PR aims to reduce calls to g.writeln(), g.write(), sb.write_string(), sb.writeln().

_{Huly®: V_0.6-21059}

[spytheman]

The standard deviations (σ) in the above screenshot are very big, relative to the measured change. The measurements are not reliable, when that happens.

Can you redo them, on a machine, that is quiet, without other background tasks, so that the σ can be lower?

Another way would be to run v repeat with a higher -r N (the default is 10), and -a 5 for example (i.e. discard the 5 highest results, which are most likely caused by background activity/scheduling overhead on your system). That however will be slower to run, due to the increased repetitions.

[felipensp]

The standard deviations (σ) in the above screenshot are very big, relative to the measured change. The measurements are not reliable, when that happens.

Can you redo them, on a machine, that is quiet, without other background tasks, so that the σ can be lower?

Another way would be to run v repeat with a higher -r N (the default is 10), and -a 5 for example (i.e. discard the 5 highest results, which are most likely caused by background activity/scheduling overhead on your system). That however will be slower to run, due to the increased repetitions.

Not a good machine for that. hehe But I'll try get better results. Thanks for the advices.

[medvednikov]

@spytheman did you manage to get reliable stats? Old code is more readable.

[spytheman]

@spytheman did you manage to get reliable stats? Old code is more readable.

@medvednikov, yes, the results from a more quiet machine are below.

The TLDR is that they are inconclusive - the performance effect is not consistently positive.

It however reduced the generated C code for V itself with (6052 - 6047) = 5KB, so I decided to merge it.

#1 16:28:18 ^ use_write2_and_writeln2_in_cgen /v/oo>v run .github/workflows/compare_pr_to_master.v 
Current git branch: use_write2_and_writeln2_in_cgen, commit: b2ac2ed
    Compiling new V executables from PR branch: use_write2_and_writeln2_in_cgen, commit: b2ac2ed ...
V self compiling (-g -o v2)...
V built successfully as executable "v".
CPU: 2.83s      Real: 2.54s     Elapsed: 0:02.54        RAM: 420780KB   ./v -g self
CPU: 2.71s      Real: 2.40s     Elapsed: 0:02.40        RAM: 395052KB   ./v -o vnew1 cmd/v
CPU: 2.69s      Real: 2.40s     Elapsed: 0:02.40        RAM: 394680KB   ./vnew1 -o vnew2 cmd/v
CPU: 2.70s      Real: 2.40s     Elapsed: 0:02.40        RAM: 394716KB   ./vnew2 -o vnew cmd/v
Switched to branch 'master'
Your branch is behind 'origin/master' by 13 commits, and can be fast-forwarded.
  (use "git pull" to update your local branch)
    Compiling old V executables from branch: master, commit: 7a0febb ...
V self compiling (-g -o v2)...
V built successfully as executable "v".
CPU: 2.84s      Real: 2.54s     Elapsed: 0:02.54        RAM: 421376KB   ./v -g self
CPU: 2.64s      Real: 2.35s     Elapsed: 0:02.35        RAM: 395096KB   ./v -o vold1 cmd/v
CPU: 2.64s      Real: 2.40s     Elapsed: 0:02.40        RAM: 395408KB   ./vold1 -o vold2 cmd/v
CPU: 2.64s      Real: 2.37s     Elapsed: 0:02.37        RAM: 395036KB   ./vold2 -o vold cmd/v
Switched to branch 'use_write2_and_writeln2_in_cgen'
    Measuring at PR branch: use_write2_and_writeln2_in_cgen, commit: b2ac2ed ...
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  1                                                                                                                                  
    1   -1.9% 1.02x faster 115.8ms ± σ:   0.7ms, 115.3ms…116.8ms `./vnew -check-syntax examples/hello_world.v`
 >  2         base         118.0ms ± σ:   0.5ms, 117.3ms…118.4ms `./vold -check-syntax examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  2                                                                                                                                  
 >  1         base         116.1ms ± σ:   0.9ms, 115.3ms…117.4ms `./vold -check-syntax examples/hello_world.v`
    2   +1.5% 1.02x slower 117.9ms ± σ:   0.1ms, 117.8ms…118.0ms `./vnew -check-syntax examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  3                                                                                                                                  
 >  1         base         115.7ms ± σ:   1.4ms, 113.8ms…117.2ms `./vold -check-syntax examples/hello_world.v`
    2   +1.9% 1.02x slower 117.9ms ± σ:   0.1ms, 117.8ms…118.1ms `./vnew -check-syntax examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  1                                                                                                                                  
 >  1         base         166.6ms ± σ:   0.3ms, 166.3ms…166.9ms `./vold -check        examples/hello_world.v`
    2   +0.3% 1.00x slower 167.1ms ± σ:   0.9ms, 166.4ms…168.4ms `./vnew -check        examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  2                                                                                                                                  
 >  1         base         166.6ms ± σ:   0.4ms, 166.2ms…167.1ms `./vold -check        examples/hello_world.v`
    2   +1.8% 1.02x slower 169.6ms ± σ:   1.0ms, 168.1ms…170.4ms `./vnew -check        examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  3                                                                                                                                  
    1   -0.3% 1.00x faster 167.7ms ± σ:   1.5ms, 166.4ms…169.8ms `./vnew -check        examples/hello_world.v`
 >  2         base         168.2ms ± σ:   0.8ms, 167.1ms…169.0ms `./vold -check        examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  1                                                                                                                                  
    1   -1.4% 1.01x faster 212.9ms ± σ:   1.7ms, 211.0ms…215.2ms `./vnew -o    hw.c    examples/hello_world.v`
 >  2         base         216.0ms ± σ:   1.6ms, 214.1ms…218.0ms `./vold -o    hw.c    examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  2                                                                                                                                  
    1   -1.6% 1.02x faster 212.0ms ± σ:   1.5ms, 210.3ms…213.9ms `./vnew -o    hw.c    examples/hello_world.v`
 >  2         base         215.6ms ± σ:   1.1ms, 214.3ms…217.1ms `./vold -o    hw.c    examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  3                                                                                                                                  
 >  1         base         216.8ms ± σ:   1.0ms, 215.7ms…218.1ms `./vold -o    hw.c    examples/hello_world.v`
    2   +0.1% 1.00x ~same~ 217.0ms ± σ:   1.2ms, 215.4ms…218.2ms `./vnew -o    hw.c    examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  1                                                                                                                                  
    1   -1.9% 1.02x faster 243.4ms ± σ:   3.3ms, 239.0ms…246.8ms `./vnew -o    hw      examples/hello_world.v`
 >  2         base         248.0ms ± σ:   1.5ms, 246.0ms…249.6ms `./vold -o    hw      examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  2                                                                                                                                  
    1   -1.1% 1.01x faster 244.0ms ± σ:   2.1ms, 242.0ms…247.0ms `./vnew -o    hw      examples/hello_world.v`
 >  2         base         246.8ms ± σ:   2.2ms, 243.9ms…249.2ms `./vold -o    hw      examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  3                                                                                                                                  
    1   -0.6% 1.01x faster 245.9ms ± σ:   2.6ms, 242.6ms…249.1ms `./vnew -o    hw      examples/hello_world.v`
 >  2         base         247.5ms ± σ:   1.5ms, 245.5ms…249.1ms `./vold -o    hw      examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  1                                                                                                                                  
 >  1         base         907.4ms ± σ:   1.5ms, 906.2ms…909.5ms `./vold -check-syntax cmd/v`
    2   +0.7% 1.01x slower 913.6ms ± σ:   2.2ms, 911.1ms…916.4ms `./vnew -check-syntax cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  2                                                                                                                                  
    1   -0.5% 1.00x faster 908.9ms ± σ:   2.4ms, 905.6ms…911.3ms `./vnew -check-syntax cmd/v`
 >  2         base         913.4ms ± σ:   0.2ms, 913.1ms…913.7ms `./vold -check-syntax cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  3                                                                                                                                  
 >  1         base         912.1ms ± σ:   1.0ms, 910.7ms…913.1ms `./vold -check-syntax cmd/v`
    2   +0.0% 1.00x ~same~ 912.4ms ± σ:   2.5ms, 909.7ms…915.6ms `./vnew -check-syntax cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  1                                                                                                                                  
 >  1         base         1518.5ms ± σ:   2.5ms, 1515.2ms…1521.4ms `./vold -check        cmd/v`
    2   +0.6% 1.01x slower 1527.5ms ± σ:   2.6ms, 1523.8ms…1529.4ms `./vnew -check        cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  2                                                                                                                                  
 >  1         base         1519.4ms ± σ:   2.6ms, 1515.8ms…1521.3ms `./vold -check        cmd/v`
    2   +0.4% 1.00x slower 1526.1ms ± σ:   1.3ms, 1524.7ms…1527.9ms `./vnew -check        cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  3                                                                                                                                  
 >  1         base         1512.8ms ± σ:   2.0ms, 1510.7ms…1515.4ms `./vold -check        cmd/v`
    2   +0.7% 1.01x slower 1523.0ms ± σ:   1.2ms, 1521.5ms…1524.5ms `./vnew -check        cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  1                                                                                                                                  
 >  1         base         1946.4ms ± σ:   1.5ms, 1945.0ms…1948.5ms `./vold -o    ov.c    cmd/v`
    2   +0.4% 1.00x slower 1954.0ms ± σ:   6.8ms, 1944.6ms…1960.2ms `./vnew -o    nv.c    cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  2                                                                                                                                  
 >  1         base         1946.2ms ± σ:   1.4ms, 1944.7ms…1948.1ms `./vold -o    ov.c    cmd/v`
    2   +0.3% 1.00x slower 1952.1ms ± σ:   5.4ms, 1947.3ms…1959.7ms `./vnew -o    nv.c    cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  3                                                                                                                                  
 >  1         base         1945.9ms ± σ:   4.2ms, 1939.9ms…1949.3ms `./vold -o    ov.c    cmd/v`
    2   +0.3% 1.00x slower 1950.9ms ± σ:   3.4ms, 1947.1ms…1955.3ms `./vnew -o    nv.c    cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  1                                                                                                                                  
 >  1         base         2375.2ms ± σ:   6.7ms, 2369.9ms…2384.8ms `./vold -o    ov      cmd/v`
    2   +0.8% 1.01x slower 2393.6ms ± σ:   3.7ms, 2388.5ms…2396.9ms `./vnew -o    nv      cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  2                                                                                                                                  
 >  1         base         2379.6ms ± σ:   3.5ms, 2375.3ms…2384.0ms `./vold -o    ov      cmd/v`
    2   +0.6% 1.01x slower 2392.7ms ± σ:   9.0ms, 2380.0ms…2399.4ms `./vnew -o    nv      cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  3                                                                                                                                  
 >  1         base         2369.9ms ± σ:   3.8ms, 2364.5ms…2373.1ms `./vold -o    ov      cmd/v`
    2   +0.6% 1.01x slower 2383.9ms ± σ:   1.6ms, 2381.6ms…2385.1ms `./vnew -o    nv      cmd/v`
Done.
#0 16:37:46 ^ use_write2_and_writeln2_in_cgen /v/oo>
#0 16:38:07 ^ use_write2_and_writeln2_in_cgen /v/oo>
#0 16:38:07 ^ use_write2_and_writeln2_in_cgen /v/oo>
#0 16:38:07 ^ use_write2_and_writeln2_in_cgen /v/oo>
#0 16:38:07 ^ use_write2_and_writeln2_in_cgen /v/oo>v run .github/workflows/compare_pr_to_master.v -prod
Current git branch: use_write2_and_writeln2_in_cgen, commit: b2ac2ed
    Compiling new V executables from PR branch: use_write2_and_writeln2_in_cgen, commit: b2ac2ed ...
V self compiling (-g -o v2)...
V built successfully as executable "v".
CPU: 2.81s      Real: 2.52s     Elapsed: 0:02.52        RAM: 420820KB   ./v -g self
CPU: 2.69s      Real: 2.39s     Elapsed: 0:02.39        RAM: 394680KB   ./v -o vnew1 cmd/v
CPU: 2.68s      Real: 2.38s     Elapsed: 0:02.38        RAM: 394592KB   ./vnew1 -o vnew2 cmd/v
CPU: 2.77s      Real: 2.48s     Elapsed: 0:02.48        RAM: 395068KB   ./vnew2 -o vnew cmd/v
CPU: 96.69s     Real: 99.41s    Elapsed: 1:39.41        RAM: 417720KB   ./vnew -prod -o vnew_prod cmd/v
Switched to branch 'master'
Your branch is behind 'origin/master' by 13 commits, and can be fast-forwarded.
  (use "git pull" to update your local branch)
    Compiling old V executables from branch: master, commit: 7a0febb ...
V self compiling (-g -o v2)...
V built successfully as executable "v".
CPU: 2.82s      Real: 2.53s     Elapsed: 0:02.53        RAM: 421256KB   ./v -g self
CPU: 2.67s      Real: 2.38s     Elapsed: 0:02.38        RAM: 395040KB   ./v -o vold1 cmd/v
CPU: 2.65s      Real: 2.37s     Elapsed: 0:02.37        RAM: 395456KB   ./vold1 -o vold2 cmd/v
CPU: 2.63s      Real: 2.36s     Elapsed: 0:02.36        RAM: 394860KB   ./vold2 -o vold cmd/v
CPU: 96.88s     Real: 99.41s    Elapsed: 1:39.41        RAM: 417632KB   ./vold -prod -o vold_prod cmd/v
Switched to branch 'use_write2_and_writeln2_in_cgen'
    Measuring at PR branch: use_write2_and_writeln2_in_cgen, commit: b2ac2ed ...
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  1                                                                                                                                  
    1   -0.1% 1.00x ~same~  43.7ms ± σ:   0.3ms,  43.3ms… 43.9ms `./vnew_prod -check-syntax examples/hello_world.v`
 >  2         base          43.7ms ± σ:   0.0ms,  43.7ms… 43.7ms `./vold_prod -check-syntax examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  2                                                                                                                                  
    1   -0.7% 1.01x faster  43.2ms ± σ:   0.4ms,  42.8ms… 43.7ms `./vnew_prod -check-syntax examples/hello_world.v`
 >  2         base          43.5ms ± σ:   0.1ms,  43.4ms… 43.6ms `./vold_prod -check-syntax examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  3                                                                                                                                  
    1   -1.2% 1.01x faster  43.2ms ± σ:   0.6ms,  42.4ms… 43.7ms `./vnew_prod -check-syntax examples/hello_world.v`
 >  2         base          43.7ms ± σ:   0.4ms,  43.1ms… 44.0ms `./vold_prod -check-syntax examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  1                                                                                                                                  
    1   -2.2% 1.02x faster  60.3ms ± σ:   0.1ms,  60.2ms… 60.5ms `./vnew_prod -check        examples/hello_world.v`
 >  2         base          61.7ms ± σ:   1.4ms,  60.6ms… 63.6ms `./vold_prod -check        examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  2                                                                                                                                  
 >  1         base          60.4ms ± σ:   0.6ms,  59.5ms… 61.1ms `./vold_prod -check        examples/hello_world.v`
    2   +0.8% 1.01x slower  60.8ms ± σ:   0.6ms,  60.3ms… 61.8ms `./vnew_prod -check        examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  3                                                                                                                                  
 >  1         base          60.5ms ± σ:   0.2ms,  60.3ms… 60.7ms `./vold_prod -check        examples/hello_world.v`
    2   +0.2% 1.00x slower  60.6ms ± σ:   0.2ms,  60.4ms… 60.7ms `./vnew_prod -check        examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  1
 >  1         base          83.7ms ± σ:   2.7ms,  80.7ms… 87.3ms `./vold_prod -o    hw.c    examples/hello_world.v`
    2   +4.8% 1.05x slower  87.7ms ± σ:   1.0ms,  86.4ms… 88.6ms `./vnew_prod -o    hw.c    examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  2
    1   -2.5% 1.03x faster  85.1ms ± σ:   1.7ms,  82.7ms… 86.8ms `./vnew_prod -o    hw.c    examples/hello_world.v`
 >  2         base          87.3ms ± σ:   1.2ms,  86.2ms… 89.0ms `./vold_prod -o    hw.c    examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  3
    1   -0.5% 1.01x faster  86.0ms ± σ:   1.2ms,  84.7ms… 87.6ms `./vnew_prod -o    hw.c    examples/hello_world.v`
 >  2         base          86.4ms ± σ:   1.4ms,  84.5ms… 87.6ms `./vold_prod -o    hw.c    examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  1
    1   -4.8% 1.05x faster 114.8ms ± σ:   0.7ms, 114.2ms…115.8ms `./vnew_prod -o    hw      examples/hello_world.v`
 >  2         base         120.7ms ± σ:   0.8ms, 119.5ms…121.5ms `./vold_prod -o    hw      examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  2
 >  1         base         119.6ms ± σ:   0.4ms, 119.1ms…119.9ms `./vold_prod -o    hw      examples/hello_world.v`
    2   +0.0% 1.00x ~same~ 119.6ms ± σ:   0.2ms, 119.4ms…120.0ms `./vnew_prod -o    hw      examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  3
    1   -0.9% 1.01x faster 117.3ms ± σ:   2.1ms, 114.5ms…119.6ms `./vnew_prod -o    hw      examples/hello_world.v`
 >  2         base         118.4ms ± σ:   3.2ms, 114.1ms…121.4ms `./vold_prod -o    hw      examples/hello_world.v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  1
 >  1         base         324.2ms ± σ:   1.0ms, 323.0ms…325.5ms `./vold_prod -check-syntax cmd/v`
    2   +0.5% 1.00x slower 325.6ms ± σ:   2.0ms, 322.8ms…327.3ms `./vnew_prod -check-syntax cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  2
    1   -0.3% 1.00x faster 323.8ms ± σ:   1.7ms, 322.1ms…326.1ms `./vnew_prod -check-syntax cmd/v`
 >  2         base         324.9ms ± σ:   0.5ms, 324.2ms…325.3ms `./vold_prod -check-syntax cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  3
    1   -1.0% 1.01x faster 324.1ms ± σ:   1.1ms, 322.5ms…324.9ms `./vnew_prod -check-syntax cmd/v`
 >  2         base         327.4ms ± σ:   2.7ms, 324.1ms…330.9ms `./vold_prod -check-syntax cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  1
    1   -0.6% 1.01x faster 528.2ms ± σ:   1.4ms, 526.8ms…530.1ms `./vnew_prod -check        cmd/v`
 >  2         base         531.6ms ± σ:   1.4ms, 530.0ms…533.4ms `./vold_prod -check        cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  2
    1   -0.6% 1.01x faster 528.7ms ± σ:   1.4ms, 527.4ms…530.6ms `./vnew_prod -check        cmd/v`
 >  2         base         532.0ms ± σ:   2.5ms, 528.4ms…534.0ms `./vold_prod -check        cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  3
    1   -0.3% 1.00x faster 529.2ms ± σ:   0.6ms, 528.4ms…529.6ms `./vnew_prod -check        cmd/v`
 >  2         base         530.9ms ± σ:   2.2ms, 528.0ms…533.4ms `./vold_prod -check        cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  1
 >  1         base         753.0ms ± σ:   3.0ms, 749.1ms…756.4ms `./vold_prod -o    ov.c    cmd/v`
    2   +0.1% 1.00x ~same~ 753.5ms ± σ:   4.0ms, 747.8ms…756.9ms `./vnew_prod -o    nv.c    cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  2
 >  1         base         750.5ms ± σ:   2.5ms, 747.1ms…752.8ms `./vold_prod -o    ov.c    cmd/v`
    2   +0.5% 1.00x slower 753.9ms ± σ:   2.1ms, 751.7ms…756.7ms `./vnew_prod -o    nv.c    cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  3
    1   -0.5% 1.00x faster 752.3ms ± σ:   0.4ms, 751.8ms…752.6ms `./vnew_prod -o    nv.c    cmd/v`
 >  2         base         756.0ms ± σ:   0.5ms, 755.4ms…756.7ms `./vold_prod -o    ov.c    cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  1
    1   -1.0% 1.01x faster 1176.9ms ± σ:   5.4ms, 1169.3ms…1181.4ms `./vnew_prod -o    nv      cmd/v`
 >  2         base         1188.9ms ± σ:   4.1ms, 1183.4ms…1193.0ms `./vold_prod -o    ov      cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  2
    1   -0.1% 1.00x ~same~ 1179.5ms ± σ:   4.6ms, 1173.6ms…1184.9ms `./vnew_prod -o    nv      cmd/v`
 >  2         base         1181.0ms ± σ:   5.5ms, 1173.8ms…1187.1ms `./vold_prod -o    ov      cmd/v`
Summary after 1 series x 10 runs (%s are relative to first command, or `base`), discard maxs:  7, repeat:  3
 >  1         base         1181.2ms ± σ:   6.3ms, 1174.2ms…1189.5ms `./vold_prod -o    ov      cmd/v`
    2   +0.3% 1.00x slower 1184.8ms ± σ:   2.1ms, 1182.3ms…1187.4ms `./vnew_prod -o    nv      cmd/v`
Done.
#0 16:45:37 ^ use_write2_and_writeln2_in_cgen /v/oo>

[spytheman]

Old code is more readable.

I agree.