refactor: do more early returns

[mkroening]

This PR makes the kernel use early returns in more places as appropriate. This makes the code more readable, as we avoid indentation creep and don't put the happy path into ifs. Handling the exceptional cases earlier and be done with them should also be easier for the brain's stack when reading this code.

This is a rather big commit because of the indentation changes. Semantically, the changes should be much smaller. All changes should be independent.

[github-actions]

Benchmark Results

Details

Benchmark	Current: 907e825	Previous: 258bff0	Performance Ratio
startup_benchmark Build Time	100.00 s	98.63 s	1.01 ❗
startup_benchmark File Size	0.86 MB	0.86 MB	1.00 ❗
Startup Time - 1 core	0.96 s (±0.04 s)	0.94 s (±0.03 s)	1.02
Startup Time - 2 cores	0.96 s (±0.03 s)	0.95 s (±0.04 s)	1.01
Startup Time - 4 cores	0.97 s (±0.03 s)	0.97 s (±0.03 s)	1.00
multithreaded_benchmark Build Time	99.03 s	102.84 s	0.96 ❗
multithreaded_benchmark File Size	0.96 MB	0.96 MB	1.00 ❗
Multithreaded Pi Efficiency - 2 Threads	90.20 % (±8.26 %)	87.52 % (±8.51 %)	1.03
Multithreaded Pi Efficiency - 4 Threads	44.71 % (±3.75 %)	43.60 % (±3.51 %)	1.03
Multithreaded Pi Efficiency - 8 Threads	25.47 % (±1.73 %)	24.84 % (±1.86 %)	1.03
micro_benchmarks Build Time	108.50 s	112.75 s	0.96 ❗
micro_benchmarks File Size	0.97 MB	0.97 MB	1.00 ❗
Scheduling time - 1 thread	71.76 ticks (±3.84 ticks)	70.01 ticks (±3.16 ticks)	1.02
Scheduling time - 2 threads	39.03 ticks (±4.36 ticks)	39.42 ticks (±5.17 ticks)	0.99
Micro - Time for syscall (getpid)	3.02 ticks (±0.25 ticks)	2.95 ticks (±0.23 ticks)	1.02
Memcpy speed - (built_in) block size 4096	64910.17 MByte/s (±46297.10 MByte/s)	66147.09 MByte/s (±47456.43 MByte/s)	0.98
Memcpy speed - (built_in) block size 1048576	30235.12 MByte/s (±25239.01 MByte/s)	29898.56 MByte/s (±24839.33 MByte/s)	1.01
Memcpy speed - (built_in) block size 16777216	22625.09 MByte/s (±19052.90 MByte/s)	25221.14 MByte/s (±21073.26 MByte/s)	0.90
Memset speed - (built_in) block size 4096	65508.57 MByte/s (±46682.12 MByte/s)	66767.11 MByte/s (±47848.49 MByte/s)	0.98
Memset speed - (built_in) block size 1048576	31091.54 MByte/s (±25737.71 MByte/s)	30679.37 MByte/s (±25280.32 MByte/s)	1.01
Memset speed - (built_in) block size 16777216	22810.76 MByte/s (±19112.77 MByte/s)	26013.80 MByte/s (±21589.28 MByte/s)	0.88
Memcpy speed - (rust) block size 4096	56713.19 MByte/s (±41874.61 MByte/s)	57963.01 MByte/s (±42274.40 MByte/s)	0.98
Memcpy speed - (rust) block size 1048576	30258.31 MByte/s (±25306.94 MByte/s)	30131.39 MByte/s (±25149.51 MByte/s)	1.00
Memcpy speed - (rust) block size 16777216	22303.09 MByte/s (±18739.41 MByte/s)	23049.72 MByte/s (±19442.99 MByte/s)	0.97
Memset speed - (rust) block size 4096	57861.67 MByte/s (±42676.20 MByte/s)	58596.88 MByte/s (±42654.44 MByte/s)	0.99
Memset speed - (rust) block size 1048576	31128.14 MByte/s (±25814.66 MByte/s)	30929.09 MByte/s (±25590.85 MByte/s)	1.01
Memset speed - (rust) block size 16777216	22510.17 MByte/s (±18809.53 MByte/s)	23845.41 MByte/s (±20010.10 MByte/s)	0.94
alloc_benchmarks Build Time	108.72 s	110.10 s	0.99 ❗
alloc_benchmarks File Size	0.93 MB	0.93 MB	1.00 ❗
Allocations - Allocation success	100.00 %	100.00 %	1
Allocations - Deallocation success	100.00 %	100.00 %	1
Allocations - Pre-fail Allocations	100.00 %	100.00 %	1
Allocations - Average Allocation time	10599.47 Ticks (±194.01 Ticks)	10487.89 Ticks (±195.98 Ticks)	1.01
Allocations - Average Allocation time (no fail)	10599.47 Ticks (±194.01 Ticks)	10487.89 Ticks (±195.98 Ticks)	1.01
Allocations - Average Deallocation time	1207.18 Ticks (±623.08 Ticks)	1237.03 Ticks (±628.80 Ticks)	0.98
mutex_benchmark Build Time	106.01 s	103.43 s	1.02 ❗
mutex_benchmark File Size	0.96 MB	0.96 MB	1.00 ❗
Mutex Stress Test Average Time per Iteration - 1 Threads	13.70 ns (±0.67 ns)	12.92 ns (±0.56 ns)	1.06
Mutex Stress Test Average Time per Iteration - 2 Threads	16.46 ns (±0.92 ns)	16.02 ns (±0.81 ns)	1.03

This comment was automatically generated by workflow using github-action-benchmark.