Add benchmarks for `runtime.memory_*` comparison procedures

tests/benchmark/runtime/benchmark_runtime.odin

@@ -0,0 +1,227 @@
+package benchmark_runtime
+
+import "base:runtime"
+import "core:fmt"
+import "core:log"
+import "core:testing"
+import "core:strings"
+import "core:text/table"
+import "core:time"
+
+RUNS_PER_SIZE :: 2500
+
+sizes := [?]int {
+	7, 8, 9,
+	15, 16, 17,
+	31, 32, 33,
+	63, 64, 65,
+	95, 96, 97,
+	128,
+	256,
+	512,
+	1024,
+	4096,
+	1024 * 1024,
+}
+
+// These are the normal, unoptimized algorithms.
+
+plain_memory_equal :: proc "contextless" (x, y: rawptr, n: int) -> bool {
+	switch {
+	case n == 0: return true
+	case x == y: return true
+	}
+	a, b := ([^]byte)(x), ([^]byte)(y)
+	length := uint(n)
+
+	for i := uint(0); i < length; i += 1 {
+		if a[i] != b[i] {
+			return false
+		}
+	}
+	return true
+}
+
+plain_memory_compare :: proc "contextless" (a, b: rawptr, n: int) -> int #no_bounds_check {
+	switch {
+	case a == b:   return 0
+	case a == nil: return -1
+	case b == nil: return +1
+	}
+
+	x := uintptr(a)
+	y := uintptr(b)
+	n := uintptr(n)
+
+	SU :: size_of(uintptr)
+	fast := n/SU + 1
+	offset := (fast-1)*SU
+	curr_block := uintptr(0)
+	if n < SU {
+		fast = 0
+	}
+
+	for /**/; curr_block < fast; curr_block += 1 {
+		va := (^uintptr)(x + curr_block * size_of(uintptr))^
+		vb := (^uintptr)(y + curr_block * size_of(uintptr))^
+		if va ~ vb != 0 {
+			for pos := curr_block*SU; pos < n; pos += 1 {
+				a := (^byte)(x+pos)^
+				b := (^byte)(y+pos)^
+				if a ~ b != 0 {
+					return -1 if (int(a) - int(b)) < 0 else +1
+				}
+			}
+		}
+	}
+
+	for /**/; offset < n; offset += 1 {
+		a := (^byte)(x+offset)^
+		b := (^byte)(y+offset)^
+		if a ~ b != 0 {
+			return -1 if (int(a) - int(b)) < 0 else +1
+		}
+	}
+
+	return 0
+}
+
+plain_memory_compare_zero :: proc "contextless" (a: rawptr, n: int) -> int #no_bounds_check {
+	x := uintptr(a)
+	n := uintptr(n)
+
+	SU :: size_of(uintptr)
+	fast := n/SU + 1
+	offset := (fast-1)*SU
+	curr_block := uintptr(0)
+	if n < SU {
+		fast = 0
+	}
+
+	for /**/; curr_block < fast; curr_block += 1 {
+		va := (^uintptr)(x + curr_block * size_of(uintptr))^
+		if va ~ 0 != 0 {
+			for pos := curr_block*SU; pos < n; pos += 1 {
+				a := (^byte)(x+pos)^
+				if a ~ 0 != 0 {
+					return -1 if int(a) < 0 else +1
+				}
+			}
+		}
+	}
+
+	for /**/; offset < n; offset += 1 {
+		a := (^byte)(x+offset)^
+		if a ~ 0 != 0 {
+			return -1 if int(a) < 0 else +1
+		}
+	}
+
+	return 0
+}
+
+run_trial_size_cmp :: proc(p: proc "contextless" (rawptr, rawptr, int) -> $R, size: int, idx: int, runs: int, loc := #caller_location) -> (timing: time.Duration) {
+	left  := make([]u8, size)
+	right := make([]u8, size)
+	defer {
+		delete(left)
+		delete(right)
+	}
+
+	right[idx] = 0x01
+
+	accumulator: int
+
+	watch: time.Stopwatch
+
+	time.stopwatch_start(&watch)
+	for _ in 0..<runs {
+		result := p(&left[0], &right[0], size)
+		when R == bool {
+			assert(result == false, loc = loc)
+			accumulator += 1
+		} else when R == int {
+			assert(result == -1, loc = loc)
+			accumulator += result
+		}
+	}
+	time.stopwatch_stop(&watch)
+	timing = time.stopwatch_duration(watch)
+
+	log.debug(accumulator)
+	return
+}
+
+run_trial_size_zero :: proc(p: proc "contextless" (rawptr, int) -> int, size: int, idx: int, runs: int, loc := #caller_location) -> (timing: time.Duration) {
+	data := make([]u8, size)
+	defer delete(data)
+
+	data[idx] = 0x01
+
+	accumulator: int
+
+	watch: time.Stopwatch
+
+	time.stopwatch_start(&watch)
+	for _ in 0..<runs {
+		result := p(&data[0], size)
+		assert(result == 1, loc = loc)
+		accumulator += result
+	}
+	time.stopwatch_stop(&watch)
+	timing = time.stopwatch_duration(watch)
+
+	log.debug(accumulator)
+	return
+}
+
+run_trial_size :: proc {
+	run_trial_size_cmp,
+	run_trial_size_zero,
+}
+
+
+bench_table :: proc(algo_name: string, plain, simd: $P) {
+	string_buffer := strings.builder_make()
+	defer strings.builder_destroy(&string_buffer)
+
+	tbl: table.Table
+	table.init(&tbl)
+	defer table.destroy(&tbl)
+
+	table.aligned_header_of_values(&tbl, .Right, "Algorithm", "Size", "Iterations", "Scalar", "SIMD", "SIMD Relative (%)", "SIMD Relative (x)")
+
+	for size in sizes {
+		// Place the non-zero byte somewhere in the middle.
+		needle_index := size / 2
+
+		plain_timing := run_trial_size(plain, size, needle_index, RUNS_PER_SIZE)
+		simd_timing  := run_trial_size(simd,  size, needle_index, RUNS_PER_SIZE)
+
+		_plain := fmt.tprintf("%8M",  plain_timing)
+		_simd  := fmt.tprintf("%8M",  simd_timing)
+		_relp  := fmt.tprintf("%.3f %%", f64(simd_timing) / f64(plain_timing) * 100.0)
+		_relx  := fmt.tprintf("%.3f x",  1 / (f64(simd_timing) / f64(plain_timing)))
+
+		table.aligned_row_of_values(
+			&tbl,
+			.Right,
+			algo_name,
+			size, RUNS_PER_SIZE, _plain, _simd, _relp, _relx)
+	}
+
+	builder_writer := strings.to_writer(&string_buffer)
+
+	fmt.sbprintln(&string_buffer)
+	table.write_plain_table(builder_writer, &tbl)
+
+	my_table_string := strings.to_string(string_buffer)
+	log.info(my_table_string)
+}
+
+@test
+benchmark_memory_procs :: proc(t: ^testing.T) {
+	bench_table("memory_equal", plain_memory_equal, runtime.memory_equal)
+	bench_table("memory_compare", plain_memory_compare, runtime.memory_compare)
+	bench_table("memory_compare_zero", plain_memory_compare_zero, runtime.memory_compare_zero)
+}