Add benchmarks for vectorized `index_*` procs

tests/benchmark/all.odin

@@ -2,3 +2,4 @@ package benchmarks
 
 @(require) import "crypto"
 @(require) import "hash"
+@(require) import "simd/util"

tests/benchmark/simd/util/benchmark_simd_util.odin

@@ -0,0 +1,117 @@
+//+build i386, amd64
+package benchmark_simd_util
+
+import "core:fmt"
+import "core:log"
+import simd_util "core:simd/util"
+import "core:testing"
+import "core:time"
+
+
+// These are the normal, unoptimized algorithms.
+
+plain_index_byte :: proc(s: []u8, c: byte) -> (res: int) #no_bounds_check {
+	for i := 0; i < len(s); i += 1 {
+		if s[i] == c {
+			return i
+		}
+	}
+	return -1
+}
+
+plain_last_index_byte :: proc(s: []u8, c: byte) -> (res: int) #no_bounds_check {
+	for i := len(s)-1; i >= 0; i -= 1 {
+		if s[i] == c {
+			return i
+		}
+	}
+	return -1
+}
+
+sizes := [?]int {
+	15, 16, 17,
+	31, 32, 33,
+	256,
+	512,
+	1024,
+	1024 * 1024,
+	1024 * 1024 * 1024,
+}
+
+run_trial_size :: proc(p: proc([]u8, byte) -> int, size: int, idx: int, warmup: int, runs: int) -> (timing: time.Duration) {
+	data := make([]u8, size)
+	defer delete(data)
+
+	for i in 0..<size {
+		data[i] = u8('0' + i % 10)
+	}
+	data[idx] = 'z'
+
+	accumulator: int
+
+	for _ in 0..<warmup {
+		accumulator += p(data, 'z')
+	}
+
+	for _ in 0..<runs {
+		start := time.now()
+		accumulator += p(data, 'z')
+		done := time.since(start)
+		timing += done
+	}
+
+	timing /= time.Duration(runs)
+
+	log.debug(accumulator)
+	return
+}
+
+HOT :: 3
+
+@test
+benchmark_plain_index_cold :: proc(t: ^testing.T) {
+	report: string
+	for size in sizes {
+		timing := run_trial_size(plain_index_byte, size, size - 1, 0, 1)
+		report = fmt.tprintf("%s\n        +++ % 8M | %v", report, size, timing)
+		timing = run_trial_size(plain_last_index_byte, size, 0, 0, 1)
+		report = fmt.tprintf("%s\n (last) +++ % 8M | %v", report, size, timing)
+	}
+	log.info(report)
+}
+
+@test
+benchmark_plain_index_hot :: proc(t: ^testing.T) {
+	report: string
+	for size in sizes {
+		timing := run_trial_size(plain_index_byte, size, size - 1, HOT, HOT)
+		report = fmt.tprintf("%s\n        +++ % 8M | %v", report, size, timing)
+		timing = run_trial_size(plain_last_index_byte, size, 0, HOT, HOT)
+		report = fmt.tprintf("%s\n (last) +++ % 8M | %v", report, size, timing)
+	}
+	log.info(report)
+}
+
+@test
+benchmark_simd_index_cold :: proc(t: ^testing.T) {
+	report: string
+	for size in sizes {
+		timing := run_trial_size(simd_util.index_byte, size, size - 1, 0, 1)
+		report = fmt.tprintf("%s\n        +++ % 8M | %v", report, size, timing)
+		timing = run_trial_size(simd_util.last_index_byte, size, 0, 0, 1)
+		report = fmt.tprintf("%s\n (last) +++ % 8M | %v", report, size, timing)
+	}
+	log.info(report)
+}
+
+@test
+benchmark_simd_index_hot :: proc(t: ^testing.T) {
+	report: string
+	for size in sizes {
+		timing := run_trial_size(simd_util.index_byte, size, size - 1, HOT, HOT)
+		report = fmt.tprintf("%s\n        +++ % 8M | %v", report, size, timing)
+		timing = run_trial_size(simd_util.last_index_byte, size, 0, HOT, HOT)
+		report = fmt.tprintf("%s\n (last) +++ % 8M | %v", report, size, timing)
+	}
+	log.info(report)
+}