builtin: optimise the initialisation of the common 1 byte element arrays []u8

vlib/builtin/array.v

@@ -56,12 +56,21 @@ fn __new_array_with_default(mylen int, cap int, elm_size int, val voidptr) array
 	if val != 0 {
 		mut eptr := &u8(arr.data)
 		unsafe {
+			if eptr != nil {
+				if arr.element_size == 1 {
+					byte_value := *(&u8(val))
+					for i in 0 .. arr.len {
+						eptr[i] = byte_value
+					}
+				} else {
 					for _ in 0 .. arr.len {
 						vmemcpy(eptr, val, arr.element_size)
 						eptr += arr.element_size
 					}
 				}
 			}
+		}
+	}
 	return arr
 }
 
@@ -75,12 +84,14 @@ fn __new_array_with_array_default(mylen int, cap int, elm_size int, val array, d
 	}
 	mut eptr := &u8(arr.data)
 	unsafe {
+		if eptr != nil {
 			for _ in 0 .. arr.len {
 				val_clone := val.clone_to_depth(depth)
 				vmemcpy(eptr, &val_clone, arr.element_size)
 				eptr += arr.element_size
 			}
 		}
+	}
 	return arr
 }
 
@@ -94,12 +105,14 @@ fn __new_array_with_map_default(mylen int, cap int, elm_size int, val map) array
 	}
 	mut eptr := &u8(arr.data)
 	unsafe {
+		if eptr != nil {
 			for _ in 0 .. arr.len {
 				val_clone := val.clone()
 				vmemcpy(eptr, &val_clone, arr.element_size)
 				eptr += arr.element_size
 			}
 		}
+	}
 	return arr
 }
 
@@ -191,6 +204,7 @@ pub fn (a array) repeat_to_depth(count int, depth int) array {
 		arr_step_size := u64(a.len) * u64(arr.element_size)
 		mut eptr := &u8(arr.data)
 		unsafe {
+			if eptr != nil {
 				for _ in 0 .. count {
 					if depth > 0 {
 						ary_clone := a.clone_to_depth(depth)
@@ -202,6 +216,7 @@ pub fn (a array) repeat_to_depth(count int, depth int) array {
 				}
 			}
 		}
+	}
 	return arr
 }
 
@@ -661,7 +676,7 @@ pub fn (mut a3 array) push_many(val voidptr, size int) {
 
 // reverse_in_place reverses existing array data, modifying original array.
 pub fn (mut a array) reverse_in_place() {
-	if a.len < 2 {
+	if a.len < 2 || a.element_size == 0 {
 		return
 	}
 	unsafe {

vlib/builtin/array_d_gcboehm_opt.v

@@ -24,11 +24,21 @@ fn __new_array_with_default_noscan(mylen int, cap int, elm_size int, val voidptr
 		len: mylen
 		cap: cap_
 	}
-	if val != 0 {
+	if val != 0 && arr.data != unsafe { nil } {
+		if elm_size == 1 {
+			byte_value := *(&u8(val))
+			dptr := &u8(arr.data)
+			for i in 0 .. arr.len {
+				unsafe {
+					dptr[i] = byte_value
+				}
+			}
+		} else {
 			for i in 0 .. arr.len {
 				unsafe { arr.set_unsafe(i, val) }
 			}
 		}
+	}
 	return arr
 }