v: reduce the memory usage of the compiler (analysed with heaptrack)

vlib/builtin/string.v

@@ -742,7 +742,7 @@ pub fn (s string) index(p string) ?int {
 }
 
 // index_kmp does KMP search.
-[manualfree]
+[direct_array_access; manualfree]
 fn (s string) index_kmp(p string) int {
 	if p.len > s.len {
 		return -1

vlib/rand/seed/seed.v

@@ -14,8 +14,8 @@ fn nr_next(prev u32) u32 {
 // time_seed_array returns the required number of u32s generated from system time.
 [inline]
 pub fn time_seed_array(count int) []u32 {
-	ctime := time.now()
+	ctime := time.sys_mono_now()
-	mut seed := u32(ctime.unix_time() ^ ctime.microsecond)
+	mut seed := u32(ctime >> 32 ^ (ctime & 0x0000_0000_FFFF_FFFF))
 	mut seed_data := []u32{cap: count}
 	for _ in 0 .. count {
 		seed = nr_next(seed)

vlib/v/ast/table.v

@@ -764,12 +764,12 @@ pub fn (mut t Table) find_or_register_thread(return_type Type) int {
 
 pub fn (mut t Table) find_or_register_array(elem_type Type) int {
 	name := t.array_name(elem_type)
-	cname := t.array_cname(elem_type)
 	// existing
 	existing_idx := t.type_idxs[name]
 	if existing_idx > 0 {
 		return existing_idx
 	}
+	cname := t.array_cname(elem_type)
 	// register
 	array_type_ := TypeSymbol{
 		parent_idx: array_type_idx

vlib/v/gen/c/cgen.v

@@ -5231,10 +5231,16 @@ fn (mut g Gen) struct_init(struct_init ast.StructInit) {
 		}
 		// g.zero_struct_fields(info, inited_fields)
 		// nr_fields = info.fields.len
-		for field in info.fields {
+		for mut field in info.fields {
 			if mut sym.info is ast.Struct {
-				equal_fields := sym.info.fields.filter(it.name == field.name)
+				mut found_equal_fields := 0
-				if equal_fields.len == 0 {
+				for mut sifield in sym.info.fields {
+					if sifield.name == field.name {
+						found_equal_fields++
+						break
+					}
+				}
+				if found_equal_fields == 0 {
 					continue
 				}
 			}