gen: support non-string map equality and speed it up

Avoid allocating keys array (which wasn't freed).
Don't clone keys (which weren't freed).
Check right key exists before getting left value.
Use fast_string_eq for string values.

vlib/builtin/map_test.v

@@ -487,7 +487,10 @@ fn test_int_keys() {
 	assert m[5] == 25
 	m2 := {3:9 4:16 5:25}
 	assert m2.len == 3
+	// clone
 	mc := m.clone()
+	same := mc == m
+	assert same
 	assert mc.len == 3
 	mut all := []int{}
 	for k, v in mc {

vlib/v/gen/auto_eq_methods.v

@@ -102,9 +102,10 @@ fn (mut g Gen) gen_map_equality_fn(left table.Type) string {
 	fn_builder.writeln('\tif (a.len != b.len) {')
 	fn_builder.writeln('\t\treturn false;')
 	fn_builder.writeln('\t}')
-	fn_builder.writeln('\tarray_string _keys = map_keys(&a);')
-	fn_builder.writeln('\tfor (int i = 0; i < _keys.len; ++i) {')
-	fn_builder.writeln('\t\tstring k = string_clone( ((string*)_keys.data)[i]);')
+	fn_builder.writeln('\tfor (int i = 0; i < a.key_values.len; ++i) {')
+	fn_builder.writeln('\t\tif (!DenseArray_has_index(&a.key_values, i)) continue;')
+	fn_builder.writeln('\t\tvoidptr k = DenseArray_key(&a.key_values, i);')
+	fn_builder.writeln('\t\tif (!map_exists_1(&b, k)) return false;')
 	if value_sym.kind == .function {
 		func := value_sym.info as table.FnType
 		ret_styp := g.typ(func.func.return_type)
@@ -117,25 +118,32 @@ fn (mut g Gen) gen_map_equality_fn(left table.Type) string {
 				fn_builder.write(', ')
 			}
 		}
-		fn_builder.writeln(') = (*(voidptr*)map_get_1(&a, &k, &(voidptr[]){ 0 }));')
+		fn_builder.writeln(') = *(voidptr*)map_get_1(&a, k, &(voidptr[]){ 0 });')
 	} else {
-		fn_builder.writeln('\t\t$ptr_value_typ v = (*($ptr_value_typ*)map_get_1(&a, &k, &($ptr_value_typ[]){ 0 }));')
+		fn_builder.writeln('\t\t$ptr_value_typ v = *($ptr_value_typ*)map_get_1(&a, k, &($ptr_value_typ[]){ 0 });')
 	}
-	if value_sym.kind == .string {
-		fn_builder.writeln('\t\tif (!map_exists_1(&b, &k) || string_ne((*(string*)map_get_1(&b, &k, &(string[]){_SLIT("")})), v)) {')
-	} else if value_sym.kind == .struct_ && !value_typ.is_ptr() {
-		eq_fn := g.gen_struct_equality_fn(value_typ)
-		fn_builder.writeln('\t\tif (!map_exists_1(&b, &k) || !${eq_fn}_struct_eq(*($ptr_value_typ*)map_get_1(&b, &k, &($ptr_value_typ[]){ 0 }), v)) {')
-	} else if value_sym.kind == .array && !value_typ.is_ptr() {
-		eq_fn := g.gen_array_equality_fn(value_typ)
-		fn_builder.writeln('\t\tif (!map_exists_1(&b, &k) || !${eq_fn}_arr_eq(*($ptr_value_typ*)map_get_1(&b, &k, &($ptr_value_typ[]){ 0 }), v)) {')
-	} else if value_sym.kind == .map && !value_typ.is_ptr() {
-		eq_fn := g.gen_map_equality_fn(value_typ)
-		fn_builder.writeln('\t\tif (!map_exists_1(&b, &k) || !${eq_fn}_map_eq(*($ptr_value_typ*)map_get_1(&b, &k, &($ptr_value_typ[]){ 0 }), v)) {')
-	} else if value_sym.kind == .function {
-		fn_builder.writeln('\t\tif (!map_exists_1(&b, &k) || (*(voidptr*)map_get_1(&b, &k, &(voidptr[]){ 0 })) != v) {')
-	} else {
-		fn_builder.writeln('\t\tif (!map_exists_1(&b, &k) || (*($ptr_value_typ*)map_get_1(&b, &k, &($ptr_value_typ[]){ 0 })) != v) {')
+	match value_sym.kind {
+		.string {
+			fn_builder.writeln('\t\tif (!fast_string_eq(*(string*)map_get_1(&b, k, &(string[]){_SLIT("")}), v)) {')
+		}
+		.struct_ {
+			eq_fn := g.gen_struct_equality_fn(value_typ)
+			fn_builder.writeln('\t\tif (!${eq_fn}_struct_eq(*($ptr_value_typ*)map_get_1(&b, k, &($ptr_value_typ[]){ 0 }), v)) {')
+		}
+		.array {
+			eq_fn := g.gen_array_equality_fn(value_typ)
+			fn_builder.writeln('\t\tif (!${eq_fn}_arr_eq(*($ptr_value_typ*)map_get_1(&b, k, &($ptr_value_typ[]){ 0 }), v)) {')
+		}
+		.map {
+			eq_fn := g.gen_map_equality_fn(value_typ)
+			fn_builder.writeln('\t\tif (!${eq_fn}_map_eq(*($ptr_value_typ*)map_get_1(&b, k, &($ptr_value_typ[]){ 0 }), v)) {')
+		}
+		.function {
+			fn_builder.writeln('\t\tif (*(voidptr*)map_get_1(&b, k, &(voidptr[]){ 0 }) != v) {')
+		}
+		else {
+			fn_builder.writeln('\t\tif (*($ptr_value_typ*)map_get_1(&b, k, &($ptr_value_typ[]){ 0 }) != v) {')
+		}
 	}
 	fn_builder.writeln('\t\t\treturn false;')
 	fn_builder.writeln('\t\t}')