native: add printing support for boolean and string variables (#15868)

vlib/v/gen/native/amd64.v

@@ -3009,6 +3009,34 @@ fn (mut g Gen) init_struct(var Var, init ast.StructInit) {
 	}
 }
 
+fn (mut g Gen) convert_bool_to_string(reg Register) {
+	g.cmp_zero(reg)
+	false_label := g.labels.new_label()
+	false_cjmp_addr := g.cjmp(.je)
+	g.labels.patches << LabelPatch{
+		id: false_label
+		pos: false_cjmp_addr
+	}
+	g.println('; jump to label $false_label')
+
+	g.learel(reg, g.allocate_string('true', 3, .rel32))
+
+	end_label := g.labels.new_label()
+	end_jmp_addr := g.jmp(0)
+	g.labels.patches << LabelPatch{
+		id: end_label
+		pos: end_jmp_addr
+	}
+	g.println('; jump to label $end_label')
+
+	g.labels.addrs[false_label] = g.pos()
+	g.println('; label $false_label')
+	g.learel(reg, g.allocate_string('false', 3, .rel32))
+
+	g.labels.addrs[end_label] = g.pos()
+	g.println('; label $end_label')
+}
+
 fn (mut g Gen) convert_int_to_string(r1 Register, r2 Register) {
 	if r1 != .rax {
 		g.mov_reg(.rax, r1)

vlib/v/gen/native/builtins.v

@@ -24,6 +24,12 @@ pub fn (mut g Gen) init_builtins() {
 			}
 			arg_regs: [.rcx, .rdi]
 		}
+		'bool_to_string': BuiltinFn{
+			body: fn (builtin BuiltinFn, mut g Gen) {
+				g.convert_bool_to_string(builtin.arg_regs[0])
+			}
+			arg_regs: [.rax]
+		}
 		'reverse_string': BuiltinFn{
 			body: fn (builtin BuiltinFn, mut g Gen) {
 				g.reverse_string(builtin.arg_regs[0])

vlib/v/gen/native/gen.v

@@ -567,6 +567,11 @@ fn (mut g Gen) gen_var_to_string(reg Register, var Var, config VarConfig) {
 		g.lea_var_to_reg(g.get_builtin_arg_reg('int_to_string', 1), buffer)
 		g.call_builtin('int_to_string')
 		g.lea_var_to_reg(reg, buffer)
+	} else if typ.is_bool() {
+		g.mov_var_to_reg(g.get_builtin_arg_reg('bool_to_string', 0), var, config)
+		g.call_builtin('bool_to_string')
+	} else if typ.is_string() {
+		g.mov_var_to_reg(.rax, var, config)
 	} else {
 		g.n_error('int-to-string conversion not implemented for type $typ')
 	}
@@ -708,6 +713,13 @@ g.expr
 	}
 }
 
+fn (mut g Gen) extern_fn_decl(node ast.FnDecl) {
+	// declarations like: fn C.malloc()
+	// TODO: implement extern function calls here
+	// Must store an address where the function label is located in the RelA elf section
+	panic('C. functions are not implemented yet')
+}
+
 fn (mut g Gen) fn_decl(node ast.FnDecl) {
 	name := if node.is_method {
 		'${g.table.get_type_name(node.receiver.typ)}.$node.name'
@@ -723,6 +735,11 @@ fn (mut g Gen) fn_decl(node ast.FnDecl) {
 	if node.is_builtin {
 		g.warning('fn_decl: $name is builtin', node.pos)
 	}
+	if node.no_body {
+		g.extern_fn_decl(node)
+		return
+	}
+
 	g.stack_var_pos = 0
 	g.register_function_address(name)
 	g.labels = &LabelTable{}

vlib/v/gen/native/tests/print.vv

@@ -30,6 +30,8 @@ fn test_stderr() {
 }
 
 fn test_idents() {
+	// signed integer
+	
 	x := 0
 	println(x)
 
@@ -44,6 +46,22 @@ fn test_idents() {
 
 	b := -456
 	println(b)
+
+	// booleans
+
+	bool_true := true
+	println(bool_true)
+
+	bool_false := false
+	println(bool_false)
+
+	// strings
+
+	str := 'string blah blah blah'
+	println(str)
+
+	unicode := '😀😆😎💻🌎'
+	println(unicode)
 }
 
 fn main() {

vlib/v/gen/native/tests/print.vv.out

@@ -7,4 +7,8 @@ Hello World
 5
 -8
 123
--456
+-456
+true
+false
+string blah blah blah
+😀😆😎💻🌎