native: fix int prints

vlib/v/gen/native/amd64.v

@@ -1323,6 +1323,7 @@ fn (mut c Amd64) gen_print(s string, fd i32) {
 	c.g.println('; print }')
 }
 
+// write a string of size n stored in r to fd
 pub fn (mut c Amd64) gen_print_reg(r Register, n i32, fd i32) {
 	c.g.println('; print_reg: (reg:${r} fd:${fd} len:${n}) {')
 	str_reg := if c.g.pref.os == .windows { Amd64Register.rdx } else { Amd64Register.rsi }

vlib/v/gen/native/builtins.v

@@ -30,7 +30,7 @@ pub fn (mut g Gen) init_builtins() {
 			body:     fn (builtin BuiltinFn, mut g Gen) {
 				g.code_gen.convert_int_to_string(builtin.arg_regs[0], builtin.arg_regs[1])
 			}
-			arg_regs: [Amd64Register.rcx, Amd64Register.rdi]
+			arg_regs: [Amd64Register.rcx, Amd64Register.rdi] // rcx: int to convert, rdi: end of 32byte buffer (with 4 bytes at the beggining for len) see allocate_array
 		}
 		.bool_to_string: BuiltinFn{
 			body:     fn (builtin BuiltinFn, mut g Gen) {

vlib/v/gen/native/gen.v

@@ -859,7 +859,7 @@ fn (mut g Gen) allocate_string(s string, opsize i32, typ RelocType) i32 {
 // allocates a buffer variable: name, size of stored type (nb of bytes), nb of items
 fn (mut g Gen) allocate_array(name string, size i32, items i32) i32 {
 	g.println('; allocate array `${name}` item-size:${size} items:${items}:')
-	pos := g.code_gen.allocate_var(name, size, items) // store the lenght of the array on the stack
+	pos := g.code_gen.allocate_var(name, 4, items) // store the lenght of the array on the stack in a 4 byte var
 	g.stack_var_pos += (size * items) // reserve space on the stack for the items
 	return pos
 }
@@ -950,15 +950,16 @@ fn (mut g Gen) gen_to_string(reg Register, typ ast.Type) {
 	g.println('; to_string (reg:${reg}) {')
 	if typ.is_int() {
 		buffer := g.allocate_array('itoa-buffer', 1, 32) // 32 characters should be enough
-		g.code_gen.lea_var_to_reg(g.get_builtin_arg_reg(.int_to_string, 1), buffer)
+		end_of_buffer := buffer + 4 + 32 - 1 // 4 bytes for the size and 32 for the chars, -1 to not go out of array
+		g.code_gen.lea_var_to_reg(g.get_builtin_arg_reg(.int_to_string, 1), end_of_buffer)
 
 		arg0_reg := g.get_builtin_arg_reg(.int_to_string, 0)
 		if arg0_reg != reg {
 			g.code_gen.mov_reg(arg0_reg, reg)
 		}
 
 		g.call_builtin(.int_to_string)
-		g.code_gen.lea_var_to_reg(g.code_gen.main_reg(), buffer)
+		g.code_gen.lea_var_to_reg(g.code_gen.main_reg(), end_of_buffer) // the (int) string starts at the end of the buffer
 	} else if typ.is_bool() {
 		arg_reg := g.get_builtin_arg_reg(.bool_to_string, 0)
 		if arg_reg != reg {
@@ -983,10 +984,11 @@ fn (mut g Gen) gen_var_to_string(reg Register, expr ast.Expr, var Var, config Va
 		g.code_gen.convert_rune_to_string(reg, buffer, var, config)
 	} else if typ.is_int() {
 		buffer := g.allocate_array('itoa-buffer', 1, 32) // 32 characters should be enough
+		end_of_buffer := buffer + 4 + 32 - 1 // 4 bytes for the size and 32 for the chars, -1 to not go out of array
 		g.code_gen.mov_var_to_reg(g.get_builtin_arg_reg(.int_to_string, 0), var, config)
-		g.code_gen.lea_var_to_reg(g.get_builtin_arg_reg(.int_to_string, 1), buffer)
+		g.code_gen.lea_var_to_reg(g.get_builtin_arg_reg(.int_to_string, 1), end_of_buffer)
 		g.call_builtin(.int_to_string)
-		g.code_gen.lea_var_to_reg(reg, buffer)
+		g.code_gen.lea_var_to_reg(reg, end_of_buffer) // the (int) string starts at the end of the buffer
 	} else if typ.is_bool() {
 		g.code_gen.mov_var_to_reg(g.get_builtin_arg_reg(.bool_to_string, 0), var, config)
 		g.call_builtin(.bool_to_string)

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

@@ -110,6 +110,18 @@ fn test_intermediate() {
 	println(c)
 }
 
+fn test_for_range() {
+	for i in 0 .. 10 {
+		println(i)
+	}
+}
+
+fn test_2_in_a_row() {
+	a := 12345
+	println(a)
+	println(a)
+}
+
 fn main() {
 	test_stdout()
 	test_stderr()
@@ -120,4 +132,6 @@ fn main() {
 	test_sizeof()
 	test_interpolated()
 	test_intermediate()
+	test_for_range()
+	test_2_in_a_row()
 }

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

@@ -22,3 +22,15 @@ sizeof: 4, 12
 this is an interpolated string
 num: 42; bool: true
 0
+0
+1
+2
+3
+4
+5
+6
+7
+8
+9
+12345
+12345