native: support else, break, continue (#14738)

vlib/v/gen/native/amd64.v

@@ -206,10 +206,13 @@ fn (mut g Gen) cjmp(op JumpOp) int {
 	return int(pos)
 }
 
-fn (mut g Gen) jmp(addr int) {
+fn (mut g Gen) jmp(addr int) int {
 	g.write8(0xe9)
+	pos := g.pos()
 	g.write32(addr) // 0xffffff
 	g.println('jmp')
+	// return the position of jump address for placeholder
+	return int(pos)
 }
 
 fn abs(a i64) i64 {
@@ -1149,6 +1152,20 @@ fn (mut g Gen) patch_calls() {
 	}
 }
 
+fn (mut g Gen) patch_labels() {
+	for label in g.labels.patches {
+		addr := g.labels.addrs[label.id]
+		if addr == 0 {
+			g.n_error('label addr = 0')
+			return
+		}
+		// Update jmp or cjmp address.
+		// The value is the relative address, difference between current position and the location
+		// after `jxx 00 00 00 00`
+		g.write32_at(label.pos, int(addr - label.pos - 4))
+	}
+}
+
 fn (mut g Gen) delay_fn_call(name string) {
 	pos := g.buf.len
 	g.callpatches << CallPatch{name, pos}
@@ -1567,10 +1584,17 @@ fn (mut g Gen) gen_assert(assert_node ast.AssertStmt) {
 	} else {
 		g.n_error('Unsupported expression in assert')
 	}
+	label := g.labels.new_label()
 	cjmp_addr = g.condition(ine, true)
+	g.labels.patches << LabelPatch{
+		id: label
+		pos: cjmp_addr
+	}
+	g.println('; jump to label $label')
 	g.expr(assert_node.expr)
 	g.trap()
-	g.write32_at(cjmp_addr, int(g.pos() - cjmp_addr - 4)) // 4 is for "00 00 00 00"
+	g.labels.addrs[label] = g.pos()
+	g.println('; label $label')
 }
 
 fn (mut g Gen) cjmp_notop(op token.Kind) int {
@@ -1669,28 +1693,50 @@ fn (mut g Gen) if_expr(node ast.IfExpr) {
 	if node.is_comptime {
 		g.n_error('ignored comptime')
 	}
-	if node.has_else {
-		g.n_error('else statements not yet supported')
-	}
 	if node.branches.len == 0 {
 		return
 	}
+	mut endif_label := 0
+	has_endif := node.branches.len > 1
+	if has_endif {
+		endif_label = g.labels.new_label()
+	}
 	for idx in 0 .. node.branches.len {
 		branch := node.branches[idx]
-		if branch.cond is ast.BoolLiteral {
-			if branch.cond.val {
-				g.stmts(branch.stmts)
+		if idx == node.branches.len - 1 && node.has_else {
+			g.stmts(branch.stmts)
+		} else {
+			if branch.cond is ast.BoolLiteral {
+				if branch.cond.val {
+					g.stmts(branch.stmts)
+				}
+				continue
 			}
-			continue
+			infix_expr := branch.cond as ast.InfixExpr
+			label := g.labels.new_label()
+			cjmp_addr := g.condition(infix_expr, false)
+			g.labels.patches << LabelPatch{
+				id: label
+				pos: cjmp_addr
+			}
+			g.println('; jump to label $label')
+			g.stmts(branch.stmts)
+			if has_endif {
+				jump_addr := g.jmp(0)
+				g.labels.patches << LabelPatch{
+					id: endif_label
+					pos: jump_addr
+				}
+				g.println('; jump to label $endif_label')
+			}
+			// println('after if g.pos=$g.pos() jneaddr=$cjmp_addr')
+			g.labels.addrs[label] = g.pos()
+			g.println('; label $label')
 		}
-		infix_expr := branch.cond as ast.InfixExpr
-		cjmp_addr := g.condition(infix_expr, false)
-		g.stmts(branch.stmts)
-		// Now that we know where we need to jump if the condition is false, update the `jne` call.
-		// The value is the relative address, difference between current position and the location
-		// after `jne 00 00 00 00`
-		// println('after if g.pos=$g.pos() jneaddr=$cjmp_addr')
-		g.write32_at(cjmp_addr, int(g.pos() - cjmp_addr - 4)) // 4 is for "00 00 00 00"
+	}
+	if has_endif {
+		g.labels.addrs[endif_label] = g.pos()
+		g.println('; label $endif_label')
 	}
 }
 
@@ -1712,14 +1758,29 @@ fn (mut g Gen) for_stmt(node ast.ForStmt) {
 		}
 		// infinite loop
 		start := g.pos()
+		start_label := g.labels.new_label()
+		g.labels.addrs[start_label] = start
+		g.println('; label $start_label')
+		end_label := g.labels.new_label()
+		g.labels.branches << BranchLabel{
+			name: node.label
+			start: start_label
+			end: end_label
+		}
 		g.stmts(node.stmts)
+		g.labels.branches.pop()
 		g.jmp(int(0xffffffff - (g.pos() + 5 - start) + 1))
 		g.println('jmp after infinite for')
+		g.labels.addrs[end_label] = g.pos()
+		g.println('; label $end_label')
 		return
 	}
 	infix_expr := node.cond as ast.InfixExpr
 	mut jump_addr := 0 // location of `jne *00 00 00 00*`
 	start := g.pos()
+	start_label := g.labels.new_label()
+	g.labels.addrs[start_label] = start
+	g.println('; label $start_label')
 	match infix_expr.left {
 		ast.Ident {
 			match infix_expr.right {
@@ -1752,12 +1813,25 @@ fn (mut g Gen) for_stmt(node ast.ForStmt) {
 			g.n_error('unhandled infix.left')
 		}
 	}
+	end_label := g.labels.new_label()
+	g.labels.patches << LabelPatch{
+		id: end_label
+		pos: jump_addr
+	}
+	g.println('; jump to label $end_label')
+	g.labels.branches << BranchLabel{
+		name: node.label
+		start: start_label
+		end: end_label
+	}
 	g.stmts(node.stmts)
+	g.labels.branches.pop()
 	// Go back to `cmp ...`
 	// Diff between `jmp 00 00 00 00 X` and `cmp`
 	g.jmp(int(0xffffffff - (g.pos() + 5 - start) + 1))
 	// Update the jump addr to current pos
-	g.write32_at(jump_addr, int(g.pos() - jump_addr - 4)) // 4 is for "00 00 00 00"
+	g.labels.addrs[end_label] = g.pos()
+	g.println('; label $end_label')
 	g.println('jmp after for')
 }
 
@@ -1789,6 +1863,8 @@ fn (mut g Gen) fn_decl_amd64(node ast.FnDecl) {
 		return
 	}
 	// g.leave()
+	g.labels.addrs[0] = g.pos()
+	g.println('; label 0: return')
 	g.add8(.rsp, g.stackframe_size)
 	g.pop(.rbp)
 	g.ret()

vlib/v/gen/native/gen.v

@@ -47,6 +47,7 @@ mut:
 	nlines               int
 	callpatches          []CallPatch
 	strs                 []String
+	labels               &LabelTable
 }
 
 enum RelocType {
@@ -68,6 +69,32 @@ struct CallPatch {
 	pos  int
 }
 
+struct LabelTable {
+mut:
+	label_id   int
+	return_ids []int = [0] // array is for defer
+	addrs      []i64 = [i64(0)] // register address of label here
+	patches    []LabelPatch // push placeholders
+	branches   []BranchLabel
+}
+
+struct LabelPatch {
+	id  int
+	pos int
+}
+
+struct BranchLabel {
+	name  string
+	start int
+	end   int
+}
+
+fn (mut l LabelTable) new_label() int {
+	l.label_id++
+	l.addrs << 0
+	return l.label_id
+}
+
 enum Size {
 	_8
 	_16
@@ -108,6 +135,7 @@ pub fn gen(files []&ast.File, table &ast.Table, out_name string, pref &pref.Pref
 			eprintln('No available backend for this configuration. Use `-a arm64` or `-a amd64`.')
 			exit(1)
 		}
+		labels: 0
 	}
 	g.code_gen.g = g
 	g.generate_header()
@@ -458,11 +486,13 @@ fn (mut g Gen) fn_decl(node ast.FnDecl) {
 	}
 	g.stack_var_pos = 0
 	g.register_function_address(node.name)
+	g.labels = &LabelTable{}
 	if g.pref.arch == .arm64 {
 		g.fn_decl_arm64(node)
 	} else {
 		g.fn_decl_amd64(node)
 	}
+	g.patch_labels()
 }
 
 pub fn (mut g Gen) register_function_address(name string) {
@@ -505,6 +535,7 @@ fn (mut g Gen) gen_forc_stmt(node ast.ForCStmt) {
 		g.stmts([node.init])
 	}
 	start := g.pos()
+	start_label := g.labels.new_label()
 	mut jump_addr := i64(0)
 	if node.has_cond {
 		cond := node.cond
@@ -537,12 +568,27 @@ fn (mut g Gen) gen_forc_stmt(node ast.ForCStmt) {
 		// dump(node.cond)
 		g.expr(node.cond)
 	}
+	end_label := g.labels.new_label()
+	g.labels.patches << LabelPatch{
+		id: end_label
+		pos: int(jump_addr)
+	}
+	g.println('; jump to label $end_label')
+	g.labels.branches << BranchLabel{
+		name: node.label
+		start: start_label
+		end: end_label
+	}
 	g.stmts(node.stmts)
+	g.labels.addrs[start_label] = g.pos()
+	g.println('; label $start_label')
 	if node.has_inc {
 		g.stmts([node.inc])
 	}
+	g.labels.branches.pop()
 	g.jmp(int(0xffffffff - (g.pos() + 5 - start) + 1))
-	g.write32_at(jump_addr, int(g.pos() - jump_addr - 4))
+	g.labels.addrs[end_label] = g.pos()
+	g.println('; jump to label $end_label')
 
 	// loop back
 }
@@ -558,14 +604,30 @@ fn (mut g Gen) for_in_stmt(node ast.ForInStmt) {
 		g.expr(node.cond)
 		g.mov_reg_to_var(i, .rax) // i = node.cond // initial value
 		start := g.pos() // label-begin:
+		start_label := g.labels.new_label()
 		g.mov_var_to_reg(.rbx, i) // rbx = iterator value
 		g.expr(node.high) // final value
 		g.cmp_reg(.rbx, .rax) // rbx = iterator, rax = max value
 		jump_addr := g.cjmp(.jge) // leave loop if i is beyond end
+		end_label := g.labels.new_label()
+		g.labels.patches << LabelPatch{
+			id: end_label
+			pos: jump_addr
+		}
+		g.println('; jump to label $end_label')
+		g.labels.branches << BranchLabel{
+			name: node.label
+			start: start_label
+			end: end_label
+		}
 		g.stmts(node.stmts)
+		g.labels.addrs[start_label] = g.pos()
+		g.println('; label $start_label')
 		g.inc_var(node.val_var)
+		g.labels.branches.pop()
 		g.jmp(int(0xffffffff - (g.pos() + 5 - start) + 1))
-		g.write32_at(jump_addr, int(g.pos() - jump_addr - 4))
+		g.labels.addrs[end_label] = g.pos()
+		g.println('; label $end_label')
 		/*
 		} else if node.kind == .array {
 	} else if node.kind == .array_fixed {
@@ -593,6 +655,26 @@ fn (mut g Gen) stmt(node ast.Stmt) {
 		ast.Block {
 			g.stmts(node.stmts)
 		}
+		ast.BranchStmt {
+			label_name := node.label
+			for i := g.labels.branches.len - 1; i >= 0; i-- {
+				branch := g.labels.branches[i]
+				if label_name == '' || label_name == branch.name {
+					label := if node.kind == .key_break {
+						branch.end
+					} else { // continue
+						branch.start
+					}
+					jump_addr := g.jmp(0)
+					g.labels.patches << LabelPatch{
+						id: label
+						pos: jump_addr
+					}
+					g.println('; jump to $label: $node.kind')
+					break
+				}
+			}
+		}
 		ast.ConstDecl {}
 		ast.ExprStmt {
 			g.expr(node.expr)
@@ -654,10 +736,15 @@ fn (mut g Gen) stmt(node ast.Stmt) {
 					g.n_error('unknown return type $e0.type_name()')
 				}
 			}
-			// intel specific
-			g.add8(.rsp, g.stackframe_size)
-			g.pop(.rbp)
-			g.ret()
+
+			// jump to return label
+			label := g.labels.return_ids.last()
+			pos := g.jmp(0)
+			g.labels.patches << LabelPatch{
+				id: label
+				pos: pos
+			}
+			g.println('; jump to label $label')
 		}
 		ast.AsmStmt {
 			g.gen_asm_stmt(node)

vlib/v/gen/native/macho_test.v

@@ -12,6 +12,7 @@ fn test_macho() {
 		code_gen: native.Amd64{
 			g: 0
 		}
+		labels: 0
 	}
 	g.generate_macho_header()
 	g.generate_macho_footer()

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

@@ -1,4 +1,4 @@
-fn main() {
+fn simple_for_test() {
 	mut i := 0
 	for i = 0; i < 3; i++ {
 		println('loop0')
@@ -23,4 +23,65 @@ fn main() {
 		println('loop5')
 		i--
 	}
+
+}
+
+fn break_continue_test() {
+	mut i := 0
+	for i = 0; i < 3; i++ {
+		if i == 2 {
+			break
+		}
+		println('loop1')
+	}
+	i = 0
+	for i < 3 {
+		if i == 2 {
+			break
+		}
+		println('loop2')
+		i++
+	}
+	for j in 0 .. 3 {
+		if j == 2 {
+			break
+		}
+		println('loop3')
+	}
+	for i = 0; i < 3; i++ {
+		if i < 1 {
+			continue
+		}
+		println('loop4')
+	}
+	i = 0
+	for i < 3 {
+		if i < 1 {
+			i++
+			continue
+		}
+		println('loop5')
+		i++
+	}
+	for j in 0 .. 3 {
+		if j < 1 {
+			continue
+		}
+		println('loop6')
+	}
+	outer: for j in 0 .. 3 {
+		for k in 0 .. 3 {
+			println('loop7')
+			if j == 1 {
+				if k == 1 {
+					break outer
+				}
+			}
+		}
+	}
+}
+
+fn main() {
+	simple_for_test()
+	break_continue_test()
 }

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

@@ -16,3 +16,20 @@ loop4
 loop5
 loop5
 loop5
+loop1
+loop1
+loop2
+loop2
+loop3
+loop3
+loop4
+loop4
+loop5
+loop5
+loop6
+loop6
+loop7
+loop7
+loop7
+loop7
+loop7

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

@@ -40,7 +40,6 @@ fn test_add() {
 	}
 }
 
-/*
 fn test_elses() {
 	println('start else')
 	if 1 < 2 {
@@ -55,11 +54,10 @@ fn test_elses() {
 	}
 	println('end else')
 }
-*/
 
 fn main() {
 	println('start')
 	test_add()
-	// test_elses()
+	test_elses()
 	println('end')
 }

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

@@ -4,4 +4,8 @@ var(3) > 1
 1 < 3
 1 == 1
 1 != 3
+start else
+ok
+ok
+end else
 end