compiler: support recover()

pkg/compiler/func_scope.go

@@ -32,6 +32,9 @@ type funcScope struct {
 
 	// deferStack is a stack containing encountered `defer` statements.
 	deferStack []deferInfo
+	// finallyProcessed is a index of static slot with boolean flag determining
+	// if `defer` statement was already processed.
+	finallyProcessedIndex int
 
 	// Local variables
 	vars varScope
@@ -49,6 +52,7 @@ type funcScope struct {
 }
 
 type deferInfo struct {
+	catchLabel   uint16
 	finallyLabel uint16
 	expr         *ast.CallExpr
 }
@@ -123,6 +127,7 @@ func (c *funcScope) analyzeVoidCalls(node ast.Node) bool {
 
 func (c *funcScope) countLocals() int {
 	size := 0
+	hasDefer := false
 	ast.Inspect(c.decl, func(n ast.Node) bool {
 		switch n := n.(type) {
 		case *ast.FuncType:
@@ -134,6 +139,9 @@ func (c *funcScope) countLocals() int {
 			if n.Tok == token.DEFINE {
 				size += len(n.Lhs)
 			}
+		case *ast.DeferStmt:
+			hasDefer = true
+			return false
 		case *ast.ReturnStmt, *ast.IfStmt:
 			size++
 		// This handles the inline GenDecl like "var x = 2"
@@ -151,6 +159,10 @@ func (c *funcScope) countLocals() int {
 		}
 		return true
 	})
+	if hasDefer {
+		c.finallyProcessedIndex = size
+		size++
+	}
 	return size
 }