diff --git a/src/Php/CompilerBase.php b/src/Php/CompilerBase.php
index 8d7444e3..2b74ef00 100644
--- a/src/Php/CompilerBase.php
+++ b/src/Php/CompilerBase.php
@@ -923,6 +923,12 @@ class CompilerBase extends \PhpAot\Core\Translator
         }
         $this->indentLevel--;
         $code .= $this->genDebugInfo();
+
+        // 函数中存在动态调用的函数，需要在运行时动态切换作用域
+        if ($this->methodDef and $this->methodDef->hasDynamicCall) {
+            $code .= $this->genScopeSwitchCode();
+        }
+
         $code .= $stmts;
         $code .= "}\n";
 
@@ -3856,7 +3862,7 @@ class CompilerBase extends \PhpAot\Core\Translator
             }
         }
 
-        $dynamicCall = false;
+        $magicMethod = false;
         $method = $this->identifierToStr($expr->name, literal: true);
 
         // 可转为原生调用的 MethodCall
@@ -3873,7 +3879,7 @@ class CompilerBase extends \PhpAot\Core\Translator
                     }
                 }
             } catch (DynamicCall) {
-                $dynamicCall = true;
+                $magicMethod = true;
             }
         }
 
@@ -3883,12 +3889,16 @@ class CompilerBase extends \PhpAot\Core\Translator
             $funcName = '';
         }
 
-        if ($class and $funcName and !$dynamicCall) {
+        if ($class and $funcName and !$magicMethod) {
             $methodPtr = $this->getMethodPtr($class, $funcName);
         } else {
             $methodPtr = $method;
         }
 
+        if ($object === 'this_' or $object === 'self' or $object === 'static') {
+            $this->methodDef->hasDynamicCall = true;
+        }
+
         if (empty($expr->args)) {
             return $object . '.call(' . $methodPtr . ')';
         }
diff --git a/src/Php/Entity/MethodDef.php b/src/Php/Entity/MethodDef.php
index e2cfabcd..050f85f9 100644
--- a/src/Php/Entity/MethodDef.php
+++ b/src/Php/Entity/MethodDef.php
@@ -13,6 +13,7 @@ class MethodDef
     public int $flags;
     public string $name;
     public ?FunctionDef $functionDef = null;
+    public bool $hasDynamicCall = false;
 
     public function __construct(int $flags, string $name)
     {
diff --git a/src/Php/Translator.php b/src/Php/Translator.php
index 8186b106..12fb9717 100644
--- a/src/Php/Translator.php
+++ b/src/Php/Translator.php
@@ -1179,6 +1179,23 @@ class Translator extends Preprocessor
         $this->method = $name;
         $flags = $this->parseModifiers($v->flags);
 
+        $classDef = $this->classDef;
+        while (true) {
+            $extends = $classDef->extends;
+            if (!$extends) {
+                break;
+            }
+            $classDef = $this->getClass($extends);
+            if ($classDef->hasMethod($this->method)) {
+                $methodDef = $classDef->getMethod($this->method);
+                if ($methodDef->flags & Modifiers::PRIVATE) {
+                    $this->fatalError($v,
+                        'Cannot override private method `' .
+                        $classDef->getNamespacedName(false) . '::' . $this->method . '()`');
+                }
+            }
+        }
+
         if (!($flags & Modifiers::ABSTRACT)) {
             $this->methodDef = new MethodDef($flags, $name);
             $methodCodes[$name] = $this->parseFunction($v);
diff --git a/tests/zend/concat/bug40809.phpt b/tests/zend/concat/bug40809.phpt
new file mode 100644
index 00000000..f0ba1d97
--- /dev/null
+++ b/tests/zend/concat/bug40809.phpt
@@ -0,0 +1,32 @@
+--TEST--
+Bug #40809 (Poor performance of ".=")
+--FILE--
+<?php
+
+$num_increments = 100;
+$num_repeats = 1000;
+$increment = 50;
+
+/* Create some more holes to give the memory allocator something to
+ * work with. */
+$num = 5000;
+$a = Array();
+for ($i=0; $i<$num; $i++) {
+  $a[$i] = Array(1);
+}
+for ($i=0; $i<$num; $i++) {
+  $b[$i] = $a[$i][0];
+}
+unset($a);
+
+for ($i=0;$i<$num_repeats;$i++) {
+  $evil = "";
+  for ($j=0;$j<$num_increments;$j++) {
+    $evil .= str_repeat("a", $increment);
+  }
+  unset($evil);
+}
+echo "ok\n";
+?>
+--EXPECT--
+ok
diff --git a/tests/zend/concat/bug44069.phpt b/tests/zend/concat/bug44069.phpt
new file mode 100644
index 00000000..b18e16b2
--- /dev/null
+++ b/tests/zend/concat/bug44069.phpt
@@ -0,0 +1,21 @@
+--TEST--
+Bug #44069 (Huge memory usage with concatenation using . instead of .=)
+--FILE--
+<?php
+$array = array();
+$newstring = "";
+$string = str_repeat('This is a teststring.', 50);
+for($i = 1; $i <= 2000; $i++)
+{
+//	$newstring .= $string; //This uses an expected amount of mem.
+    $newstring = $newstring . $string; //This uses very much mem.
+
+    for($j = 1; $j <= 10; $j++)
+    {
+        $array[] = 'test';
+    }
+}
+echo "ok\n";
+?>
+--EXPECT--
+ok
diff --git a/tests/zend/dynamic_call/bug46246.phpt b/tests/zend/dynamic_call/bug46246.phpt
new file mode 100644
index 00000000..86769f11
--- /dev/null
+++ b/tests/zend/dynamic_call/bug46246.phpt
@@ -0,0 +1,42 @@
+--TEST--
+Bug #46246 (difference between call_user_func(array($this, $method)) and $this->$method())
+--FILE--
+<?php
+class A
+{
+    protected function Test()
+    {
+        echo 'Hello from '.get_class($this)."\n";
+    }
+
+    public function call($method, $args = array())
+    {
+        $this->Test();
+        $this->$method();
+        call_user_func(array($this, $method));
+    }
+}
+
+class B extends A
+{
+    protected function Test()
+    {
+        echo 'Overridden hello from '.get_class($this)."\n";
+    }
+}
+
+function main() {
+    $a = new A;
+    $b = new B;
+
+    $a->call('Test');
+    $b->call('Test');
+}
+?>
+--EXPECT--
+Hello from A
+Hello from A
+Hello from A
+Overridden hello from B
+Overridden hello from B
+Overridden hello from B