feat(generator): 优化属性默认值代码生成逻辑

- 替换原有的 ZVAL_UNDEF 初始化方式为类型特定的默认值设置
- 添加 getTypeDefaultValueCode 方法处理各种数据类型的默认值
- 支持整型、浮点型、布尔型、字符串、数组等类型的默认值初始化
- 为测试用例添加对象整型属性优化功能
- 确保可空类型正确初始化为 NULL 值

src/gen_stub.php

@@ -3257,7 +3257,8 @@ class PropertyInfo extends VariableLike
 
         $zvalName = "property_{$propertyName}_default_value";
         if ($this->defaultValue === null && $this->type !== null) {
-            $code .= "\tzval $zvalName;\n\tZVAL_UNDEF(&$zvalName);\n";
+            $code .= "\tzval $zvalName;\n";
+            $code .= $this->getTypeDefaultValueCode($zvalName);
         } else {
             $code .= $defaultValue->initializeZval($zvalName, varName: $this->name->__toString());
         }
@@ -3344,6 +3345,32 @@ class PropertyInfo extends VariableLike
             $fieldsynopsisElement->appendChild($doc->createElement("modifier", "readonly"));
         }
     }
+
+    private function getTypeDefaultValueCode(string $zvalName): string
+    {
+        if ($this->type->isNullable()) {
+            return "\tZVAL_NULL(&$zvalName);\n";
+        }
+        $simpleType = $this->type->tryToSimpleType();
+        if ($simpleType !== null) {
+            if ($simpleType->isInt()) {
+                return "\tZVAL_LONG(&$zvalName, 0);\n";
+            }
+            if ($simpleType->isFloat()) {
+                return "\tZVAL_DOUBLE(&$zvalName, 0.0);\n";
+            }
+            if ($simpleType->isBool()) {
+                return "\tZVAL_FALSE(&$zvalName);\n";
+            }
+            if ($simpleType->isString()) {
+                return "\tZVAL_EMPTY_STRING(&$zvalName);\n";
+            }
+            if ($simpleType->isArray()) {
+                return "\tZVAL_EMPTY_ARRAY(&$zvalName);\n";
+            }
+        }
+        return "\tZVAL_NULL(&$zvalName);\n";
+    }
 }
 
 class EnumCaseInfo {

tests/aot/optimizations/object-int-prop-02.phpt

@@ -0,0 +1,22 @@
+--TEST--
+SSA: int
+--FILE--
+<?php
+use native_types;
+class Foo {
+    public int $b;
+
+    function assign_add_prop($n) {
+        for ($i = 0; $i < $n; ++$i) {
+            $this->b += 2;
+        }
+    }
+}
+function main(): void {
+    $o = new Foo();
+    $o->assign_add_prop(100000);
+    var_dump($o->b);
+}
+?>
+--EXPECT--
+int(200000)