feat(php): 优化全局变量访问和基准测试函数类型声明

- 在CompilerBase.php中添加标量字符串维度检查，直接返回全局变量名称而不是调用php::global
- 为micro_bench.php中的read_global_var、read_hash、read_str_offset和issetor函数添加int类型声明
- 改进全局变量处理逻辑，避免不必要的php::global调用
- 提升代码类型安全性和性能表现

examples/micro_bench.php

@@ -188,27 +188,27 @@ function read_auto_global($n) {
     }
 }
 
-function read_global_var($n) {
+function read_global_var(int $n) {
     for ($i = 0; $i < $n; ++$i) {
         $x = $GLOBALS['g_var'];
     }
 }
 
-function read_hash($n) {
+function read_hash(int $n) {
     $hash = array('test' => 0);
     for ($i = 0; $i < $n; ++$i) {
         $x = $hash['test'];
     }
 }
 
-function read_str_offset($n) {
+function read_str_offset(int $n) {
     $str = "test";
     for ($i = 0; $i < $n; ++$i) {
         $x = $str[1];
     }
 }
 
-function issetor($n) {
+function issetor(int $n) {
     $val = array(0,1,2,3,4,5,6,7,8,9);
     for ($i = 0; $i < $n; ++$i) {
         $x = $val ?: null;

src/Php/CompilerBase.php

@@ -2284,6 +2284,13 @@ class CompilerBase extends \PhpAot\Core\Translator
                 if ($node->dim === null) {
                     $this->fatalError($node, 'Cannot use [] for GLOBALS');
                 }
+                if ($this->isScalarString($node->dim)) {
+                    $name = $node->dim->value;
+                    if (!$this->hasGlobalVar($name)) {
+                        $this->addGlobalVar($name, self::TYPE_VAR);
+                    }
+                    return $name;
+                }
                 return 'php::global(' . $this->parseIdentifier($node->dim) . ')';
             }
             if (!$this->hasVar($var)) {