Fix phpGH-17577: JIT packed type guard crash

When a guard check is created for a variable to check if it's a packed array,
it is possible that there was no prior type check for that variable.
This happens in the global scope for example when the variable aliases.
In the test, this causes a dereference of address 8 because the integer
element in `$a` is interpreted as an array address.

This patch adds a check to see if the zval type is an array.
If we were not able to determine or guard the type then we also cannot know the array is packed.

ext/opcache/jit/zend_jit_trace.c

@@ -4162,6 +4162,7 @@ static const void *zend_jit_trace(zend_jit_trace_rec *trace_buffer, uint32_t par
 			}
 
 			if ((info & MAY_BE_PACKED_GUARD) != 0
+			 && STACK_TYPE(stack, i) == IS_ARRAY
 			 && (trace_buffer->stop == ZEND_JIT_TRACE_STOP_LOOP
 			  || trace_buffer->stop == ZEND_JIT_TRACE_STOP_RECURSIVE_CALL
 			  || trace_buffer->stop == ZEND_JIT_TRACE_STOP_RECURSIVE_RET)

ext/opcache/tests/jit/gh17577.phpt

@@ -0,0 +1,27 @@
+--TEST--
+GH-17577 (JIT packed type guard crash)
+--EXTENSIONS--
+opcache
+--INI--
+opcache.jit_buffer_size=16M
+opcache.jit_hot_func=1
+--FILE--
+<?php
+$a = array(
+    array(1,2,3),
+    0,
+);
+function my_dump($var) {
+}
+foreach($a as $b) {
+    for ($i = 0; $i < 3; $i++) {
+        my_dump($b[$i]);
+    }
+}
+?>
+--EXPECTF--
+Warning: Trying to access array offset on int in %s on line %d
+
+Warning: Trying to access array offset on int in %s on line %d
+
+Warning: Trying to access array offset on int in %s on line %d