From bf123da562c8bd71083138ba329bb044c3006c75 Mon Sep 17 00:00:00 2001
From: Tony Su <tao.su@intel.com>
Date: Tue, 4 Apr 2023 18:09:38 +0800
Subject: [PATCH] [Zend]: Fix unnecessary alignment in ZEND_CALL_FRAME_SLOT
 macro (#10988)

Alignment is not necessary while calculating slots reserved for
zend_execute_data and _zend_vm_stack.

ZEND_STATIC_ASSERT ensures the correct alignment while code
compilation. Credit is to Ilija Tovilo.

PR: https://github.com/php/php-src/pull/10988

Signed-off-by: Tony Su <tao.su@intel.com>
Reviewed-by  : Ilija Tovilo
Reviewed-by  : Dmitry Stogov
Reviewed-by  : Niels Dossche
---
 Zend/zend_compile.h     | 6 +++++-
 Zend/zend_execute.h     | 6 +++++-
 Zend/zend_portability.h | 6 ++++++
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/Zend/zend_compile.h b/Zend/zend_compile.h
index 31ed95f6751..9a2129d908d 100644
--- a/Zend/zend_compile.h
+++ b/Zend/zend_compile.h
@@ -606,8 +606,12 @@ struct _zend_execute_data {
 #define ZEND_CALL_NUM_ARGS(call) \
 	(call)->This.u2.num_args
 
+/* Ensure the correct alignment before slots calculation */
+ZEND_STATIC_ASSERT(ZEND_MM_ALIGNED_SIZE(sizeof(zval)) == sizeof(zval),
+                   "zval must be aligned by ZEND_MM_ALIGNMENT");
+/* A number of call frame slots (zvals) reserved for zend_execute_data. */
 #define ZEND_CALL_FRAME_SLOT \
-	((int)((ZEND_MM_ALIGNED_SIZE(sizeof(zend_execute_data)) + ZEND_MM_ALIGNED_SIZE(sizeof(zval)) - 1) / ZEND_MM_ALIGNED_SIZE(sizeof(zval))))
+	((int)((sizeof(zend_execute_data) + sizeof(zval) - 1) / sizeof(zval)))
 
 #define ZEND_CALL_VAR(call, n) \
 	((zval*)(((char*)(call)) + ((int)(n))))
diff --git a/Zend/zend_execute.h b/Zend/zend_execute.h
index 323b6269ee5..6e868d75a0d 100644
--- a/Zend/zend_execute.h
+++ b/Zend/zend_execute.h
@@ -195,8 +195,12 @@ struct _zend_vm_stack {
 	zend_vm_stack prev;
 };
 
+/* Ensure the correct alignment before slots calculation */
+ZEND_STATIC_ASSERT(ZEND_MM_ALIGNED_SIZE(sizeof(zval)) == sizeof(zval),
+                   "zval must be aligned by ZEND_MM_ALIGNMENT");
+/* A number of call frame slots (zvals) reserved for _zend_vm_stack. */
 #define ZEND_VM_STACK_HEADER_SLOTS \
-	((ZEND_MM_ALIGNED_SIZE(sizeof(struct _zend_vm_stack)) + ZEND_MM_ALIGNED_SIZE(sizeof(zval)) - 1) / ZEND_MM_ALIGNED_SIZE(sizeof(zval)))
+	((sizeof(struct _zend_vm_stack) + sizeof(zval) - 1) / sizeof(zval))
 
 #define ZEND_VM_STACK_ELEMENTS(stack) \
 	(((zval*)(stack)) + ZEND_VM_STACK_HEADER_SLOTS)
diff --git a/Zend/zend_portability.h b/Zend/zend_portability.h
index 48e648ce4ba..c098d29d518 100644
--- a/Zend/zend_portability.h
+++ b/Zend/zend_portability.h
@@ -750,4 +750,10 @@ extern "C++" {
 # define ZEND_CGG_DIAGNOSTIC_IGNORED_END
 #endif
 
+#if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 201112L) /* C11 */
+# define ZEND_STATIC_ASSERT(c, m) _Static_assert((c), m)
+#else
+# define ZEND_STATIC_ASSERT(c, m)
+#endif
+
 #endif /* ZEND_PORTABILITY_H */