@@ -62,7 +62,7 @@ int parse_qapi_name(const char *name, bool complete);
#define QAPI_LIST_LENGTH(list) \
({ \
size_t _len = 0; \
- typeof(list) _tail; \
+ typeof_strip_qual(list) _tail; \
for (_tail = list; _tail != NULL; _tail = _tail->next) { \
_len++; \
} \
@@ -20,48 +20,6 @@
/* Compiler barrier */
#define barrier() ({ asm volatile("" ::: "memory"); (void)0; })
-/* The variable that receives the old value of an atomically-accessed
- * variable must be non-qualified, because atomic builtins return values
- * through a pointer-type argument as in __atomic_load(&var, &old, MODEL).
- *
- * This macro has to handle types smaller than int manually, because of
- * implicit promotion. int and larger types, as well as pointers, can be
- * converted to a non-qualified type just by applying a binary operator.
- */
-#define typeof_strip_qual(expr) \
- typeof( \
- __builtin_choose_expr( \
- __builtin_types_compatible_p(typeof(expr), bool) || \
- __builtin_types_compatible_p(typeof(expr), const bool) || \
- __builtin_types_compatible_p(typeof(expr), volatile bool) || \
- __builtin_types_compatible_p(typeof(expr), const volatile bool), \
- (bool)1, \
- __builtin_choose_expr( \
- __builtin_types_compatible_p(typeof(expr), signed char) || \
- __builtin_types_compatible_p(typeof(expr), const signed char) || \
- __builtin_types_compatible_p(typeof(expr), volatile signed char) || \
- __builtin_types_compatible_p(typeof(expr), const volatile signed char), \
- (signed char)1, \
- __builtin_choose_expr( \
- __builtin_types_compatible_p(typeof(expr), unsigned char) || \
- __builtin_types_compatible_p(typeof(expr), const unsigned char) || \
- __builtin_types_compatible_p(typeof(expr), volatile unsigned char) || \
- __builtin_types_compatible_p(typeof(expr), const volatile unsigned char), \
- (unsigned char)1, \
- __builtin_choose_expr( \
- __builtin_types_compatible_p(typeof(expr), signed short) || \
- __builtin_types_compatible_p(typeof(expr), const signed short) || \
- __builtin_types_compatible_p(typeof(expr), volatile signed short) || \
- __builtin_types_compatible_p(typeof(expr), const volatile signed short), \
- (signed short)1, \
- __builtin_choose_expr( \
- __builtin_types_compatible_p(typeof(expr), unsigned short) || \
- __builtin_types_compatible_p(typeof(expr), const unsigned short) || \
- __builtin_types_compatible_p(typeof(expr), volatile unsigned short) || \
- __builtin_types_compatible_p(typeof(expr), const volatile unsigned short), \
- (unsigned short)1, \
- (expr)+0))))))
-
#ifndef __ATOMIC_RELAXED
#error "Expecting C11 atomic ops"
#endif
@@ -227,4 +227,50 @@
#define SECOND_ARG(first, second, ...) second
#define IS_EMPTY_(junk_maybecomma) SECOND_ARG(junk_maybecomma 1, 0)
+#ifndef __cplusplus
+/*
+ * Useful in macros that need to declare temporary variables. For example,
+ * the variable that receives the old value of an atomically-accessed
+ * variable must be non-qualified, because atomic builtins return values
+ * through a pointer-type argument as in __atomic_load(&var, &old, MODEL).
+ *
+ * This macro has to handle types smaller than int manually, because of
+ * implicit promotion. int and larger types, as well as pointers, can be
+ * converted to a non-qualified type just by applying a binary operator.
+ */
+#define typeof_strip_qual(expr) \
+ typeof( \
+ __builtin_choose_expr( \
+ __builtin_types_compatible_p(typeof(expr), bool) || \
+ __builtin_types_compatible_p(typeof(expr), const bool) || \
+ __builtin_types_compatible_p(typeof(expr), volatile bool) || \
+ __builtin_types_compatible_p(typeof(expr), const volatile bool), \
+ (bool)1, \
+ __builtin_choose_expr( \
+ __builtin_types_compatible_p(typeof(expr), signed char) || \
+ __builtin_types_compatible_p(typeof(expr), const signed char) || \
+ __builtin_types_compatible_p(typeof(expr), volatile signed char) || \
+ __builtin_types_compatible_p(typeof(expr), const volatile signed char), \
+ (signed char)1, \
+ __builtin_choose_expr( \
+ __builtin_types_compatible_p(typeof(expr), unsigned char) || \
+ __builtin_types_compatible_p(typeof(expr), const unsigned char) || \
+ __builtin_types_compatible_p(typeof(expr), volatile unsigned char) || \
+ __builtin_types_compatible_p(typeof(expr), const volatile unsigned char), \
+ (unsigned char)1, \
+ __builtin_choose_expr( \
+ __builtin_types_compatible_p(typeof(expr), signed short) || \
+ __builtin_types_compatible_p(typeof(expr), const signed short) || \
+ __builtin_types_compatible_p(typeof(expr), volatile signed short) || \
+ __builtin_types_compatible_p(typeof(expr), const volatile signed short), \
+ (signed short)1, \
+ __builtin_choose_expr( \
+ __builtin_types_compatible_p(typeof(expr), unsigned short) || \
+ __builtin_types_compatible_p(typeof(expr), const unsigned short) || \
+ __builtin_types_compatible_p(typeof(expr), volatile unsigned short) || \
+ __builtin_types_compatible_p(typeof(expr), const volatile unsigned short), \
+ (unsigned short)1, \
+ (expr)+0))))))
+#endif
+
#endif /* COMPILER_H */
The typeof_strip_qual() is most useful for the atomic fetch-and-modify operations in atomic.h, but it can be used elsewhere as well. For example, QAPI_LIST_LENGTH() assumes that the argument is not const, which is not a requirement. Move the macro to compiler.h and, while at it, move it under #ifndef __cplusplus to emphasize that it uses C-only constructs. A C++ version of typeof_strip_qual() using type traits is possible[1], but beyond the scope of this patch because the little C++ code that is in QEMU does not use QAPI. The patch was tested by changing the declaration of strv_from_str_list() in qapi/qapi-type-helpers.c to: char **strv_from_str_list(const strList *const list) This is valid C code, and it fails to compile without this change. [1] https://lore.kernel.org/qemu-devel/20240624205647.112034-1-flwu@google.com/ Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org> Tested-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- include/qapi/util.h | 2 +- include/qemu/atomic.h | 42 ------------------------------------- include/qemu/compiler.h | 46 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 47 insertions(+), 43 deletions(-)