xnu-7195.101.1.tar.gz

[apple/xnu.git] / libkern / os / overflow.h

diff --git a/libkern/os/overflow.h b/libkern/os/overflow.h
index 2b6034ca66d9c9df5cf06281482cf5eee71e4ee6..f00a6024fe37a803a803f4310449f2ffe0367256 100644 (file)
--- a/libkern/os/overflow.h
+++ b/libkern/os/overflow.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015 Apple Inc. All rights reserved.
+ * Copyright (c) 2015-2018 Apple Inc. All rights reserved.
  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  *
@@ -42,70 +42,77 @@
 #define _OS_OVERFLOW_H
 
 #include <sys/cdefs.h>
+#include <stdbool.h>
+#include <os/base.h>
 
-/* compile-time assertion that 'x' and 'y' are equivalent types */
-#define __OS_TYPE_CHECK(x, y) do { \
-       _Static_assert(__builtin_types_compatible_p(typeof(x),typeof(y)), \
-                       "overflow arithmetic: incompatible types"); \
-} while (0)
-
-#define __os_add_overflow_func(T,U,V) _Generic((T), \
-               unsigned:           __builtin_uadd_overflow, \
-               unsigned long:      __builtin_uaddl_overflow, \
-               unsigned long long: __builtin_uaddll_overflow, \
-               int:                __builtin_sadd_overflow, \
-               long:               __builtin_saddl_overflow, \
-               long long:          __builtin_saddll_overflow \
-       )(T,U,V)
-
-#define __os_sub_overflow_func(T,U,V) _Generic((T), \
-               unsigned:           __builtin_usub_overflow, \
-               unsigned long:      __builtin_usubl_overflow, \
-               unsigned long long: __builtin_usubll_overflow, \
-               int:                __builtin_ssub_overflow, \
-               long:               __builtin_ssubl_overflow, \
-               long long:          __builtin_ssubll_overflow \
-       )(T,U,V)
-
-#define __os_mul_overflow_func(T,U,V) _Generic((T), \
-               unsigned:           __builtin_umul_overflow, \
-               unsigned long:      __builtin_umull_overflow, \
-               unsigned long long: __builtin_umulll_overflow, \
-               int:                __builtin_smul_overflow, \
-               long:               __builtin_smull_overflow, \
-               long long:          __builtin_smulll_overflow \
-       )(T,U,V)
-
-int __header_always_inline __attribute__((__warn_unused_result__))
-__os_warn_unused(const int x)
+bool __header_always_inline OS_WARN_RESULT
+__os_warn_unused(__const bool x)
 {
        return x;
 }
 
-#define os_add_overflow(a, b, res) __os_warn_unused(({ \
-       __OS_TYPE_CHECK((a), (b)); \
-       __OS_TYPE_CHECK((b), *(res)); \
-       __os_add_overflow_func((a), (b), (res)); \
-}))
+#if __has_builtin(__builtin_add_overflow) && \
+        __has_builtin(__builtin_sub_overflow) && \
+        __has_builtin(__builtin_mul_overflow)
+
+#define os_add_overflow(a, b, res) __os_warn_unused(__builtin_add_overflow((a), (b), (res)))
+#define os_sub_overflow(a, b, res) __os_warn_unused(__builtin_sub_overflow((a), (b), (res)))
+#define os_mul_overflow(a, b, res) __os_warn_unused(__builtin_mul_overflow((a), (b), (res)))
 
-#define os_add3_overflow(a, b, c, res) __os_warn_unused(({ \
-       typeof(a) _tmp; \
-       int _s, _t; \
+#else
+# error os_overflow expects type-generic builtins
+#endif /* __has_builtin(...) */
+
+/* os_add3_overflow(a, b, c) -> (a + b + c) */
+#define os_add3_overflow(a, b, c, res) __os_warn_unused(__extension__({ \
+       __typeof(*(res)) _tmp; \
+       bool _s, _t; \
        _s = os_add_overflow((a), (b), &_tmp); \
        _t = os_add_overflow((c), _tmp, (res)); \
        _s | _t; \
 }))
 
-#define os_sub_overflow(a, b, res) __os_warn_unused(({ \
-       __OS_TYPE_CHECK((a), (b)); \
-       __OS_TYPE_CHECK((b), *(res)); \
-       __os_sub_overflow_func((a), (b), (res)); \
+/* os_mul3_overflow(a, b, c) -> (a * b * c) */
+#define os_mul3_overflow(a, b, c, res) __os_warn_unused(__extension__({ \
+       __typeof(*(res)) _tmp; \
+       bool _s, _t; \
+       _s = os_mul_overflow((a), (b), &_tmp); \
+       _t = os_mul_overflow((c), _tmp, (res)); \
+       _s | _t; \
 }))
 
-#define os_mul_overflow(a, b, res) __os_warn_unused(({ \
-       __OS_TYPE_CHECK((a), (b)); \
-       __OS_TYPE_CHECK((b), *(res)); \
-       __os_mul_overflow_func((a), (b), (res)); \
+/* os_add_and_mul_overflow(a, b, x) -> (a + b)*x */
+#define os_add_and_mul_overflow(a, b, x, res) __os_warn_unused(__extension__({ \
+       __typeof(*(res)) _tmp; \
+       bool _s, _t; \
+       _s = os_add_overflow((a), (b), &_tmp); \
+       _t = os_mul_overflow((x), _tmp, (res)); \
+       _s | _t; \
 }))
 
+/* os_mul_and_add_overflow(a, x, b) -> a*x + b */
+#define os_mul_and_add_overflow(a, x, b, res) __os_warn_unused(__extension__({ \
+       __typeof(*(res)) _tmp; \
+       bool _s, _t; \
+       _s = os_mul_overflow((a), (x), &_tmp); \
+       _t = os_add_overflow((b), _tmp, (res)); \
+       _s | _t; \
+}))
+
+/* os_convert_overflow(a) -> a [converted to the result type] */
+#define os_convert_overflow(a, res) os_add_overflow((a), 0, (res))
+
+/* os_inc_overflow(res) -> *res += 1 */
+#define os_inc_overflow(res) __os_warn_unused(__extension__({ \
+       __typeof((res)) _tmp = (res); \
+       os_add_overflow(*_tmp, 1, _tmp); \
+}))
+
+/* os_dec_overflow(res) -> *res -= 1 */
+#define os_dec_overflow(res) __os_warn_unused(__extension__({ \
+       __typeof((res)) _tmp = (res); \
+       os_sub_overflow(*_tmp, 1, _tmp); \
+}))
+
+
 #endif /* _OS_OVERFLOW_H */