This header file is part of the Lely libraries; it contains the compiler feature definitions. More...
#include <limits.h>
Go to the source code of this file.
Macros | |
| #define | _Alignas(x) __attribute__((__aligned__(x))) |
| Specifies the alignment requirement of the declared object or member. | |
| #define | _Alignof(x) __alignof__(x) |
| Yields the alignment requirement of its operand type. | |
| #define | _Noreturn __attribute__((__noreturn__)) |
A function declared with a _Noreturn function specifier SHALL not return to its caller. | |
| #define | _Thread_local __thread |
An object whose identifier is declared with the storage-class specifier _Thread_local has thread storage duration. More... | |
| #define | __likely(x) __builtin_expect(!!(x), 1) |
| Indicates to the compiler that the expression is most-likely true. More... | |
| #define | __unlikely(x) __builtin_expect(!!(x), 0) |
| Indicates to the compiler that the expression is most-likely false. More... | |
| #define | LONG_BIT __WORDSIZE |
| The number of bits in a long. | |
Detailed Description
This header file is part of the Lely libraries; it contains the compiler feature definitions.
- Copyright
- 2013-2019 Lely Industries N.V.
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
Definition in file features.h.
Macro Definition Documentation
◆ _Thread_local
| #define _Thread_local __thread |
An object whose identifier is declared with the storage-class specifier _Thread_local has thread storage duration.
Its lifetime is the entire execution of the thread for which it is created, and its stored value is initialized when the thread is started. There is a distinct object per thread, and use of the declared name in an expression refers to the object associated with the thread evaluating the expression.
Definition at line 239 of file features.h.
◆ __likely
| #define __likely | ( | x | ) | __builtin_expect(!!(x), 1) |
Indicates to the compiler that the expression is most-likely true.
Subject to the same considerations as __unlikely().
Definition at line 273 of file features.h.
◆ __unlikely
| #define __unlikely | ( | x | ) | __builtin_expect(!!(x), 0) |
Indicates to the compiler that the expression is most-likely false.
This should only be used in performance-critical sections as compilers are very good at branch prediction nowadays. The only exception to this rule is error and exception checking, e.g. if (__unlikely(!ptr)) { handle NULL pointer }, since we never optimize exceptions.
- See also
- __likely()
Definition at line 286 of file features.h.
