(0989400a925cd201defdca9eb28eb87200b30785)
Defines ASSUME / RB_LIKELY / UNREACHABLE. More...
#include "ruby/internal/config.h"#include "ruby/internal/assume.h"#include "ruby/internal/has/builtin.h"
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Macros | |
| #define | ASSUME RBIMPL_ASSUME |
| Old name of RBIMPL_ASSUME. More... | |
| #define | UNREACHABLE RBIMPL_UNREACHABLE() |
| Old name of RBIMPL_UNREACHABLE. More... | |
| #define | UNREACHABLE_RETURN RBIMPL_UNREACHABLE_RETURN |
| Old name of RBIMPL_UNREACHABLE_RETURN. More... | |
| #define | RB_LIKELY(x) (__builtin_expect(!!(x), 1)) |
| Asserts that the given Boolean expression likely holds. More... | |
| #define | RB_UNLIKELY(x) (__builtin_expect(!!(x), 0)) |
| Asserts that the given Boolean expression likely doesn't hold. More... | |
Detailed Description
Defines ASSUME / RB_LIKELY / UNREACHABLE.
- Copyright
- This file is a part of the programming language Ruby. Permission is hereby granted, to either redistribute and/or modify this file, provided that the conditions mentioned in the file COPYING are met. Consult the file for details.
- Warning
- Symbols prefixed with either
RBIMPLorrbimplare implementation details. Don't take them as canon. They could rapidly appear then vanish. The name (path) of this header file is also an implementation detail. Do not expect it to persist at the place it is now. Developers are free to move it anywhere anytime at will.
- Note
- To ruby-core: remember that this header can be possibly recursively included from extension libraries written in C++. Do not expect for instance
__VA_ARGS__is always available. We assume C99 for ruby itself but we don't assume languages of extension libraries. They could be written in C++98.
Definition in file assume.h.
Macro Definition Documentation
◆ RB_LIKELY
| #define RB_LIKELY | ( | x | ) | (__builtin_expect(!!(x), 1)) |
Asserts that the given Boolean expression likely holds.
- Parameters
-
x An expression that likely holds.
- Note
- Consider this macro carefully. It has been here since when CPUs were like babies, but contemporary processors are beasts. They are smarter than mare mortals like us today. Their branch predictions highly expectedly outperform your use of this macro.
