From e59e839dd949136d2f1b63c59df141e1b01f4763 Mon Sep 17 00:00:00 2001 From: Vadim Yanitskiy Date: Wed, 2 Feb 2022 01:17:45 +0600 Subject: [PATCH] core/utils.h: add OSMO_LIKELY / OSMO_UNLIKELY macros These macros are built on top of the __builtin_expect() function [1], which provides the compiler with branch prediction information. Similar macros exist in the Linux kernel: likely() / unlikely(). [1] https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html Change-Id: I0b029654ba050f079eed4a0574a3fa8019677067 --- include/osmocom/core/utils.h | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/include/osmocom/core/utils.h b/include/osmocom/core/utils.h index eda0e3996..7625da167 100644 --- a/include/osmocom/core/utils.h +++ b/include/osmocom/core/utils.h @@ -38,6 +38,15 @@ /*! Copy a C-string into a sized buffer using sizeof to detect buffer's size */ #define OSMO_STRLCPY_ARRAY(array, src) osmo_strlcpy(array, src, sizeof(array)) +/*! Branch prediction optimizations */ +#if defined(__GNUC__) +#define OSMO_LIKELY(exp) __builtin_expect(!!(exp), 1) +#define OSMO_UNLIKELY(exp) __builtin_expect(!!(exp), 0) +#else +#define OSMO_LIKELY(exp) exp +#define OSMO_UNLIKELY(exp) exp +#endif + /*! A mapping between human-readable string and numeric value */ struct value_string { uint32_t value; /*!< numeric value */