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Compiler Reference Guide

Preface armclang Command-line Options Compiler-specific Keywords and Operators Compiler-specific Function, Variable, and Type Att Function attributes __attribute__((always_inline)) function attribute __attribute__((cmse_nonsecure_call)) function attr __attribute__((cmse_nonsecure_entry)) function att __attribute__((const)) function attribute __attribute__((constructor(priority))) function at __attribute__((format_arg(string-index))) function __attribute__((interrupt("type"))) function attrib __attribute__((malloc)) function attribute __attribute__((naked)) function attribute __attribute__((noinline)) function attribute __attribute__((nonnull)) function attribute __attribute__((noreturn)) function attribute __attribute__((nothrow)) function attribute __attribute__((pcs("calling_convention"))) functio __attribute__((pure)) function attribute __attribute__((section("name"))) function attribut __attribute__((unused)) function attribute __attribute__((used)) function attribute __attribute__((value_in_regs)) function attribute __attribute__((visibility("visibility_type"))) fun __attribute__((weak)) function attribute __attribute__((weakref("target"))) function attrib Type attributes __attribute__((aligned)) type attribute __attribute__((packed)) type attribute __attribute__((transparent_union)) type attribute Variable attributes __attribute__((alias)) variable attribute __attribute__((aligned)) variable attribute __attribute__((deprecated)) variable attribute __attribute__((packed)) variable attribute __attribute__((section("name"))) variable attribut __attribute__((unused)) variable attribute __attribute__((used)) variable attribute __attribute__((visibility("visibility_type"))) var __attribute__((weak)) variable attribute __attribute__((weakref("target"))) variable attrib Compiler-specific Intrinsics Compiler-specific Pragmas Other Compiler-specific Features Standard C Implementation Definition Standard C++ Implementation Definition armclang Integrated Assembler armclang Inline Assembler

__attribute__((always_inline)) function attribute

3.2 __attribute__((always_inline)) function attribute

This function attribute indicates that a function must be inlined.

The compiler attempts to inline the function, regardless of the characteristics of the function.

In some circumstances, the compiler might choose to ignore __attribute__((always_inline)), and not inline the function. For example:

  • A recursive function is never inlined into itself.
  • Functions that use alloca() might not be inlined.

Example

static int max(int x, int y) __attribute__((always_inline));
static int max(int x, int y)
{
    return x > y ? x : y; // always inline if possible
}

Note:

__attribute__((always_inline)) does not affect the linkage characteristics of the function in the same way that the inline function-specifier does. When using __attribute__((always_inline)), if you want the declaration and linkage of the function to follow the rules of the inline function-specifier of the source language, then you must also use the keyword inline or __inline__ (for C90). For example:

inline int max(int x, int y) __attribute__((always_inline));
int max(int x, int y)
{
    return x > y ? x : y; // always inline if possible
}
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