CODEWITHSUNDEEP
cinline
Gábor
Gábor

Reputation: 451

Why the following function is not getting inlined?

Can you please tell me why the following function func1 is not getting inlined?

Code

#include <stdio.h>
#include <stdlib.h>

static inline int func1(int a) {
    return a*2;
}

int main(int argc, char **argv) {

    int value = strtol(argv[1], NULL, 0);

    value = func1(value);

    printf("value: %d\n", value);

    return 0;
}

Run

$ gcc -Wall -o main main.c
$ objdump -D main | grep func1
0000000000000700 <func1>:
 742:   e8 b9 ff ff ff          callq  700 <func1>

Upvotes: 0

Views: 145

Answers (2)

Neil
Neil

Reputation: 1922

I believe it is not inlined because one is not doing optimisation, (for debugging, I assume.) From the GCC online docs,

GCC does not inline any functions when not optimizing unless you specify the ‘always_inline’ attribute for the function

Upvotes: 2

Andrew Henle
Andrew Henle

Reputation: 1

inline is literally a mere "suggestion".

Per 6.7.4 Function specifiers, paragraph 6 of the C standard:

A function declared with an inline function specifier is an inline function. Making a function an inline function suggests that calls to the function be as fast as possible. The extent to which such suggestions are effective is implementation-defined.

As inline is just a suggestion, a function with the inline specifier may or may not be inlined as the implementation determines.

Upvotes: 2

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