In GCC, many function attributes can be used to give syntax to the compiler for useful optimization/profiling of the code.
Helpful link: https://www.acrc.bris.ac.uk/acrc/RedHat/rhel-gcc-en-4/function-attributes.html
For instance, the typical usage of function attribute would look something like this:
// foo.h
__attribute__((no_instrument_function)) void foo();
// test.c
// gcc -finstrument-functions test.c -o test
#include <stdio.h>
#include "foo.h"
void foo() { printf("Foo\n"); }
int main() { foo(); return 0; }
Compiling the above code will insert __cyg_profile_func_enter and __cyg_profile_func_exit only in main function, and avoid inserting them in foo.
Now I wonder whether it is possible to declare a function attribute(s) of target function(s) in a separate file.
For instance, if I have foo.h and bar.h without the attribute, is there a way to have a single file that gives attributes to both foo and bar functions?
For instance, I tried to solve this question by doing something like this (incorrect solution):
// attributes.c
void foo() __attribute__((no_instrument_function));
void bar() __attribute__((no_instrument_function));
// bar.h
void bar();
// foo.h
void foo();
// test.c
// gcc -finstrument-functions attributes.c test.c -o test
#include <stdio.h>
#include "foo.h"
#include "bar.h"
void foo() { printf("Foo\n"); }
void bar() { printf("Bar\n"); }
int main() { foo(); return 0; }
The use case or the reason I am trying to solve this problem is that, unlike these microbenchmarks, I am trying to apply function attributes to a much larger program with many source/header files. In other words, there are many functions that I wish to declare function attributes for many functions that are spread across different files, and I think it is a lot easier to create a single file and insert that into the Makefile.
I think I could create a script to scan through the folder and add the attributes automatically (using regex) or manually by inserting the code. Still, I am exploring whether there is a cleaner solution to this question. Thank you in advance!
