recommending gcc to inline the function

I don't know how fea开发者_运维知识库sible it is and how sensible is this question here.

Is there any changes that we can make in makefile to recommend GCC inline all the function although the functions are not inlined during the declaration or nowhere in the source file.

There are a few ways you can make gcc inline functions. One of them is the option -finline-functions, which will make gcc inline "simple" functions. The compiler uses some heuristics to determine whether the function is small enough to be inlined. However, the user has some control over this algorithm through -finline-limit. Read the gcc manual to find the actual values you need.

When inlining functions you should remember that obviously not all functions can be inlined (the simplest example being recursive functions) and the compiler can inline only functions defined within the same translation unit. Also, it is worth mentioning that -finline-functions is on by default at -O3, so just -O3 may sometimes be your solution.

In the makefile you will have to add the right options to all calls to gcc. In a well written makefile you'll easily spot variables with other gcc options, where you can simply place your own.

The gcc -finline_functions option sounds like it might do what you want. Here is some documentation. If your makefile defines a CFLAGS variable, that would be the place to put it.