The linker can inline small functions in place of a branch instruction to that function. For the linker to be able to do this, the function (without the return instruction) must fit in the four bytes of the branch instruction.
options to control branch inlining.
If branch inlining optimization is enabled, the linker scans each function call in the image and then inlines as appropriate. When the linker finds a suitable function to inline, it replaces the function call with the instruction from the function that is being called.
The linker applies branch inlining optimization before any unused sections are eliminated so that inlined sections can also be removed if they are no longer called.
The linker can inline two 16-bit instructions in place of
the 32-bit Thumb
--info=inline command-line option
to list all the inlined functions.