I'm wondering where are gcc macros like builtin_expect , __attribute ((warn_unused_result)) etc. stored ? I needed to create a tag file with ctags , for things like those above.
_builtin_expect is a GCC builtin, this means that the compiler has some special code to handle it. It it nowhere really defined; if you care about its implementation, look inside the file
The GCC documentation lists the set of builtins & attributes understood by GCC. Plugins (or MELT extensions) for GCC can augment it.
Some of these, like all