On Wed, Sep 20, 2006 at 02:52:40AM -0300, Alexandre Oliva wrote: > The linker already has code to merge sections. There's nothing to > stop us from compiling every function into say: > > foo: > jmp .foo.impl > .section .gnu.impl.foo, "axM" > .foo.impl: > [actual code for foo emitted] > .previous > > Then the linker doesn't need any smarts whatsoever to merge functions > with identical code. Hmm, maybe it does, since it must compare > relocations as well, but this doesn't sound too hard at first. > > For extra bonus points, it may short-circuit relocations that call foo > (as opposed to taking its address) when it binds locally and skip the > jmp altogether. Ditto for *all* relocations that reference foo, when > it doesn't merge .foo.impl with anything else.
Alternatively, the compiler could arrange that pointers to functions always point to a jump that then leads to the function, while direct calls go directly to the function. That way pointers compare unequal but the code is merged.
