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Re: [Bug c++/14639] New: Incorrect emission of unused compiler-generateddestructor at -O2
So when the function itself gets marked as necesary we automatically
emit the thunk when the mark_used_thunk has been called, right?
Yes. Whenever a function is emittted, so are all of its associated thunks.
I guess we need two thinks - we need to manage that once we discover
thunk to be necesary we need to mark the function it is refering to and
we need to emit thunks iff they are really reachable (not just used,
right)?
Yes.
It would be ideal if the thunk was behaving like ordinary function, but
for some reason it is not. Is there way to recognize thunk in C++
independent way?
No. But, you could always change things so that was possible, I
suppose. Thunks cannot be represented as ordinary functions until we
have multiple entry points, and we don't yet have that.
I guess we will need kind of hooks - tell cgraph code that given decl is
thunk and thunk is like function but not quite as it has no body and
reffers to other function and it is not necesay to assemble it as it
gets assembled magically with the function body.
Yes.
Hmm, perhaps I am getting overzelaous here (hope so). I am not quite
sure how emit_p works. When the emit_p is set? If it is at function
expansion time, it is too late - we need to be finished this in advance.
emit_p is set from emit_associated_thunks, which is called for a
function's thunks right before the function itself is sent to
tree_rest_of_compilation.
--
Mark Mitchell
CodeSourcery, LLC
mark@codesourcery.com