c++ - Non virtual thunk on gcc 7.2 sometimes too big -


i try migrate gcc 7.2 gcc 4.9 (gcc-arm-none-eabi, -o2). code builds successfully, result program bigger on gcc 4.9.

i make investigation , realize, size of "non virtual thunk on xxx" big, if overriding function defined in class:

struct ia { virtual void fa() = 0; }; struct ib { virtual void fb() = 0; }; struct c : ia, ib {   void fa() override {}   void fb() override // if place definition here,    // size of "non virtual thunk c::fb()" same, function }; // if place definition outside class,  // size of non virtual thunk 6-8 bytes, same in gcc4.9

there may option prevents such inlining?


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