How to get the offset of a local variable relative to the stack frame address

[gkour...@freemail.gr]

The offset of a local variable relative to the frame address in C or C++ 
may be found by||:
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|(char*)&a -(char*)__builtin_frame_address(0)|
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|||A more straightforward builtin should be already available by gcc. 
Which is it ?|
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|p.s. the previous code adds the offset to bp and afterwards subtracts 
from the result bp.|

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