[Dwarf-discuss] Re: Dwarf2 Beginner's Question: Pointer variable...
Wed Jun 15 05:24:14 GMT 2005
Thank you so much for all the feedbacks.
>>>David Anderson wrote:
> Instead, produce a .o file and use
> readelf (gnu tool) or dwarfdump (from my web site)
> to display the .debug_info section readably.
I didn't know the difference between the gcc -S -gdwarf-2 -dA output
and the readelf/dwarfdump outputs.
>>>Ron 603-884-2088 said:
> The lack of a DW_AT_location attribute on the DIE for p_int
> indicates that it has no address. That is, it was "optimized
> away". In this example, value propagation might well move the
> address of bbb directly into the point of use without ever
> allocating a place specifically for p_int.
Does this mean these two lines
p_int = &bbb;
can be optimized into the following one line?
printf(..., &bbb )
In this case, is it possible to determine the register of '&bbb'
from the DWARF output?
I was hoping that the DW_AT_location of 'p_int' would still be the register of
the '&bbb' even after this 'optimized away' step.
> Compilers for so-called "garbage collected languages" generally
> need to be especially tuned to avoid creating temporaries that cannot
> be handled by the runtime garbage collector.
Thanks. My goal was to track the pointers without sacrificing
the optimization, but I guess it was an impossible dream.
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