Re: Size optimization for objects

["Rego, P." <pvrego@gmail.com>]

> > and the read size of bla.o is 611 bytes.
> What do you mean by "read size"? Perhaps this is a typo, and you meant
> to write "real size"?
> If you mean the total size of the file bla.o (from the directory
> listing, e.g "ls -l"), this is not a useful comparison, because the file
> contains much more data than just the machine code: there are headers,
> symbol tables, and other debug information -- among other things, the
> information that "nm" uses to associate machine code addresses with
> identifier symbols.

Yes, it is from directory listing. In this case, the 'size' provided by "ls -l" should be bigger, right? 

> > If I add the second values,
> > the total result is 16#44" which is 68 in decimal, which is not 611 bytes.
> > Also, if I run 
> >    nm --print-size --size-sort bla.exe > bla.txt
> > the bla.parse is big,

> What do you mean by "bla.parse"? Perhaps "bla.txt"? The size of this
> text file is totally irrelevant.
Sorry, I meant "bla.txt". I agree, it was just a comment.

> > but adding the second column, the result (in Excel I convert it
> > to decimal before adding) is 8.61147E+12 and the real bla.exe
> > size is 1512500 bytes, also very different.
> Again, if by "real size" you mean the entire size of the file bla.exe,
> the comparison it not useful, just as for bla.o: bla.exe contains a lot
> more data than just the machine code.
I don't think 8.61147E+12 is irrelevant. Again, if you consider the lots of things added by "ls -l", the size of bla.exe should be bigger.
 
> The Excel summed size that you show is surprising. Perhaps the method
> "nm" uses to compute function size (as the difference between to
> adjacent symbols) does not work correctly for some special case, such as
> the function with the highest address. Without seeing the whole output
> from "nm", it is difficult to say.
Since the output is big, I will paste it in the next post.

> To find the total amount of data/code, in an exe, I would look either at
> the link map output, or use "objdump" to see the sizes of the segments.
I will run objdump so.

Thanks.

Rego.

> -- 
> 
> Niklas Holsti
> 
> Tidorum Ltd
> 
> niklas holsti tidorum fi
> 
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