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Re: RFC: printing pointers to global (data) variable on Windows...
- From: Tom Tromey <tromey at redhat dot com>
- To: Joel Brobecker <brobecker at adacore dot com>
- Cc: gdb-patches at sourceware dot org
- Date: Thu, 16 Aug 2012 14:06:40 -0600
- Subject: Re: RFC: printing pointers to global (data) variable on Windows...
- References: <20120816152255.GA2836@adacore.com>
>>>>> "Joel" == Joel Brobecker <brobecker@adacore.com> writes:
Joel> if (msymbol != NULL
Joel> && MSYMBOL_SIZE (msymbol) == 0
Joel> && MSYMBOL_TYPE (msymbol) != mst_text
Joel> && MSYMBOL_TYPE (msymbol) != mst_text_gnu_ifunc
Joel> && MSYMBOL_TYPE (msymbol) != mst_file_text)
Joel> msymbol = NULL;
I think the reason for this is here:
http://sourceware.org/ml/gdb-patches/2012-04/msg00175.html
text symbols are allowed since without them (according to a later
message) asm-source.exp would regress.
Joel> I looked at the COFF/PE documentation, and I do not think that there
Joel> is a way to provide the size of each symbol in the symbol table.
Joel> So the block of code above discards our minimal symbol entry due to
Joel> the size (always) being zero. And since our global is not a function,
Joel> we do not find anything from the debugging info either.
Joel> Does anyone know why we have the block discarding zero-sized non-text
Joel> symbols? I ran the testsuite on x86_64-linux, and got no regression.
I wonder what happens if you set the symbol sizes to 1.
Ok, horrible idea. Perhaps some flag bit on the minsym instead?
Or on the objfile?
Joel> My second question is regarding the fact that we looking symbols for
Joel> functions only. This probably made sense if the function was used for
Joel> text addresses (like disass), but does it now? Or perhaps it's the
Joel> GNU/Linux output that should be fixed, and only text symbols should
Joel> be printed when printing addresses (somehow, I do not think that this
Joel> would be right).
IIRC the full symbol tables only record address information for text
symbols, not for data symbols. If so, one cannot do this lookup.
That's what I remember from when I wrote this change. It would be nice
to be wrong since the current approach means we can't always print a
sensible answer for users.
Tom