Re: Slow handling of C++ symbol names

[Daniel Jacobowitz <drow@mvista.com>]

On Thu, Nov 20, 2003 at 11:54:33AM -0500, Andrew Cagney wrote:
> >
> >Well, I remember fixing some startup time issues since then :P  For
> >instance, the cache shared between minimal and partial symbols should
> >cut demangling time about in half.
> 
> Ah, this: symbol_set_names?  I was looking at the demangler.
> 
> >Which leads to the question.  Why does GDB demangle symbols?  My 
> >>simplistic understanding of the code is that GDB only needs the "iw" 
> >>(a.k.a., demangled string up to  but excluding the lparen and ignoring 
> >>white space) part of the symbol in the search table (the rest isn't so 
> >>critical and can be constructed on-demand).
> >
> >
> >A substantial amount of  demangling is needed to produce the part of
> >the symbol before the lparen; consider templates.  Also, we need the
> >full names in the minimal symbol for break 'foo(int)' with quotes to
> >work.  And there are assumptions of unique symbol names in our
> >hashing/searching, IIRC.
> 
> But without looking at the data we've no idea how substantial any 
> particular part really is.  For instance, when analysing the bcache 
> found that when debugging a C program every entry is 28 bytes in size!
> 
> 'foo(int)' can be broken down into "foo" "(int)" the latter only being 
> demanged and stored on-demand.

"They" tell me that the demangler did not support doing this.  But it
may soon.

Will, you may want to test a CVS snapshot from today or later.  The
demangler for GNU v3 was replaced last night; the new one appears to be
about twice as efficient.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer