Re: [Valgrind-developers] get_sym_name

[Philippe W. <phi...@sk...>]

On Fri, 2014-07-25 at 05:58 -0700, John Reiser wrote:
> > +      VG_(strncpy_safely)(buf, "???", nbuf);   // unknown symbol
> 
> Beware performance loss.  strncpy _always_ writes nbuf bytes (3rd argument),
> so the execution of that code finishes with the equivalent of
> 	memset(&buf[3], 0, nbuf - 3);
> 
> This will be much faster:
> 	memcpy(buf, "???", 3+1);
> as long as the other code requires only one terminating '\0'.
> [Dress up with the appropriate VG_() and other adornments.]

Funny that we just got a big performance regression due to the
rewriting of VG_(strncpy_safely) : it was not zero-filling
and since rev 14186, it is zero filling.

That gave for some tests more than 50% perf regressions.

Philippe