FYI: clang static analyzer page has moved to
uqs at spoerlein.net
Tue Jan 11 10:33:25 UTC 2011
On Sun, 09.01.2011 at 01:13:54 +0100, Jilles Tjoelker wrote:
> On Wed, Jan 05, 2011 at 10:30:43PM +0100, Ulrich Spörlein wrote:
> > On Wed, 05.01.2011 at 20:36:53 +0100, Jilles Tjoelker wrote:
> > > On Wed, Jan 05, 2011 at 05:55:45PM +0100, Ulrich Spörlein wrote:
> > > > *But*, it should grok that for err(3) and exit(3). Now there are some
> > > > possible remedies:
> > > > - get IPA to work with clang, or at least file a bug
> > > > - mark functions as __dead2 (please don't do that)
> > > Why not?
> > Cause IMHO it adds clutter, is noisy and needs to be maintained
> > manually, when we have these "computer" things that should deduct this
> > by themselves.
> Yes, but to me it seems the only realistic option of your three.
> Upstream is unlikely to add IPA to the checker and other kinds of
> annotation are probably either similar to __dead2 with the same problems
> and an additional one that gcc does not check it or very specific to a
> particular complaint from the checker.
> > > I have done this in some cases because it leads to better code with gcc
> > > (the system version in 9-current). See SVN commit r212508 to
> > > bin/sh/parser.c. Although synexpect() and synerror() are static, adding
> > > __dead2 to both makes the executable 576 bytes smaller on i386 (these
> > > functions are called many times). Adding __dead2 to synexpect() only
> > > causes a warning "noreturn function does return" (it calls synerror()).
> > > Adding __dead2 to synerror() only also makes the executable smaller but
> > > not as much as adding it to both.
> > > Reordering the functions in the file does not help to make gcc see that
> > > the functions do not return.
> > This is too bad and really makes me sad. It shouldn't be necessary to
> > hand-hold the compilers like that. Could you try some tests with gcc 4.5
> > to confirm this is still required?
> gcc 4.5 still needs it. gcc 4.6 and clang (the compiler) do not need it.
> (For gcc, used ports gcc and compiled head bin/sh with some patches on
> stable/8. For clang, used base clang and compiled head bin/sh on head.)
Thank you for confirming this, this is good to know. Looks like I need
to stop worrying and learn to love the __dead2! :D
More information about the freebsd-current