Re: beware of dead string constants

[Peter Samuelson <peter@cadcamlab.org>]

    [I wrote]
> > >   void foo (void)
> > >   {
> > >     if (0)
> > >       printk(KERN_INFO "bar");
> > >   }
> > > 

[J . A . Magallon]
> Is it related to opt level ? -O3 does auto-inlining and -O2 does not
> (discovered that here, auto inlining in kernel trashes the cache...)

See for yourself.  'gcc -S' is most helpful.  The above generates a
string constant "bar\0" for all optimization levels.

Jakub Jelinek claims to have fixed this particular bug in the last week
or so, although I have not downloaded and compiled recent CVS to verify
this.  (Didn't someone at some point have a cgi frontend to
CVS-snapshot 'gcc -S'?  I can't find it now.)

There is a similar case of scoped 'static' variables, like 'bar' here:

  extern void baz (int *);
  void foo (void)
  {
    if (0) {
      static int bar[1024];	/* useless 4096-byte hole in bss */
      baz(bar);
    }
  }

and according to Jeff Law, this case is *not* fixed yet.

Peter
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