Re: -O0 dead code

[Geoff Keating <geoffk at cygnus dot com>]

Richard Henderson <rth@cygnus.com> writes:

> So how do people feel about the notion of dead code elimination at -O0?

We already do some dead code elimination at -O0.  It seems likely that
this would actually make compiles faster (less I/O, which is the
limiting factor at -O0). 

The only thing to worry about would be the possibility of affecting
debugging information; someone might write

int foo(int a, int b);
{
  int c;
  c = a + b;
  /* c is not used */
}

and might expect to be able to put a breakpoint on the } and examine
the value of c.  Perhaps you could do the elimination only for
non-user variables?

-- 
- Geoffrey Keating <geoffk@cygnus.com>