[2/2] Reducing the overhead of dwarf2 location tracking

[Richard Guenther]

On Fri, Mar 4, 2011 at 2:56 PM, Richard Sandiford
<richard.sandiford@linaro.org> wrote:
> Suppose we have a function F that is inlined several times.  Suppose too
> that F has a local variable X, and that no "real" (as opposed to debug)
> references to X remain after pre-inlining optimisations.  In this case,
> we will add X to BLOCK_NONLOCALIZED_VARS rather than duplicate it each
> time F is inlined.  Location notes for each inlining of F will then
> refer to the same non-localised X decl.  This in turn means that each
> inlining of F has the same location list for X, with the list specifying
> the location of X for all inlinings of F.
>
> Jakub confirms that this indeed the intended behaviour, and I haven't
> seen any problem with the output.

Hm, but isn't it incorrect debug info?  I would have expected this
non-localized var to be the abstract origin of a copy for location
list purposes.

Well, for

static inline int foo (int p) { int q = p; return q; }
int bar1 (int i)
{
  return foo (i);
}
int bar2 (int j)
{
  return foo (j);
}

I don't even see location lists for q, but maybe I'm blind ;)

Richard.