On Mon, Feb 16, 2015 at 10:20:23PM +0100, Richard Biener wrote:
> On February 16, 2015 10:11:07 PM CET, Jakub Jelinek <ja...@redhat.com> wrote:
> >On Mon, Feb 16, 2015 at 02:00:32PM -0700, Jeff Law wrote:
> >> --- a/gcc/tree-vrp.c
> >> +++ b/gcc/tree-vrp.c
> >> @@ -10176,13 +10176,20 @@ identify_jump_threads (void)
> >> /* We only care about blocks ending in a COND_EXPR. While
> >there
> >> may be some value in handling SWITCH_EXPR here, I doubt it's
> >> terribly important. */
> >> - last = gsi_stmt (gsi_last_bb (bb));
> >> + last = gsi_stmt (gsi_last_nondebug_bb (bb));
>
> And if the comment is correct then it should not even matter as the condition
> ends a basic block.
It matters, because the use is:
if (!last
|| gimple_code (last) == GIMPLE_SWITCH
|| (gimple_code (last) == GIMPLE_COND
&& TREE_CODE (gimple_cond_lhs (last)) == SSA_NAME
&& (INTEGRAL_TYPE_P (TREE_TYPE (gimple_cond_lhs (last)))
|| POINTER_TYPE_P (TREE_TYPE (gimple_cond_lhs (last))))
&& (TREE_CODE (gimple_cond_rhs (last)) == SSA_NAME
|| is_gimple_min_invariant (gimple_cond_rhs (last)))))
thus, if a bb contains only debug statements and nothing else,
the condition is false, while if it for corresponding -g0 doesn't contain
anything, it is true (!last).
Jakub
