On Tue, Feb 04, 2014 at 01:57:19PM +0100, Richard Biener wrote:
> > @@ -1691,6 +1691,13 @@ vect_finish_stmt_generation (gimple stmt
> > }
> >
> > gimple_set_location (vec_stmt, gimple_location (stmt));
> > +
> > + /* While EH edges will generally prevent vectorization, stmt might
> > + e.g. be in a must-not-throw region. Ensure newly created stmts
> > + that could throw are part of the same region. */
> > + int lp_nr = lookup_stmt_eh_lp (stmt);
> > + if (lp_nr != 0 && stmt_could_throw_p (vec_stmt))
> > + add_stmt_to_eh_lp (vec_stmt, lp_nr);
>
> Can you instead use maybe_clean_or_replace_eh_stmt (stmt, vec_stmt)?
> That should (maybe) take care of the missed DCE as well (maybe only
> for the first scalar stmt though).
No, because you can have several vec_stmts that could throw created
for a single scalar stmt that can throw. By doing
maybe_clean_or_replace_eh_stmt the EH will be moved on the first
vec_stmt and the rest of stmts will not be added to the region,
furthermore, the scalar stmt which still remains in the IL will
not be in the EH table anymore either (the vectorizer apparently has
code to make scalar stmts used even after vectorization, not sure
if it can happen for loads/stores).
If/when the scalar stmt is removed (right now just stores), it
is removed from the EH tables.
Jakub
