https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106126
--- Comment #13 from luoxhu at gcc dot gnu.org --- Otherwise we need record first_bb when conditions_in_bbs->is_empty, then check that in is_beneficial, ordered_remove the info entry if that bb is not the first "if condition" with side_effect statement in it, the fix would be as below, but I am not sure whether it is worth&correct way doing this to handle both PR105740 and PR106126? git diff diff --git a/gcc/gimple-if-to-switch.cc b/gcc/gimple-if-to-switch.cc index f7b0b02628b..44bb0228856 100644 --- a/gcc/gimple-if-to-switch.cc +++ b/gcc/gimple-if-to-switch.cc @@ -63,7 +63,7 @@ struct condition_info condition_info (gcond *cond): m_cond (cond), m_bb (gimple_bb (cond)), m_forwarder_bb (NULL), m_ranges (), m_true_edge (NULL), m_false_edge (NULL), - m_true_edge_phi_mapping (), m_false_edge_phi_mapping () + m_true_edge_phi_mapping (), m_false_edge_phi_mapping (), first_bb(false) { m_ranges.create (0); } @@ -80,6 +80,7 @@ struct condition_info edge m_false_edge; mapping_vec m_true_edge_phi_mapping; mapping_vec m_false_edge_phi_mapping; + bool first_bb; }; /* Recond PHI mapping for an original edge E and save these into vector VEC. */ @@ -194,6 +195,16 @@ if_chain::is_beneficial () auto_vec<cluster *> clusters; clusters.create (m_entries.length ()); + for (unsigned i = 0; i < m_entries.length (); i++) + { + condition_info *info = m_entries[i]; + if (info->first_bb && i != 0 && !no_side_effect_bb (info->m_bb)) + { + m_entries.ordered_remove (i); + break; + } + } + for (unsigned i = 0; i < m_entries.length (); i++) { condition_info *info = m_entries[i]; @@ -397,6 +408,8 @@ find_conditions (basic_block bb, tree_code code = gimple_cond_code (cond); condition_info *info = new condition_info (cond); + if (conditions_in_bbs->is_empty ()) + info->first_bb = true;