Hi!
When trying to use the gsi_safe_insert*before APIs in bitint lowering,
I've discovered 3 issues and the following patch addresses those:
1) both split_block and split_edge update CDI_DOMINATORS if they are
available, but because edge_before_returns_twice_call first splits
and then adds an extra EDGE_ABNORMAL edge and then removes another
one, the immediate dominators of both the new bb and the bb with
returns_twice call need to change
2) the new EDGE_ABNORMAL edge had uninitialized probability; this patch
copies the probability from the edge that is going to be removed
and similarly copies other flags (EDGE_EXECUTABLE, EDGE_DFS_BACK,
EDGE_IRREDUCIBLE_LOOP etc.)
3) if edge_before_returns_twice_call splits a block, then the bb with
returns_twice call changes, so the gimple_stmt_iterator for it is
no longer accurate, it points to the right statement, but gsi_bb
and gsi_seq are no longer correct; the patch updates it
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2024-03-14 Jakub Jelinek <ja...@redhat.com>
* gimple-iterator.cc (edge_before_returns_twice_call): Copy all
flags and probability from ad_edge to e edge. If CDI_DOMINATORS
are computed, recompute immediate dominator of other_edge->src
and other_edge->dest.
(gsi_safe_insert_before, gsi_safe_insert_seq_before): Update *iter
for the returns_twice call case to the gsi_for_stmt (stmt) to deal
with update it for bb splitting.
--- gcc/gimple-iterator.cc.jj 2024-03-13 13:03:08.073117732 +0100
+++ gcc/gimple-iterator.cc 2024-03-13 15:16:45.294317700 +0100
@@ -997,7 +997,18 @@ edge_before_returns_twice_call (basic_bl
add_phi_arg (new_phi, gimple_phi_arg_def_from_edge (phi, ad_edge),
e, gimple_phi_arg_location_from_edge (phi, ad_edge));
}
+ e->flags = ad_edge->flags;
+ e->probability = ad_edge->probability;
remove_edge (ad_edge);
+ if (dom_info_available_p (CDI_DOMINATORS))
+ {
+ set_immediate_dominator (CDI_DOMINATORS, other_edge->src,
+ recompute_dominator (CDI_DOMINATORS,
+ other_edge->src));
+ set_immediate_dominator (CDI_DOMINATORS, other_edge->dest,
+ recompute_dominator (CDI_DOMINATORS,
+ other_edge->dest));
+ }
}
return other_edge;
}
@@ -1045,6 +1056,7 @@ gsi_safe_insert_before (gimple_stmt_iter
if (new_bb)
e = single_succ_edge (new_bb);
adjust_before_returns_twice_call (e, g);
+ *iter = gsi_for_stmt (stmt);
}
else
gsi_insert_before (iter, g, GSI_SAME_STMT);
@@ -1075,6 +1087,7 @@ gsi_safe_insert_seq_before (gimple_stmt_
if (g == l)
break;
}
+ *iter = gsi_for_stmt (stmt);
}
else
gsi_insert_seq_before (iter, seq, GSI_SAME_STMT);
Jakub
