On Thu, 14 Mar 2024, Jakub Jelinek wrote:
> 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?
OK
> 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
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
