On Fri, Jun 13, 2025 at 10:05:14AM +0200, Jakub Jelinek wrote:
> On Fri, Jun 13, 2025 at 08:52:55AM +0100, Richard Sandiford wrote:
> > > 2025-06-12 Jakub Jelinek <ja...@redhat.com>
> > >
> > > * cfgexpand.cc (construct_init_block): If first_block isn't BB_RTL,
> > > has any PHI nodes and false_edge->dest_idx before redirection is
> > > different from make_single_succ_edge result's dest_idx, swap the
> > > latter with the former last pred edge and their dest_idx members.
> >
> > OK, thanks. But now that there are two instances, I wonder if it would
> > be worth hiding this detail in a helper function?
>
> Will try to come up with something incrementally if that is ok.
Here it is, so far lightly tested. Ok for trunk if it passes full
bootstrap/regtest?
2025-06-13 Jakub Jelinek <ja...@redhat.com>
PR middle-end/120629
* cfgexpand.cc (expand_split_edge): New function.
(expand_gimple_cond, construct_init_block): Use it.
--- gcc/cfgexpand.cc.jj 2025-06-13 14:01:15.168637257 +0200
+++ gcc/cfgexpand.cc 2025-06-13 14:17:14.896303981 +0200
@@ -2830,6 +2830,31 @@ expand_remove_edge (edge e)
remove_edge (e);
}
+/* Split edge E during expansion and instead of creating a new
+ bb on that edge, add there BB. FLAGS should be flags on the
+ new edge from BB to former E->dest. */
+
+static void
+expand_split_edge (edge e, basic_block bb, int flags)
+{
+ unsigned int dest_idx = e->dest_idx;
+ basic_block dest = e->dest;
+ redirect_edge_succ (e, bb);
+ e = make_single_succ_edge (bb, dest, flags);
+ if ((dest->flags & BB_RTL) == 0
+ && phi_nodes (dest)
+ && e->dest_idx != dest_idx)
+ {
+ /* If there are any PHI nodes on dest, swap the new succ edge
+ with the one moved into false_edge's former position, so that
+ PHI arguments don't need adjustment. */
+ edge e2 = EDGE_PRED (dest, dest_idx);
+ std::swap (e->dest_idx, e2->dest_idx);
+ std::swap (EDGE_PRED (dest, e->dest_idx),
+ EDGE_PRED (dest, e2->dest_idx));
+ }
+}
+
/* A subroutine of expand_gimple_cond. Given E, a fallthrough edge
of a basic block where we just expanded the conditional at the end,
@@ -3013,8 +3038,7 @@ expand_gimple_cond (basic_block bb, gcon
new_bb = create_basic_block (NEXT_INSN (last), get_last_insn (), bb);
dest = false_edge->dest;
- unsigned int dest_idx = false_edge->dest_idx;
- redirect_edge_succ (false_edge, new_bb);
+ expand_split_edge (false_edge, new_bb, 0);
false_edge->flags |= EDGE_FALLTHRU;
new_bb->count = false_edge->count ();
loop_p loop = find_common_loop (bb->loop_father, dest->loop_father);
@@ -3022,19 +3046,6 @@ expand_gimple_cond (basic_block bb, gcon
if (loop->latch == bb
&& loop->header == dest)
loop->latch = new_bb;
- edge e = make_single_succ_edge (new_bb, dest, 0);
- if ((dest->flags & BB_RTL) == 0
- && phi_nodes (dest)
- && e->dest_idx != dest_idx)
- {
- /* If there are any PHI nodes on dest, swap the new succ edge
- with the one moved into false_edge's former position, so that
- PHI arguments don't need adjustment. */
- edge e2 = EDGE_PRED (dest, dest_idx);
- std::swap (e->dest_idx, e2->dest_idx);
- std::swap (EDGE_PRED (dest, e->dest_idx),
- EDGE_PRED (dest, e2->dest_idx));
- }
if (BARRIER_P (BB_END (new_bb)))
BB_END (new_bb) = PREV_INSN (BB_END (new_bb));
update_bb_for_insn (new_bb);
@@ -6538,7 +6549,7 @@ expand_gimple_basic_block (basic_block b
static basic_block
construct_init_block (void)
{
- basic_block init_block, first_block;
+ basic_block init_block;
edge e = NULL;
int flags;
@@ -6569,24 +6580,7 @@ construct_init_block (void)
init_block->count = ENTRY_BLOCK_PTR_FOR_FN (cfun)->count;
add_bb_to_loop (init_block, ENTRY_BLOCK_PTR_FOR_FN (cfun)->loop_father);
if (e)
- {
- unsigned int dest_idx = e->dest_idx;
- first_block = e->dest;
- redirect_edge_succ (e, init_block);
- e = make_single_succ_edge (init_block, first_block, flags);
- if ((first_block->flags & BB_RTL) == 0
- && phi_nodes (first_block)
- && e->dest_idx != dest_idx)
- {
- /* If there are any PHI nodes on dest, swap the new succ edge
- with the one moved into false_edge's former position, so that
- PHI arguments don't need adjustment. */
- edge e2 = EDGE_PRED (first_block, dest_idx);
- std::swap (e->dest_idx, e2->dest_idx);
- std::swap (EDGE_PRED (first_block, e->dest_idx),
- EDGE_PRED (first_block, e2->dest_idx));
- }
- }
+ expand_split_edge (e, init_block, flags);
else
make_single_succ_edge (init_block, EXIT_BLOCK_PTR_FOR_FN (cfun),
EDGE_FALLTHRU);
Jakub
