https://gcc.gnu.org/g:9050cbed34135c8472c2654c4dd6a8739d69b92e
commit r16-1506-g9050cbed34135c8472c2654c4dd6a8739d69b92e
Author: Jakub Jelinek <ja...@redhat.com>
Date: Fri Jun 13 23:17:17 2025 +0200
expand: Add a helper function for edge splitting [PR120629]
On Fri, Jun 13, 2025 at 08:52:55AM +0100, Richard Sandiford wrote:
> But now that there are two instances, I wonder if it would
> be worth hiding this detail in a helper function?
Here it is.
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.
Diff:
---
gcc/cfgexpand.cc | 62 +++++++++++++++++++++++++-------------------------------
1 file changed, 28 insertions(+), 34 deletions(-)
diff --git a/gcc/cfgexpand.cc b/gcc/cfgexpand.cc
index 2e6241d1e39a..e1cdb718e127 100644
--- a/gcc/cfgexpand.cc
+++ b/gcc/cfgexpand.cc
@@ -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, gcond *stmt)
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, gcond *stmt)
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 bb, bool
disable_tail_calls)
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);
