This moves 2 checks dealing with abnormal and phis earlier
before going through the walk of the bb stmts. This should provide
a small compile time performance improvement when doing cfgcleanup in a
few (maybe not so many) cases.
gcc/ChangeLog:
* tree-cfgcleanup.cc (maybe_remove_forwarder_block): Move a few
checks earlier.
Signed-off-by: Andrew Pinski <[email protected]>
---
gcc/tree-cfgcleanup.cc | 52 ++++++++++++++++++++----------------------
1 file changed, 25 insertions(+), 27 deletions(-)
diff --git a/gcc/tree-cfgcleanup.cc b/gcc/tree-cfgcleanup.cc
index b9384db9f3d..872ded3d15e 100644
--- a/gcc/tree-cfgcleanup.cc
+++ b/gcc/tree-cfgcleanup.cc
@@ -378,7 +378,6 @@ cleanup_control_flow_bb (basic_block bb)
return retval;
}
-
/* If all the PHI nodes in DEST have alternatives for E1 and E2 and
those alternatives are equal in each of the PHI nodes, then return
true, else return false. */
@@ -517,8 +516,32 @@ maybe_remove_forwarder_block (basic_block bb, bool
can_split = false)
&& single_succ_p (single_pred_edge (bb)->src))
return false;
+ bool has_phi = !gimple_seq_empty_p (phi_nodes (bb));
basic_block dest = single_succ_edge (bb)->dest;
+ /* If there is an abnormal edge to basic block BB, but not into
+ dest, problems might occur during removal of the phi node at out
+ of ssa due to overlapping live ranges of registers.
+
+ If there is an abnormal edge in DEST, the problems would occur
+ anyway since cleanup_dead_labels would then merge the labels for
+ two different eh regions, and rest of exception handling code
+ does not like it.
+
+ So if there is an abnormal edge to BB, proceed only if there is
+ no abnormal edge to DEST and there are no phi nodes in DEST.
+ If the BB has phi, we don't want to deal with abnormal edges either. */
+ if (bb_has_abnormal_pred (bb)
+ && (bb_has_abnormal_pred (dest)
+ || !gimple_seq_empty_p (phi_nodes (dest))
+ || has_phi))
+ return false;
+
+ /* When we have a phi, we have to feed into another
+ basic block with PHI nodes. */
+ if (has_phi && gimple_seq_empty_p (phi_nodes (dest)))
+ return false;
+
/* Now walk through the statements backward. We can ignore labels,
anything else means this is not a forwarder block. */
for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi); gsi_prev (&gsi))
@@ -547,8 +570,6 @@ maybe_remove_forwarder_block (basic_block bb, bool
can_split = false)
return false;
}
}
-
- bool has_phi = !gimple_seq_empty_p (phi_nodes (bb));
/* If BB has PHIs and does not dominate DEST,
then the PHI nodes at DEST must be the only
users of the results of the PHI nodes at BB.
@@ -610,7 +631,7 @@ maybe_remove_forwarder_block (basic_block bb, bool
can_split = false)
/* cleanup_tree_cfg_noloop just created the loop preheader, don't
remove it if it has phis. */
else if (bb->loop_father == loop_outer (dest->loop_father)
- && gimple_seq_empty_p (phi_nodes (bb))
+ && !has_phi
&& !loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS))
;
else
@@ -624,29 +645,6 @@ maybe_remove_forwarder_block (basic_block bb, bool
can_split = false)
gimple *stmt;
gimple_stmt_iterator gsi_to;
- /* If there is an abnormal edge to basic block BB, but not into
- dest, problems might occur during removal of the phi node at out
- of ssa due to overlapping live ranges of registers.
-
- If there is an abnormal edge in DEST, the problems would occur
- anyway since cleanup_dead_labels would then merge the labels for
- two different eh regions, and rest of exception handling code
- does not like it.
-
- So if there is an abnormal edge to BB, proceed only if there is
- no abnormal edge to DEST and there are no phi nodes in DEST.
- If the BB has phi, we don't want to deal with abnormal edges either. */
- if (bb_has_abnormal_pred (bb)
- && (bb_has_abnormal_pred (dest)
- || !gimple_seq_empty_p (phi_nodes (dest))
- || has_phi))
- return false;
-
- /* When we have a phi, we have to feed into another
- basic block with PHI nodes. */
- if (has_phi && gimple_seq_empty_p (phi_nodes (dest)))
- return false;
-
/* If there are phi nodes in DEST, and some of the blocks that are
predecessors of BB are also predecessors of DEST, check that the
phi node arguments match.
--
2.43.0
