Avoid computing RPO for update_ssa
Commit Message
At some point when domwalk got the ability to use RPO for ordering
dominator children we carefully avoided update_ssa eating the cost
of RPO compute. Unfortunately some later consolidation of CTORs
lost this again so the following makes this explicit via a special
value to the bb_index_to_rpo argument of domwalk, speeding up
update_ssa again.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
* domwalk.h (dom_walker::dom_walker): Update comment to
reflect reality and new special argument value for
bb_index_to_rpo.
* domwalk.cc (dom_walker::dom_walker): Recognize -1
bb_index_to_rpo.
* tree-into-ssa.cc
(rewrite_update_dom_walker::rewrite_update_dom_walker): Tell
dom_walker to not use RPO.
---
gcc/domwalk.cc | 6 ++++--
gcc/domwalk.h | 5 +++--
gcc/tree-into-ssa.cc | 2 +-
3 files changed, 8 insertions(+), 5 deletions(-)
@@ -191,7 +191,8 @@ dom_walker::dom_walker (cdi_direction direction,
m_reachability (reachability),
m_user_bb_to_rpo (bb_index_to_rpo != NULL),
m_unreachable_dom (NULL),
- m_bb_to_rpo (bb_index_to_rpo)
+ m_bb_to_rpo (bb_index_to_rpo == (int *)(uintptr_t)-1
+ ? NULL : bb_index_to_rpo)
{
}
@@ -272,7 +273,8 @@ void
dom_walker::walk (basic_block bb)
{
/* Compute the basic-block index to RPO mapping lazily. */
- if (!m_bb_to_rpo
+ if (!m_user_bb_to_rpo
+ && !m_bb_to_rpo
&& m_dom_direction == CDI_DOMINATORS)
{
int *postorder = XNEWVEC (int, n_basic_blocks_for_fn (cfun));
@@ -62,8 +62,9 @@ public:
/* You can provide a mapping of basic-block index to RPO if you
have that readily available or you do multiple walks. If you
- specify NULL as BB_INDEX_TO_RPO dominator children will not be
- walked in RPO order. */
+ specify NULL as BB_INDEX_TO_RPO this mapping will be computed
+ lazily at walk time. If you specify -1 dominator children will
+ not be walked in RPO order. */
dom_walker (cdi_direction direction, enum reachability = ALL_BLOCKS,
int *bb_index_to_rpo = NULL);
@@ -2146,7 +2146,7 @@ class rewrite_update_dom_walker : public dom_walker
{
public:
rewrite_update_dom_walker (cdi_direction direction)
- : dom_walker (direction, ALL_BLOCKS, NULL) {}
+ : dom_walker (direction, ALL_BLOCKS, (int *)(uintptr_t)-1) {}
edge before_dom_children (basic_block) final override;
void after_dom_children (basic_block) final override;