https://gcc.gnu.org/g:0ceeb9926d69dbb382622a8eae9eef7ed8ac3e97
commit r15-3191-g0ceeb9926d69dbb382622a8eae9eef7ed8ac3e97
Author: Richard Biener <rguent...@suse.de>
Date: Mon Aug 26 10:01:44 2024 +0200
tree-optimization/116460 - improve forwprop compile-time
The following improves forwprop block reachability which I noticed
when debugging PR116460 and what is also noted in the comment. It
avoids processing blocks in natural loops determined unreachable,
thereby making the issue in PR116460 latent.
PR tree-optimization/116460
* tree-ssa-forwprop.cc (pass_forwprop::execute): Do not
process blocks in unreachable natural loops.
Diff:
---
gcc/tree-ssa-forwprop.cc | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/gcc/tree-ssa-forwprop.cc b/gcc/tree-ssa-forwprop.cc
index e7342b4dc092..2964420ad1a1 100644
--- a/gcc/tree-ssa-forwprop.cc
+++ b/gcc/tree-ssa-forwprop.cc
@@ -3498,6 +3498,8 @@ pass_forwprop::execute (function *fun)
cfg_changed = false;
+ calculate_dominance_info (CDI_DOMINATORS);
+
/* Combine stmts with the stmts defining their operands. Do that
in an order that guarantees visiting SSA defs before SSA uses. */
lattice.create (num_ssa_names);
@@ -3537,12 +3539,11 @@ pass_forwprop::execute (function *fun)
FOR_EACH_EDGE (e, ei, bb->preds)
{
if ((e->flags & EDGE_EXECUTABLE)
- /* With dominators we could improve backedge handling
- when e->src is dominated by bb. But for irreducible
- regions we have to take all backedges conservatively.
- We can handle single-block cycles as we know the
- dominator relationship here. */
- || bb_to_rpo[e->src->index] > i)
+ /* We can handle backedges in natural loops correctly but
+ for irreducible regions we have to take all backedges
+ conservatively when we did not visit the source yet. */
+ || (bb_to_rpo[e->src->index] > i
+ && !dominated_by_p (CDI_DOMINATORS, e->src, e->dest)))
{
any = true;
break;
