The testcase in this PR shows very slow IDF compute:
tree SSA rewrite : 76.99 ( 31%)
24.78% 243663 cc1plus cc1plus [.] compute_idf
which can be mitigated to some extent by refactoring the bitmap
operations to simpler variants. With the patch below this becomes
tree SSA rewrite : 15.23 ( 8%)
when not optimizing and in addition to that
tree SSA incremental : 181.52 ( 30%)
to
tree SSA incremental : 24.09 ( 6%)
when optimizing.
Bootstrap and regtest running on x86_64-unknown-linux-gnu.
OK if that succeeds?
Thanks,
Richard.
PR middle-end/114480
* cfganal.cc (compute_idf): Use simpler bitmap iteration,
touch work_set only when phi_insertion_points changed.
---
gcc/cfganal.cc | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/gcc/cfganal.cc b/gcc/cfganal.cc
index 432775decf1..5ef629f677e 100644
--- a/gcc/cfganal.cc
+++ b/gcc/cfganal.cc
@@ -1701,8 +1701,7 @@ compute_idf (bitmap def_blocks, bitmap_head *dfs)
on earlier blocks first is better.
??? Basic blocks are by no means guaranteed to be ordered in
optimal order for this iteration. */
- bb_index = bitmap_first_set_bit (work_set);
- bitmap_clear_bit (work_set, bb_index);
+ bb_index = bitmap_clear_first_set_bit (work_set);
/* Since the registration of NEW -> OLD name mappings is done
separately from the call to update_ssa, when updating the SSA
@@ -1712,12 +1711,9 @@ compute_idf (bitmap def_blocks, bitmap_head *dfs)
gcc_checking_assert (bb_index
< (unsigned) last_basic_block_for_fn (cfun));
- EXECUTE_IF_AND_COMPL_IN_BITMAP (&dfs[bb_index], phi_insertion_points,
- 0, i, bi)
- {
+ EXECUTE_IF_SET_IN_BITMAP (&dfs[bb_index], 0, i, bi)
+ if (bitmap_set_bit (phi_insertion_points, i))
bitmap_set_bit (work_set, i);
- bitmap_set_bit (phi_insertion_points, i);
- }
}
return phi_insertion_points;
--
2.35.3
