The following avoids copying an sbitmap and one traversal by avoiding
to re-allocate old_ssa_names when not necessary. In addition this
actually checks what the comment before PHI insert iterating promises,
that the old_ssa_names set does not grow.
Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
* tree-into-ssa.cc (iterating_old_ssa_names): New.
(add_new_name_mapping): Grow {new,old}_ssa_names separately
and only when actually needed. Assert we are not growing
the old_ssa_names set when iterating over it.
(update_ssa): Remove old_ssa_names copying and empty_p
query, note we are iterating over it and expect no set changes.
---
gcc/tree-into-ssa.cc | 36 ++++++++++++++++++++----------------
1 file changed, 20 insertions(+), 16 deletions(-)
diff --git a/gcc/tree-into-ssa.cc b/gcc/tree-into-ssa.cc
index c90651c3a89..9f45e62c6d0 100644
--- a/gcc/tree-into-ssa.cc
+++ b/gcc/tree-into-ssa.cc
@@ -587,6 +587,8 @@ add_to_repl_tbl (tree new_tree, tree old)
bitmap_set_bit (*set, SSA_NAME_VERSION (old));
}
+/* Debugging aid to fence old_ssa_names changes when iterating over it. */
+static bool iterating_old_ssa_names;
/* Add a new mapping NEW_TREE -> OLD REPL_TBL. Every entry N_i in REPL_TBL
represents the set of names O_1 ... O_j replaced by N_i. This is
@@ -602,10 +604,15 @@ add_new_name_mapping (tree new_tree, tree old)
/* We may need to grow NEW_SSA_NAMES and OLD_SSA_NAMES because our
caller may have created new names since the set was created. */
- if (SBITMAP_SIZE (new_ssa_names) <= num_ssa_names - 1)
+ if (SBITMAP_SIZE (new_ssa_names) <= SSA_NAME_VERSION (new_tree))
{
unsigned int new_sz = num_ssa_names + NAME_SETS_GROWTH_FACTOR;
new_ssa_names = sbitmap_resize (new_ssa_names, new_sz, 0);
+ }
+ if (SBITMAP_SIZE (old_ssa_names) <= SSA_NAME_VERSION (old))
+ {
+ gcc_assert (!iterating_old_ssa_names);
+ unsigned int new_sz = num_ssa_names + NAME_SETS_GROWTH_FACTOR;
old_ssa_names = sbitmap_resize (old_ssa_names, new_sz, 0);
}
@@ -619,8 +626,11 @@ add_new_name_mapping (tree new_tree, tree old)
/* Register NEW_TREE and OLD in NEW_SSA_NAMES and OLD_SSA_NAMES,
respectively. */
+ if (iterating_old_ssa_names)
+ gcc_assert (bitmap_bit_p (old_ssa_names, SSA_NAME_VERSION (old)));
+ else
+ bitmap_set_bit (old_ssa_names, SSA_NAME_VERSION (old));
bitmap_set_bit (new_ssa_names, SSA_NAME_VERSION (new_tree));
- bitmap_set_bit (old_ssa_names, SSA_NAME_VERSION (old));
}
@@ -3460,20 +3470,14 @@ update_ssa (unsigned update_flags)
bitmap_initialize (&dfs[bb->index], &bitmap_default_obstack);
compute_dominance_frontiers (dfs);
- if (bitmap_first_set_bit (old_ssa_names) >= 0)
- {
- sbitmap_iterator sbi;
-
- /* insert_update_phi_nodes_for will call add_new_name_mapping
- when inserting new PHI nodes, so the set OLD_SSA_NAMES
- will grow while we are traversing it (but it will not
- gain any new members). Copy OLD_SSA_NAMES to a temporary
- for traversal. */
- auto_sbitmap tmp (SBITMAP_SIZE (old_ssa_names));
- bitmap_copy (tmp, old_ssa_names);
- EXECUTE_IF_SET_IN_BITMAP (tmp, 0, i, sbi)
- insert_updated_phi_nodes_for (ssa_name (i), dfs, update_flags);
- }
+ /* insert_update_phi_nodes_for will call add_new_name_mapping
+ when inserting new PHI nodes, but it will not add any
+ new members to OLD_SSA_NAMES. */
+ iterating_old_ssa_names = true;
+ sbitmap_iterator sbi;
+ EXECUTE_IF_SET_IN_BITMAP (old_ssa_names, 0, i, sbi)
+ insert_updated_phi_nodes_for (ssa_name (i), dfs, update_flags);
+ iterating_old_ssa_names = false;
symbols_to_rename.qsort (insert_updated_phi_nodes_compare_uids);
FOR_EACH_VEC_ELT (symbols_to_rename, i, sym)
--
2.35.3
