Move SLP nodes to an alloc-pool

This introduces a global alloc-pool for SLP nodes to reduce overhead
on SLP allocation churn which will get worse and to eventually release
SLP cycles which will retain a refcount of one and thus are never
freed at the moment.

2020-10-26  Richard Biener  <rguenther@suse.de>

	* tree-vectorizer.h (slp_tree_pool): Declare.
	(_slp_tree::operator new): Likewise.
	(_slp_tree::operator delete): Likewise.
	* tree-vectorizer.c (vectorize_loops): Allocate and free the
	slp_tree_pool.
	(pass_slp_vectorize::execute): Likewise.
	* tree-vect-slp.c (slp_tree_pool): Define.
	(_slp_tree::operator new): Likewise.
	(_slp_tree::operator delete): Likewise.

3 files changed, 35 insertions, 0 deletions

diff --git a/gcc/tree-vect-slp.c b/gcc/tree-vect-slp.c
index 014bcba..894f045 100644
--- a/gcc/tree-vect-slp.c
+++ b/gcc/tree-vect-slp.c
@@ -52,6 +52,23 @@ along with GCC; see the file COPYING3.  If not see
 static bool vectorizable_slp_permutation (vec_info *, gimple_stmt_iterator *,
 					  slp_tree, stmt_vector_for_cost *);
 
+object_allocator<_slp_tree> *slp_tree_pool;
+
+void *
+_slp_tree::operator new (size_t n)
+{
+  gcc_assert (n == sizeof (_slp_tree));
+  return slp_tree_pool->allocate_raw ();
+}
+
+void
+_slp_tree::operator delete (void *node, size_t n)
+{
+  gcc_assert (n == sizeof (_slp_tree));
+  slp_tree_pool->remove_raw (node);
+}
+
+
 /* Initialize a SLP node.  */
 
 _slp_tree::_slp_tree ()
diff --git a/gcc/tree-vectorizer.c b/gcc/tree-vectorizer.c
index 778177a..0e08652 100644
--- a/gcc/tree-vectorizer.c
+++ b/gcc/tree-vectorizer.c
@@ -1170,6 +1170,8 @@ vectorize_loops (void)
   if (vect_loops_num <= 1)
     return 0;
 
+  slp_tree_pool = new object_allocator<_slp_tree> ("SLP nodes for vect");
+
   if (cfun->has_simduid_loops)
     note_simd_array_uses (&simd_array_to_simduid_htab);
 
@@ -1292,6 +1294,8 @@ vectorize_loops (void)
     shrink_simd_arrays (simd_array_to_simduid_htab, simduid_to_vf_htab);
   delete simduid_to_vf_htab;
   cfun->has_simduid_loops = false;
+  delete slp_tree_pool;
+  slp_tree_pool = NULL;
 
   if (num_vectorized_loops > 0)
     {
@@ -1427,8 +1431,13 @@ pass_slp_vectorize::execute (function *fun)
 	}
     }
 
+  slp_tree_pool = new object_allocator<_slp_tree> ("SLP nodes for slp");
+
   vect_slp_function (fun);
 
+  delete slp_tree_pool;
+  slp_tree_pool = NULL;
+
   if (!in_loop_pipeline)
     {
       scev_finalize ();
diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
index b56073c..9c55383 100644
--- a/gcc/tree-vectorizer.h
+++ b/gcc/tree-vectorizer.h
@@ -26,6 +26,7 @@ typedef class _stmt_vec_info *stmt_vec_info;
 #include "tree-data-ref.h"
 #include "tree-hash-traits.h"
 #include "target.h"
+#include "alloc-pool.h"
 
 
 /* Used for naming of new temporaries.  */
@@ -115,6 +116,8 @@ typedef hash_map<tree_operand_hash,
  ************************************************************************/
 typedef struct _slp_tree *slp_tree;
 
+extern object_allocator<_slp_tree> *slp_tree_pool;
+
 /* A computation tree of an SLP instance.  Each node corresponds to a group of
    stmts to be packed in a SIMD stmt.  */
 struct _slp_tree {
@@ -163,6 +166,12 @@ struct _slp_tree {
   enum tree_code code;
 
   int vertex;
+
+  /* Allocate from slp_tree_pool.  */
+  static void *operator new (size_t);
+
+  /* Return memory to slp_tree_pool.  */
+  static void operator delete (void *, size_t);
 };