From 9fcd8bdbfcb556b72378ca6432ddf681b78f5a53 Mon Sep 17 00:00:00 2001 From: Jason Ekstrand Date: Wed, 18 Mar 2020 11:32:15 -0500 Subject: [PATCH] util/sparse_array: Add a node_size_log2 temporary We use this value several times. It's probably best to encourage the compiler to only read it once. I have no proof that this actually makes any performance improvement whatsoever. Reviewed-by: Lionel Landwerlin Part-of: --- src/util/sparse_array.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/src/util/sparse_array.c b/src/util/sparse_array.c index 06816401309..7f583cfe133 100644 --- a/src/util/sparse_array.c +++ b/src/util/sparse_array.c @@ -108,12 +108,13 @@ _util_sparse_array_set_or_free_node(struct util_sparse_array_node **node_ptr, void * util_sparse_array_get(struct util_sparse_array *arr, uint64_t idx) { + const unsigned node_size_log2 = arr->node_size_log2; struct util_sparse_array_node *root = p_atomic_read(&arr->root); if (unlikely(root == NULL)) { unsigned root_level = 0; - uint64_t idx_iter = idx >> arr->node_size_log2; + uint64_t idx_iter = idx >> node_size_log2; while (idx_iter) { - idx_iter >>= arr->node_size_log2; + idx_iter >>= node_size_log2; root_level++; } struct util_sparse_array_node *new_root = @@ -122,8 +123,8 @@ util_sparse_array_get(struct util_sparse_array *arr, uint64_t idx) } while (1) { - uint64_t root_idx = idx >> (root->level * arr->node_size_log2); - if (likely(root_idx < (1ull << arr->node_size_log2))) + uint64_t root_idx = idx >> (root->level * node_size_log2); + if (likely(root_idx < (1ull << node_size_log2))) break; /* In this case, we have a root but its level is low enough that the @@ -147,8 +148,8 @@ util_sparse_array_get(struct util_sparse_array *arr, uint64_t idx) struct util_sparse_array_node *node = root; while (node->level > 0) { - uint64_t child_idx = (idx >> (node->level * arr->node_size_log2)) & - ((1ull << arr->node_size_log2) - 1); + uint64_t child_idx = (idx >> (node->level * node_size_log2)) & + ((1ull << node_size_log2) - 1); struct util_sparse_array_node **children = _util_sparse_array_node_data(node); @@ -164,7 +165,7 @@ util_sparse_array_get(struct util_sparse_array *arr, uint64_t idx) node = child; } - uint64_t elem_idx = idx & ((1ull << arr->node_size_log2) - 1); + uint64_t elem_idx = idx & ((1ull << node_size_log2) - 1); return (void *)((char *)_util_sparse_array_node_data(node) + (elem_idx * arr->elem_size)); } -- 2.30.2