From 304a7be7a875e76a040bce0d1247d17d475e460a Mon Sep 17 00:00:00 2001 From: Nicholas Nethercote Date: Mon, 1 Apr 2019 16:40:45 +1100 Subject: [PATCH] Reduce the `DepNode` pre-allocation ratio. A code size of increase of 15% is overly generous. 2% is more realistic. This change reduces peak memory size by 20+ MiB on some workloads. --- src/librustc/dep_graph/graph.rs | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/src/librustc/dep_graph/graph.rs b/src/librustc/dep_graph/graph.rs index db81a9d826f8..1ecc580d8c5c 100644 --- a/src/librustc/dep_graph/graph.rs +++ b/src/librustc/dep_graph/graph.rs @@ -992,8 +992,9 @@ impl CurrentDepGraph { // Pre-allocate the dep node structures. We over-allocate a little so // that we hopefully don't have to re-allocate during this compilation - // session. - let new_node_count_estimate = (prev_graph_node_count * 115) / 100; + // session. The over-allocation is 2% plus a small constant to account + // for the fact that in very small crates 2% might not be enough. + let new_node_count_estimate = (prev_graph_node_count * 102) / 100 + 200; CurrentDepGraph { data: IndexVec::with_capacity(new_node_count_estimate),