From 0afa0da19f26ccda4172358602bd5ae9cd404f6c Mon Sep 17 00:00:00 2001
From: Keith Rothman <537074+litghost@users.noreply.github.com>
Date: Mon, 1 Mar 2021 09:48:29 -0800
Subject: Add absl::flat_hash_map.

This lowers the CPU cost of using the flat wire map in router2, and should
use less memory as well.

Signed-off-by: Keith Rothman <537074+litghost@users.noreply.github.com>
---
 common/router2.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

(limited to 'common')

diff --git a/common/router2.cc b/common/router2.cc
index abe5f302..2f9f0ac4 100644
--- a/common/router2.cc
+++ b/common/router2.cc
@@ -27,6 +27,7 @@
  */
 
 #include "router2.h"
+#include <absl/container/flat_hash_map.h>
 #include <algorithm>
 #include <boost/container/flat_map.hpp>
 #include <chrono>
@@ -191,7 +192,7 @@ struct Router2
         }
     }
 
-    std::unordered_map<WireId, int> wire_to_idx;
+    absl::flat_hash_map<WireId, int> wire_to_idx;
     std::vector<PerWireData> flat_wires;
 
     PerWireData &wire_data(WireId w) { return flat_wires[wire_to_idx.at(w)]; }
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