bench: Add a benchmark for descriptor expansion

src/Makefile.bench.include

@@ -27,6 +27,7 @@ bench_bench_bitcoin_SOURCES = \
   bench/crypto_hash.cpp \
   bench/data.cpp \
   bench/data.h \
+  bench/descriptors.cpp \
   bench/duplicate_inputs.cpp \
   bench/examples.cpp \
   bench/gcs_filter.cpp \

src/bench/descriptors.cpp

@@ -0,0 +1,30 @@
+// Copyright (c) 2019 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <bench/bench.h>
+#include <key.h>
+#include <script/descriptor.h>
+#include <script/standard.h>
+
+#include <string>
+#include <utility>
+
+static void ExpandDescriptor(benchmark::Bench& bench)
+{
+    const auto desc_str = "sh(wsh(multi(16,03669b8afcec803a0d323e9a17f3ea8e68e8abe5a278020a929adbec52421adbd0,0260b2003c386519fc9eadf2b5cf124dd8eea4c4e68d5e154050a9346ea98ce600,0362a74e399c39ed5593852a30147f2959b56bb827dfa3e60e464b02ccf87dc5e8,0261345b53de74a4d721ef877c255429961b7e43714171ac06168d7e08c542a8b8,02da72e8b46901a65d4374fe6315538d8f368557dda3a1dcf9ea903f3afe7314c8,0318c82dd0b53fd3a932d16e0ba9e278fcc937c582d5781be626ff16e201f72286,0297ccef1ef99f9d73dec9ad37476ddb232f1238aff877af19e72ba04493361009,02e502cfd5c3f972fe9a3e2a18827820638f96b6f347e54d63deb839011fd5765d,03e687710f0e3ebe81c1037074da939d409c0025f17eb86adb9427d28f0f7ae0e9,02c04d3a5274952acdbc76987f3184b346a483d43be40874624b29e3692c1df5af,02ed06e0f418b5b43a7ec01d1d7d27290fa15f75771cb69b642a51471c29c84acd,036d46073cbb9ffee90473f3da429abc8de7f8751199da44485682a989a4bebb24,02f5d1ff7c9029a80a4e36b9a5497027ef7f3e73384a4a94fbfe7c4e9164eec8bc,02e41deffd1b7cce11cde209a781adcffdabd1b91c0ba0375857a2bfd9302419f3,02d76625f7956a7fc505ab02556c23ee72d832f1bac391bcd2d3abce5710a13d06,0399eb0a5487515802dc14544cf10b3666623762fbed2ec38a3975716e2c29c232)))";
+    const std::pair<int64_t, int64_t> range = {0, 1000};
+    FlatSigningProvider provider;
+    std::string error;
+    auto desc = Parse(desc_str, provider, error);
+
+    bench.run([&] {
+        for (int i = range.first; i <= range.second; ++i) {
+            std::vector<CScript> scripts;
+            bool success = desc->Expand(i, provider, scripts, provider);
+            assert(success);
+        }
+    });
+}
+
+BENCHMARK(ExpandDescriptor);