bench: add benchmark for SignTransaction

src/Makefile.bench.include

@@ -52,6 +52,7 @@ bench_bench_bitcoin_SOURCES = \
   bench/rollingbloom.cpp \
   bench/rpc_blockchain.cpp \
   bench/rpc_mempool.cpp \
+  bench/sign_transaction.cpp \
   bench/streams_findbyte.cpp \
   bench/strencodings.cpp \
   bench/util_time.cpp \

src/bench/sign_transaction.cpp

@@ -0,0 +1,70 @@
+// Copyright (c) 2023 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 <addresstype.h>
+#include <coins.h>
+#include <key.h>
+#include <primitives/transaction.h>
+#include <pubkey.h>
+#include <script/interpreter.h>
+#include <script/script.h>
+#include <script/sign.h>
+#include <uint256.h>
+#include <util/translation.h>
+
+enum class InputType {
+    P2WPKH, // segwitv0, witness-pubkey-hash (ECDSA signature)
+    P2TR,   // segwitv1, taproot key-path spend (Schnorr signature)
+};
+
+static void SignTransactionSingleInput(benchmark::Bench& bench, InputType input_type)
+{
+    ECC_Context ecc_context{};
+
+    FlatSigningProvider keystore;
+    std::vector<CScript> prev_spks;
+
+    // Create a bunch of keys / UTXOs to avoid signing with the same key repeatedly
+    for (int i = 0; i < 32; i++) {
+        CKey privkey = GenerateRandomKey();
+        CPubKey pubkey = privkey.GetPubKey();
+        CKeyID key_id = pubkey.GetID();
+        keystore.keys.emplace(key_id, privkey);
+        keystore.pubkeys.emplace(key_id, pubkey);
+
+        // Create specified locking script type
+        CScript prev_spk;
+        switch (input_type) {
+        case InputType::P2WPKH: prev_spk = GetScriptForDestination(WitnessV0KeyHash(pubkey)); break;
+        case InputType::P2TR:   prev_spk = GetScriptForDestination(WitnessV1Taproot(XOnlyPubKey{pubkey})); break;
+        default: assert(false);
+        }
+        prev_spks.push_back(prev_spk);
+    }
+
+    // Simple 1-input tx with artificial outpoint
+    // (note that for the purpose of signing with SIGHASH_ALL we don't need any outputs)
+    COutPoint prevout{/*hashIn=*/Txid::FromUint256(uint256::ONE), /*nIn=*/1337};
+    CMutableTransaction unsigned_tx;
+    unsigned_tx.vin.emplace_back(prevout);
+
+    // Benchmark.
+    int iter = 0;
+    bench.minEpochIterations(100).run([&] {
+        CMutableTransaction tx{unsigned_tx};
+        std::map<COutPoint, Coin> coins;
+        CScript prev_spk = prev_spks[(iter++) % prev_spks.size()];
+        coins[prevout] = Coin(CTxOut(10000, prev_spk), /*nHeightIn=*/100, /*fCoinBaseIn=*/false);
+        std::map<int, bilingual_str> input_errors;
+        bool complete = SignTransaction(tx, &keystore, coins, SIGHASH_ALL, input_errors);
+        assert(complete);
+    });
+}
+
+static void SignTransactionECDSA(benchmark::Bench& bench)   { SignTransactionSingleInput(bench, InputType::P2WPKH); }
+static void SignTransactionSchnorr(benchmark::Bench& bench) { SignTransactionSingleInput(bench, InputType::P2TR);   }
+
+BENCHMARK(SignTransactionECDSA, benchmark::PriorityLevel::HIGH);
+BENCHMARK(SignTransactionSchnorr, benchmark::PriorityLevel::HIGH);