[PAN-2756] EIP-2028 - Reduce intrinsic gas cost (#1739)

Reduce the non-zero byte of intrinsic gas cost from 68 to 16.
Keep all other values the same.

Signed-off-by: Adrian Sutton <adrian.sutton@consensys.net>

ethereum/core/src/main/java/tech/pegasys/pantheon/ethereum/mainnet/IstanbulGasCalculator.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2019 ConsenSys AG.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ */
+package tech.pegasys.pantheon.ethereum.mainnet;
+
+import tech.pegasys.pantheon.ethereum.core.Gas;
+import tech.pegasys.pantheon.ethereum.core.Transaction;
+import tech.pegasys.pantheon.util.bytes.BytesValue;
+
+public class IstanbulGasCalculator extends ConstantinopleFixGasCalculator {
+
+  private static final Gas TX_DATA_ZERO_COST = Gas.of(4L);
+  private static final Gas TX_DATA_NON_ZERO_COST = Gas.of(16L);
+  private static final Gas TX_BASE_COST = Gas.of(21_000L);
+
+  @Override
+  public Gas transactionIntrinsicGasCost(final Transaction transaction) {
+    final BytesValue payload = transaction.getPayload();
+    int zeros = 0;
+    for (int i = 0; i < payload.size(); i++) {
+      if (payload.get(i) == 0) {
+        ++zeros;
+      }
+    }
+    final int nonZeros = payload.size() - zeros;
+
+    Gas cost =
+        Gas.ZERO
+            .plus(TX_BASE_COST)
+            .plus(TX_DATA_ZERO_COST.times(zeros))
+            .plus(TX_DATA_NON_ZERO_COST.times(nonZeros));
+
+    if (transaction.isContractCreation()) {
+      cost = cost.plus(txCreateExtraGasCost());
+    }
+
+    return cost;
+  }
+}

ethereum/core/src/main/java/tech/pegasys/pantheon/ethereum/mainnet/MainnetProtocolSpecs.java

@@ -292,7 +292,7 @@ public abstract class MainnetProtocolSpecs {
     final int stackSizeLimit = configStackSizeLimit.orElse(DEFAULT_MAX_STACK_SIZE);
     return constantinopleFixDefinition(
             chainId, configContractSizeLimit, configStackSizeLimit, enableRevertReason)
-        .gasCalculator(ConstantinopleGasCalculator::new)
+        .gasCalculator(IstanbulGasCalculator::new)
         .evmBuilder(gasCalculator -> MainnetEvmRegistries.istanbul(gasCalculator, chainId.get()))
         .precompileContractRegistryBuilder(MainnetPrecompiledContractRegistries::istanbul)
         .transactionProcessorBuilder(

ethereum/core/src/test-support/java/tech/pegasys/pantheon/ethereum/core/ExecutionContextTestFixture.java

@@ -110,7 +110,7 @@ public class ExecutionContextTestFixture {
       if (protocolSchedule == null) {
         protocolSchedule =
             new ProtocolScheduleBuilder<>(
-                    new StubGenesisConfigOptions().istanbulBlock(0),
+                    new StubGenesisConfigOptions().constantinopleFixBlock(0),
                     BigInteger.valueOf(42),
                     Function.identity(),
                     new PrivacyParameters(),

ethereum/core/src/test/java/tech/pegasys/pantheon/ethereum/mainnet/IntrinsicGasTest.java

@@ -0,0 +1,114 @@
+/*
+ * Copyright 2019 ConsenSys AG.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ */
+package tech.pegasys.pantheon.ethereum.mainnet;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import tech.pegasys.pantheon.ethereum.core.Gas;
+import tech.pegasys.pantheon.ethereum.core.Transaction;
+import tech.pegasys.pantheon.ethereum.rlp.RLP;
+import tech.pegasys.pantheon.ethereum.vm.GasCalculator;
+import tech.pegasys.pantheon.util.bytes.BytesValue;
+
+import java.util.Arrays;
+import java.util.Collection;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.junit.runners.Parameterized.Parameters;
+
+@RunWith(Parameterized.class)
+public class IntrinsicGasTest {
+
+  private final GasCalculator gasCalculator;
+  private final Gas expectedGas;
+  private final String txRlp;
+
+  public IntrinsicGasTest(
+      final GasCalculator gasCalculator, final Gas expectedGas, final String txRlp) {
+    this.gasCalculator = gasCalculator;
+    this.expectedGas = expectedGas;
+    this.txRlp = txRlp;
+  }
+
+  @Parameters
+  public static Collection<Object[]> data() {
+    final GasCalculator frontier = new FrontierGasCalculator();
+    final GasCalculator istanbul = new IstanbulGasCalculator();
+    return Arrays.asList(
+        new Object[][] {
+          // EnoughGAS
+          {
+            frontier,
+            Gas.of(21952),
+            "0xf86d80018259d894095e7baea6a6c7c4c2dfeb977efac326af552d870a8e0358ac39584bc98a7c979f984b031ba048b55bfa915ac795c431978d8a6a992b628d557da5ff759b307d495a36649353a01fffd310ac743f371de3b9f7f9cb56c0b28ad43601b4ab949f53faa07bd2c804"
+          },
+          {
+            istanbul,
+            Gas.of(21224),
+            "0xf86d80018259d894095e7baea6a6c7c4c2dfeb977efac326af552d870a8e0358ac39584bc98a7c979f984b031ba048b55bfa915ac795c431978d8a6a992b628d557da5ff759b307d495a36649353a01fffd310ac743f371de3b9f7f9cb56c0b28ad43601b4ab949f53faa07bd2c804"
+          },
+          // FirstZeroBytes
+          {
+            frontier,
+            Gas.of(21180),
+            "0xf87c80018261a894095e7baea6a6c7c4c2dfeb977efac326af552d870a9d00000000000000000000000000010000000000000000000000000000001ba048b55bfa915ac795c431978d8a6a992b628d557da5ff759b307d495a36649353a01fffd310ac743f371de3b9f7f9cb56c0b28ad43601b4ab949f53faa07bd2c804"
+          },
+          {
+            istanbul,
+            Gas.of(21128),
+            "0xf87c80018261a894095e7baea6a6c7c4c2dfeb977efac326af552d870a9d00000000000000000000000000010000000000000000000000000000001ba048b55bfa915ac795c431978d8a6a992b628d557da5ff759b307d495a36649353a01fffd310ac743f371de3b9f7f9cb56c0b28ad43601b4ab949f53faa07bd2c804"
+          },
+          // LastZeroBytes
+          {
+            frontier,
+            Gas.of(21180),
+            "0xf87c80018261a894095e7baea6a6c7c4c2dfeb977efac326af552d870a9d01000000000000000000000000000000000000000000000000000000001ba048b55bfa915ac795c431978d8a6a992b628d557da5ff759b307d495a36649353a01fffd310ac743f371de3b9f7f9cb56c0b28ad43601b4ab949f53faa07bd2c804"
+          },
+          {
+            istanbul,
+            Gas.of(21128),
+            "0xf87c80018261a894095e7baea6a6c7c4c2dfeb977efac326af552d870a9d01000000000000000000000000000000000000000000000000000000001ba048b55bfa915ac795c431978d8a6a992b628d557da5ff759b307d495a36649353a01fffd310ac743f371de3b9f7f9cb56c0b28ad43601b4ab949f53faa07bd2c804"
+          },
+          // NotEnoughGAS
+          {
+            frontier,
+            Gas.of(21952),
+            "0xf86d800182521c94095e7baea6a6c7c4c2dfeb977efac326af552d870a8e0358ac39584bc98a7c979f984b031ba048b55bfa915ac795c431978d8a6a992b628d557da5ff759b307d495a36649353a0efffd310ac743f371de3b9f7f9cb56c0b28ad43601b4ab949f53faa07bd2c804"
+          },
+          {
+            istanbul,
+            Gas.of(21224),
+            "0xf86d800182521c94095e7baea6a6c7c4c2dfeb977efac326af552d870a8e0358ac39584bc98a7c979f984b031ba048b55bfa915ac795c431978d8a6a992b628d557da5ff759b307d495a36649353a0efffd310ac743f371de3b9f7f9cb56c0b28ad43601b4ab949f53faa07bd2c804"
+          },
+          // ZeroBytes
+          {
+            frontier,
+            Gas.of(21116),
+            "0xf87c80018261a894095e7baea6a6c7c4c2dfeb977efac326af552d870a9d00000000000000000000000000000000000000000000000000000000001ba048b55bfa915ac795c431978d8a6a992b628d557da5ff759b307d495a36649353a01fffd310ac743f371de3b9f7f9cb56c0b28ad43601b4ab949f53faa07bd2c804"
+          },
+          {
+            istanbul,
+            Gas.of(21116),
+            "0xf87c80018261a894095e7baea6a6c7c4c2dfeb977efac326af552d870a9d00000000000000000000000000000000000000000000000000000000001ba048b55bfa915ac795c431978d8a6a992b628d557da5ff759b307d495a36649353a01fffd310ac743f371de3b9f7f9cb56c0b28ad43601b4ab949f53faa07bd2c804"
+          },
+        });
+  }
+
+  @Test
+  public void validateGasCost() {
+    Transaction t = Transaction.readFrom(RLP.input(BytesValue.fromHexString(txRlp)));
+    assertThat(gasCalculator.transactionIntrinsicGasCost(t)).isEqualTo(expectedGas);
+  }
+}