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feat(vm): implement TIP-7939 CLZ opcode #6656

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feat(vm): implement TIP-7939 CLZ opcode #6656

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2 changes: 2 additions & 0 deletions actuator/src/main/java/org/tron/core/vm/Op.java
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Original file line number Diff line number Diff line change
Expand Up @@ -64,6 +64,8 @@ public class Op {
public static final int SHR = 0x1c;
// (0x1d) Arithmetic shift right
public static final int SAR = 0x1d;
// (0x1e) Count leading zeros
public static final int CLZ = 0x1e;

/* Cryptographic Operations */
// (0x20) Compute SHA3-256 hash
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12 changes: 12 additions & 0 deletions actuator/src/main/java/org/tron/core/vm/OperationActions.java
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Expand Up @@ -2,6 +2,7 @@

import static org.tron.common.crypto.Hash.sha3;
import static org.tron.common.utils.ByteUtil.EMPTY_BYTE_ARRAY;
import static org.tron.common.utils.ByteUtil.numberOfLeadingZeros;

import java.math.BigInteger;
import java.util.ArrayList;
Expand Down Expand Up @@ -287,6 +288,17 @@ public static void sarAction(Program program) {
program.step();
}

public static void clzAction(Program program) {
DataWord word = program.stackPop();
int clz = numberOfLeadingZeros(word.getData());
if (clz == 256) {
program.stackPush(new DataWord(256));
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} else {
program.stackPush(DataWord.of((byte) clz));
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@CodeNinjaEvan CodeNinjaEvan Apr 9, 2026

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Nice work overall! One minor suggestion: since DataWord.of(byte num) directly assigns bb[31] = num, casting clz to (byte) when it's in [128, 255] introduces a subtle signed/unsigned ambiguity. Would it be worth simplifying both branches into one using new DataWord(int), which handles the full range cleanly?

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@yanghang8612 yanghang8612 Apr 10, 2026

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Thanks for the review! The (byte) cast here is safe — DataWord.of(byte) assigns the raw bit pattern to bb[31], and DataWord.value() reads it back as unsigned via new BigInteger(1, data). This is consistent with how byte arrays are used throughout the codebase (e.g., DataWord.of((byte) 0xFF) correctly represents 255). The split avoids the double ByteBuffer.allocate overhead in DataWord(int) for the common non-zero path.

}
program.step();
}

public static void sha3Action(Program program) {
DataWord memOffsetData = program.stackPop();
DataWord lengthData = program.stackPop();
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20 changes: 19 additions & 1 deletion actuator/src/main/java/org/tron/core/vm/OperationRegistry.java
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Expand Up @@ -13,6 +13,7 @@ public enum Version {
TRON_V1_2,
TRON_V1_3,
TRON_V1_4,
TRON_V1_5,
// add more
// TRON_V2,
// ETH
Expand All @@ -26,6 +27,7 @@ public enum Version {
tableMap.put(Version.TRON_V1_2, newTronV12OperationSet());
tableMap.put(Version.TRON_V1_3, newTronV13OperationSet());
tableMap.put(Version.TRON_V1_4, newTronV14OperationSet());
tableMap.put(Version.TRON_V1_5, newTronV15OperationSet());
}

public static JumpTable newTronV10OperationSet() {
Expand Down Expand Up @@ -63,12 +65,18 @@ public static JumpTable newTronV14OperationSet() {
return table;
}

public static JumpTable newTronV15OperationSet() {
JumpTable table = newTronV14OperationSet();
appendOsakaOperations(table);
return table;
}

// Just for warming up class to avoid out_of_time
public static void init() {}

public static JumpTable getTable() {
// always get the table which has the newest version
JumpTable table = tableMap.get(Version.TRON_V1_4);
JumpTable table = tableMap.get(Version.TRON_V1_5);

// next make the corresponding changes, exclude activating opcode
if (VMConfig.allowHigherLimitForMaxCpuTimeOfOneTx()) {
Expand Down Expand Up @@ -700,6 +708,16 @@ public static void appendCancunOperations(JumpTable table) {
tvmBlobProposal));
}

public static void appendOsakaOperations(JumpTable table) {
BooleanSupplier proposal = VMConfig::allowTvmOsaka;

table.set(new Operation(
Op.CLZ, 1, 1,
EnergyCost::getLowTierCost,
OperationActions::clzAction,
proposal));
}

public static void adjustSelfdestruct(JumpTable table) {
table.set(new Operation(
Op.SUICIDE, 1, 0,
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75 changes: 75 additions & 0 deletions framework/src/test/java/org/tron/common/runtime/vm/OperationsTest.java
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Expand Up @@ -904,6 +904,81 @@ public void testPush0() throws ContractValidateException {
VMConfig.initAllowTvmShangHai(0);
}

@Test
public void testCLZ() throws ContractValidateException {
VMConfig.initAllowTvmOsaka(1);

invoke = new ProgramInvokeMockImpl();
Protocol.Transaction trx = Protocol.Transaction.getDefaultInstance();
InternalTransaction interTrx =
new InternalTransaction(trx, InternalTransaction.TrxType.TRX_UNKNOWN_TYPE);

// CLZ(0) = 256
byte[] op = buildCLZBytecode(new byte[32]);
program = new Program(op, op, invoke, interTrx);
testOperations(program);
Assert.assertEquals(new DataWord(256), program.getStack().pop());

// CLZ(0x80...00) = 0 (highest bit set)
byte[] val = new byte[32];
val[0] = (byte) 0x80;
op = buildCLZBytecode(val);
program = new Program(op, op, invoke, interTrx);
testOperations(program);
Assert.assertEquals(new DataWord(0), program.getStack().pop());

// CLZ(0xFF...FF) = 0
val = new byte[32];
for (int i = 0; i < 32; i++) {
val[i] = (byte) 0xFF;
}
op = buildCLZBytecode(val);
program = new Program(op, op, invoke, interTrx);
testOperations(program);
Assert.assertEquals(new DataWord(0), program.getStack().pop());

// CLZ(0x40...00) = 1
val = new byte[32];
val[0] = (byte) 0x40;
op = buildCLZBytecode(val);
program = new Program(op, op, invoke, interTrx);
testOperations(program);
Assert.assertEquals(new DataWord(1), program.getStack().pop());

// CLZ(0x7F...FF) = 1
val = new byte[32];
for (int i = 0; i < 32; i++) {
val[i] = (byte) 0xFF;
}
val[0] = (byte) 0x7F;
op = buildCLZBytecode(val);
program = new Program(op, op, invoke, interTrx);
testOperations(program);
Assert.assertEquals(new DataWord(1), program.getStack().pop());

// CLZ(1) = 255
val = new byte[32];
val[31] = 0x01;
op = buildCLZBytecode(val);
program = new Program(op, op, invoke, interTrx);
testOperations(program);
Assert.assertEquals(new DataWord(255), program.getStack().pop());

// Verify energy cost = LOW_TIER(5) + PUSH32 cost(3) = 8
Assert.assertEquals(8, program.getResult().getEnergyUsed());
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@alan-eth alan-eth Apr 16, 2026

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The test coverage is really solid — the chosen vectors (0, 1, 255, 256, boundary bits) cover the most critical scenarios nicely! 🎯

One thing that might be worth adding: a couple of test cases where the CLZ result falls in the 128-255 range (e.g., byte[16]=0x01 → CLZ=128, byte[30]=0x01 → CLZ=247). This would explicitly exercise the (byte) cast path for values above 127, giving extra confidence in the signed/unsigned handling. Would make the already-great test suite even more bulletproof!


VMConfig.initAllowTvmOsaka(0);
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@alan-eth alan-eth Apr 16, 2026

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Nice work on properly resetting VMConfig.initAllowTvmOsaka(0) in cleanup — shows good testing discipline!

Would it be worth adding a small negative test to verify that CLZ is correctly rejected when allowTvmOsaka is disabled? This would serve as a safety net to ensure the feature gate can never be accidentally bypassed. Just a suggestion to make the gating even more robust 🙂

}

// Build bytecode: PUSH32 <value> CLZ
private byte[] buildCLZBytecode(byte[] value) {
byte[] op = new byte[34];
op[0] = 0x7f; // PUSH32
System.arraycopy(value, 0, op, 1, 32);
op[33] = Op.CLZ;
return op;
}

@Test
public void testSuicideCost() throws ContractValidateException {
invoke = new ProgramInvokeMockImpl(StoreFactory.getInstance(), new byte[0], new byte[21]);
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