feat(avm-simulator): add NULLIFIEREXISTS opcode to avm simulator, tra…

…nspiler, noir test, TS tests (#4747)

avm-transpiler/src/transpile.rs

@@ -244,6 +244,7 @@ fn handle_foreign_call(
             destinations,
             inputs,
         ),
+        "nullifierExists" => handle_nullifier_exists(avm_instrs, destinations, inputs),
         "keccak256" | "sha256" => {
             handle_2_field_hash_instruction(avm_instrs, function, destinations, inputs)
         }
@@ -298,6 +299,40 @@ fn handle_emit_note_hash_or_nullifier(
     });
 }
 
+/// Handle an AVM NULLIFIEREXISTS instruction
+/// (a nullifierExists brillig foreign call was encountered)
+/// Adds the new instruction to the avm instructions list.
+fn handle_nullifier_exists(
+    avm_instrs: &mut Vec<AvmInstruction>,
+    destinations: &Vec<ValueOrArray>,
+    inputs: &Vec<ValueOrArray>,
+) {
+    if destinations.len() != 1 || inputs.len() != 1 {
+        panic!("Transpiler expects ForeignCall::CHECKNULLIFIEREXISTS to have 1 destinations and 1 input, got {} and {}", destinations.len(), inputs.len());
+    }
+    let nullifier_offset_operand = match &inputs[0] {
+        ValueOrArray::MemoryAddress(offset) => offset.to_usize() as u32,
+        _ => panic!("Transpiler does not know how to handle ForeignCall::EMITNOTEHASH with HeapArray/Vector inputs"),
+    };
+    let exists_offset_operand = match &destinations[0] {
+        ValueOrArray::MemoryAddress(offset) => offset.to_usize() as u32,
+        _ => panic!("Transpiler does not know how to handle ForeignCall::EMITNOTEHASH with HeapArray/Vector inputs"),
+    };
+    avm_instrs.push(AvmInstruction {
+        opcode: AvmOpcode::NULLIFIEREXISTS,
+        indirect: Some(ALL_DIRECT),
+        operands: vec![
+            AvmOperand::U32 {
+                value: nullifier_offset_operand,
+            },
+            AvmOperand::U32 {
+                value: exists_offset_operand,
+            },
+        ],
+        ..Default::default()
+    });
+}
+
 /// Two field hash instructions represent instruction's that's outputs are larger than a field element
 ///
 /// This includes:

noir-projects/aztec-nr/aztec/src/context/avm.nr

@@ -52,6 +52,9 @@ impl AVMContext {
     #[oracle(emitNoteHash)]
     pub fn emit_note_hash(self, note_hash: Field) {}
 
+    #[oracle(nullifierExists)]
+    pub fn check_nullifier_exists(self, nullifier: Field) -> u8 {}
+
     #[oracle(emitNullifier)]
     pub fn emit_nullifier(self, nullifier: Field) {}
 

noir-projects/noir-contracts/contracts/avm_test_contract/src/main.nr

@@ -152,6 +152,20 @@ contract AvmTest {
         context.push_new_nullifier(nullifier, 0);
     }
 
+    // Use the standard context interface to emit a new nullifier
+    #[aztec(public-vm)]
+    fn check_nullifier_exists(nullifier: Field) -> pub u8 {
+        context.check_nullifier_exists(nullifier)
+    }
+
+    // Use the standard context interface to emit a new nullifier
+    #[aztec(public-vm)]
+    fn emit_nullifier_and_check(nullifier: Field) {
+        context.emit_nullifier(nullifier);
+        let exists = context.check_nullifier_exists(nullifier);
+        assert(exists == 1, "Nullifier was just created, but its existence wasn't detected!");
+    }
+
     // Create the same nullifier twice (shouldn't work!)
     #[aztec(public-vm)]
     fn nullifier_collision(nullifier: Field) {

yarn-project/simulator/src/avm/avm_simulator.test.ts

@@ -280,6 +280,86 @@ describe('AVM simulator', () => {
 
         expect(context.persistableState.flush().newNullifiers).toEqual([utxo]);
       });
+      it(`Should execute contract function that checks if a nullifier existence (it does not)`, async () => {
+        const utxo = new Fr(42);
+        const calldata = [utxo];
+
+        // Get contract function artifact
+        const artifact = AvmTestContractArtifact.functions.find(f => f.name === 'avm_check_nullifier_exists')!;
+
+        // Decode bytecode into instructions
+        const bytecode = Buffer.from(artifact.bytecode, 'base64');
+
+        const context = initContext({ env: initExecutionEnvironment({ calldata }) });
+        jest
+          .spyOn(context.persistableState.hostStorage.contractsDb, 'getBytecode')
+          .mockReturnValue(Promise.resolve(bytecode));
+
+        await new AvmSimulator(context).execute();
+        const results = await new AvmSimulator(context).execute();
+        expect(results.reverted).toBe(false);
+        expect(results.output).toEqual([/*exists=false*/ new Fr(0)]);
+
+        // Nullifier existence check should be in trace
+        const sideEffects = context.persistableState.flush();
+        expect(sideEffects.nullifierChecks.length).toEqual(1);
+        expect(sideEffects.nullifierChecks[0].exists).toEqual(false);
+      });
+      it(`Should execute contract function that checks if a nullifier existence (it does)`, async () => {
+        const utxo = new Fr(42);
+        const calldata = [utxo];
+
+        // Get contract function artifact
+        const artifact = AvmTestContractArtifact.functions.find(f => f.name === 'avm_check_nullifier_exists')!;
+
+        // Decode bytecode into instructions
+        const bytecode = Buffer.from(artifact.bytecode, 'base64');
+
+        const context = initContext({ env: initExecutionEnvironment({ calldata }) });
+        jest
+          .spyOn(context.persistableState.hostStorage.contractsDb, 'getBytecode')
+          .mockReturnValue(Promise.resolve(bytecode));
+
+        // nullifier exists!
+        jest
+          .spyOn(context.persistableState.hostStorage.commitmentsDb, 'getNullifierIndex')
+          .mockReturnValue(Promise.resolve(BigInt(42)));
+
+        await new AvmSimulator(context).execute();
+        const results = await new AvmSimulator(context).execute();
+        expect(results.reverted).toBe(false);
+        expect(results.output).toEqual([/*exists=true*/ new Fr(1)]);
+
+        // Nullifier existence check should be in trace
+        const sideEffects = context.persistableState.flush();
+        expect(sideEffects.nullifierChecks.length).toEqual(1);
+        expect(sideEffects.nullifierChecks[0].exists).toEqual(true);
+      });
+      it(`Should execute contract function that checks emits a nullifier and checks its existence`, async () => {
+        const utxo = new Fr(42);
+        const calldata = [utxo];
+
+        // Get contract function artifact
+        const artifact = AvmTestContractArtifact.functions.find(f => f.name === 'avm_emit_nullifier_and_check')!;
+
+        // Decode bytecode into instructions
+        const bytecode = Buffer.from(artifact.bytecode, 'base64');
+
+        const context = initContext({ env: initExecutionEnvironment({ calldata }) });
+        jest
+          .spyOn(context.persistableState.hostStorage.contractsDb, 'getBytecode')
+          .mockReturnValue(Promise.resolve(bytecode));
+
+        await new AvmSimulator(context).execute();
+        const results = await new AvmSimulator(context).execute();
+        expect(results.reverted).toBe(false);
+
+        // Nullifier existence check should be in trace
+        const sideEffects = context.persistableState.flush();
+        expect(sideEffects.newNullifiers).toEqual([utxo]);
+        expect(sideEffects.nullifierChecks.length).toEqual(1);
+        expect(sideEffects.nullifierChecks[0].exists).toEqual(true);
+      });
       it(`Should execute contract function that emits same nullifier twice (should fail)`, async () => {
         const utxo = new Fr(42);
         const calldata = [utxo];

yarn-project/simulator/src/avm/journal/journal.test.ts

@@ -8,12 +8,13 @@ import { AvmPersistableStateManager, JournalData } from './journal.js';
 
 describe('journal', () => {
   let publicDb: MockProxy<PublicStateDB>;
+  let commitmentsDb: MockProxy<CommitmentsDB>;
   let journal: AvmPersistableStateManager;
 
   beforeEach(() => {
     publicDb = mock<PublicStateDB>();
+    commitmentsDb = mock<CommitmentsDB>();
     const contractsDb = mock<PublicContractsDB>();
-    const commitmentsDb = mock<CommitmentsDB>();
 
     const hostStorage = new HostStorage(publicDb, contractsDb, commitmentsDb);
     journal = new AvmPersistableStateManager(hostStorage);
@@ -60,6 +61,27 @@ describe('journal', () => {
       const journalUpdates = journal.flush();
       expect(journalUpdates.newNoteHashes).toEqual([utxo]);
     });
+    it('checkNullifierExists works for missing nullifiers', async () => {
+      const contractAddress = new Fr(1);
+      const utxo = new Fr(2);
+      const exists = await journal.checkNullifierExists(contractAddress, utxo);
+      expect(exists).toEqual(false);
+
+      const journalUpdates = journal.flush();
+      expect(journalUpdates.nullifierChecks.map(c => [c.nullifier, c.exists])).toEqual([[utxo, false]]);
+    });
+    it('checkNullifierExists works for existing nullifiers', async () => {
+      const contractAddress = new Fr(1);
+      const utxo = new Fr(2);
+      const storedLeafIndex = BigInt(42);
+
+      commitmentsDb.getNullifierIndex.mockResolvedValue(Promise.resolve(storedLeafIndex));
+      const exists = await journal.checkNullifierExists(contractAddress, utxo);
+      expect(exists).toEqual(true);
+
+      const journalUpdates = journal.flush();
+      expect(journalUpdates.nullifierChecks.map(c => [c.nullifier, c.exists])).toEqual([[utxo, true]]);
+    });
     it('Should maintain nullifiers', async () => {
       const contractAddress = new Fr(1);
       const utxo = new Fr(2);
@@ -100,6 +122,7 @@ describe('journal', () => {
     journal.writeLog(logs);
     journal.writeL1Message(logs);
     await journal.writeNullifier(contractAddress, commitment);
+    await journal.checkNullifierExists(contractAddress, commitment);
 
     const childJournal = new AvmPersistableStateManager(journal.hostStorage, journal);
     childJournal.writeStorage(contractAddress, key, valueT1);
@@ -108,6 +131,7 @@ describe('journal', () => {
     childJournal.writeLog(logsT1);
     childJournal.writeL1Message(logsT1);
     await childJournal.writeNullifier(contractAddress, commitmentT1);
+    await childJournal.checkNullifierExists(contractAddress, commitmentT1);
 
     journal.acceptNestedCallState(childJournal);
 
@@ -132,6 +156,10 @@ describe('journal', () => {
     expect(journalUpdates.newNoteHashes).toEqual([commitment, commitmentT1]);
     expect(journalUpdates.newLogs).toEqual([logs, logsT1]);
     expect(journalUpdates.newL1Messages).toEqual([logs, logsT1]);
+    expect(journalUpdates.nullifierChecks.map(c => [c.nullifier, c.exists])).toEqual([
+      [commitment, true],
+      [commitmentT1, true],
+    ]);
     expect(journalUpdates.newNullifiers).toEqual([commitment, commitmentT1]);
   });
 
@@ -158,6 +186,7 @@ describe('journal', () => {
     await journal.readStorage(contractAddress, key);
     journal.writeNoteHash(commitment);
     await journal.writeNullifier(contractAddress, commitment);
+    await journal.checkNullifierExists(contractAddress, commitment);
     journal.writeLog(logs);
     journal.writeL1Message(logs);
 
@@ -166,6 +195,7 @@ describe('journal', () => {
     await childJournal.readStorage(contractAddress, key);
     childJournal.writeNoteHash(commitmentT1);
     await childJournal.writeNullifier(contractAddress, commitmentT1);
+    await childJournal.checkNullifierExists(contractAddress, commitmentT1);
     childJournal.writeLog(logsT1);
     childJournal.writeL1Message(logsT1);
 
@@ -189,8 +219,12 @@ describe('journal', () => {
     const slotWrites = contractWrites?.get(key.toBigInt());
     expect(slotWrites).toEqual([value, valueT1]);
 
-    // Check that the UTXOs _traces_ are merged even on rejection
+    // Check that the world state _traces_ are merged even on rejection
     expect(journalUpdates.newNoteHashes).toEqual([commitment, commitmentT1]);
+    expect(journalUpdates.nullifierChecks.map(c => [c.nullifier, c.exists])).toEqual([
+      [commitment, true],
+      [commitmentT1, true],
+    ]);
     expect(journalUpdates.newNullifiers).toEqual([commitment, commitmentT1]);
 
     // Check that rejected Accrued Substate is absent

yarn-project/simulator/src/avm/journal/journal.ts

@@ -4,12 +4,14 @@ import { HostStorage } from './host_storage.js';
 import { Nullifiers } from './nullifiers.js';
 import { PublicStorage } from './public_storage.js';
 import { WorldStateAccessTrace } from './trace.js';
+import { TracedNullifierCheck } from './trace_types.js';
 
 /**
  * Data held within the journal
  */
 export type JournalData = {
   newNoteHashes: Fr[];
+  nullifierChecks: TracedNullifierCheck[];
   newNullifiers: Fr[];
 
   newL1Messages: Fr[][];
@@ -97,8 +99,8 @@ export class AvmPersistableStateManager {
   }
 
   public async checkNullifierExists(storageAddress: Fr, nullifier: Fr) {
-    const [exists, _isPending, _leafIndex] = await this.nullifiers.checkExists(storageAddress, nullifier);
-    //this.trace.traceNullifierCheck(storageAddress, nullifier, exists, isPending, leafIndex);
+    const [exists, isPending, leafIndex] = await this.nullifiers.checkExists(storageAddress, nullifier);
+    this.trace.traceNullifierCheck(storageAddress, nullifier, exists, isPending, leafIndex);
     return Promise.resolve(exists);
   }
 
@@ -148,6 +150,7 @@ export class AvmPersistableStateManager {
   public flush(): JournalData {
     return {
       newNoteHashes: this.trace.newNoteHashes,
+      nullifierChecks: this.trace.nullifierChecks,
       newNullifiers: this.trace.newNullifiers,
       newL1Messages: this.newL1Messages,
       newLogs: this.newLogs,