feat: initial external calls

yarn-project/acir-simulator/src/avm/avm_context.ts

@@ -1,3 +1,4 @@
+import { FunctionSelector } from '@aztec/circuits.js';
 import { Fr } from '@aztec/foundation/fields';
 
 import { AvmExecutionEnvironment } from './avm_execution_environment.js';
@@ -33,10 +34,18 @@ export class AvmContext {
    *
    * @param calldata -
    */
-  public call(calldata: Fr[]): AvmMessageCallResult {
+  public async call(calldata: Fr[]): Promise<AvmMessageCallResult> {
     // NOTE: the following is mocked as getPublicBytecode does not exist yet
-    // const bytecode = journal.journal.hostStorage.contractsDb.getBytecode(this.executionEnvironment.address);
-    const bytecode = Buffer.from('0x01000100020003');
+    const selector = new FunctionSelector(0);
+    const bytecode = await this.journal.hostStorage.contractsDb.getBytecode(
+      this.executionEnvironment.address,
+      selector,
+    );
+
+    // TODO: handle this gracefully ! with account abstraction can we allow this?
+    if (!bytecode) {
+      throw new Error('No bytecode found');
+    }
 
     const instructions: Instruction[] = decodeBytecode(bytecode);
 
@@ -45,4 +54,24 @@ export class AvmContext {
 
     return interpreter.run();
   }
+
+  /**
+   * Create a new forked avm context - for internal calls
+   */
+  public newWithForkedState(): AvmContext {
+    const forkedState = AvmJournal.branchParent(this.journal);
+    return new AvmContext(this.executionEnvironment, forkedState);
+  }
+
+  // TODO: more documentation / thinking
+  /**
+   * Create a new forked avm context - for external calls
+   */
+  public static newWithForkedState(
+    executionEnvironment: AvmExecutionEnvironment,
+    journal: AvmJournal,
+  ): AvmContext {
+    const forkedState = AvmJournal.branchParent(journal);
+    return new AvmContext(executionEnvironment, forkedState);
+  }
 }

yarn-project/acir-simulator/src/avm/avm_execution_environment.test.ts

@@ -0,0 +1,49 @@
+import { Fr } from '@aztec/foundation/fields';
+
+import { initExecutionEnvironment } from './fixtures/index.js';
+
+describe('Execution Environment', () => {
+  it('New call should fork execution environment correctly', () => {
+    const newAddress = new Fr(123456n);
+
+    const executionEnvironment = initExecutionEnvironment();
+    const newExecutionEnvironment = executionEnvironment.newCall(newAddress);
+
+    allTheSameExcept(executionEnvironment, newExecutionEnvironment, { address: newAddress });
+  });
+
+  it('New delegate call should fork execution environment correctly', () => {
+    const newAddress = new Fr(123456n);
+
+    const executionEnvironment = initExecutionEnvironment();
+    const newExecutionEnvironment = executionEnvironment.newDelegateCall(newAddress);
+
+    allTheSameExcept(executionEnvironment, newExecutionEnvironment, {
+      storageAddress: newAddress,
+      isDelegateCall: true,
+    });
+  });
+
+  it('New static call call should fork execution environment correctly', () => {
+    const newAddress = new Fr(123456n);
+
+    const executionEnvironment = initExecutionEnvironment();
+    const newExecutionEnvironment = executionEnvironment.newStaticCall(newAddress);
+
+    allTheSameExcept(executionEnvironment, newExecutionEnvironment, { address: newAddress, isStaticCall: true });
+  });
+});
+
+/**
+ * Check all properties of one object are the same, except for the specified differentProperties
+ * TODO: maybe move this into some foundation test utilities file?
+ */
+function allTheSameExcept(referenceObject: any, comparingObject: any, differentProperties: Record<string, any>): void {
+  for (const key in referenceObject) {
+    if (Object.keys(differentProperties).includes(key)) {
+      expect(comparingObject[key]).toEqual(differentProperties[key]);
+    } else {
+      expect(comparingObject[key]).toEqual(referenceObject[key]);
+    }
+  }
+}

yarn-project/acir-simulator/src/avm/avm_execution_environment.ts

@@ -36,4 +36,60 @@ export class AvmExecutionEnvironment {
     /** - */
     public readonly calldata: Fr[],
   ) {}
+
+  // TODO: gas not implemented
+  public newCall(address: AztecAddress): AvmExecutionEnvironment {
+    return new AvmExecutionEnvironment(
+      address,
+      this.storageAddress,
+      this.origin,
+      this.sender,
+      this.portal,
+      this.feePerL1Gas,
+      this.feePerL2Gas,
+      this.feePerDaGas,
+      this.contractCallDepth,
+      this.globals,
+      this.isStaticCall,
+      this.isDelegateCall,
+      this.calldata,
+    );
+  }
+
+  public newStaticCall(address: AztecAddress): AvmExecutionEnvironment {
+    return new AvmExecutionEnvironment(
+      address,
+      this.storageAddress,
+      this.origin,
+      this.sender,
+      this.portal,
+      this.feePerL1Gas,
+      this.feePerL2Gas,
+      this.feePerDaGas,
+      this.contractCallDepth,
+      this.globals,
+      true,
+      this.isDelegateCall,
+      this.calldata,
+    );
+  }
+
+  // TODO: gas not implemented
+  public newDelegateCall(storageAddress: AztecAddress): AvmExecutionEnvironment {
+    return new AvmExecutionEnvironment(
+      this.address,
+      storageAddress,
+      this.origin,
+      this.sender,
+      this.portal,
+      this.feePerL1Gas,
+      this.feePerL2Gas,
+      this.feePerDaGas,
+      this.contractCallDepth,
+      this.globals,
+      this.isStaticCall,
+      true,
+      this.calldata,
+    );
+  }
 }

yarn-project/acir-simulator/src/avm/opcodes/external_calls.test.ts

@@ -0,0 +1,79 @@
+import { BlockHeader } from '@aztec/circuits.js';
+import { Fr } from '@aztec/foundation/fields';
+
+import { jest } from '@jest/globals';
+import { MockProxy, mock } from 'jest-mock-extended';
+
+import { CommitmentsDB, PublicContractsDB, PublicStateDB } from '../../index.js';
+import { AvmMachineState } from '../avm_machine_state.js';
+import { initExecutionEnvironment } from '../fixtures/index.js';
+import { HostStorage } from '../journal/host_storage.js';
+import { AvmJournal } from '../journal/journal.js';
+import { encodeToBytecode } from './encode_to_bytecode.js';
+import { Call } from './external_calls.js';
+import { Opcode } from './opcodes.js';
+
+describe('External Calls', () => {
+  let machineState: AvmMachineState;
+  let journal: AvmJournal;
+
+  let contractsDb: MockProxy<PublicContractsDB>;
+
+  beforeEach(() => {
+    machineState = new AvmMachineState([], initExecutionEnvironment());
+
+    contractsDb = mock<PublicContractsDB>();
+
+    const commitmentsDb = mock<CommitmentsDB>();
+    const publicStateDb = mock<PublicStateDB>();
+    const hostStorage = new HostStorage(publicStateDb, contractsDb, commitmentsDb);
+    journal = new AvmJournal(hostStorage);
+  });
+
+  describe('Call', () => {
+    it('Should create a new call context correctly', async () => {
+      // TODO: gas not implemented
+      // prettier-ignore-start
+      // mem index         |  value
+      const gasOffset = 0;
+      const gas = Fr.zero();
+      const addrOffset = 1;
+      const addr = new Fr(123456n);
+      const argsOffset = 2;
+      const args = [new Fr(1n), new Fr(2n), new Fr(3n)];
+      // prettier-ignore-end
+
+      const argsSize = args.length;
+      const retOffset = 8;
+      const retSize = 2;
+      const successOffset = 7;
+
+      machineState.writeMemory(0, gas);
+      machineState.writeMemory(1, addr);
+      machineState.writeMemoryChunk(2, args);
+
+      // TODO: mock the call that is made -> set the bytecode to be a return of two values
+      const otherContextInstructions: [Opcode, any[]][] = [
+        [Opcode.SET, [/* value */ 1, /* destOffset */ 0]],
+        [Opcode.SET, [/* value */ 2, /* destOffset */ 1]],
+        [Opcode.RETURN, [/* retOffset */ 0, /* size */ 2]],
+      ];
+
+      const otherContextInstructionsBytecode = Buffer.concat(
+        otherContextInstructions.map(([opcode, args]) => encodeToBytecode(opcode, args)),
+      );
+      jest
+        .spyOn(journal.hostStorage.contractsDb, 'getBytecode')
+        .mockReturnValue(Promise.resolve(otherContextInstructionsBytecode));
+
+      const instruction = new Call(gasOffset, addrOffset, argsOffset, argsSize, retOffset, retSize, successOffset);
+      await instruction.execute(machineState, journal);
+
+      const successValue = machineState.readMemory(successOffset);
+      expect(successValue).toEqual(new Fr(1n));
+
+      const retValue = machineState.readMemoryChunk(retOffset, retSize);
+      expect(retValue).toEqual([new Fr(1n), new Fr(2n)]);
+    });
+  });
+});

yarn-project/acir-simulator/src/avm/opcodes/external_calls.ts

@@ -0,0 +1,52 @@
+import { Fr } from '@aztec/foundation/fields';
+
+import { AvmContext } from '../avm_context.js';
+import { AvmMachineState } from '../avm_machine_state.js';
+import { Instruction } from './instruction.js';
+import { AvmJournal } from '../journal/journal.js';
+
+/** - */
+export class Call extends Instruction {
+  static type: string = 'CALL';
+  static numberOfOperands = 7;
+
+  constructor(
+    private /* Unused due to no formal gas implementation at this moment */ _gasOffset: number,
+    private addrOffset: number,
+    private argsOffset: number,
+    private argSize: number,
+    private retOffset: number,
+    private retSize: number,
+    private successOffset: number,
+  ) {
+    super();
+  }
+
+  // TODO: there is no concept of remaining / available gas at this moment
+  async execute(machineState: AvmMachineState, journal: AvmJournal): Promise<void> {
+    // This instruction will need to create another instance of the AVM with:
+    // - a forked State Manager
+    // - the same execution environment variables
+    // - a fresh memory instance
+
+    const callAddress = machineState.readMemory(this.addrOffset);
+    // TODO: check that we can assume that this memory chunk will be field elements
+    const calldata = machineState.readMemoryChunk(this.argsOffset, this.argSize);
+
+    // TODO: could this be consolidated within an AVMContext static member?
+    const newExecutionEnvironment = machineState.executionEnvironment.newCall(callAddress);
+    const avmContext = AvmContext.newWithForkedState(newExecutionEnvironment, journal);
+
+    const returnObject = await avmContext.call(calldata);
+    const success = !returnObject.reverted;
+
+    // We only take as much data as was specified in the return size -> TODO: should we be reverting here
+    const returnData = returnObject.output.slice(0, this.retSize);
+
+    // Write our return data into memory
+    machineState.writeMemory(this.successOffset, new Fr(success));
+    machineState.writeMemoryChunk(this.retOffset, returnData);
+
+    this.incrementPc(machineState);
+  }
+}

yarn-project/acir-simulator/src/avm/opcodes/instruction_set.ts

@@ -1,6 +1,7 @@
 import { Add, Div, Mul, Sub } from './arithmetic.js';
 import { And, Not, Or, Shl, Shr, Xor } from './bitwise.js';
 import { InternalCall, InternalReturn, Jump, JumpI, Return } from './control_flow.js';
+// import { Call } from './external_calls.js';
 import { Instruction } from './instruction.js';
 import { CMov, CalldataCopy, Cast, Mov, Set } from './memory.js';
 import { Opcode } from './opcodes.js';
@@ -87,7 +88,7 @@ export const INSTRUCTION_SET: Map<Opcode, InstructionConstructorAndMembers> = ne
     //[Opcode.EMITUNENCRYPTEDLOG, Emitunencryptedlog],
 
     //// Control Flow - Contract Calls
-    //[Opcode.CALL, Call],
+    // [Opcode.CALL, Call],
     //[Opcode.STATICCALL, Staticcall],
     [Opcode.RETURN, Return],
     //[Opcode.REVERT, Revert],

yarn-project/acir-simulator/src/avm/opcodes/memory.test.ts

@@ -1,6 +1,6 @@
 import { Fr } from '@aztec/foundation/fields';
 
-import { mock } from 'jest-mock-extended';
+import { MockProxy, mock } from 'jest-mock-extended';
 
 import { AvmMachineState } from '../avm_machine_state.js';
 import { initExecutionEnvironment } from '../fixtures/index.js';
@@ -9,7 +9,7 @@ import { CMov, CalldataCopy, Cast, Mov, Set } from './memory.js';
 
 describe('Memory instructions', () => {
   let machineState: AvmMachineState;
-  let journal = mock<AvmJournal>();
+  let journal: MockProxy<AvmJournal>;
 
   beforeEach(() => {
     machineState = new AvmMachineState([], initExecutionEnvironment());