chore(simulator): initialize ACVM's SimulatedBackend separately (setup pedersen init only happens once)

yarn-project/acir-simulator/package.json

@@ -35,7 +35,7 @@
     "@aztec/circuits.js": "workspace:^",
     "@aztec/foundation": "workspace:^",
     "@aztec/types": "workspace:^",
-    "acvm_js": "github:noir-lang/acvm-simulator-wasm#b9d9ca9dfc5140839f23998d9466307215607c42",
+    "acvm_js": "github:dbanks12/acvm-simulator-wasm#db/init-sim-backend",
     "levelup": "^5.1.1",
     "memdown": "^6.1.1",
     "tslib": "^2.4.0"

yarn-project/acir-simulator/src/acvm/acvm.ts

@@ -3,7 +3,7 @@ import { EthAddress } from '@aztec/foundation/eth-address';
 import { Fr } from '@aztec/foundation/fields';
 import { createDebugLogger } from '@aztec/foundation/log';
 
-import { ForeignCallInput, ForeignCallOutput, WitnessMap, executeCircuit } from 'acvm_js';
+import { ForeignCallInput, ForeignCallOutput, SimulatedBackend, WitnessMap, executeCircuit } from 'acvm_js';
 
 /**
  * The format for fields on the ACVM.
@@ -69,26 +69,32 @@ export interface ACIRExecutionResult {
  * The function call that executes an ACIR.
  */
 export async function acvm(
+  backend: SimulatedBackend,
   acir: Buffer,
   initialWitness: ACVMWitness,
   callback: ACIRCallback,
 ): Promise<ACIRExecutionResult> {
   const logger = createDebugLogger('aztec:simulator:acvm');
-  const partialWitness = await executeCircuit(acir, initialWitness, async (name: string, args: ForeignCallInput[]) => {
-    try {
-      logger(`Oracle callback ${name}`);
-      const oracleFunction = callback[name as ORACLE_NAMES];
-      if (!oracleFunction) {
-        throw new Error(`Oracle callback ${name} not found`);
+  const partialWitness = await executeCircuit(
+    backend,
+    acir,
+    initialWitness,
+    async (name: string, args: ForeignCallInput[]) => {
+      try {
+        logger(`Oracle callback ${name}`);
+        const oracleFunction = callback[name as ORACLE_NAMES];
+        if (!oracleFunction) {
+          throw new Error(`Oracle callback ${name} not found`);
+        }
+
+        const result = await oracleFunction.call(callback, ...args);
+        return [result];
+      } catch (err: any) {
+        logger(`Error in oracle callback ${name}: ${err.message ?? err ?? 'Unknown'}`);
+        throw err;
       }
-
-      const result = await oracleFunction.call(callback, ...args);
-      return [result];
-    } catch (err: any) {
-      logger(`Error in oracle callback ${name}: ${err.message ?? err ?? 'Unknown'}`);
-      throw err;
-    }
-  });
+    },
+  );
   return Promise.resolve({ partialWitness });
 }
 

yarn-project/acir-simulator/src/client/private_execution.ts

@@ -24,7 +24,7 @@ import {
   toAcvmCallPrivateStackItem,
   toAcvmEnqueuePublicFunctionResult,
 } from '../acvm/index.js';
-import { ExecutionResult, NewNoteData, NewNullifierData } from '../index.js';
+import { AcirSimulator, ExecutionResult, NewNoteData, NewNullifierData } from '../index.js';
 import { ClientTxExecutionContext } from './client_execution_context.js';
 import { acvmFieldMessageToString, oracleDebugCallToFormattedStr } from './debug.js';
 
@@ -63,7 +63,7 @@ export class PrivateFunctionExecution {
     const encryptedLogs = new FunctionL2Logs([]);
     const unencryptedLogs = new FunctionL2Logs([]);
 
-    const { partialWitness } = await acvm(acir, initialWitness, {
+    const { partialWitness } = await acvm(await AcirSimulator.getBackend(), acir, initialWitness, {
       packArguments: async args => {
         return toACVMField(await this.context.packedArgsCache.pack(args.map(fromACVMField)));
       },

yarn-project/acir-simulator/src/client/simulator.ts

@@ -8,6 +8,8 @@ import { Fr } from '@aztec/foundation/fields';
 import { DebugLogger, createDebugLogger } from '@aztec/foundation/log';
 import { AztecNode, FunctionCall, TxExecutionRequest } from '@aztec/types';
 
+import { SimulatedBackend, createBackend } from 'acvm_js';
+
 import { PackedArgsCache } from '../packed_args_cache.js';
 import { ClientTxExecutionContext } from './client_execution_context.js';
 import { DBOracle } from './db_oracle.js';
@@ -20,12 +22,31 @@ import { UnconstrainedFunctionExecution } from './unconstrained_execution.js';
  * The ACIR simulator.
  */
 export class AcirSimulator {
+  private static backend: SimulatedBackend; // ACVM's backend
   private log: DebugLogger;
 
   constructor(private db: DBOracle) {
     this.log = createDebugLogger('aztec:simulator');
   }
 
+  /**
+   * Gets or initializes the ACVM SimulatedBackend.
+   *
+   * @remarks
+   *
+   * Occurs only once across all instances of AcirSimulator.
+   * Speeds up execution by only performing setup tasks (like pedersen
+   * generator initialization) one time.
+   * WARNING: it is unclear whether this will work in a multi-threaded
+   * environment where multiple threads seek to use the same backend.
+   *
+   * @returns ACVM SimulatedBackend
+   */
+  public static async getBackend(): Promise<SimulatedBackend> {
+    if (!this.backend) this.backend = await createBackend();
+    return this.backend;
+  }
+
   /**
    * Runs a private function.
    * @param request - The transaction request.

yarn-project/acir-simulator/src/client/unconstrained_execution.ts

@@ -7,6 +7,7 @@ import { AztecNode } from '@aztec/types';
 
 import { extractReturnWitness, frToAztecAddress } from '../acvm/deserialize.js';
 import { ACVMField, ZERO_ACVM_FIELD, acvm, fromACVMField, toACVMField, toACVMWitness } from '../acvm/index.js';
+import { AcirSimulator } from '../index.js';
 import { ClientTxExecutionContext } from './client_execution_context.js';
 import { oracleDebugCallToFormattedStr } from './debug.js';
 
@@ -40,7 +41,7 @@ export class UnconstrainedFunctionExecution {
     const acir = Buffer.from(this.abi.bytecode, 'base64');
     const initialWitness = toACVMWitness(1, this.args);
 
-    const { partialWitness } = await acvm(acir, initialWitness, {
+    const { partialWitness } = await acvm(await AcirSimulator.getBackend(), acir, initialWitness, {
       getSecretKey: ([ownerX], [ownerY]) => this.context.getSecretKey(this.contractAddress, ownerX, ownerY),
       getPublicKey: async ([acvmAddress]) => {
         const address = frToAztecAddress(fromACVMField(acvmAddress));

yarn-project/acir-simulator/src/public/executor.ts

@@ -25,6 +25,7 @@ import {
   toAcvmL1ToL2MessageLoadOracleInputs,
 } from '../acvm/index.js';
 import { oracleDebugCallToFormattedStr } from '../client/debug.js';
+import { AcirSimulator } from '../index.js';
 import { PackedArgsCache } from '../packed_args_cache.js';
 import { CommitmentsDB, PublicContractsDB, PublicStateDB } from './db.js';
 import { PublicExecution, PublicExecutionResult } from './execution.js';
@@ -71,7 +72,7 @@ export class PublicExecutor {
     // We use this cache to hold the packed arguments.
     const packedArgs = await PackedArgsCache.create([]);
 
-    const { partialWitness } = await acvm(acir, initialWitness, {
+    const { partialWitness } = await acvm(await AcirSimulator.getBackend(), acir, initialWitness, {
       packArguments: async args => {
         return toACVMField(await packedArgs.pack(args.map(fromACVMField)));
       },

yarn-project/yarn.lock

@@ -80,7 +80,7 @@ __metadata:
     "@rushstack/eslint-patch": ^1.1.4
     "@types/jest": ^29.5.0
     "@types/node": ^18.7.23
-    acvm_js: "github:noir-lang/acvm-simulator-wasm#b9d9ca9dfc5140839f23998d9466307215607c42"
+    acvm_js: "github:dbanks12/acvm-simulator-wasm#db/init-sim-backend"
     jest: ^29.5.0
     jest-mock-extended: ^3.0.4
     levelup: ^5.1.1
@@ -4018,10 +4018,10 @@ __metadata:
   languageName: node
   linkType: hard
 
-"acvm_js@github:noir-lang/acvm-simulator-wasm#b9d9ca9dfc5140839f23998d9466307215607c42":
-  version: 0.0.0-d576736
-  resolution: "acvm_js@https://github.com/noir-lang/acvm-simulator-wasm.git#commit=b9d9ca9dfc5140839f23998d9466307215607c42"
-  checksum: ea88c231451e7aeab2ecf4219c062d1193860c5bd782ea1b0d8f778990798a27ab983ae5036e2cb99248cb75d22d961d1dd4b9c1c8c0ce0215e955f00e07944f
+"acvm_js@github:dbanks12/acvm-simulator-wasm#db/init-sim-backend":
+  version: 0.21.0
+  resolution: "acvm_js@https://github.com/dbanks12/acvm-simulator-wasm.git#commit=15662eefb304eb79eb84497302da8ea83d6a7b63"
+  checksum: 3177d578421b65c164483f0ef2f83a74790df22b68b482116ce6880c1be096882ba1764caa25c182e642321df8346723e69fef8102fdb8fe54c7ffdcc7465058
   languageName: node
   linkType: hard