test: improve performance of test-crypto-timing-safe-equal-benchmarks

Using `eval()` rather than `require()`'ing a fixture and deleting it
from the cache results in a roughtly 10x improvement in running time.

Fixes: #25984
Refs: #26229

PR-URL: #26237
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Yang Guo <yangguo@chromium.org>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>

Author: Trott

test/fixtures/crypto-timing-safe-equal-benchmark-func.js

@@ -6,21 +6,24 @@ if (!common.hasCrypto)
 if (!common.enoughTestMem)
   common.skip('memory-intensive test');
 
-const fixtures = require('../common/fixtures');
 const assert = require('assert');
 const crypto = require('crypto');
 
-const BENCHMARK_FUNC_PATH =
-  `${fixtures.fixturesDir}/crypto-timing-safe-equal-benchmark-func`;
-function runOneBenchmark(...args) {
-  const benchmarkFunc = require(BENCHMARK_FUNC_PATH);
-  const result = benchmarkFunc(...args);
-
-  // Don't let the comparison function get cached. This avoid a timing
-  // inconsistency due to V8 optimization where the function would take
-  // less time when called with a specific set of parameters.
-  delete require.cache[require.resolve(BENCHMARK_FUNC_PATH)];
-  return result;
+function runOneBenchmark(compareFunc, firstBufFill, secondBufFill, bufSize) {
+  return eval(`
+      const firstBuffer = Buffer.alloc(bufSize, firstBufFill);
+      const secondBuffer = Buffer.alloc(bufSize, secondBufFill);
+
+      const startTime = process.hrtime();
+      const result = compareFunc(firstBuffer, secondBuffer);
+      const endTime = process.hrtime(startTime);
+
+      // Ensure that the result of the function call gets used, so it doesn't
+      // get discarded due to engine optimizations.
+      assert.strictEqual(result, firstBufFill === secondBufFill);
+
+      endTime[0] * 1e9 + endTime[1];
+    `);
 }
 
 function getTValue(compareFunc) {