[js-perf-test] Performance benchmark for adding random BigInts

Bug: v8:9213
Change-Id: Iee04bfe25e37cfe639964f8ab31e6702d3750bfb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1645319
Commit-Queue: Nico Hartmann <nicohartmann@google.com>
Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62016}

test/js-perf-test/BigInt/add.js

@@ -9,9 +9,11 @@ load('bigint-util.js');
 const TEST_ITERATIONS = 1000;
 const SLOW_TEST_ITERATIONS = 50;
 const BITS_CASES = [32, 64, 128, 256, 512, 1024, 2048, 4096, 8192];
+const RANDOM_BIGINTS_MAX_BITS = 64 * 100;
 
 let initial_sum = 0n;
 let a = 0n;
+let random_bigints = [];
 
 // This dummy ensures that the feedback for benchmark.run() in the Measure
 // function from base.js is not monomorphic, thereby preventing the benchmarks
@@ -49,6 +51,12 @@ BITS_CASES.forEach((d) => {
 });
 
 
+new BenchmarkSuite('Add-Random', [1000], [
+  new Benchmark('Add-Random', true, false, 0, TestAddRandom,
+    SetUpTestAddRandom)
+]);
+
+
 function SetUpTestAddTypeError() {
   initial_sum = 42n;
 }
@@ -115,3 +123,25 @@ function TestAddDifferentSign() {
 
   return sum;
 }
+
+
+function SetUpTestAddRandom() {
+  random_bigints = [];
+  // RandomBigIntWithBits needs multiples of 4 bits.
+  const max_in_4bits = RANDOM_BIGINTS_MAX_BITS / 4;
+  for (let i = 0; i < TEST_ITERATIONS; ++i) {
+    const bits = Math.floor(Math.random() * max_in_4bits) * 4;
+    const bigint = RandomBigIntWithBits(bits);
+    random_bigints.push(Math.random() < 0.5 ? -bigint : bigint);
+  }
+}
+
+function TestAddRandom() {
+  let sum = 0n;
+
+  for (let i = 0; i < TEST_ITERATIONS; ++i) {
+    sum = random_bigints[i] + sum;
+  }
+
+  return sum;
+}

test/js-perf-test/BigInt/bigint-util.js

@@ -20,6 +20,7 @@ function SmallRandomBigIntWithBits(bits) {
     return 0n;
   }
 
+  // Make sure it does not start with four 0-bits.
   let s = "0x" + RandomHexDigit(false);
   bits -= 4;
   // Digits are at least 32 bits long, so we round down to the next smaller
@@ -44,3 +45,21 @@ function MaxBigIntWithBits(bits) {
   }
   return BigInt(s);
 }
+
+
+// Generates a random BigInt between 2^(bits-4) and 2^bits-1 (for bits > 0).
+function RandomBigIntWithBits(bits) {
+  console.assert(bits % 4 === 0);
+  if (bits <= 0) {
+    return 0n;
+  }
+
+  // Make sure it does not start with four 0-bits.
+  let s = "0x" + RandomHexDigit(false);
+  bits -= 4;
+  // Randomly generate remaining bits.
+  for (; bits > 0; bits -= 4) {
+    s += RandomHexDigit(true);
+  }
+  return BigInt(s);
+}

test/js-perf-test/JSTests1.json

@@ -78,7 +78,8 @@
         { "name": "Add-SameSign-4096" },
         { "name": "Add-DifferentSign-4096" },
         { "name": "Add-SameSign-8192" },
-        { "name": "Add-DifferentSign-8192" }
+        { "name": "Add-DifferentSign-8192" },
+        { "name": "Add-Random" }
     ]
     },
     {