1 files changed, 34 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/gc/helper-thread-params.js b/js/src/jit-test/tests/gc/helper-thread-params.js
new file mode 100644
index 0000000000..282ea82a54
--- /dev/null
+++ b/js/src/jit-test/tests/gc/helper-thread-params.js
@@ -0,0 +1,34 @@
+// |jit-test| skip-if: helperThreadCount() === 0
+
+function assertError(thunk) {
+  let threw = false;
+  try {
+    thunk();
+  } catch (e) {
+    threw = true;
+  }
+  assertEq(threw, true);
+}
+
+let initialHelperThreads = helperThreadCount();
+
+// Test that setting maxHelperThreads limits the number of threads.
+gcparam("helperThreadRatio", 100);
+for (let i = 1; i <= initialHelperThreads; i++) {
+  gcparam("maxHelperThreads", i);
+  assertEq(gcparam("helperThreadCount"), i);
+}
+
+// Test that setting helperThreadRatio works as expected.
+gcparam("maxHelperThreads", 1000);
+for (let i = 25; i <= 400; i *= 2) {
+  gcparam("helperThreadRatio", i);
+  let ratio = i / 100;
+  let expected = Math.max(Math.floor(initialHelperThreads * ratio), 1);
+  assertEq(gcparam("helperThreadCount"), expected);
+  assertEq(helperThreadCount(), Math.max(initialHelperThreads, expected));
+}
+
+// Test that illegal settings are checked.
+assertError(() => gcparam("helperThreadRatio", 0));
+assertError(() => gcparam("maxHelperThreads", 0));