1 files changed, 17 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/cacheir/string-fromCharCode-double.js b/js/src/jit-test/tests/cacheir/string-fromCharCode-double.js
new file mode 100644
index 0000000000..4db1787148
--- /dev/null
+++ b/js/src/jit-test/tests/cacheir/string-fromCharCode-double.js
@@ -0,0 +1,17 @@
+// Test inlining String.fromCharCode with Double instead of Int32 inputs.
+
+function test() {
+  for (let i = 0; i < 0xffff; ++i) {
+    let expected = String.fromCharCode(i);
+
+    // Ensure the Double input is truncated to Int32.
+    assertEq(String.fromCharCode(i + 0.5), expected);
+
+    // The input is converted using ToUint16. 
+    assertEq(String.fromCharCode(i + 0.5 + 0x10_000), expected);
+
+    // Test ToUint16 conversion when adding INT32_MAX + 1.
+    assertEq(String.fromCharCode(i + 0x8000_0000), expected);
+  }
+}
+for (let i = 0; i < 2; ++i) test();