1 files changed, 82 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/warp/guard-specific-atom-with-short-atom.js b/js/src/jit-test/tests/warp/guard-specific-atom-with-short-atom.js
new file mode 100644
index 0000000000..84be75fbfd
--- /dev/null
+++ b/js/src/jit-test/tests/warp/guard-specific-atom-with-short-atom.js
@@ -0,0 +1,82 @@
+// Test case to cover constant atom guards.
+//
+// GuardSpecificAtom for short (≤32 characters) constant atoms is optimised.
+
+function* characters(...ranges) {
+  for (let [start, end] of ranges) {
+    for (let i = start; i <= end; ++i) {
+      yield i;
+    }
+  }
+}
+
+const ascii = [...characters(
+  [0x41, 0x5A], // A..Z
+  [0x61, 0x7A], // a..z
+  [0x30, 0x39], // 0..9
+)];
+
+const latin1 = [...characters(
+  [0xC0, 0xFF], // À..ÿ
+)];
+
+const twoByte = [...characters(
+  [0x100, 0x17E], // Ā..ž
+)];
+
+function toRope(s) {
+  try {
+    return newRope(s[0], s.substring(1));
+  } catch {}
+  // newRope can fail when |s| fits into an inline string. In that case simply
+  // return the input.
+  return s;
+}
+
+function atomize(s) {
+  return Object.keys({[s]: 0})[0];
+}
+
+for (let i = 1; i <= 32; ++i) {
+  let strings = [ascii, latin1, twoByte].flatMap(codePoints => [
+    // Same string as the input.
+    String.fromCodePoint(...codePoints.slice(0, i)),
+
+    // Same length as the input, but a different string.
+    String.fromCodePoint(...codePoints.slice(1, i + 1)),
+
+    // Shorter string than the input.
+    String.fromCodePoint(...codePoints.slice(0, i - 1)),
+
+    // Longer string than the input.
+    String.fromCodePoint(...codePoints.slice(0, i + 1)),
+  ]).flatMap(x => [
+    x,
+    toRope(x),
+    newString(x, {twoByte: true}),
+    atomize(x),
+  ]);
+
+  // Must be small enough to transition to megamorphic ICs.
+  const stringsPerLoop = 4;
+
+  for (let codePoints of [ascii, latin1, twoByte]) {
+    let str = String.fromCodePoint(...codePoints.slice(0, i));
+
+    for (let i = 0; i < strings.length; i += stringsPerLoop) {
+      let fn = Function("strings", `
+        var obj = {["${str}"]: 0};
+
+        for (let i = 0; i < 250; ++i) {
+          let idx = i % strings.length;
+          let str = strings[idx];
+      
+          let actual = str in obj;
+          let expected = str === "${str}";
+          if (actual !== expected) throw new Error();
+        }
+      `);
+      fn(strings.slice(i, stringsPerLoop));
+    }
+  }
+}