1 files changed, 43 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/warp/scalar-replace-array-apply-array.js b/js/src/jit-test/tests/warp/scalar-replace-array-apply-array.js
new file mode 100644
index 0000000000..7b8d12bd06
--- /dev/null
+++ b/js/src/jit-test/tests/warp/scalar-replace-array-apply-array.js
@@ -0,0 +1,43 @@
+// |jit-test| --fast-warmup; --no-threads
+
+setJitCompilerOption("baseline.warmup.trigger", 0);
+setJitCompilerOption("ion.warmup.trigger", 100);
+
+// Prevent GC from cancelling/discarding Ion compilations.
+gczeal(0);
+
+// Create a fresh set of functions for each argument count to avoid type pollution.
+function makeTest(count) {
+  var args = Array(count).fill(0).join(",");
+
+  return Function(`
+    function g() {
+      return arguments.length;
+    }
+
+    function f(...args) {
+      // When |f| is inlined into its caller, the number of arguments is fixed and
+      // we can scalar replace the inlined rest array.
+      assertRecoveredOnBailout(args, true);
+      return g(...args);
+    }
+
+    // |f| must be small enough to be inlined into the test function.
+    assertEq(isSmallFunction(f), true);
+
+    function test() {
+      for (let i = 0; i < 1000; ++i) {
+        assertEq(f(${args}), ${count});
+      }
+    }
+
+    return test;
+  `)();
+}
+
+// Limited by gc::CanUseFixedElementsForArray(), see also WarpBuilder::build_Rest().
+const maxRestArgs = 14;
+
+for (let i = 0; i <= maxRestArgs; ++i) {
+  makeTest(i)();
+}