1 files changed, 75 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/parser/stencil-eager-delazify.js b/js/src/jit-test/tests/parser/stencil-eager-delazify.js
new file mode 100644
index 0000000000..d638b16e78
--- /dev/null
+++ b/js/src/jit-test/tests/parser/stencil-eager-delazify.js
@@ -0,0 +1,75 @@
+// |jit-test| skip-if: helperThreadCount() === 0 || isLcovEnabled()
+
+// Extra GCs can empty the StencilCache to reclaim memory. This lines
+// re-configure the gc-zeal setting to prevent this from happening in this test
+// case which waits for the cache to contain some entry.
+if ('gczeal' in this)
+  gczeal(0);
+
+let u = 0;
+
+// At each function, create `width` inner functions.
+let width = 2;
+// Depth of inner functions.
+let depth = 4;
+// Number of additional parser & delazification workload running concurrently
+// with the one we are attempting to measure, such that we can see differences
+// in the report of `isInStencilCache`.
+let load = 14;
+
+// Return the number of function generated by a to `depthFirstExec` given the
+// same parameters.
+function count(w, d) {
+  return (Math.pow(w, d + 1) - 1) / (w - 1);
+}
+
+// Generate a source code with a large number of inner functions, such that
+// eager delazification can be observe while running JS code concurrently.
+function depthFirstExec(indent, name, w, d) {
+  let fun = `${indent}function ${name} (arg) {\n`;
+  let inner = "";
+  let val = `arg + isInStencilCache(${name})`;
+  if (d > 0) {
+    for (let i = 0; i < w; i++) {
+      inner += depthFirstExec(`${indent}  `, `${name}_${i}`, w, d - 1);
+      val = `${name}_${i}(${val})`;
+    }
+  }
+  fun += inner;
+  fun += `${indent}  return ${u} + ${val} - ${u};\n`;
+  fun += `${indent}}\n`;
+  u += 1;
+  return fun;
+};
+
+const options = {
+  fileName: "depthFirstExec.js",
+  lineNumber: 1,
+  eagerDelazificationStrategy: "ConcurrentDepthFirst",
+};
+let script = depthFirstExec("", "raceMe", width, depth);
+
+let jobs = [];
+for (let i = 0; i < load; i++) {
+  // Spin up extra compilation workload...
+  jobs.push(offThreadCompileToStencil(script, options));
+}
+
+const stencil = finishOffThreadStencil(jobs[0]);
+evalStencil(stencil, options);
+
+waitForStencilCache(raceMe);
+let start = raceMe(0);
+let mid = raceMe(0);
+let end = raceMe(0);
+
+// The garbage collector should clear the cache and suppress all delazification
+// tasks.
+gc();
+let afterGc = raceMe(0);
+
+assertEq(1 <= start, true);
+assertEq(start <= mid, true);
+assertEq(mid <= end, true);
+assertEq(end <= count(width, depth), true);
+assertEq(afterGc, 0);