Bug 1330373 - Capture JSScript::lazyScript field when encoding bytecode incrementally. r=shu

js/src/frontend/BytecodeCompiler.cpp

@@ -712,13 +712,6 @@ frontend::CompileLazyFunction(JSContext* cx, Handle<LazyScript*> lazy, const cha
     if (!NameFunctions(cx, pn))
         return false;
 
-    // XDR the newly delazified function.
-    if (script->scriptSource()->hasEncoder() &&
-        !script->scriptSource()->xdrEncodeFunction(cx, fun, sourceObject))
-    {
-        return false;
-    }
-
     return true;
 }
 

js/src/jit-test/tests/xdr/relazify.js

@@ -0,0 +1,29 @@
+load(libdir + 'bytecode-cache.js');
+var test = "";
+gczeal(0);
+
+// Check that a GC can relazify decoded functions.
+//
+// Generations 0 and 3 are executed from the source, thus f is not executed yet.
+// Generations 1 and 2 are decoded, thus we recorded the delazified f function.
+test = `
+  function f() { return 1; };
+  assertEq(isLazyFunction(f), generation == 0 || generation == 3);
+  f();
+  expect = isRelazifiableFunction(f);
+  assertEq(isLazyFunction(f), false);
+`;
+evalWithCache(test, {
+  checkAfter: function (ctx) {
+    gc(ctx.global.f, "shrinking"); // relazify f, if possible.
+    evaluate("assertEq(isLazyFunction(f), expect);", ctx);
+  }
+});
+
+evalWithCache(test, {
+  incremental: true,
+  checkAfter: function (ctx) {
+    gc(ctx.global.f, "shrinking"); // relazify f, if possible.
+    evaluate("assertEq(isLazyFunction(f), expect);", ctx);
+  }
+});

js/src/jsfun.cpp

@@ -1567,6 +1567,14 @@ JSFunction::createScriptForLazilyInterpretedFunction(JSContext* cx, HandleFuncti
             // Only functions without inner functions are re-lazified.
             script->setLazyScript(lazy);
         }
+
+        // XDR the newly delazified function.
+        if (script->scriptSource()->hasEncoder()) {
+            RootedScriptSource sourceObject(cx, lazy->sourceObject());
+            if (!script->scriptSource()->xdrEncodeFunction(cx, fun, sourceObject))
+                return false;
+        }
+
         return true;
     }