Allow a ParseInfo without a script for %SetCode users

src/runtime/runtime-function.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/runtime/runtime-utils.h"
 
 #include "src/accessors.h"
 #include "src/arguments.h"
 #include "src/compiler.h"
 #include "src/frames-inl.h"
@@ skipping 152 matching lines @@
 RUNTIME_FUNCTION(Runtime_SetCode) {
   HandleScope scope(isolate);
   DCHECK_EQ(2, args.length());
 
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, target, 0);
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, source, 1);
 
   Handle<SharedFunctionInfo> target_shared(target->shared());
   Handle<SharedFunctionInfo> source_shared(source->shared());
 
+  if (FLAG_mark_shared_functions_for_tier_up) {
+    // During bootstrapping with stress-opt, it can happen that we've
+    // marked some builtin code for optimization. Defeat this, as
+    // that optimization attempt may fail on code without a script
+    // (all the %SetCode usages are like this).
+    source_shared->set_marked_for_tier_up(false);
+  }

[Leszek Swirski, 2017/02/09 13:22:33]

Hm, I'm not sure I like your solution here -- for one, it doesn't solve the
problem that the second %SetCode will clear the script of the target function,
so optimising the target function will also fail. Currently this happens to not
happen, but if the target function happened to get hot while in stress opt, it
could, and some other poor soul will have to spend the day debugging this.

+
   if (!Compiler::Compile(source, Compiler::KEEP_EXCEPTION)) {
     return isolate->heap()->exception();
   }
 
   // Mark both, the source and the target, as un-flushable because the
   // shared unoptimized code makes them impossible to enqueue in a list.
   DCHECK(target_shared->code()->gc_metadata() == NULL);
   DCHECK(source_shared->code()->gc_metadata() == NULL);
   target_shared->set_dont_flush(true);
   source_shared->set_dont_flush(true);
@@ skipping 124 matching lines @@
   DCHECK_EQ(1, args.length());
   CONVERT_ARG_HANDLE_CHECKED(JSReceiver, function, 0);
   return function->IsJSBoundFunction()
              ? *JSBoundFunction::ToString(
                    Handle<JSBoundFunction>::cast(function))
              : *JSFunction::ToString(Handle<JSFunction>::cast(function));
 }
 
 }  // namespace internal
 }  // namespace v8