Fix background compilation: allocate stubs at safepoint

runtime/vm/stub_code.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/stub_code.h"
 
 #include "platform/assert.h"
 #include "platform/globals.h"
 #include "vm/assembler.h"
+#include "vm/compiler.h"  // SafepointOperationScope.

[siva, 2016/02/17 21:07:49]

#include "vm/safepoint.h"

(SafepointOperationScope is defined here).

[srdjan, 2016/02/17 21:15:14]

Done.

 #include "vm/disassembler.h"
 #include "vm/flags.h"
 #include "vm/object_store.h"
 #include "vm/snapshot.h"
 #include "vm/virtual_memory.h"
 #include "vm/visitor.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool, disassemble_stubs, false, "Disassemble generated stubs.");
@@ skipping 93 matching lines @@
   const Error& error = Error::Handle(zone, cls.EnsureIsFinalized(thread));
   ASSERT(error.IsNull());
   if (cls.id() == kArrayCid) {
     return AllocateArray_entry()->code();
   }
   Code& stub = Code::Handle(zone, cls.allocation_stub());
   if (stub.IsNull()) {
     Assembler assembler;
     const char* name = cls.ToCString();
     StubCode::GenerateAllocationStubForClass(&assembler, cls);
-    stub ^= Code::FinalizeCode(name, &assembler, false /* optimized */);
-    stub.set_owner(cls);
-    cls.set_allocation_stub(stub);
+
+    if (thread->IsMutatorThread()) {
+      stub ^= Code::FinalizeCode(name, &assembler, false /* optimized */);
+      stub.set_owner(cls);
+      cls.set_allocation_stub(stub);
+    } else {
+      // This part of compilation must be at a safepoint.

[siva, 2016/02/17 21:07:49]

This part of stub code generation must be at a safepoint.

[srdjan, 2016/02/17 21:15:15]

Done.

+      // Stop mutator thread before creating the instruction object and
+      // installing code.
+      // Mutator thread may not run code while we are creating the
+      // instruction object, since the creation of instruction object
+      // changes code page access permissions (makes them temporary not
+      // executable).
+      {
+        SafepointOperationScope safepoint_scope(thread);
+        // Do not Garbage collect during this stage and instead allow the
+        // heap to grow.
+        NoHeapGrowthControlScope no_growth_control;
+        stub ^= Code::FinalizeCode(name, &assembler, false /* optimized */);
+        stub.set_owner(cls);
+        cls.set_allocation_stub(stub);
+      }
+      Isolate* isolate = thread->isolate();
+      if (isolate->heap()->NeedsGarbageCollection()) {
+        isolate->heap()->CollectAllGarbage();
+      }
+    }

[siva, 2016/02/17 21:07:49]

I am wondering if it makes sense to move this to Code::FinalizeCode instead of
repeating it twice here and in the compiler.

[srdjan, 2016/02/17 21:15:15]

The situations are not exactly identical. Leaving it as it is.

     if (FLAG_support_disassembler && FLAG_disassemble_stubs) {
       LogBlock lb;
       THR_Print("Code for allocation stub '%s': {\n", name);
 #ifndef PRODUCT
       DisassembleToStdout formatter;
       stub.Disassemble(&formatter);
 #endif
       THR_Print("}\n");
       const ObjectPool& object_pool = ObjectPool::Handle(stub.object_pool());
       object_pool.DebugPrint();
@@ skipping 43 matching lines @@
   if ((name##_entry() != NULL) &&                                              \
       (entry_point == name##_entry()->EntryPoint())) {                         \
     return ""#name;                                                            \
   }
   VM_STUB_CODE_LIST(VM_STUB_CODE_TESTER);
 #undef VM_STUB_CODE_TESTER
   return NULL;
 }
 
 }  // namespace dart