Restore back pointer from Instructions to Code

runtime/vm/object.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/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/cpu.h"
@@ skipping 13031 matching lines @@
   intptr_t pointer_offset_count = assembler->CountPointerOffsets();
   Code& code = Code::ZoneHandle(Code::New(pointer_offset_count));
 #ifdef TARGET_ARCH_IA32
   assembler->set_code_object(code);
 #endif
   Instructions& instrs =
       Instructions::ZoneHandle(Instructions::New(assembler->CodeSize()));
   INC_STAT(Thread::Current(), total_instr_size, assembler->CodeSize());
   INC_STAT(Thread::Current(), total_code_size, assembler->CodeSize());
 
+  // TODO(johnmccutchan): Protect this behind precompilation flag.

[rmacnak, 2015/09/29 16:50:12]

This is safe. Reading is the problem.

+  instrs.set_code(code.raw());
   // Copy the instructions into the instruction area and apply all fixups.
   // Embedded pointers are still in handles at this point.
   MemoryRegion region(reinterpret_cast<void*>(instrs.EntryPoint()),
                       instrs.size());
   assembler->FinalizeInstructions(region);
   VerifiedMemory::Accept(region.start(), region.size());
   CPU::FlushICache(instrs.EntryPoint(), instrs.size());
 
   code.set_compile_timestamp(OS::GetCurrentTimeMicros());
   CodeObservers::NotifyAll(name,
@@ skipping 61 matching lines @@
     return FinalizeCode(function.ToLibNamePrefixedQualifiedCString(),
                         assembler,
                         optimized);
   } else {
     return FinalizeCode("", assembler);
   }
 }
 
 
 // Check if object matches find condition.
-bool Code::FindRawCodeVisitor::FindObject(RawObject* obj) const {
-  return RawCode::ContainsPC(obj, pc_);
+bool Code::FindRawCodeVisitor::FindObject(RawObject* raw_obj) const {
+  uword tags = raw_obj->ptr()->tags_;
+  if (RawObject::ClassIdTag::decode(tags) == kInstructionsCid) {
+    RawInstructions* raw_insts = reinterpret_cast<RawInstructions*>(raw_obj);
+    return RawInstructions::ContainsPC(raw_insts, pc_);
+  }
+  return false;
 }
 
 
 RawCode* Code::LookupCodeInIsolate(Isolate* isolate, uword pc) {
   ASSERT((isolate == Isolate::Current()) || (isolate == Dart::vm_isolate()));

[rmacnak, 2015/09/29 16:50:12]

if (Dart::IsRunningPrecompiledCode()) {
  // Fall back to checked-in path or return null and TODO.
}

[Cutch, 2015/09/29 23:24:29]

Done.

   NoSafepointScope no_safepoint;
   FindRawCodeVisitor visitor(pc);
-  RawObject* instr;
+  RawInstructions* instr;
   if (isolate->heap() == NULL) {
     return Code::null();
   }
-  instr = isolate->heap()->FindOldObject(&visitor);
-  if (instr != Code::null()) {
-    return static_cast<RawCode*>(instr);
+  instr = isolate->heap()->FindObjectInCodeSpace(&visitor);
+  if (instr != Instructions::null()) {
+    return instr->ptr()->code_;

[rmacnak, 2015/09/29 16:50:12]

instr->code() for ASSERT

[Cutch, 2015/09/29 23:24:29]

Done.

   }
   return Code::null();
 }
 
 
 RawCode* Code::LookupCode(uword pc) {
   return LookupCodeInIsolate(Isolate::Current(), pc);
 }
 
 
@@ skipping 8305 matching lines @@
   return tag_label.ToCString();
 }
 
 
 void UserTag::PrintJSONImpl(JSONStream* stream, bool ref) const {
   Instance::PrintJSONImpl(stream, ref);
 }
 
 
 }  // namespace dart