Precompilation: don't include an object header for instructions in the text section.

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index b0b4f4f57626a1215ed5c10b2efe8bfe7834c7d5..e69817737dc05d81b1188c6eaacddbd454fead3b 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -12972,6 +12972,26 @@ void Code::set_static_calls_target_table(const Array& value) const {
 }
 
 
+uword Code::EntryPoint() const {
+  RawObject* instr = instructions();
+  if (!instr->IsHeapObject()) {
+    return active_entry_point();
+  } else {
+    return Instructions::EntryPoint(instructions());
+  }
+}
+
+
+intptr_t Code::Size() const {
+  RawObject* instr = instructions();
+  if (!instr->IsHeapObject()) {
+    return Smi::Value(raw_ptr()->precompiled_instructions_size_);
+  } else {
+    return instructions()->ptr()->size_;
+  }
+}
+
+
 bool Code::HasBreakpoint() const {
   if (!FLAG_support_debugger) {
     return false;
@@ -13317,10 +13337,13 @@ RawCode* Code::FinalizeCode(const char* name,
     }
 
     // Hook up Code and Instructions objects.
-    code.SetActiveInstructions(instrs.raw());
     code.set_instructions(instrs.raw());
+    code.SetActiveInstructions(instrs.raw());
     code.set_is_alive(true);
 
+    ASSERT(code.EntryPoint() == instrs.EntryPoint());
+    ASSERT(code.Size() == instrs.size());
+
     // Set object pool in Instructions object.
     INC_STAT(Thread::Current(),
              total_code_size, object_pool.Length() * sizeof(uintptr_t));
@@ -13518,9 +13541,10 @@ bool Code::IsFunctionCode() const {
 void Code::DisableDartCode() const {
   DEBUG_ASSERT(IsMutatorOrAtSafepoint());
   ASSERT(IsFunctionCode());
-  ASSERT(instructions() == active_instructions());
+  ASSERT(!IsDisabled());
   const Code& new_code =
       Code::Handle(StubCode::FixCallersTarget_entry()->code());
+  ASSERT(new_code.instructions()->IsVMHeapObject());
   SetActiveInstructions(new_code.instructions());
 }
 
@@ -13528,9 +13552,10 @@ void Code::DisableDartCode() const {
 void Code::DisableStubCode() const {
   ASSERT(Thread::Current()->IsMutatorThread());
   ASSERT(IsAllocationStubCode());
-  ASSERT(instructions() == active_instructions());
+  ASSERT(!IsDisabled());
   const Code& new_code =
       Code::Handle(StubCode::FixAllocationStubTarget_entry()->code());
+  ASSERT(new_code.instructions()->IsVMHeapObject());
   SetActiveInstructions(new_code.instructions());
 }
 
@@ -13539,7 +13564,6 @@ void Code::SetActiveInstructions(RawInstructions* instructions) const {
   DEBUG_ASSERT(IsMutatorOrAtSafepoint() || !is_alive());
   // RawInstructions are never allocated in New space and hence a
   // store buffer update is not needed here.
-  StorePointer(&raw_ptr()->active_instructions_, instructions);
   StoreNonPointer(&raw_ptr()->entry_point_,
                   reinterpret_cast<uword>(instructions->ptr()) +
                   Instructions::HeaderSize());