Lazy deopt:

runtime/vm/code_generator.cc

 // Copyright (c) 2013, 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/code_generator.h"
 
 #include "vm/assembler.h"
 #include "vm/ast.h"
 #include "vm/code_patcher.h"
 #include "vm/compiler.h"
@@ skipping 2021 matching lines @@
     for (intptr_t i = 0; i < handlers.num_entries(); ++i) {
       handlers.GetHandlerInfo(i, &info);
       const uword patch_pc = instrs.PayloadStart() + info.handler_pc_offset;
       CodePatcher::InsertDeoptimizationCallAt(patch_pc);
       if (FLAG_trace_patching) {
         OS::PrintErr("  at handler 0x%" Px "\n", patch_pc);
       }
     }
   }
 #else  // !DBC
-  uword lazy_deopt_entry =
-      StubCode::DeoptimizeLazyFromReturn_entry()->EntryPoint();
-  if (frame->pc() == lazy_deopt_entry) {
+  if (frame->IsMarkedForLazyDeopt()) {
     // Deopt already scheduled.
     if (FLAG_trace_deoptimization) {
       THR_Print("Lazy deopt already scheduled for fp=%" Pp "\n", frame->fp());
     }
   } else {
     uword deopt_pc = frame->pc();
     ASSERT(optimized_code.ContainsInstructionAt(deopt_pc));
+
+    // N.B.: Update the pending deopt table before updating the frame. The
+    // profiler may attempt a stack walk in between.
+    MallocGrowableArray<PendingLazyDeopt>* pending_deopts =
+        thread->isolate()->pending_deopts();
+    for (intptr_t i = 0; i < pending_deopts->length(); i++) {
+      ASSERT((*pending_deopts)[i].fp() != frame->fp());
+    }
     PendingLazyDeopt pair(frame->fp(), deopt_pc);
-    thread->isolate()->pending_deopts()->Add(pair);
-    frame->set_pc(lazy_deopt_entry);
+    pending_deopts->Add(pair);
+
+#if defined(DEBUG)
+    ValidateFrames();
+#endif
+
+    frame->MarkForLazyDeopt();
 
     if (FLAG_trace_deoptimization) {
       THR_Print("Lazy deopt scheduled for fp=%" Pp ", pc=%" Pp "\n",
                 frame->fp(), deopt_pc);
     }
   }
 #endif  // !DBC
 
   // Mark code as dead (do not GC its embedded objects).
   optimized_code.set_is_alive(false);
@@ skipping 88 matching lines @@
        function.ToFullyQualifiedCString(),
        deoptimizing_code ? "code & frame" : "frame",
        is_lazy_deopt ? "lazy-deopt" : "");
   }
 
 #if !defined(TARGET_ARCH_DBC)
   if (is_lazy_deopt) {
     uword deopt_pc = 0;
     MallocGrowableArray<PendingLazyDeopt>* pending_deopts =
         isolate->pending_deopts();
-    for (intptr_t i = pending_deopts->length() - 1; i >= 0; i--) {
+    for (intptr_t i = 0; i < pending_deopts->length(); i++) {
       if ((*pending_deopts)[i].fp() == caller_frame->fp()) {
         deopt_pc = (*pending_deopts)[i].pc();
         break;
       }
     }
+#if defined(DEBUG)
+    // Check for conflicting entries.
+    for (intptr_t i = 0; i < pending_deopts->length(); i++) {
+      if ((*pending_deopts)[i].fp() == caller_frame->fp()) {
+        ASSERT((*pending_deopts)[i].pc() == deopt_pc);
+      }
+    }
+#endif
+    if (FLAG_trace_deoptimization) {
+      THR_Print("Lazy deopt fp=%" Pp " pc=%" Pp "\n",
+                caller_frame->fp(), deopt_pc);
+    }
+    ASSERT(deopt_pc != 0);
+
+    // N.B.: Update frame before updating pending deopt table. The profiler
+    // may attempt a stack walk in between.
+    caller_frame->set_pc(deopt_pc);
+    ASSERT(caller_frame->pc() == deopt_pc);
+    ASSERT(optimized_code.ContainsInstructionAt(caller_frame->pc()));
+
     for (intptr_t i = pending_deopts->length() - 1; i >= 0; i--) {
       if ((*pending_deopts)[i].fp() <= caller_frame->fp()) {
         pending_deopts->RemoveAt(i);
       }
     }
-    if (FLAG_trace_deoptimization) {
-      THR_Print("Lazy deopt fp=%" Pp " pc=%" Pp "\n",
-                caller_frame->fp(), deopt_pc);
-      THR_Print("%" Pd " pending lazy deopts\n",
-                pending_deopts->length());
-    }
-    ASSERT(deopt_pc != 0);
-    caller_frame->set_pc(deopt_pc);
-    ASSERT(caller_frame->pc() == deopt_pc);
-    ASSERT(optimized_code.ContainsInstructionAt(caller_frame->pc()));
   } else {
     if (FLAG_trace_deoptimization) {
       THR_Print("Eager deopt fp=%" Pp " pc=%" Pp "\n",
                 caller_frame->fp(), caller_frame->pc());
     }
   }
 #endif  // !DBC
 
   // Copy the saved registers from the stack.
   fpu_register_t* fpu_registers;
@@ skipping 67 matching lines @@
 // Returns number of bytes to remove from the expression stack of the
 // bottom-most deoptimized frame. Those arguments were artificially injected
 // under return address to keep them discoverable by GC that can occur during
 // materialization phase.
 DEFINE_RUNTIME_ENTRY(DeoptimizeMaterialize, 0) {
 #if !defined(DART_PRECOMPILED_RUNTIME)
 #if defined(DEBUG)
   {
     // We may rendezvous for a safepoint at entry or GC from the allocations
     // below. Check the stack is walkable.
-    StackFrameIterator frames_iterator(StackFrameIterator::kValidateFrames);
-    StackFrame* frame = frames_iterator.NextFrame();
-    while (frame != NULL) {
-      frame = frames_iterator.NextFrame();
-    }
+    ValidateFrames();
   }
 #endif
   DeoptContext* deopt_context = isolate->deopt_context();
   intptr_t deopt_arg_count = deopt_context->MaterializeDeferredObjects();
   isolate->set_deopt_context(NULL);
   delete deopt_context;
 
   // Return value tells deoptimization stub to remove the given number of bytes
   // from the stack.
   arguments.SetReturn(Smi::Handle(Smi::New(deopt_arg_count * kWordSize)));
@@ skipping 70 matching lines @@
   const intptr_t elm_size = old_data.ElementSizeInBytes();
   const TypedData& new_data =
       TypedData::Handle(TypedData::New(cid, new_size, Heap::kOld));
   TypedData::Copy(new_data, 0, old_data, 0, old_size * elm_size);
   typed_data_cell.SetAt(0, new_data);
   arguments.SetReturn(new_data);
 }
 
 
 }  // namespace dart